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SLS / Orion / Beyond-LEO HSF - Constellation => Missions To The Moon (HSF) => Topic started by: edkyle99 on 07/20/2018 03:29 pm

Title: Lunar Gateway Debate
Post by: edkyle99 on 07/20/2018 03:29 pm
Time has a balanced article discussing the pluses and minuses of the Lunar Gateway, including an interesting part about the orbital dynamics issue.  I'm still not sure what to think about the subject.  It does seem to me that a station of some type would more readily allow commercial and international cooperation.   
http://time.com/5342743/nasa-moon-mars/

 - Ed Kyle
Title: Re: Lunar Gateway Debate
Post by: Eric Hedman on 07/20/2018 07:49 pm
It looks like the author is unaware of the changes to the design done with ISECG to bring in the international partners to add additional modules, added complexity, added delays and added cost to the LOP-G station.  No mention of the shrinking PPE and the new Esprit module, the US Utilization element, the international partner supplied habitation module, the US supplied habitation module, the now indeterminate sourced air lock, logistics modules.  All shown as the latest config from MSFC's roadshow presentation:

https://www.youtube.com/watch?v=KBa26DqcH24&feature=youtu.be&t=834 (https://www.youtube.com/watch?v=KBa26DqcH24&feature=youtu.be&t=834)
Title: Re: Lunar Gateway Debate
Post by: tesla66 on 07/20/2018 08:56 pm
I’m an on the fence, leaning towards liking the Gateway skeptic. I really like the idea of the Gateway (LOP-G is a terrible name) as a useful political solution. SLS/Orion is a big scary monster that will be here to stay for the foreseeable future, the ISS partnerships seem fruitful, and any kind of direct ‘journey to mars’ seems like pie in the sky for now. My biggest question about the Gateway is will it be within the serviceable capability of the current, or near term upgradable range, commercial supply fleet? Are current EELV class and upcoming medium-heavy launchers (Vulcan, FH, NG) capable of reaching and delivering useful mass or payloads to this thing?
Title: Re: Lunar Gateway Debate
Post by: Steve G on 07/20/2018 09:15 pm
If it gets us out of LEO, then do it. Just do it.
Title: Re: Lunar Gateway Debate
Post by: TripleSeven on 07/20/2018 09:32 pm
the least useful comparison of the gateway are comparisons to the current station.

The space station is in all respects a failure.  Go back to the 80's and see all the promises made for the station.  From the cost and years to complete it, to what it would do from an international standpoint, to what it would accomplish "period" nothing has been accurate.  Nothing

it is possible that changes in policy could make the ISS useful, but so far these changes are slow in coming and yet the station consumes at least 3 billion dollars a year...and does "nothing" of value that exceeds the cost of doing it

the "gateway" will exactly the same trap, because in the end the same mistakes will be made...the difference is that instead of permanently crewed, it will only have "guest" every so often, who might as well be as far from the moon as ISS is

And at BEST building it will take a decade after SLS starts flying, whenever that is

as long as we do the same thing, the same way, with the same methods...it doesnt matter where we do it
Title: Re: Lunar Gateway Debate
Post by: edkyle99 on 07/21/2018 03:25 am
the least useful comparison of the gateway are comparisons to the current station.

The space station is in all respects a failure. 
I see it as an astonishing success.  What began as a Cold War idea has ended up serving as a giant commercial space incubator.  (Consider this.  If no ISS, there would be no Dragon and no SpaceX as we know it.)  The international co-operation, getting all of those pieces to fit together, literally and figuratively, all of those delicate rendezvous, those spacewalks, all of that dozens of tonnes of refueling, parts joined the first and only time in space, people spending literally years of their lives in orbit, in the face of multiple giant setbacks, budget cuts, and disasters, makes my head spin.  Launches, too many of them, have failed.  People, too many of them, have died.  Governments and giant companies have collapsed.  Friends have become not so friendly.  But ISS has continued.  People working together all over the world and in space have risen above all of it to achieve something magnificent. 

ISS is one of humanity's greatest achievements.

 - Ed Kyle 
Title: Re: Lunar Gateway Debate
Post by: QuantumG on 07/21/2018 04:25 am
Consider this.  If no ISS, there would be no Dragon and no SpaceX as we know it

Yeah, it might actually have carried a crew by now and SpaceX might be about human spaceflight.
Title: Re: Lunar Gateway Debate
Post by: FinalFrontier on 07/21/2018 05:06 am
A station in Lunar Orbit seems worthless for a variety of reasons.

If you are going to do an international outpost at the moon do it on the surface. Perfect opportunity to develop and test surface habitats and ISRU technologies before heading to Mars. Better yet you can also always commercially develop real-estate/habitats on the moon and sell them. Crazy as that idea sounds I could see in the not so distant future quite a few people with moderate wealth wanting to live there. Wouldn't be that hard, IMO to develop significant colonies/communities on the moon. They would however, most likely not be self sustaining. The Moon lacks too many things including decent gravity.

This is not an issue however given the relatively *short* distance between Earth and the Moon.

International surface station with commercial partners? Sure do it. Lunar orbital gateway thing with no real purpose or actual value for deep space exploration? Waste of time and money and further delays meaningful activity on Mars.

And right now what is planned is the second one unfortunately which makes it all the more likely it never gets done. That and being totally unfunded of course.
Title: Re: Lunar Gateway Debate
Post by: MATTBLAK on 07/21/2018 05:21 am
A 'Lunar Gateway' would only be a 'success' or useful if it included a small/medium propellant depot for a reusable, crewed Lander that was based there. And because of the Lander; it would have to have the right orbit to allow good access and coverage to much of the Lunar surface for useful periods of time - could someone nail down for me/us what type of orbit that would be?

Without a Lander based there, I'd say the Gateway serves little purpose...
Title: Re: Lunar Gateway Debate
Post by: Steven Pietrobon on 07/21/2018 08:07 am
I was surprised by this part of the article.

“We’re working to have astronauts on the moon by the mid-2020s–probably the 2025-to-2026 time frame,” says Bill Gerstenmaier, NASA’s associate administrator for human exploration and operations.

Not sure if that is possible when it has taken something like 14.5 years for Orion so far and we got another 5 years before crew will fly!

I'm in the camp where I see LOP-G as a waste of time and money. Where is the cost-benefit analysis that shows that LOP-G decreases the cost of going to the Moon? Does a reusable lander operating from LOP-G make economic sense?
Title: Re: Lunar Gateway Debate
Post by: TrevorMonty on 07/21/2018 09:36 am
Moon direct would be cheaper than via Gateway, but money is not there for such large project. The last two projects ended with nothing to show for it except half built Orion capsule.

The gateway is achievable, even if that is all that happens this time round we'll be 3.5km/s closer to moon. Next attempt will only need to develop HW to complete the last 2.5km/s.

Best hope this time around is small robotic missions and commercial extraction of lunar water. Then access to surface becomes lot cheaper.
Title: Re: Lunar Gateway Debate
Post by: TripleSeven on 07/21/2018 09:49 am
the least useful comparison of the gateway are comparisons to the current station.

The space station is in all respects a failure. 
I see it as an astonishing success.  What began as a Cold War idea has ended up serving as a giant commercial space incubator.  (Consider this.  If no ISS, there would be no Dragon and no SpaceX as we know it.)  The international co-operation, getting all of those pieces to fit together, literally and figuratively, all of those delicate rendezvous, those spacewalks, all of that dozens of tonnes of refueling, parts joined the first and only time in space, people spending literally years of their lives in orbit, in the face of multiple giant setbacks, budget cuts, and disasters, makes my head spin.  Launches, too many of them, have failed.  People, too many of them, have died.  Governments and giant companies have collapsed.  Friends have become not so friendly.  But ISS has continued.  People working together all over the world and in space have risen above all of it to achieve something magnificent. 

ISS is one of humanity's greatest achievements.

 - Ed Kyle
 

I think it CAN be if appropriate policy changes are made in terms of acquisition and use.

we need to admit that there is no real reason to spend money in space on human spaceflight EXCEPT to "anchor" the development of private infrastructure which can serve government needs...and then use the excess capability that infrastructure has...to sell to private industry...much as the US airmail contract did

this is going to take some major acquisition change AND a change in how the station operates.  (and probably eventually ditching the Russians who have become a drag on the station)

I am encouraged by Starliner/Dragon and OSC/SN efforts (particularly OSC who has been working in my view to turn their resupply effort into a more versatile effort (such as reboost and in my view eventually a micro g free flying platform)

but unless these changes are made the station will in my view continue to be a drag on human spaceflight AND the "gateway" will be even worse
Title: Re: Lunar Gateway Debate
Post by: TripleSeven on 07/21/2018 09:58 am
The gateway only serves a purpose if it is in an orbit that allows it to be some sort of supply depot AND to change the delta V requirement of a lander system and to keep it supplied. 

the problem with lunar exploration is that 1) we have no clue where exactly to put a lunar base and 2) need to do a massive amount of uncrewed exploration with very sophisticated robots (think the kind of robots that are being developed by that Boston company and others) before we try crewed landings.

Crewed landings as reccee missions are only useful in the final stage, in the start...we need uncrewed flights...

but the real thing is that government policy is not really interested in lunar exploration

:(
Title: Re: Lunar Gateway Debate
Post by: TaurusLittrow on 07/21/2018 10:52 am
I'm in the camp where I see LOP-G as a waste of time and money. Where is the cost-benefit analysis that shows that LOP-G decreases the cost of going to the Moon? Does a reusable lander operating from LOP-G make economic sense?

Exactly. If there is any silver lining to LOP-G it is that it could serve to promote a Lunar-COTS-type commercial infrastructure. Basically acting like an anchor tenant. I just hope and pray LOP-G doesn't become an anchor in lunar orbit delaying lunar surface and Mars system activities.
Title: Re: Lunar Gateway Debate
Post by: Rocket Science on 07/21/2018 11:56 am
Itshould be designed and funded as a complete system "LOP-G/Reusable-Lander" or not done at all in the point and time. It reminds me of the "field of dreams build it and they will come" SLS... If new players then wish to build privately funded reusable landers in the future and refuel at LOP-G great!
Title: Re: Lunar Gateway Debate
Post by: edkyle99 on 07/21/2018 02:50 pm
A 'Lunar Gateway' would only be a 'success' or useful if it included a small/medium propellant depot for a reusable, crewed Lander that was based there. And because of the Lander; it would have to have the right orbit to allow good access and coverage to much of the Lunar surface for useful periods of time - could someone nail down for me/us what type of orbit that would be?

Without a Lander based there, I'd say the Gateway serves little purpose...
A refueling station is needed for a reusable lander.  Agreed.  The station would also have to support the lander in other ways.  Cargo transfer.  Human transfer and temporary habitation.  Maintenance and testing.  Is this what the current gateway design reflects?  Could the gateway be somewhere else?

 - Ed Kyle
Title: Re: Lunar Gateway Debate
Post by: TripleSeven on 07/21/2018 03:05 pm
A 'Lunar Gateway' would only be a 'success' or useful if it included a small/medium propellant depot for a reusable, crewed Lander that was based there. And because of the Lander; it would have to have the right orbit to allow good access and coverage to much of the Lunar surface for useful periods of time - could someone nail down for me/us what type of orbit that would be?

Without a Lander based there, I'd say the Gateway serves little purpose...
A refueling station is needed for a reusable lander.  Agreed.  The station would also have to support the lander in other ways.  Cargo transfer.  Human transfer and temporary habitation.  Maintenance and testing.  Is this what the current gateway design reflects?  Could the gateway be somewhere else?

 - Ed Kyle

I dont think that the gateway has any purpose right now other then just a simple "build program"

the space station today should be undidicated to micro g, that moved onto a free flyer and the station changed to a technology development center
Title: Re: Lunar Gateway Debate
Post by: spacenut on 07/21/2018 03:11 pm
What about all the previous studies that determined that an LL1 or LL2 station would be the best?  Easier to get to from earth.  It could become a refueling station for a lunar lander, or refueling on the way to Mars.  LOX made from lunar soil could be delivered to the station.  Hydrogen or Methane from earth for the refueling of all exploration vehicles. 
Title: Re: Lunar Gateway Debate
Post by: HIP2BSQRE on 07/21/2018 03:21 pm
There is a very good article about it in thespacereview last week..
Title: Re: Lunar Gateway Debate
Post by: pathfinder_01 on 07/21/2018 11:03 pm
Here is my take. LEO is a better place for commercialization. Smaller rockets are easier to fund and develop and reusability is easier from LEO than from deep space.

As presented there really isn’t enough for commercial to do. Too few flights needed. I am not against a station near the moon, but I fear that instead of an additional destination to go to it becomes the ISS replacement and human spaceflight gets reduced to nothing more than one flight every other year or 2 flights per year that only stay in space for a few weeks. Compared to the ISS that is a great reduction of capability. The ISS gets about 4 cargo flights a year and this thing looks like it might only need 1-2. In addition the ISS is planned to get another 2 flights per year from each provider for crew. If SLS launches the crew then there is no work for commercial to do in terms of crew.

As for international partners they have their own objectives in space and ESA, Japan, Canada would be willing to go almost anywhere NASA would. I don’t see any advantage here at all. In fact I dare say that this would be something that slows it down as each partner adds their own requirements.

I also don’t like the reusable lander. I love reusability, but I see no such item.  The problem with a lander is that most of the mass is propellant and I see no plan to cheaply send propellant to this station. I see no use of say a SEP tug and a smaller rocker to send a tanker to the station or the use of BFR(or something like it) to send and retrieve a lander from the station for servicing on Earth. The tanker craft will need to cost substantial less than the lander in order for it to make any sense and the launch costs are going to be about the same for sending the tanker as sending the lander, so how does reusability save money in this instance? The tanker is going to need many of the same systems as the lander so making it much cheaper is going to be hard.
Title: Re: Lunar Gateway Debate
Post by: spacenut on 07/22/2018 03:12 am
Existing rockets can reach LL1 with decent payloads, human capsules, and various potential lunar landers. 
Title: Re: Lunar Gateway Debate
Post by: Archibald on 07/22/2018 08:19 am
I've been a die hard fan of the Gateway concept in its varied shapes since its inception in 1999. What bothers me with LOP-G
- no clear role
- SLS-Orion are too expensive, and LOP-G is only "cannon fodder" to provide SLS with payloads
- Distant Retrograde Orbit: EML-1 and EML-2 are better, as underlined in another post.

It is a shame, because (I will seek an earlier post of mine) there really are boatload of missions that could be done from an EML-2 Gateway, a multirole platform. From telescope servicing to GEO cleanup, and many other.
Oh well, see my post on the other thread (before it was moved to the space policy section)

https://forum.nasaspaceflight.com/index.php?topic=45240.msg1810063#msg1810063

Then again, the ISS started completely and entirely wrong (Freedom - Alpha - Fred) yet, since 2010, it had proved its worth - see Ed Kyle post, he is perfectly right. NASA really turned lemons (Freedom) into lemonade (current ISS).
Title: Re: Lunar Gateway Debate
Post by: TrevorMonty on 07/22/2018 10:20 am
I've been a die hard fan of the Gateway concept in its varied shapes since its inception in 1999. What bothers me with LOP-G
- no clear role
- SLS-Orion are too expensive, and LOP-G is only "cannon fodder" to provide SLS with payloads
- Distant Retrograde Orbit: EML-1 and EML-2 are better, as underlined in another post.

It is a shame, because (I will seek an earlier post of mine) there really are boatload of missions that could be done from an EML-2 Gateway, a multirole platform. From telescope servicing to GEO cleanup, and many other.
Oh well, see my post on the other thread (before it was moved to the space policy section)

https://forum.nasaspaceflight.com/index.php?topic=45240.msg1810063#msg1810063

Then again, the ISS started completely and entirely wrong (Freedom - Alpha - Fred) yet, since 2010, it had proved its worth - see Ed Kyle post, he is perfectly right. NASA really turned lemons (Freedom) into lemonade (current ISS).
The Gateway is not locked into an orbit for life, it can move around cislunar space. Thats main reason for such capable propulsion module.
Title: Re: Lunar Gateway Debate
Post by: TripleSeven on 07/22/2018 10:50 am
Here is my take. LEO is a better place for commercialization. Smaller rockets are easier to fund and develop and reusability is easier from LEO than from deep space.

As presented there really isn’t enough for commercial to do. Too few flights needed. I am not against a station near the moon, but I fear that instead of an additional destination to go to it becomes the ISS replacement and human spaceflight gets reduced to nothing more than one flight every other year or 2 flights per year that only stay in space for a few weeks. Compared to the ISS that is a great reduction of capability. The ISS gets about 4 cargo flights a year and this thing looks like it might only need 1-2. In addition the ISS is planned to get another 2 flights per year from each provider for crew. If SLS launches the crew then there is no work for commercial to do in terms of crew.

As for international partners they have their own objectives in space and ESA, Japan, Canada would be willing to go almost anywhere NASA would. I don’t see any advantage here at all. In fact I dare say that this would be something that slows it down as each partner adds their own requirements.

I also don’t like the reusable lander. I love reusability, but I see no such item.  The problem with a lander is that most of the mass is propellant and I see no plan to cheaply send propellant to this station. I see no use of say a SEP tug and a smaller rocker to send a tanker to the station or the use of BFR(or something like it) to send and retrieve a lander from the station for servicing on Earth. The tanker craft will need to cost substantial less than the lander in order for it to make any sense and the launch costs are going to be about the same for sending the tanker as sending the lander, so how does reusability save money in this instance? The tanker is going to need many of the same systems as the lander so making it much cheaper is going to be hard.

My theory on landers is that they need to smaller rather than larger...and attach to some ground base infrastructure
Title: Re: Lunar Gateway Debate
Post by: Proponent on 07/22/2018 01:15 pm
Time has a balanced article discussing the pluses and minuses of the Lunar Gateway....
http://time.com/5342743/nasa-moon-mars/

A couple of concrete errors in the Time article:

* Orion is described as "similar to the old Apollo, but significantly bigger and more capable."  Delta-V being a key measure of a spacecraft's capability, it's a stretch to that Orion is flat out more capable than Apollo, even if it can support a larger crew for a longer period.

* "For the first time in five decades, the U.S.–along with private-industry and international partners–has committed itself to returning to the moon, and to doing it on a defined timeline."  Aside from wishful thinking expressed by NASA and contractors, no timeline has been established.  In fact, Pres. Trump's Space Policy Directive 1 (referenced in the article and attached below) specifically removes even the loose timeline established in Obama's Presidential Policy Directive 4 (also attached).

But the biggest problem is that whole idea of NASA could be landing people on the moon 8 years from now is absurd from a budget perspective.  The existing Orion/SLS budget line will be fully utilized just to fly a crew to a gateway once per year, and ISS shows every sign of living until 2028.  The Europeans are already tapped out in that they're paying for Orion's ESM.

If humans go from LOP-G to the lunar surface on a time-scale anything like that discussed in the article, my money would be on it being done by Blue Origin, not NASA.
Title: Re: Lunar Gateway Debate
Post by: Proponent on 07/22/2018 01:28 pm
A 'Lunar Gateway' would only be a 'success' or useful if it included a small/medium propellant depot for a reusable, crewed Lander that was based there. And because of the Lander; it would have to have the right orbit to allow good access and coverage to much of the Lunar surface for useful periods of time - could someone nail down for me/us what type of orbit that would be?

Without a Lander based there, I'd say the Gateway serves little purpose...
A refueling station is needed for a reusable lander.  Agreed.  The station would also have to support the lander in other ways.  Cargo transfer.  Human transfer and temporary habitation.  Maintenance and testing.

I'm not so sure about that.  Assuming lander propellant comes from earth and not from the moon, maybe the lander simply docks with a tanker, propellant is transferred and then tanker and lander go their separate ways, no station needed.  Ditto for human transfer.

If the point is to build a base on the surface, wouldn't you likely do maintenance there?  If no surface base is foreseen and the plan is sorties globally, then maybe the case for high-orbit station increases.  But, given that just operating LOP-G, never mind funding landers or surface operations, will likely cost over $3 billion a year, you have to ask whether it is a net benefit.

Title: Re: Lunar Gateway Debate
Post by: Oli on 07/22/2018 01:33 pm
LOP-G looks like a big compromise to me:

- It gives SLS/Orion something to do.
- It's far cheaper than an outpost on the lunar surface.
- The modular structure allows for contributions by international/commercial partners.
- From a science POV it actually seems relatively useful. Again, given the budget limitations.

I think orbital outposts are the future of government-funded human spaceflight BEO. Going down to the surface is just too much of a PITA.
Title: Re: Lunar Gateway Debate
Post by: MATTBLAK on 07/22/2018 01:36 pm
Orion is great but for two things: it's a little too heavy and it's propellant load is a little too small; which of course, limits delta-v capability. The craft should have been able to insert itself and a payload into and then leave lunar orbit by itself, as Apollo could. By all means have a bit more internal volume than Apollo: Apollo CM had about 70 cubic feet per crew member. Assuming that Orion was definitely a 4x crew vehicle and using the same ratio per person, this would give 280 cubic feet habitable volume. I wonder what sort of diameter the Orion CM would then have to be - not 5 meters as it is now - to achieve that 280 cubic feet value approximate value? 4.2 meters? 4.3? The habitable volume of Starliner, which is 4.56 meters is 390 cubic feet (11 cubic meters) and Dragon is 350 cubic feet (10 cu meters). Both of those Command capsules are much lighter than the Orion; which is 10 metric tons just for the Command Module!! I wonder how much lighter it would have been if it had been limited to a diameter under 4.5 meters? A lot less, or just a little?
Title: Re: Lunar Gateway Debate
Post by: MATTBLAK on 07/22/2018 01:39 pm
A 'Lunar Gateway' would only be a 'success' or useful if it included a small/medium propellant depot for a reusable, crewed Lander that was based there. And because of the Lander; it would have to have the right orbit to allow good access and coverage to much of the Lunar surface for useful periods of time - could someone nail down for me/us what type of orbit that would be?

Without a Lander based there, I'd say the Gateway serves little purpose...
A refueling station is needed for a reusable lander.  Agreed.  The station would also have to support the lander in other ways.  Cargo transfer.  Human transfer and temporary habitation.  Maintenance and testing.

I'm not so sure about that.  Assuming lander propellant comes from earth and not from the moon, maybe the lander simply docks with a tanker, propellant is transferred and then tanker and lander go their separate ways, no station needed.  Ditto for human transfer.

If the point is to build a base on the surface, wouldn't you likely do maintenance there?  If no surface base is foreseen and the plan is sorties globally, then maybe the case for high-orbit station increases.  But, given that just operating LOP-G, never mind funding landers or surface operations, will likely cost over $3 billion a year, you have to ask whether it is a net benefit.


Orion/SLS (Block 1B) is supposed to have a 'surplus', co-manifested payload ability of about 10 metric tons. Perhaps the Orion could bring a tanker module with it each time to refuel a reusable Lander? Just an idea...
Title: Re: Lunar Gateway Debate
Post by: Proponent on 07/22/2018 01:43 pm
LOP-G looks like a big compromise to me:

- It gives SLS/Orion something to do.
- It's far cheaper than an outpost on the lunar surface.
- The modular structure allows for contributions by international/commercial partners.
- From a science POV it actually seems relatively useful. Again, given the budget limitations.

What scientific benefits do you see?

We hear about tele-operated rovers on the lunar surface.  I can see why a low-latency link to a controller on LOP-G would be helpful, but, when we have self-driving cars on Earth coping for the most part successfully with moving hazards (other vehicles and pedestrians), I struggle to imagine that it's a great advantage in the moon's very static environment.

You get to soak astronauts in the interplanetary radiation field, which you can't do on ISS.  But only for about six weeks at a time, so I'm not sure it's all that relevant to preparing for missions to Mars.

EDIT:  Capitalized "Earth" and added missing "with"
Title: Re: Lunar Gateway Debate
Post by: Archibald on 07/22/2018 02:52 pm
how much delta-v does the ppm provides ?
Title: Re: Lunar Gateway Debate
Post by: TripleSeven on 07/22/2018 02:57 pm
LOP-G looks like a big compromise to me:

- It gives SLS/Orion something to do.
- It's far cheaper than an outpost on the lunar surface.
- The modular structure allows for contributions by international/commercial partners.
- From a science POV it actually seems relatively useful. Again, given the budget limitations.

What scientific benefits do you see?

We hear about tele-operated rovers on the lunar surface.  I can see why a low-latency link to a controller on LOP-G would be helpful, but, when we have self-driving cars on earth coping for the most part successfully moving hazards (other vehicles and pedestrians), I struggle to imagine that it's a great advantage in the moon's very static environment.

You get to soak astronauts in the interplanetary radiation field, which you can't do on ISS.  But only for about six weeks at a time, so I'm not sure it's all that relevant to preparing for missions to Mars.

of all the "good things" the notion of low latency link to a controller seems like the most made up one

not only for the reasons you mention, (which as you point out is dealt with handily by vehicles on and flying above and below the sea on earth) but also in that it goes the opposite way from where "things" are going on earth to use robotic vehicles

what it does is put yet another "layer" between the people who should be using the drone to do things...and the drone.  In addition it puts a premium on the person at the Gateway who is controlling the drone...and since this person does not work 24 hours a day...a limitation on the drones operation.

we should be putting the operation of the "drones" closer to the people who are actually using them, not farther away
Title: Re: Lunar Gateway Debate
Post by: Proponent on 07/22/2018 03:10 pm
Orion/SLS (Block 1B) is supposed to have a 'surplus', co-manifested payload ability of about 10 metric tons. Perhaps the Orion could bring a tanker module with it each time to refuel a reusable Lander? Just an idea...

Hmmm.....  The Apollo LM's total propellant load (ascent and descent stages together) was about 11 tonnes.  An Apollo-style lander today could no doubt get away with less propellant by saving weight and burning, say, lox/methane or maybe even lox/hydrogen rather than NTO/Aerozine 50.  But the dry weight of the LM's ascent stage was less than a quarter that of the descent stage.  If you want a reusable lander, you're going to have to haul something roughly equivalent to the descent stage all the way from the surface back to the staging point, and that means burning a lot more propellant.  That propellant itself needs to be landed on the moon in the first place, so we're talking about a much larger vehicle.

Then there's the fact that, delta-V-wise, LOP-G is about 700 m/s further (one way) from the lunar surface than was the Apollo LM when it began its descent from LLO.

So I don't think Orion/SLS's 10-tonne co-manifested payload capability helps much for fueling a crewed lander.
Title: Re: Lunar Gateway Debate
Post by: speedevil on 07/22/2018 03:17 pm
of all the "good things" the notion of low latency link to a controller seems like the most made up one

Lunkakhod drove quite a long way indeed, using ridiculously long latency. significantly over 2*triptime, due to the long frame transmit time, and despite only being able to drive a small fraction of the time due to comms and other constraints.

It is somewhat arguable that reducing delay by having nearby astronauts to do teleoperation has a benefit for Mars.
For the moon - well - no.

Shipping nice high-res images, with depth information from LIDAR, a good framerate, and building this into a centimeter accurate 3d model of the upcoming 20m or so is very tractable today with almost off the shelf hardware and software.
This would make the drivers task orders of magnitude easier than Lunakhod.

And of course, you can get people on earth to do this for well under $100/hr.
Comms is of course something that's needed. I note China already has a farside comsat in place.
Title: Re: Lunar Gateway Debate
Post by: RonM on 07/22/2018 04:33 pm
- It gives SLS/Orion something to do.

As long as Congress wants to keep funding SLS it needs something to do. LOP-G is a reasonable idea since it uses the leftover capacity of Block 1A and Orion. If Congress cancels SLS, and there's no reason to think that will happen anytime soon, then LOP-G loses its "free" ride.

- It's far cheaper than an outpost on the lunar surface.

True, but it's not nearly as useful. It could lead to a lunar outpost or reusable landers since those would be expanding on an existing project, as opposed to trying to fund direct missions. Got to get Congress to sign the check.

- The modular structure allows for contributions by international/commercial partners.

This is the best part of LOP-G, assuming it's worth building it in the first place.

- From a science POV it actually seems relatively useful. Again, given the budget limitations.

Big lunar science can be done from individual orbiters, but smaller projects can't afford it. LOP-G can be used like ISS with experiments added to the station to take advantage of the existing power and data resources. Less expensive for the researchers.

of all the "good things" the notion of low latency link to a controller seems like the most made up one

Agreed. Modern technology would allow a rover to avoid mishaps the short control delay from Earth might introduce. Controlling rovers from a crewed orbital station is a good idea for beyond cislunar space, such as at Mars, Venus, etc.
Title: Re: Lunar Gateway Debate
Post by: ncb1397 on 07/22/2018 04:53 pm
Orion/SLS (Block 1B) is supposed to have a 'surplus', co-manifested payload ability of about 10 metric tons. Perhaps the Orion could bring a tanker module with it each time to refuel a reusable Lander? Just an idea...

Hmmm.....  The Apollo LM's total propellant load (ascent and descent stages together) was about 11 tonnes.  An Apollo-style lander today could no doubt get away with less propellant by saving weight and burning, say, lox/methane or maybe even lox/hydrogen rather than NTO/Aerozine 50.  But the dry weight of the LM's ascent stage was less than a quarter that of the descent stage.  If you want a reusable lander, you're going to have to haul something roughly equivalent to the descent stage all the way from the surface back to the staging point, and that means burning a lot more propellant.  That propellant itself needs to be landed on the moon in the first place, so we're talking about a much larger vehicle.

Then there's the fact that, delta-V-wise, LOP-G is about 700 m/s further (one way) from the lunar surface than was the Apollo LM when it began its descent from LLO.

So I don't think Orion/SLS's 10-tonne co-manifested payload capability helps much for fueling a crewed lander.

The Apollo LM did things this wouldn't necessarily have to do like carry a rover. With LOX/H2 fuel, you could potentially get away with 10 metric tons of propellant with the following specifications:

fuel: 10,000 kg
payload: 1500 kg (crew environment, equivalent to dry mass of Cygnus version 1)
stage dry mass: 2700 kg
stage fueled dry fraction : 21%
total vehicle fueled dry fraction: 30%
isp: 430 (middle of the road LOX/H2 performance)
delta -v: 5133 m/s

IIRC, 30% dry fraction is about where Shuttle was when you consider the combined orbiter and fuel tank. There likely is some version of these numbers for other fuels as well. This gives you a lander that can potentially launch crew and cargo, have compatibility with a range of launch vehicle sizes down to around Atlas V and up to SLS (with  payloads to the surface scaling accordingly) and operate in a reusable mode with the gateway for crew or light payloads. 

edit: It seems I didn't remember correctly. Shuttle tank with a gross mass of 760,000 kg, dry mass of 26,500 kg and the orbiter with a dry mass of 68,585 kg gives a dry mass fraction of 11.5%(95,085 kg / 828,585 kg).

edit 2: I forgot at least two space-suited individuals at 150 kg each which drops the delta v by 200 m/s so ISP has to go to 440(still 8 seconds less than J-2x) and you have to save 100 kg somewhere else to get back over 5100 m/s. Worse outcome is you need a 3000 kg shipment equivalent to an ISS cargo resupply to get the extra water to generate the extra fuel(electrolysis is commonly done on ISS so I see no technical hurdles here).

edit 3: After looking at hydrogen engines that exist, it seems nearly every hydrolox engine out there (even the upper stage ones) are too big for this application (assuming you want to land on main engines at close to 1 thrust to weight ratio). It is too bad that one of the smallsat launchers doesn't have a hydrolox upper stage as a cluster of something sized for that might work. So, we are looking at a new engine, albeit very small.

edit 4: Looking at hypergolics, you need the following specifications:

fuel: 10,000 kg
payload: 1400 kg (crew environment, equivalent to dry mass of Cygnus version 1) + 300 kg crew, 1700 kg
stage dry mass: 900 kg
stage fueled dry fraction : 8.3%
total vehicle fueled dry fraction: 18.7%
isp: 330
delta -v: 5103 m/s

So, the propulsion portion needs to carry same amount of fuel as the lunar descent module but weigh about half as much. But looking at the descent module layout, there probably was quite a bit of room for weight savings:

(https://upload.wikimedia.org/wikipedia/commons/thumb/4/4a/LM_illustration_02.jpg/800px-LM_illustration_02.jpg)

You wouldn't use something like the hypergolic common bulkhead on the proton 2nd stage for something manned, but two tanks stacked one on top of each other with a separation wall might be a happy medium.
Title: Re: Lunar Gateway Debate
Post by: butters on 07/22/2018 05:48 pm
A cislunar gateway station makes sense as one of the last pieces of the transportation architecture, after lunar surface spacecraft are already using lunar ISRU propellant for the return trip. Making it the first piece of infrastructure is like building container ports before clipper ships.

Delivering terrestrial propellant to a cislunar station is big PITA compared to LEO. A lunar lander based at LOP-G would be cryogenic, probably hydrolox. The only conceivable providers would be ULA with ACES and Blue Origin with TBD. The ACES tanker would be expendable and would have a cost disconcertingly close to that of an EUS. Who knows what Blue could bring to the table in terms of a long-coast cryogenic tanker, but reusability seems doubtful.

These tanker missions are going to be expensive, there may not be more than one capable provider, and the NewSpace players will struggle to identify how developing to these requirements could be helpful for their proprietary roadmaps.

If we're going to be pushing an expendable ACES full of propellant out to cislunar orbit, then we might as well give it the landing accessories from the DTAL concept and just land it on the darn surface.
Title: Re: Lunar Gateway Debate
Post by: oldAtlas_Eguy on 07/22/2018 07:10 pm
A cislunar gateway station makes sense as one of the last pieces of the transportation architecture, after lunar surface spacecraft are already using lunar ISRU propellant for the return trip. Making it the first piece of infrastructure is like building container ports before clipper ships.

Delivering terrestrial propellant to a cislunar station is big PITA compared to LEO. A lunar lander based at LOP-G would be cryogenic, probably hydrolox. The only conceivable providers would be ULA with ACES and Blue Origin with TBD. The ACES tanker would be expendable and would have a cost disconcertingly close to that of an EUS. Who knows what Blue could bring to the table in terms of a long-coast cryogenic tanker, but reusability seems doubtful.

These tanker missions are going to be expensive, there may not be more than one capable provider, and the NewSpace players will struggle to identify how developing to these requirements could be helpful for their proprietary roadmaps.

If we're going to be pushing an expendable ACES full of propellant out to cislunar orbit, then we might as well give it the landing accessories from the DTAL concept and just land it on the darn surface.
ACES other then its RL-10 engines is potentially the cheapest expendable US. If AJR is able to decrease costs of RL10C-X as much as they are indicating (up to ~1/2 the current costs), a ACES tanker or even the ultimate of a ACES derived DTAL could be the cheapest and quickest way to the Lunar surface. Much of the solutions have been under study for the last decade. This low costs is because of several factors. The first is the stainless steel balloon tank of the ACES is still the cheapest tank to manufacture ever. As a comparison to EUS is that the rate is that of 5 to 10 or molre per year to EUS  of ~1/year. Another factor is the IVF tech of ACES reduces the total hardware and hardware costs. Leaving only the engines as the major cost driver but even here the decision to use the new design/manufacture process RL10C-X also reduces costs for ACES further.

The only actual detractor is the cost of the Vulcan to get ACES into orbit.

But what if BO and ULA collaborate on using ACES as a third stage/tanker on top of the NG then you could easily deliver as much as 20mt of cryo prop to the LOP-G location per NG flight. So it is possible in this case to deliver 20mt of cryo prop to LOP-G for under $100M each trip. And the plus is that the ACES is a miniature Depot such that operationally there are tremendous number of options available to mission planners with this capability.
Title: Re: Lunar Gateway Debate
Post by: speedevil on 07/22/2018 11:34 pm
Delivering terrestrial propellant to a cislunar station is big PITA compared to LEO. A lunar lander based at LOP-G would be cryogenic, probably hydrolox. The only conceivable providers would be ULA with ACES and Blue Origin with TBD. The ACES tanker would be expendable and would have a cost disconcertingly close to that of an EUS. Who knows what Blue could bring to the table in terms of a long-coast cryogenic tanker, but reusability seems doubtful.
'Only conceivable' ?

It is not unreasonable to have schedule and other doubts about BFS, but to dismiss it against 'TBD' seems at best pessimistic.

BFS, with 8 launches, including one used as a tanker, gets you a hundred tons to the surface and substantial payload back.
(fill tanks in LEO, top off in HEO, TLI, meet up with tanker already in LLO, transfer fuel, land, rendevous, take on TEI fuel, burn for earth).

The BFS is using 55 tons to ascend to 85 tons dry over 1800m/s, and 150 tons to descend with that 100 tons of payload.
This is at ISP of 370, and 85 tons dead weight.
Call it 200 tons of propellant.
If we imagine a hydrolox stage using that 200 tons, with 20 tons dry, it would take 10 tons to ascend, payload would go up to 160 tons from 100. (not quite this good, as the extra payload and H2 tanks cut into the mass).

The cost to SpaceX of the first option is around $40M for 100 tons down.

The cost of a whole BFS in LLO semi-permenantly is according to IAC 2016/7 figures likely to be under $200M.

Cost, is of course, not price.
A very small hydrolox thruster to do TEI using the existing hydrogen tank the second architecture requires anyway would defray the H2 tank mass cost.

As one data point, Apollo lander had about 11 tons of fuel. To get that into LLO would cost one falcon heavy launch in expendable mode, with a disposable dragon for guidance, and a large tank taking place of the trunk, using near-off-the-shelf commercial earth grade tanks with insulation for some months stay. (assuming a mass fraction of a third for the tanks).
That is at least a cap on pricing of fuel  in LLO. - around $10M/ton.
There are certainly much better ways to do this, but if your landers amortised cost is not well under $100M/mission, cheaper fuel (hypothetically available from some lunar station with a clever architecture) does not help.
Title: Re: Lunar Gateway Debate
Post by: A_M_Swallow on 07/23/2018 12:04 am
Personal opinion. I believe that one of the main tasks of a lunar space station will be to help build the Moon base(s).

Many houses are built out of 9 inch bricks. Each brick could be taken to the site individually by marathon runners but construction companies prefer to buy a truck and deliver a ton of bricks in one go. So to reduce construction time there will be strong pressure to make the lunar base out of large (heavy) modules. (See attached picture of a lorry carrying bricks.)

The nearest approximation to construction of a Moon base is the construction of the ISS. The ISS consists of several modules in a variety of sizes. They go up to about 20 metric tonnes. (Ref https://en.wikipedia.org/wiki/Assembly_of_the_International_Space_Station#Assembly sequence (https://en.wikipedia.org/wiki/Assembly_of_the_International_Space_Station assembly sequence).) This is compatible with the size of the Bigelow XBASE, which could form the living quarters of a Moon base.

With fittings and consumables this means we need a launch system that can deliver 25-30 tonnes to the lunar surface. Not even the Block 3 SLS can do that. However the SLS can deliver 25-30 tonne payloads to lunar orbit. The heavy lander, propellant and people would have to be sent on separate launches.

A lunar spacestation makes a good assembly point for the payload, lander, propellant and astronauts. The stations arms will simplify docking them together. The launches can be scheduled over several weeks. With mining equipment, ISRU refining equipment and manned rovers several landing will be needed.

Whether a reusable landing or several expendable landers are used is a cost trade that politicians can understand. Launches are expensive.

A lunar base can repair and refuel landers but only when it is full operational. Prior to that the lander(s) would have to be repaired in orbit and fuelled using fuel from the Earth.
Title: Re: Lunar Gateway Debate
Post by: su27k on 07/23/2018 02:20 am
As presented there really isn’t enough for commercial to do. Too few flights needed. I am not against a station near the moon, but I fear that instead of an additional destination to go to it becomes the ISS replacement and human spaceflight gets reduced to nothing more than one flight every other year or 2 flights per year that only stay in space for a few weeks. Compared to the ISS that is a great reduction of capability. The ISS gets about 4 cargo flights a year and this thing looks like it might only need 1-2. In addition the ISS is planned to get another 2 flights per year from each provider for crew. If SLS launches the crew then there is no work for commercial to do in terms of crew.

It's much worse than this, if you follow the mission plan here: https://www.nasaspaceflight.com/2017/04/nasa-goals-missions-sls-eyes-multi-step-mars/, there's only 4(!) commercial resupply mission from 2018 to 2029. It's not 1-2 per year, it's once every 2.5 years! The DSG is nothing but a blatant attempt to erase commercial capability from NASA future plans.
Title: Re: Lunar Gateway Debate
Post by: su27k on 07/23/2018 02:21 am
Time has a balanced article discussing the pluses and minuses of the Lunar Gateway, including an interesting part about the orbital dynamics issue.  I'm still not sure what to think about the subject.  It does seem to me that a station of some type would more readily allow commercial and international cooperation.   
http://time.com/5342743/nasa-moon-mars/

It's not balanced at all, given even its title is a lie: "NASA Could Have People Living on the Moon in 8 Years. And That's Just the Beginning". I have yet to see a NASA plan that can result in a Moon base in 18 years, let alone 8 years.
Title: Re: Lunar Gateway Debate
Post by: DreamyPickle on 07/23/2018 05:50 am
Existing rockets can reach LL1 with decent payloads, human capsules, and various potential lunar landers.

Do we have numbers on the capabilities of existing rockets to the Lunar Gateway? One of the strengths of the ISS is the wide variety of visiting vehicles but for LOP-G many would be cut out due to insufficient performance. For example Soyuz is almost definitely out, the Russians would have to integrate their capsule on Angara A5.

I like the idea of building space stations as a way to stimulate commercial development, but if you want to do that it might be better to expand the ISS instead. For example NASA could run a "commercial hab" program for companies to build and operate habitat modules attached to the ISS.
Title: Re: Lunar Gateway Debate
Post by: Archibald on 07/23/2018 07:02 am
Quote
Do we have numbers on the capabilities of existing rockets to the Lunar Gateway?

For a start, direct-to-GEO (not GTO) evenly matches LLO as far as delta-V goes.
Ariane 5 can throw 10 mt to GTO (2.5 km/s, so no Earth escape) and 7 mt to 4.1 km/s (direct-to-GTO or lunar orbit). Proton must be roughly similar, and Falcon 9, too - in expendable mode. Delta IV Heavy probably does a little better, Atlas 551 a bit less.

As far as delta-v is concerned: 20 mt to LEO > 10 mt to GTO > 7 mt to GEO or lunar orbit > 2 mt to Moon surface. One way trip of course. And rough numbers.

of course Falcon 9 Heavy and SLS can do far, far better than that.

The nice thing with commercial vehicles, be them cargo or crewed, is that most of them are around or below 10 mt, just light enough they might be launched to Earth escape / cislunar space on the aforementioned rockets.
- Cygnus on Atlas 551 (rather than Antares)
- Boeing CTS-100 also on Atlas 551 (provided the heatshield can handle Earth return of course)
- Dragon and Dragon 2 are a little trickier, but Falcon Heavy could probably do it.

and that's where LOP-G could be interesting: if the ISS stops in 2024, the cargo and crew vehicles might be recycled for LOP-G, without too much hassle for Boeing, SpaceX and whatever company now build Cygnus (can't remember, my mind is stuck with Orbital Sciences).

Soyuz could go to DRO on an existing rocket, that is, Proton (hello, Zond !) but as you noted, not on its usual Soyuz rocket.
Title: Re: Lunar Gateway Debate
Post by: TripleSeven on 07/23/2018 08:21 am
Existing rockets can reach LL1 with decent payloads, human capsules, and various potential lunar landers.

Do we have numbers on the capabilities of existing rockets to the Lunar Gateway? One of the strengths of the ISS is the wide variety of visiting vehicles but for LOP-G many would be cut out due to insufficient performance. For example Soyuz is almost definitely out, the Russians would have to integrate their capsule on Angara A5.

I like the idea of building space stations as a way to stimulate commercial development, but if you want to do that it might be better to expand the ISS instead. For example NASA could run a "commercial hab" program for companies to build and operate habitat modules attached to the ISS.

yes

if the US took a large chunk of the money wasted on SLS...say about 1 billion or so of the money and used it per year to expand/replace things on ISS BUT did it as commercial contracts...well the world would change for the better

1 billion a year can expand the station with Bigelow modules, Axiom, free flyers, more power etc...

and the excess commercial capability then could be sold by the commercial companies...it would be a big win win...
Title: Re: Lunar Gateway Debate
Post by: AncientU on 07/23/2018 11:45 am
LOP-G looks like a big compromise to me:

- It gives SLS/Orion something to do.
- It's far cheaper than an outpost on the lunar surface.
- The modular structure allows for contributions by international/commercial partners.
- From a science POV it actually seems relatively useful. Again, given the budget limitations.

I think orbital outposts are the future of government-funded human spaceflight BEO. Going down to the surface is just too much of a PITA.

You are saying, it's hard, so we shouldn't do it?  We've come a long way since Apollo, haven't we!

There is zero 'science' to do in DRO -- either we go to the surface of the Moon, Mars, etc. to explore, or we abandon the big-bucks human 'exploration' program.  Deep space exploration is an oxymoron.

Title: Re: Lunar Gateway Debate
Post by: Khadgars on 07/26/2018 02:41 pm
the least useful comparison of the gateway are comparisons to the current station.

The space station is in all respects a failure. 
I see it as an astonishing success.  What began as a Cold War idea has ended up serving as a giant commercial space incubator.  (Consider this.  If no ISS, there would be no Dragon and no SpaceX as we know it.)  The international co-operation, getting all of those pieces to fit together, literally and figuratively, all of those delicate rendezvous, those spacewalks, all of that dozens of tonnes of refueling, parts joined the first and only time in space, people spending literally years of their lives in orbit, in the face of multiple giant setbacks, budget cuts, and disasters, makes my head spin.  Launches, too many of them, have failed.  People, too many of them, have died.  Governments and giant companies have collapsed.  Friends have become not so friendly.  But ISS has continued.  People working together all over the world and in space have risen above all of it to achieve something magnificent. 

ISS is one of humanity's greatest achievements.

 - Ed Kyle

Couldn't agree more Ed.

I think what's beneficial with LOP-G is it allows BLEO testing without the intimidate aid of earth but being close enough than Orion or other capsule can return to earth on short notice.  I feel like most on here believe we're ready to live in BLEO today, when in-fact I believe we need years of testing of equipment and procedures before we're ready for a trip to Mars.

Simulating this in LEO isn't the same.  The environment isn't the same nor the stresses placed on people and equipment. 

It may be pie in the sky, but LOP-G is the only BLEO "program" that also has international backing.  Hopefully it can bring commercial (SpaceX and BO) along for the ride as well. 
Title: Re: Lunar Gateway Debate
Post by: Coastal Ron on 07/26/2018 04:39 pm
I think what's beneficial with LOP-G is it allows BLEO testing without the intimidate aid of earth but being close enough than Orion or other capsule can return to earth on short notice.

Moving progressively farther away from Earth is the goal, but while I've heard the assertion that being too close to Earth is bad for testing our ability to leave the vicinity of Earth, I've seen no one able to quantify such assertions.

For instance, yes there will be more radiation outside of LEO, and yes there is more reflected heat to deal with in LEO. But otherwise I see no evidence that humans will act significantly different in space dependent on how close to Mother Earth they are.

Quote
I feel like most on here believe we're ready to live in BLEO today...

You may be conflating private efforts vs NASA.

NASA is not ready to leave LEO today - it's space technology "cupboard" is bare due to a lack of funding over the past decade or so, starting back during the Constellation program. And if one pays attention to the excellent science being done on the ISS, it's clear NASA still needs to perfect a lot of technology before it is ready to go somewhere in the manner everyone expects from NASA.

As far as the private sector goes, which has far different standards, I would not be surprised if humans left Earth-local space by 2025, and land on Mars by 2030. And yes, people may die, but the private sector is willing to take such risks whereas taxpayer funded efforts can't.

Quote
...when in-fact I believe we need years of testing of equipment and procedures before we're ready for a trip to Mars.

We don't have enough validated technology to venture out into Earth-local space for a month or so, much less Mars.

The reason I liked Obama's original goals of going to an asteroid by 2025 and fly near Mars by 2035 was that it was a roadmap for progressively harder targets. Congress didn't agree with those goals, which is fine, but it's funny that what we're talking about today is not all that different than what Obama had wanted.

Quote
Simulating this in LEO isn't the same.  The environment isn't the same nor the stresses placed on people and equipment.

Again, while there are some difference regarding radiation and heat, the phrase "stresses placed on people" is not supported by any facts I know of.

Quote
It may be pie in the sky, but LOP-G is the only BLEO "program" that also has international backing.

Don't conflate "interest" with "backing". The term "backing" implies money, and money has not been committed by international partners. As of today there is only talk, which is cheap.

Quote
Hopefully it can bring commercial (SpaceX and BO) along for the ride as well.

That will be up to whoever in the U.S. Government defines the goals of the program. We should all know that America's aerospace industry is more than up to the task of supporting such an effort - it did so 50 years ago.
Title: Re: Lunar Gateway Debate
Post by: Eric Hedman on 07/28/2018 03:48 am
If you look at the image for the current configuration of LOP-G from the Marshall Road show at the top it is labeled:

Lunar Orbital Platform - Gateway
A crew-tended exploration and science outpost in orbit around the Moon.

A new version of the image now says:

GATEWAY
An exploration and science outpost in orbit around the Moon

Is the awkward LOP-G name going away?  Why did "crew-tended" get removed from the image?  Are they considering continuous occupation?

Image from  the roadshow can be found at the top of this article I wrote: http://thespacereview.com/article/3529/1 (http://thespacereview.com/article/3529/1)

New Image:  http://thespacereview.com/archive/3538b1.jpg (http://thespacereview.com/archive/3538b1.jpg)
Title: Re: Lunar Gateway Debate
Post by: Khadgars on 07/28/2018 05:45 am
It appears they going with a mini ISS, which isn't a bad thing if the same partners are involved.  Yes it adds complexity, but also staying power.  The ISS has been operating for nearly two decades, that's a hell of a track record.

Title: Re: Lunar Gateway Debate
Post by: butters on 07/28/2018 05:24 pm
It appears they going with a mini ISS, which isn't a bad thing if the same partners are involved.  Yes it adds complexity, but also staying power.  The ISS has been operating for nearly two decades, that's a hell of a track record.

Is staying power necessarily a virtue? Shuttle had staying power, and its elements have even stronger staying power, but is that a good thing, or is it really holding us back?

The 2010s have been a great decade for spaceflight, but the 2020s have distinct potential to become the most impressive decade of spaceflight development since the 1960s. If NASA ends the 2020s with an occasionally-crewed mini-ISS in a high lunar halo orbit -- but it has staying power! -- they're going to look silly. If we're pleased by the staying power of LOP-G through the 2030s, then something must have gone terribly wrong to change the trajectory of the industry.

Just as it should have become clear during the struggle to ramp flight rate in 1985 that Shuttle wasn't going to work out, LOP-G should appear obsolete before the end of its assembly sequence. But if staying power comes into play, we will wind up throwing good money after bad.
Title: Re: Lunar Gateway Debate
Post by: ncb1397 on 07/28/2018 05:51 pm
The 2010s have been a great decade for spaceflight, but the 2020s have distinct potential to become the most impressive decade of spaceflight development since the 1960s. If NASA ends the 2020s with an occasionally-crewed mini-ISS in a high lunar halo orbit -- but it has staying power! -- they're going to look silly.

There is no competition between commercial and government. NOAA operates a small fleet of research vessels (The Okeanos Explorer, Gordon Gunter and Ronald H. Brown). The largest ship operator in the world Mearsk line operates 621 container ships. Nobody cares and nobody makes the comparison. What would make them look silly is not that they don't operate 621 research vessels, but if their research vessels had the displacement of a Mearsk Triple-E class container ship.

https://en.wikipedia.org/wiki/Maersk_Triple_E-class_container_ship
Title: Re: Lunar Gateway Debate
Post by: TripleSeven on 07/28/2018 06:37 pm
the least useful comparison of the gateway are comparisons to the current station.

The space station is in all respects a failure. 
I see it as an astonishing success.  What began as a Cold War idea has ended up serving as a giant commercial space incubator.  (Consider this.  If no ISS, there would be no Dragon and no SpaceX as we know it.)  The international co-operation, getting all of those pieces to fit together, literally and figuratively, all of those delicate rendezvous, those spacewalks, all of that dozens of tonnes of refueling, parts joined the first and only time in space, people spending literally years of their lives in orbit, in the face of multiple giant setbacks, budget cuts, and disasters, makes my head spin.  Launches, too many of them, have failed.  People, too many of them, have died.  Governments and giant companies have collapsed.  Friends have become not so friendly.  But ISS has continued.  People working together all over the world and in space have risen above all of it to achieve something magnificent. 

ISS is one of humanity's greatest achievements.

 - Ed Kyle

Couldn't agree more Ed.

I think what's beneficial with LOP-G is it allows BLEO testing without the intimidate aid of earth but being close enough than Orion or other capsule can return to earth on short notice.  I feel like most on here believe we're ready to live in BLEO today, when in-fact I believe we need years of testing of equipment and procedures before we're ready for a trip to Mars.

Simulating this in LEO isn't the same.  The environment isn't the same nor the stresses placed on people and equipment. 

It may be pie in the sky, but LOP-G is the only BLEO "program" that also has international backing.  Hopefully it can bring commercial (SpaceX and BO) along for the ride as well.

there is nothing on Gateway that cannot be done in LEO for cheaper.
Title: Re: Lunar Gateway Debate
Post by: speedevil on 07/28/2018 07:42 pm
there is nothing on Gateway that cannot be done in LEO for cheaper.
The solar and radiation environments differ moderately and significantly respectively.
AIUI to get to interplanetary-like radiation environment would need >GEO, for best fidelity and somewhere in the region of 12000km or so for similar thermal.
Title: Re: Lunar Gateway Debate
Post by: Khadgars on 07/29/2018 03:38 am
It appears they going with a mini ISS, which isn't a bad thing if the same partners are involved.  Yes it adds complexity, but also staying power.  The ISS has been operating for nearly two decades, that's a hell of a track record.

Is staying power necessarily a virtue? Shuttle had staying power, and its elements have even stronger staying power, but is that a good thing, or is it really holding us back?

The 2010s have been a great decade for spaceflight, but the 2020s have distinct potential to become the most impressive decade of spaceflight development since the 1960s. If NASA ends the 2020s with an occasionally-crewed mini-ISS in a high lunar halo orbit -- but it has staying power! -- they're going to look silly. If we're pleased by the staying power of LOP-G through the 2030s, then something must have gone terribly wrong to change the trajectory of the industry.

Just as it should have become clear during the struggle to ramp flight rate in 1985 that Shuttle wasn't going to work out, LOP-G should appear obsolete before the end of its assembly sequence. But if staying power comes into play, we will wind up throwing good money after bad.

I think we can agree to disagree.  And my point wasn't about the shuttle, but of the ISS.  I believe the ISS has been the most successful long-term space operation in human history, which is why I also believe a mini ISS in lunar orbit would also be highly successful if many of the same partners contribute.

Title: Re: Lunar Gateway Debate
Post by: su27k on 07/29/2018 04:27 am
The 2010s have been a great decade for spaceflight, but the 2020s have distinct potential to become the most impressive decade of spaceflight development since the 1960s. If NASA ends the 2020s with an occasionally-crewed mini-ISS in a high lunar halo orbit -- but it has staying power! -- they're going to look silly.

There is no competition between commercial and government. NOAA operates a small fleet of research vessels (The Okeanos Explorer, Gordon Gunter and Ronald H. Brown). The largest ship operator in the world Mearsk line operates 621 container ships. Nobody cares and nobody makes the comparison. What would make them look silly is not that they don't operate 621 research vessels, but if their research vessels had the displacement of a Mearsk Triple-E class container ship.

https://en.wikipedia.org/wiki/Maersk_Triple_E-class_container_ship

Worth pointing out that NOAA spent only 2% of their annual budget building new ships and improving existing ships, comparing to 20% NASA spent on building SLS/Orion.

Also NOAA does research that no commercial entities wants to do. But in HSF, there's fairly big overlap between what commercial wants to do and what government wants to do, and this is why public private partnership for HSF makes sense.

Edit to add: Just think about what NASA can accomplish if they only use 2% of the budget for building new space transportation system! Before you brushes this off as impossible, think about it for a minute, it's entirely possible by using public private partnership, you can even say it's proven already. On the other hand, if NASA refuses to cooperate with commercial, and commercial was able to accomplish more on their own while using a lot less money, then yes, in this case NASA would look silly.
Title: Re: Lunar Gateway Debate
Post by: Coastal Ron on 07/29/2018 04:44 am
I believe the ISS has been the most successful long-term space operation in human history...

I would agree with that.

Quote
...which is why I also believe a mini ISS in lunar orbit would also be highly successful if many of the same partners contribute.

An international partnership, while good, was not the goal. It was the means to an end - the way to achieve the goal.

And that goal was to create a National Laboratory in space so that we can work on the challenges keeping us from expanding humanity out into space. Those are my words, but it's something like that...  ;)

So what we should hope to see from another international effort is something beyond just everyone putting money into the shared pot, but accomplishing a shared goal. Do we know what that shared goal is, and is the "business case" for it good enough to invest 10-20 years of NASA time and money?

I'm not sure we know, for sure, what that shared goal is yet, though there are certainly lots of suggestions. I think the Trump administration needs to settle on a goal, and then get buy-in from everyone involved. Not sure when that will happen though...
Title: Re: Lunar Gateway Debate
Post by: spacenut on 07/29/2018 12:16 pm
Do you guys think they will change from lunar orbit to LL1 or LL2?  Either would be easier for existing rockets to service.  From there a reusable lunar lander could operate.  It could operate as a refueling station for the lander as well as some earth return vehicles.  It could expand to include any number of modules, maybe even a space hotel.  It would become like ISS with international partners (which should include the Chinese or others). 

Why LOP-G? 
Title: Re: Lunar Gateway Debate
Post by: Patchouli on 07/29/2018 05:25 pm
Do you guys think they will change from lunar orbit to LL1 or LL2?  Either would be easier for existing rockets to service.  From there a reusable lunar lander could operate.  It could operate as a refueling station for the lander as well as some earth return vehicles.  It could expand to include any number of modules, maybe even a space hotel.  It would become like ISS with international partners (which should include the Chinese or others). 

Why LOP-G? 
Yah it's an awkward name.
DSG is more catchy.

Whatever they call it  I think they should go with the Skylab II concept or the Bigelow Olympus module for the core part.
Title: Re: Lunar Gateway Debate
Post by: Archibald on 07/30/2018 07:28 am
I have a (personal) hypothesis about a new "space station race" happening.

 In the 80's the soviets got Mir up and running, while NASA started developping Freedom as a symetrical answer.
Nowadays China plans to build his own Mir-like modular space station. And ESA wants to fly astronauts to it.

Considering the size and expense of the ISS, any smaller space station to replace it would look a little silly, particularly for Congress. (I mean, by NASA - private space stations like Bigelow would be different).

LOP-G is far smaller than both ISS and Chinese stations, but at least it is not stuck in LEO. Cislunar space is kind of next logical medium past LEO.
Also, LOP-G being small makes it cheaper, cheap enough to be build and used in parallel with ISS, without crippling NASA shrinking HSF budget. The two stations lives may overlap for some years, as happened with Mir and ISS in the years 1999-2000.

Perhaps there is some coherence from Trump and NASA there ? Trump first said ISS would stop in 2024 and not 2028, hence another space station was necessary (Moon and Mars = too expensive). Then again, as said above, any new LEO station would be a whimper, so they went for cislunar space instead.

What is quite fun to watch (if not a little desprating in cynism), is ESA taking no risk, and having one iron in every fire.
One one hand, they have Orion SM and perhaps an element of LOP-G. Yet the same ESA discuss with the Chinese to fly astronauts to their future modular station.

The great winner in all this, is ESA, I'm telling you. They do not have the financial burden of a crew vehicle (Hermes...) nor a space station, yet their astronauts are welcome to both sides. Call this pragmatism or cynism, pick your choice !  ::)
Title: Re: Lunar Gateway Debate
Post by: Archibald on 07/30/2018 07:57 am
Warning: what follows are random musings, extrapolating ISS current crew and cargo vehicles to LOP-G.

Let's suppose that ISS operations stops in 2024. What will happen to the varied cargo / crew vehicles developed since COTS, in 2006 ?

- Cygnus
It's a cargo vehicle. Switching from LEO to cislunar space is a bit less difficult than for a crewed vehicle. I think Orbital ATK could launch upgraded Cygnus on Atlas 551 or Vulcan, to LOP-G, with few modifications.

- Dragon and Dragon 2
SpaceX case is very interesting. Dragon can certainly ride to LOP-G, it is just a matter of picking the "right" Falcon to send it high there. While "classic Falcon 9" is not powerful enough, the Heavy can certainly do the job (hint: the now cancelled circumlunar mission: delta-V is quite close to DRO)

As for Dragon 2 - we know it was build right from the start for interplanetary reentries. Then again, even if Dragon 2 does not survives ISS demise... SpaceX does not give a damn about it.
 Because BFS/BFR is coming, and Dragon 2 looks more and more as a a "ploy" to learn the intricacies of manned space vehicles, with financial help from NASA.

So how about Boeing CST-100 ? at first glance it was build for LEO and LEO only. Then again, so was Block I Apollo. I really think that, if the end of ISS in 2024 is confirmed (perhaps in 2020 or 2021) then Boeing will lose no time building a Block II CST-100 with a thicker heatshield and redundant systems for BLEO.

So at the end of the day: if ISS really stops in 2024 and is replace by LOP-G
- Orbital ATK can do it
- SpaceX does not really care
- but Boeing might be a little embarassed.

So I think an interesting question (and perhaps a seprate thread) might be: how can CTS-100 be adapted to LOP-G and cislunar space environment ?

Side note: the fourth man in the room, DreamChaser, might be even more embarassed. Lifting bodies and more generally, winged shapes, do not like very much reentries from interplanetary speed. It can be make to work, but it will be far, far trickier than a plain old capsule.

One can also wonder about Japan HTV. Once again, H2 can't lift it to DRO. Maybe this will encourage Japan to build a more powerful variant of the H3 that could reach DRO carrying an upgraded HTV ?

As for Russia, they have some interesting possibilities. While Federatsiya on Angara is the favored option, Proton and Soyuz could do the job, too. Another alternative is Constellation services "Soyuz to the Moon" plan, where the Soyuz meets a Briz or Block D on ISS orbit.

I bet you that, once Federatsiya in service, Russia will pass the old Soyuz to a private company and start selling LOP-G tourist flights.
Three options
- Soyuz on Angara
- Soyuz on Proton
- Soyuz meets a Block D or Briz in LEO (dual launch)
Title: Re: Lunar Gateway Debate
Post by: A_M_Swallow on 07/30/2018 08:51 am
Warning: what follows are random musings, extrapolating ISS current crew and cargo vehicles to LOP-G.

Let's suppose that ISS operations stops in 2024. What will happen to the varied cargo / crew vehicles developed since COTS, in 2006 ?

{snip}

IMHO There will be strong competition to take cargo and people to a LEO Bigelow spacestation.
Title: Re: Lunar Gateway Debate
Post by: A_M_Swallow on 07/30/2018 08:53 am
In engineering form follows function. The prime mission of the spacestation in lunar orbit needs agreeing. Then we can write the requirements.
Title: Re: Lunar Gateway Debate
Post by: TripleSeven on 07/30/2018 09:29 am
if one looks very carefully at the Lunar "thing" its clear, to me anyway that NASA is setting it up to "need" only the cargo resupply of the Cygnus. 

the crewing "duties" for intermittent stays will be done (in theory at least) with only the Orion module...but resupply and probably some kind of propulsion module would come from OSC. 

they have no real need for a Dragon or Starliner...because there are no perm crews.  what NASA is trying to do with the "gateway" is recreate Apollo, ie intermittent missions just going to a place near the moon not actually on it once or so a year.


As for ISS being over in 2024.
in my view if ISS is "over by 2024" and I dont for a moment think it will...the entire "Mo" for the private human presence in space grinds quickly to a halt

Bigelow or any one else has near zero change of orbiting and sustaining anything in orbit like a private space station without at least "federal anchoring" (ie the federal government sustaining the bulk of the operations cost).  None of these companies have "real" customers...none of them have real price points, and none of them have any real product to market, other then "just being in space" (ie what are you going to do on these modules?) .  None of them are even close to launch, but if they were to launch they are the crewed equivalent of Iridium, ie bankruptcy is just a short step away.

BFR I dont think has any chance of flying  by 2024 and even if it was...1) there is no hint as to what its actual cost will be "per seat" and 2) without a cost or a product to "go to" there is no real customer base for it.

Aside from the historical lack of any evidence of being able to make a technological leap like from dragon 2 to BFR:   there is no history in technology of a "transportation" node going from single digit number of customers per flight to larger than a B737 numbers in a single leap...particularly when the transportation "node" has to provide more than transportation.  I just got back from flying a total of nearly 600 people in two sectors...and at each end of the line my companies involvement with the passengers ended with the cabin chief saying "bye".  what they did at the "end of the line" is why they bought the ticket...not something the airline has to worry about.  If you loaded BFR up and took it to orbit, what would the people do there that was worth the cost of the ticket?

Without ISS, Dragon 2 and CST will have no reason to fly...and will be very expensive to maintain without a customer guaranteed customer base and will end.

ISS is the key to our next step in space, which really is privatizing ISS operations and expansion.  We need to create a destination worth having a transportation node to go to, and then the transportation node needs to evolve in way where each step is self sustaining.

having said that, if the lunar gateway needed "private crew lift and return" both Starliner and Dragon 2 would/could be modified to do the job.  I think that "both" could also form the basis for a lunar lander as well...as could OSC's system

But I really think that the next step is at some point moving the money being spent on things useless to subsidizing private industry creating new infrastructure on ISS, and using the excess capability of that infrastructure to make money ...

if we are lucky



Title: Re: Lunar Gateway Debate
Post by: speedevil on 07/30/2018 12:27 pm
BFR I dont think has any chance of flying  by 2024 and even if it was...1) there is no hint as to what its actual cost will be "per seat" and
'Less than a long distance economy ticket'. (of the order of $1000/pax, $1m per flight)

Admittedly, this is long term.
If BFS can hit its cost goal of $5M/flight, and be certified to fly people, it can make lots of money.
$15M per flight, with 100 people equals around $150K/ticket.
A third of that goes into incremental costs, a third into paying off the airframe, and a third is profit.
At around 30-60 flights, you're in profit.

Add an initial ten flights during qualification that launch re-purposed cryogenic tanks outfitted for comfort, and you can do a week in a small hotel room with windows on the earth, with almost no development. (said tanks are $2m or so for 400m^3, leak negligible heat either way even in atmosphere, have double skins, both quite capable of supporting pressure loads with a large margin.)

You could even do a similar facility in NRHO, though the fuel cost to get there is rather higher.

If you are doing similar with launchers that can't be fully reused, and are not as capable, it gets considerably harder and more expensive.
You absolutely can't afford to spend twenty tons of launch capability on facilities for one passenger.
(Note, these are assuming SpaceX was intending to do it themselves, hence do not include launch vendor profits).

Is it reasonable to cancel LOPG now, because of BFR/NA - no.
Is it reasonable to pencil it in as a 'risk' with a specified plan to pivot over to it, and terminate all of the contracts, yes.

Title: Re: Lunar Gateway Debate
Post by: ncb1397 on 07/30/2018 01:02 pm

One can also wonder about Japan HTV. Once again, H2 can't lift it to DRO. Maybe this will encourage Japan to build a more powerful variant of the H3 that could reach DRO carrying an upgraded HTV ?


See slide 5 and 6: https://www.nasa.gov/sites/default/files/files/04-Ueno_Lunar_Access_Architecture.pdf

If Japan doesn't have the rocket, we could provide that and they get credit based on the cargo vehicle contribution towards their share of operating costs.
Title: Re: Lunar Gateway Debate
Post by: TripleSeven on 07/30/2018 01:06 pm
BFR I dont think has any chance of flying  by 2024 and even if it was...1) there is no hint as to what its actual cost will be "per seat" and
'Less than a long distance economy ticket'. (of the order of $1000/pax, $1m per flight)

Admittedly, this is long term.
If BFS can hit its cost goal of $5M/flight, and be certified to fly people, it can make lots of money.
$15M per flight, with 100 people equals around $150K/ticket.
A third of that goes into incremental costs, a third into paying off the airframe, and a third is profit.
At around 30-60 flights, you're in profit.

Add an initial ten flights during qualification that launch re-purposed cryogenic tanks outfitted for comfort, and you can do a week in a small hotel room with windows on the earth, with almost no development. (said tanks are $2m or so for 400m^3, leak negligible heat either way even in atmosphere, have double skins, both quite capable of supporting pressure loads with a large margin.)



OK a few points.

Long term?  how do you define "Long term" ? 

"If BFS can hit its cost goal of $5M/flight, and be certified to fly people, it can make lots of money."

and with wings on Titan I can fly...but you tell me...what gives you confidence that a company that has never flown people in space, that is struggling to do that right now...and at a cost per seat about 10 times what you think that the entire flight can go for....can do that

where do you find this faith.   I am all ears.  Faith to me is the evidence of things hoped for the evidenceof things unseen...

You are going to a 5M flight ...when well has Elon flown anyone?

I dont think you and Elon are going to change technological history 
Title: Re: Lunar Gateway Debate
Post by: speedevil on 07/30/2018 03:25 pm
where do you find this faith.   I am all ears.  Faith to me is the evidence of things hoped for the evidenceof things unseen...

You are going to a 5M flight ...when well has Elon flown anyone?

I dont think you and Elon are going to change technological history

Any discussion of future plans has to rely to some degree on what vendors or proposers claim about their systems.
It is certainly stronger than 'no hints of' costs, when we have actual stated prices and costs.

It's at least a starting point to consider that they are correct, in the absence of either actual knowledge of the future, or carefully reasoned informed debate, which we certainly don't have enough data for for SpaceX, and only barely for SLS.

We will know a bit more about how plausible this is in the next year with B5 more rapid reuse, which alone could significantly help with costs for lunar gateway commercial launches.
And 2020 will tell us lots more - both on the SLS and BFS tests, as well as more reuse of B5 to nail down plausibility of rapid operational costs.

Is it reasonable to bet the farm on either SLS or BFS - IMO - no.
Title: Re: Lunar Gateway Debate
Post by: envy887 on 07/30/2018 05:43 pm
Orion/SLS (Block 1B) is supposed to have a 'surplus', co-manifested payload ability of about 10 metric tons. Perhaps the Orion could bring a tanker module with it each time to refuel a reusable Lander? Just an idea...

Hmmm.....  The Apollo LM's total propellant load (ascent and descent stages together) was about 11 tonnes.  An Apollo-style lander today could no doubt get away with less propellant by saving weight and burning, say, lox/methane or maybe even lox/hydrogen rather than NTO/Aerozine 50.  But the dry weight of the LM's ascent stage was less than a quarter that of the descent stage.  If you want a reusable lander, you're going to have to haul something roughly equivalent to the descent stage all the way from the surface back to the staging point, and that means burning a lot more propellant.  That propellant itself needs to be landed on the moon in the first place, so we're talking about a much larger vehicle.

Then there's the fact that, delta-V-wise, LOP-G is about 700 m/s further (one way) from the lunar surface than was the Apollo LM when it began its descent from LLO.

So I don't think Orion/SLS's 10-tonne co-manifested payload capability helps much for fueling a crewed lander.

It's around 5,000 m/s from EML-1 to the surface and back. That means storables need a mass ratio of about 5, methalox about 4, and hydrolox about 3.

So a hydrolox lander would have 10 t of prop, about 1 t of tanks, and 4 t for all other dry mass (assuming everything that goes down also goes up). Since the whole LEM, including both stages, was only ~4300 kg dry, that seems entirely feasible.

A methalox lander would be 10 t of prop, 0.5 t of tanks, and 2.8 t for everything else. The LEM ascent stage was ~2150 kg dry, so that would be tight but perhaps possible.

A storable lander would be 10 t of prop, 0.5 t of tanks, and 2 t for everything else. That's cutting it mighty close, but might be possible with balloon tank construction.
Title: Re: Lunar Gateway Debate
Post by: jongoff on 07/31/2018 05:50 am
I wanted to share a few thoughts, though I'll admit that I haven't had the time to read everyone else's comments in detail (though I did read a few). I should also mention up-front that my startup is involved in supporting at least one of the NextSTEP habitat teams, so I can't claim to be unbiased.

I'm a bit torn on LOP-G. I think a platonically ideal Gateway could be really enabling for lunar missions, but I'm also concerned that political pressures are unlikely to let Gateway be implemented in a very useful way, but I'm also concerned that canceling LOP-G (without also canceling SLS and/or Orion) is unlikely to yield the benefits that critics assume.

To me, a platonically ideal gateway would be one that was cost-capped (say the maximum NASA contribution would be $500M), done via a PPP, and not constrained in how it was implemented (ie not required to use SLS/Orion for assembly). It would probably be in a low-ish polar lunar orbit (I think Wingo suggested 500-1000km altitude), to make it maximally useful for supporting lander missions, would incorporate propellant depot and lander servicing capabilities, and would try to keep non-logistics science capabilities to the lowest of low-hanging fruit. Keep enough docking ports available that if international partners really want to contribute a module, they can, but keep it something off the critical path for logistics support. The cost cap keeps NASA from sucking the air out of the room. The PPP part keeps it to private companies that are actually serious about trying to turn it into something useful. The orbit is selected to optimize for lower-cost lunar landers, and eventual ISRU handling. The depot/logistics focus is where the Gateway would be most useful.

I just worry that politics is pushing LOP-G in a direction far from that platonic ideal, but canceling it is likely just going to lead to another HSF program of record that is an SLS/Orion make-work project that also doesn't really enable affordable lunar exploration/development either. I know Jason Crusan, and he's doing all he can to find creative ways to do this that try to avoid some of the pitfalls of NASA business-as-usual programs, but he's got his work cut out for him.

Sorry, I'm tired enough that I think that's all I can coherently say tonight,

~Jon
Title: Re: Lunar Gateway Debate
Post by: Archibald on 07/31/2018 11:03 am
Orion/SLS (Block 1B) is supposed to have a 'surplus', co-manifested payload ability of about 10 metric tons. Perhaps the Orion could bring a tanker module with it each time to refuel a reusable Lander? Just an idea...

Hmmm.....  The Apollo LM's total propellant load (ascent and descent stages together) was about 11 tonnes.  An Apollo-style lander today could no doubt get away with less propellant by saving weight and burning, say, lox/methane or maybe even lox/hydrogen rather than NTO/Aerozine 50.  But the dry weight of the LM's ascent stage was less than a quarter that of the descent stage.  If you want a reusable lander, you're going to have to haul something roughly equivalent to the descent stage all the way from the surface back to the staging point, and that means burning a lot more propellant.  That propellant itself needs to be landed on the moon in the first place, so we're talking about a much larger vehicle.

Then there's the fact that, delta-V-wise, LOP-G is about 700 m/s further (one way) from the lunar surface than was the Apollo LM when it began its descent from LLO.

So I don't think Orion/SLS's 10-tonne co-manifested payload capability helps much for fueling a crewed lander.

It's around 5,000 m/s from EML-1 to the surface and back. That means storables need a mass ratio of about 5, methalox about 4, and hydrolox about 3.

So a hydrolox lander would have 10 t of prop, about 1 t of tanks, and 4 t for all other dry mass (assuming everything that goes down also goes up). Since the whole LEM, including both stages, was only ~4300 kg dry, that seems entirely feasible.

A methalox lander would be 10 t of prop, 0.5 t of tanks, and 2.8 t for everything else. The LEM ascent stage was ~2150 kg dry, so that would be tight but perhaps possible.

A storable lander would be 10 t of prop, 0.5 t of tanks, and 2 t for everything else. That's cutting it mighty close, but might be possible with balloon tank construction.

Dang. So much for such a large and powerful rocket as SLS. Is Orion SO heavy that it let only 10 mt to a lander ? Oh boy... :( 
Title: Re: Lunar Gateway Debate
Post by: envy887 on 07/31/2018 03:31 pm
Orion/SLS (Block 1B) is supposed to have a 'surplus', co-manifested payload ability of about 10 metric tons. Perhaps the Orion could bring a tanker module with it each time to refuel a reusable Lander? Just an idea...

Hmmm.....  The Apollo LM's total propellant load (ascent and descent stages together) was about 11 tonnes.  An Apollo-style lander today could no doubt get away with less propellant by saving weight and burning, say, lox/methane or maybe even lox/hydrogen rather than NTO/Aerozine 50.  But the dry weight of the LM's ascent stage was less than a quarter that of the descent stage.  If you want a reusable lander, you're going to have to haul something roughly equivalent to the descent stage all the way from the surface back to the staging point, and that means burning a lot more propellant.  That propellant itself needs to be landed on the moon in the first place, so we're talking about a much larger vehicle.

Then there's the fact that, delta-V-wise, LOP-G is about 700 m/s further (one way) from the lunar surface than was the Apollo LM when it began its descent from LLO.

So I don't think Orion/SLS's 10-tonne co-manifested payload capability helps much for fueling a crewed lander.

It's around 5,000 m/s from EML-1 to the surface and back. That means storables need a mass ratio of about 5, methalox about 4, and hydrolox about 3.

So a hydrolox lander would have 10 t of prop, about 1 t of tanks, and 4 t for all other dry mass (assuming everything that goes down also goes up). Since the whole LEM, including both stages, was only ~4300 kg dry, that seems entirely feasible.

A methalox lander would be 10 t of prop, 0.5 t of tanks, and 2.8 t for everything else. The LEM ascent stage was ~2150 kg dry, so that would be tight but perhaps possible.

A storable lander would be 10 t of prop, 0.5 t of tanks, and 2 t for everything else. That's cutting it mighty close, but might be possible with balloon tank construction.

Dang. So much for such a large and powerful rocket as SLS. Is Orion SO heavy that it let only 10 mt to a lander ? Oh boy... :(

That's for SLS Block 1B, which won't be available before 2024. Block 1 can only send Orion with no co-manifested payload, so if you want a lander before then it will need dedicated launches. Falcon Heavy is the only available vehicle that can send much more than 10 t to TLI, it could be used to send tanks of storable propellants to the Gateway.
Title: Re: Lunar Gateway Debate
Post by: DreamyPickle on 07/31/2018 04:24 pm
The "Gateway as Depot" doesn't sound very convincing. If you want to do ISRU on the moon and produce propellant it why not just keep the fuel on the moon in a permanently shadowed area?

A depot allows smaller intermediate craft but with fuel production on the moon you could build a hydrolox lander sized to go from the Moon's surface to Earth in a single reusable stage.

And even if you want to do refueling in a lunar orbit it would be better to do that away from any habitats for safety reasons.
Title: Re: Lunar Gateway Debate
Post by: ncb1397 on 07/31/2018 04:37 pm

And even if you want to do refueling in a lunar orbit it would be better to do that away from any habitats for safety reasons.

When Soyuz needs to relocate to a different docking port, they undock and fly to the new docking port. You could always use a similar procedure to get a few kilometers out during fueling ops. The contention that humans can't be connected to a fuel tank is just not realistic. Even with an escape system, you need a sizable amount of fuel for that.  Regardless, LOP-G is optionally manned so it can provide both roles as crewed habitat and uncrewed gas station with the added benefit that any required maintenance by crew can be done periodically as it is a crew waypoint.
Title: Re: Lunar Gateway Debate
Post by: spacenut on 07/31/2018 04:41 pm
A fuel depot would be better at one of the "L" points.  A large "in space only" mother ship or craft could refuel on it's way to Mars.  It could also help refuel either methane or hydrogen from earth with moon LOX for the reusable lander.  Even spacecraft (capsules) that could barely make it to the L point could refuel for a return trip to earth.  This would allow more companies and people to get there. 

BFR could have a 6 person capsule in the nose capable of ejection in an emergency (which NASA likes) and still have 100 tons of cargo that could be delivered to an L point or even a LOP-G point, even if it is 2026 or later, it would be able to deliver more with refueling than SLS with one shot launches. 

With cancellation of SLS and ISS, NASA money could be spent on FH, New Glenn, Vulcan, and other launches to build, supply, and maintain a lunar station. 
Title: Re: Lunar Gateway Debate
Post by: Lunadyne on 07/31/2018 05:47 pm
Unfortunately, we have to understand a little history to understand where we are now with this whole LOP-G thing.  It boils down to a few main elements:

-NASA Rockets;
-Delta-V and stable Lunar orbits;
-MARS plans

With regards to rockets, the current troubles can be traced back to the early 2000s and Bush's Vision for Spaace Exploration.  It stated that NASA would look to the commercial markets for launch solutions (and have a commercial fly-off in 2008), and not build its own rocket unless it really had to do so based on some exigent requirement.  So NASA figured out that their MARS exploration project needed a 40 metric tonne (mt) capsule to meet its mission requirements.  None of the then EELVs could handle such a payload, as they were targeted to the then market throw-weight of about 20 mt.  NASA later walked that back to 30 mt, but such a massive capsule required a NASA-designed rocket to make it useful.  And so was born ARES (MARS, get it?) and now SLS.

Thing is, at the time, crewed capsules to date had tended to be in the 6-10 mt range, which the EELVs could readily handle (were they "human rated"), and the latest iterations seemed to be in the same mass range.  Why NASA's capsule had to be 3-5x the then market was never really explained other than MARS.  Since NASA's plans were to launch to MARS from LEO, that's where the big rocket they were designing would be delivering its payloads. 

Recall that from LEO you need about 5 mt of mass to put 1 mt of mass on the Lunar surface, or from another perspective, propellant in LEO is going to be 75-80% of the mass package.  Couple this with the oversized mass of Orion, and your payload delivery capabilities Moon-wise are significantly decreased.  Certainly not enough to get Orion to the Moon.  So we go back to the 1960s when the Surveyor probes were being launched and our rockets were still building their throw-weight capabilities, and they could see that the proposed LOP-G orbit could touch an out-of-plane transfer orbit as was studied back in the day to get the Surveyor probes to higher inclination landing sites on the Moon.

The LOP-G NRHO orbit is the result of a lot of work NASA did back during the Asteroid Retrieval Mission days, when they were trying to find stable Lunar orbits that minimized the perturbations from the mascons.  Generally, stay as far away from the Moon as possible (distant retrograde orbit) or spend as little time there as possible (NRHO and other Molniya-type orbits that whip around the Moon and loiter way out (by the way, I don't see how it's a halo orbit if it goes around the Moon)).

So NASA could patch in a solution, basically taking a taxi to the destination from the last stop on the SLS rail line.  A really, really nice taxi.  It could serve as a piece of the MARS architecture, but it's an awkward one, just as it is an awkward solution for the Moon.  But NASA has developed no real strategy regarding the Moon, just a bunch of unrelated tactics, and so is left cobbling together Rube Goldberg solutions to meet Congress' idiot demands.

As other commenters have pointed out, EML-1 is really your best transport nexus solution.  For many reasons:
-It's accessible from all LEO orbital inclinations for about the same delta-V (<4 km/s);
-It's easier to go EML-1 to GEO to EML-1 (<4 km/s) than from LEO to GEO;
-It provides 24/7 access to anywhere on the Moon (<4 km/s);
-It is a clutter-free worksite, as untended items will be perturbed into one or the other gravity wells;
-It's a better place to deploy Solar Sails, away from the weird math of trying to deal with intense Sunlight and intense Earthlight and their constant shifting in relation to one another while the sail deploys.;
-It's an on-ramp to the Inter-Planetary Superhighways, which would allow us to deploy a network of Hubble-like probes around the Solar system for a constant stream of data compared with our current decadal megamissions to one destination or another.
-In conjunction with EML-3 it is a good place to keep an eye on cis-GEO activity;
-You can also go asteroid hunting there.  Picture a lighthouse lain on the line connecting the center-of-mass of the Earth and Moon.  The rotation of the lamp represents the sweeping of the sky by the probe.  Over the course of a month, it will be able to develop a really nice data set of nearby objects, especially the Sunward blindsiders that keep surprising us.
-With propellant depot capabilities in LEO, at EML-1, and on the Moon, you can go to/from anywhere in cislunar space, or at least get to a gas station, for <4 km/s, providing a nice propulsion envelope for engineers to work with.  What's likely going to happen is that given the approximately 80% propellant mass in LEO requirement noted above, and that LOX/LH is approximately 7/8ths LOX by mass, then Lunar oxygen is going to be finding its way to LEO pretty quickly, and you'll see dedicated launches of LH from Earth just-in-time for needs in LEO, and points beyond.

The list goes on...

So here's what's going to happen.  This is all strurm und drang, signifying nothing.  Trump's Moon pivot is unstrategic, and serves mainly for drama.  NASA, besotted with MARS!, was caught off guard and is scrambling.  When the presidency changes, NASA will immediately try to pivot back to MARS, and will discard the LOP-G faster than yesterday's fish.  Given the current glacial pace of progress at NASA, this change of administration will occur before any real work beyond PDR will have been done on LOP-G, so any sunk costs shouldn't incur too much in sunk costs.  NASA will again revisit their MARS architecture again, and Bob Zubrin will again publish a more directly MARS version. 

Maybe I'm just cynical and jaded because I've seen too much, but NASA has effectively become a force for stasis, not a force for change.  If they could, they'd still be launching the STS today.  The only real hope is for a substantial rejuvenation at NASA, where those who haven't been able to get anything done (for decades...) finally cede the way for others to give it a go.  There is a fine young generation of space leaders out there, worthy of a shot at making things happen, and the way things are are not the way things must be.  (Except for the physics part) 

What's really weird is that the situation we find ourselves in now, where nigh 50 years after we put people on the Moon we can't put people in orbit, the result of politics and friends working tax-dollar cash flows to their friends and working on projects that will always be finished "Real Soon Now", isn't too different from the result that, say, a nation like China might desire and work towards, that of a country so mired in stasis that its people can't even get to cislunar space while it itself puts assets in cislunar space and on the Moon, delivers crews to orbit, and has probes move from destination to destination in cislunar space.  Like something out of a bad spy novel, but actually happening in real life.  Or bad sci-fi, where the same thing keeps getting done over and over and the time loop keeps repeating the same lack of results.

So I'm having a hard time getting excited about the LOP-G, just like SLS.  They strike me as more like the current crop of STEM stuff in education, craft/make-busy projects with a thin veneer of science/engineering thrown on for legitimacy, rather than real exercises in making progress.  We have the tools at hand to make real progress in spreading human activity into cislunar space and out to translunar space throughout the Solar system.  We're just not using them right.  We could be, but we're not.
Title: Re: Lunar Gateway Debate
Post by: ncb1397 on 07/31/2018 06:29 pm
Quote
Thing is, at the time, crewed capsules to date had tended to be in the 6-10 mt range

???

Mercury -1,360 kg
Gemini - 3,851 kg
Apollo - 28,801 kg

Actually, none of them were in the 6-10 mt range.

edit: I guess we are looking at foreign sources

Soyuz - 7,150 kg
Shenzhou - 7,840 kg
Title: Re: Lunar Gateway Debate
Post by: spacenut on 07/31/2018 07:44 pm
How much does Dragon 2 weigh?  Isn't it in the 10 mt range? 
Title: Re: Lunar Gateway Debate
Post by: Lunadyne on 08/01/2018 01:25 am
Actually, I was thinking more along the lines of:

Apollo CM: 5.8 Mt
X-38 CRV: 8.2 Mt
Soyuz TMA: 7.2 Mt
Shenzhou: 7.8 Mt
Dragon: 8 Mt
Dreamchaser: 9 Mt
CST-100: 13 Mt

Various CEV concepts were also in this range; couldn't find a value for the New Glenn capsule. 

All values taken from Encyclopedia Astronautica.
Title: Re: Lunar Gateway Debate
Post by: ncb1397 on 08/01/2018 06:38 am

Apollo CM: 5.8 Mt
X-38 CRV: 8.2 Mt
Soyuz TMA: 7.2 Mt
Shenzhou: 7.8 Mt
Dragon: 8 Mt
Dreamchaser: 9 Mt
CST-100: 13 Mt


Well, if you aren't counting the service module for Apollo, you might as well add Orion at ~10.3 Mt. But your list mixes numbers with service module included and numbers without service module included.
Title: Re: Lunar Gateway Debate
Post by: Steven Pietrobon on 08/01/2018 07:21 am
With regards to rockets, the current troubles can be traced back to the early 2000s and Bush's Vision for Spaace Exploration.  It stated that NASA would look to the commercial markets for launch solutions (and have a commercial fly-off in 2008), and not build its own rocket unless it really had to do so based on some exigent requirement.  So NASA figured out that their MARS exploration project needed a 40 metric tonne (mt) capsule to meet its mission requirements.

I don't remember NASA ever developing a 40 t capsule. ESAS from 2005 used as reference a 5.5 m diameter 9.51 t capsule and 13.65 t service module (SM) for a total mass of 23.16 t and a delta-V of 1.7 km/s. By comparison, Orion has a 5.0 m diameter 9.89 t capsule and 15.46 t SM for a total mass of 25.35 t and a delta-V of 1.2 km/s.
Title: Re: Lunar Gateway Debate
Post by: Archibald on 08/01/2018 05:43 pm
Actually, I was thinking more along the lines of:

Apollo CM: 5.8 Mt
X-38 CRV: 8.2 Mt
Soyuz TMA: 7.2 Mt
Shenzhou: 7.8 Mt
Dragon: 8 Mt
Dreamchaser: 9 Mt
CST-100: 13 Mt

Various CEV concepts were also in this range; couldn't find a value for the New Glenn capsule. 

All values taken from Encyclopedia Astronautica.

Heresy ! Blasphemy ! You mentionned Astronautix on this forum. Be warned, Jim will soon roast and burn you at the stake. :p

https://www.youtube.com/watch?v=e_KOpJ2bE3o

More seriously, astronautix is useful for a start, but not reliable. It's a space wikipedia.
Title: Re: Lunar Gateway Debate
Post by: TripleSeven on 08/01/2018 06:25 pm
where do you find this faith.   I am all ears.  Faith to me is the evidence of things hoped for the evidenceof things unseen...

You are going to a 5M flight ...when well has Elon flown anyone?

I dont think you and Elon are going to change technological history

Any discussion of future plans has to rely to some degree on what vendors or proposers claim about their systems.
It is certainly stronger than 'no hints of' costs, when we have actual stated prices and costs.

It's at least a starting point to consider that they are correct, in the absence of either actual knowledge of the future, or carefully reasoned informed debate, which we certainly don't have enough data for for SpaceX, and only barely for SLS.

We will know a bit more about how plausible this is in the next year with B5 more rapid reuse, which alone could significantly help with costs for lunar gateway commercial launches.
And 2020 will tell us lots more - both on the SLS and BFS tests, as well as more reuse of B5 to nail down plausibility of rapid operational costs.

Is it reasonable to bet the farm on either SLS or BFS - IMO - no.

there are two viewpoints to look at this...first is from that of a "policy maker" which can substitute for an "investor" in terms of "realities" and the other is history

in terms of the latter, there is no history in technology of a leap from say an optimal Block V operation (ie assuming 10 flight economic reuse) to BFR.  It didnt happen in personal computers, satellite com systems, airplanes, cars, ships,

what Musk is sort of claiming is that we can go from the Boeing 247 to the Boeing 707 even when we dont have the 247. 

so from a policy investor standpoint I dont think that anyone is counting on that happening. 

and I would be surprised if it does

and worse I dont think that anything changes in the policy of US spaceflight until 1) there is some politican who has some sort of vision or interest in spaceflight who pushes policy change, 2) there is another catastrophic accident and or 3 something happens which makes money in space with the use of humans...

because really SLS /Orion /station etc are not concerned about any real goals in space just the space industrial complex

I think at some point in the next 10 years we will change policy, I am not for sure which one of the three reasons happens first.
Title: Re: Lunar Gateway Debate
Post by: Lunadyne on 08/01/2018 06:38 pm
Yes, let's take a closer look at the numbers, as it only reinforces my point that NASA was able to get itself a rocket building project because its capsule was designed to be too big for the then market of 8-10 Mt.

.CapsuleSvc ModTotalPropWet
.MassMassDry MassMassMass
Soyuz TMA4,3002,0206,3209007,220
Shenzhou4,7402,0006,8401,0007,840
Dragon....8,000
CST-100....13,000
Dreamchaser....9,000
X-38 CRV....8,163
CEV t/Space..3,7001,3005,000
......
CEV SpaceHab8,5001,50010,00010,00020,000
CEV Boeing..10,5009,50020,000
CEV Andrews10,4942,85613,3507,70721,057
......
CEV Orion9,5064,38013,8869,26723,153
Orion MPCV10,3876,46116,8489,00025,848
Apollo CM5,8066,11011,84118,48830,329

So the first group is vehicles that are currently operational for crew delivery to orbit, i.e. "the market", as well as proposed crew delivery vehicles, some of which will be available "Real Soon Now©".  But basically all stuff that was being looked at in the timeframe I was discussing.  Note that with the exception of Boeing's CST all of the vehicles' wet masses fall within an envelope of 5-9 Mt.  I had used 8-10 Mt as a thumbnail.  Close enough.

Why did I use thumbnails?  As can be seen in the table above, there are a lot of gaps as far as readily available data goes, and as Archibald notes Astronautix is a good place to start but there are better sources like the Isakowitz launcher guide.  I have an older edition, and didn't feel like digging it out of the Lunar Library.  So while I know the engineers love their precision numbers pr0n, there's not enough of it to make anything other than general statements.

The second group is from the CEV round of proposals in 2005 while NASA was considering 'spirals' of development up the TRL.  These are generally proposals for delivering crews to the Moon and potentially beyond (i.e. MARS!), and tended to max out the roughly 20 Mt delivery capabilities of the EELVS and others then on the market.  This was the group that was supposed to lead to a crewed vehicle flyoff in 2008.

The last group is the NASA vehicles.  The CEV Orion evolved into Orion MPCV, and it looks like the Boeing CEV evolved into the CST-100.  Curiously, again with the exception of Boeing, all of the fully fueled up and ready to go vehicles in the first group mass less than just the dry mass of the Orion capsule.  I had used a comparison of 3-5x the market, IIRC, and from the wet mass numbers above it looks to be 2.87-5.17x.  Again, close enough.

I did exclude the Apollo SM mass initially, as I considered its inclusion inapt, given that it also had cargo duty carrying the LEM to the Moon, which isn't really the case with any of the vehicles I was considering.  That's why I included the all-in stacks from the CEV studies this time around, as they provide a rough comparison with the Apollo stack.

So yeah, I stand by what I said.  NASA wanted their own rocket project and they put their thumb on the scale to make it happen, even if the VSE said otherwise.  The then market for crews to orbit was in the 8-10 Mt range (because that's where the data points cluster), but that wasn't good enough.  I don't entirely blame NASA; mendacious idiots in Congress deserve more than a fair share of the blame, and clueless political appointments from the Executive branch haven't helped.  But in the end it's NASA that has to execute and deliver results.

...
Title: Re: Lunar Gateway Debate
Post by: speedevil on 08/01/2018 08:54 pm
in terms of the latter, there is no history in technology of a leap from say an optimal Block V operation (ie assuming 10 flight economic reuse) to BFR.  It didnt happen in personal computers, satellite com systems, airplanes, cars, ships,

what Musk is sort of claiming is that we can go from the Boeing 247 to the Boeing 707 even when we dont have the 247. 

so from a policy investor standpoint I dont think that anyone is counting on that happening. 

and I would be surprised if it does

What would your view have been in 2010 of a claim that all F9 first stages would be able to land, with a 100% success rate? (25 in a row now?)
Or that the same stage would be reusable over 100 times? (100 is the goal for this version, not some nebulous future version IIRC. 10 was mentioned at some point for the prior version).

I note that only lasting 100 reuses of BFR/S would be quite irrelevant for all services but bulk passenger transport.
It would only add perhaps $2-3M to launch costs, certainly being capable of any reasonable lunar ambitions.

Title: Re: Lunar Gateway Debate
Post by: envy887 on 08/02/2018 01:05 am
where do you find this faith.   I am all ears.  Faith to me is the evidence of things hoped for the evidenceof things unseen...

You are going to a 5M flight ...when well has Elon flown anyone?

I dont think you and Elon are going to change technological history

Any discussion of future plans has to rely to some degree on what vendors or proposers claim about their systems.
It is certainly stronger than 'no hints of' costs, when we have actual stated prices and costs.

It's at least a starting point to consider that they are correct, in the absence of either actual knowledge of the future, or carefully reasoned informed debate, which we certainly don't have enough data for for SpaceX, and only barely for SLS.

We will know a bit more about how plausible this is in the next year with B5 more rapid reuse, which alone could significantly help with costs for lunar gateway commercial launches.
And 2020 will tell us lots more - both on the SLS and BFS tests, as well as more reuse of B5 to nail down plausibility of rapid operational costs.

Is it reasonable to bet the farm on either SLS or BFS - IMO - no.

there are two viewpoints to look at this...first is from that of a "policy maker" which can substitute for an "investor" in terms of "realities" and the other is history

in terms of the latter, there is no history in technology of a leap from say an optimal Block V operation (ie assuming 10 flight economic reuse) to BFR.  It didnt happen in personal computers, satellite com systems, airplanes, cars, ships,

what Musk is sort of claiming is that we can go from the Boeing 247 to the Boeing 707 even when we dont have the 247. 

so from a policy investor standpoint I dont think that anyone is counting on that happening. 

and I would be surprised if it does

and worse I dont think that anything changes in the policy of US spaceflight until 1) there is some politican who has some sort of vision or interest in spaceflight who pushes policy change, 2) there is another catastrophic accident and or 3 something happens which makes money in space with the use of humans...

because really SLS /Orion /station etc are not concerned about any real goals in space just the space industrial complex

I think at some point in the next 10 years we will change policy, I am not for sure which one of the three reasons happens first.

There was no jump in history like Saturn 1 to Saturn V (in terms of payload), or from Apollo to the Shuttle (in terms of entry vehicle size?

Ok, $5M per flight would be quite a jump, but how low does it really need to be in order for a real lunar exploration plan to be viable? There's a whole lot of margin between $1 billion for an SLS (with no crew vehicle or lander) and $5 million for a BFR.

Falcon Heavy is already flying and is pretty reusable. Say BFR is 5x as capable, just as reusable (as Block 5), and the same price (~100 M). That actually happens fairly frequently in disruptive technology products, particularly in cutting edge non-consumer products like supercomputers.
Title: Re: Lunar Gateway Debate
Post by: ppb on 08/02/2018 03:14 am
where do you find this faith.   I am all ears.  Faith to me is the evidence of things hoped for the evidenceof things unseen...

You are going to a 5M flight ...when well has Elon flown anyone?

I dont think you and Elon are going to change technological history

Any discussion of future plans has to rely to some degree on what vendors or proposers claim about their systems.
It is certainly stronger than 'no hints of' costs, when we have actual stated prices and costs.

It's at least a starting point to consider that they are correct, in the absence of either actual knowledge of the future, or carefully reasoned informed debate, which we certainly don't have enough data for for SpaceX, and only barely for SLS.

We will know a bit more about how plausible this is in the next year with B5 more rapid reuse, which alone could significantly help with costs for lunar gateway commercial launches.
And 2020 will tell us lots more - both on the SLS and BFS tests, as well as more reuse of B5 to nail down plausibility of rapid operational costs.

Is it reasonable to bet the farm on either SLS or BFS - IMO - no.

there are two viewpoints to look at this...first is from that of a "policy maker" which can substitute for an "investor" in terms of "realities" and the other is history

in terms of the latter, there is no history in technology of a leap from say an optimal Block V operation (ie assuming 10 flight economic reuse) to BFR.  It didnt happen in personal computers, satellite com systems, airplanes, cars, ships,

what Musk is sort of claiming is that we can go from the Boeing 247 to the Boeing 707 even when we dont have the 247. 

so from a policy investor standpoint I dont think that anyone is counting on that happening. 

and I would be surprised if it does

and worse I dont think that anything changes in the policy of US spaceflight until 1) there is some politican who has some sort of vision or interest in spaceflight who pushes policy change, 2) there is another catastrophic accident and or 3 something happens which makes money in space with the use of humans...

because really SLS /Orion /station etc are not concerned about any real goals in space just the space industrial complex

I think at some point in the next 10 years we will change policy, I am not for sure which one of the three reasons happens first.

There was no jump in history like Saturn 1 to Saturn V (in terms of payload), or from Apollo to the Shuttle (in terms of entry vehicle size?

Ok, $5M per flight would be quite a jump, but how low does it really need to be in order for a real lunar exploration plan to be viable? There's a whole lot of margin between $1 billion for an SLS (with no crew vehicle or lander) and $5 million for a BFR.

Falcon Heavy is already flying and is pretty reusable. Say BFR is 5x as capable, just as reusable (as Block 5), and the same price (~100 M). That actually happens fairly frequently in disruptive technology products, particularly in cutting edge non-consumer products like supercomputers.
Your comparison to computer technology is very apropos. We're on an exponential trendline for all forms of technology, including spaceflight. So the comparison of the development of the BFR with the 707 or Saturn V overlooks this fact.
Title: Re: Lunar Gateway Debate
Post by: TripleSeven on 08/02/2018 08:48 am
in terms of the latter, there is no history in technology of a leap from say an optimal Block V operation (ie assuming 10 flight economic reuse) to BFR.  It didnt happen in personal computers, satellite com systems, airplanes, cars, ships,

what Musk is sort of claiming is that we can go from the Boeing 247 to the Boeing 707 even when we dont have the 247. 

so from a policy investor standpoint I dont think that anyone is counting on that happening. 

and I would be surprised if it does

What would your view have been in 2010 of a claim that all F9 first stages would be able to land, with a 100% success rate? (25 in a row now?)
Or that the same stage would be reusable over 100 times? (100 is the goal for this version, not some nebulous future version IIRC. 10 was mentioned at some point for the prior version).

I note that only lasting 100 reuses of BFR/S would be quite irrelevant for all services but bulk passenger transport.
It would only add perhaps $2-3M to launch costs, certainly being capable of any reasonable lunar ambitions.

I would say now what I said then...that they will eventually figure out how to recover the first stage...the question never was, "can they figure out how to do it" (its the same question with the second stage) the question is "can they reuse a stage economically and still have a reasonable payload" 

the answer to the latter now is clear...its not completely clear what the answer to the first part is.  they have resued a first stage, but no one outside the company really knows the economics of that, how much assets it took to "reuse it" and of course we are still waiting to see how that works out on the Block 5.

we will know soon :)

MY POINT :) was about the magnitude of the steps not so much their direction (although that is also interesting)  and it is about "what is pushing those steps"

Spaceflight is compared to aviation a lot...but its not a good comparison.  in fact the only comparison to spaceflight that I think NOW is valid is operation below the oceans.

all airplane manufacturers had to do was master the technology; there were destinations, airplanes simply replaced eventually trains and now busses...there is no comparable reason to do human spaceflight, as it stands right now there is nothing of value that humans do that is worth the cost of them being there

BLock 5 hopefully will lower the cost of humans getting to space and staying there by attacking the lift equation...hopefully BFR will lower it even further, although I suspect you and I differ as to what those numbers are more likely to end up as

BUT right now nothing is done of value that equals cost by humans...and this is why thing like Lunar Gateway and ISS are important...the only importance that they have is the federal government spending "cash" to develop and operate them, cash which SHOULD be used to sustain such efforts as Blue Origin and SpaceX human spaceflight, Axiom, Bigelow etc... until SOMEONE can hit the magic formula and find something that starts the private infusion of cash to push the development cycle

this is not "new".  The Federal government after having failed with the Advent communications satellite, through NASA and Hughes built Syncom 1.  the sat communication development cycle then started but itw as very slow with VERY small and very measured increases in capability...until oh the mid 70's when 1) the industry was pretty well established and 2) the rules changed so that private companies could get into the communications game and compete domestically with satellites.  Westar and Anik were the real "change".

before long comsats were increasing in capability at an enormous rate...and today of course drive everything in spaceflight.

we have gone nearly 50 years since Apollo 11 (well 49_) and we are no where near the "chicken" that hatches and evolves to Anik and Westar...and until we get that...US federal subsidies are essential but also substantial massive cost reductions are in my view...unlikely

Title: Re: Lunar Gateway Debate
Post by: TripleSeven on 08/02/2018 08:54 am




Question
Ok, $5M per flight would be quite a jump, but how low does it really need to be in order for a real lunar exploration plan to be viable? There's a whole lot of margin between $1 billion for an SLS (with no crew vehicle or lander) and $5 million for a BFR.




we are spending 3 billion a year more or less on the space station.  I suspect that if we could get a lunar "exploration program" (which I assume by this you mean with people...uncrewed exploration is quite cheaper) down to 3 billion a year for a comparable effort such as ISS...the nation would likely do it

if that were the only choice...but the choice seems to be lunar exploration versus supporting the NASA space industrial complex (ie SLS and Orion) and clearly the politics favor the latter...sad

that choice to me is mind boggling actually
Title: Re: Lunar Gateway Debate
Post by: speedevil on 08/02/2018 10:57 am
Question
Ok, $5M per flight would be quite a jump, but how low does it really need to be in order for a real lunar exploration plan to be viable? There's a whole lot of margin between $1 billion for an SLS (with no crew vehicle or lander) and $5 million for a BFR.

There is a massive trade space between lander and base capability, and launch cost.

At one extreme, you have an ultra-light nuclear powered rover able to set up ISRU and power and ... in a package that can setup a whole base on its own, and populate it using an efficient hydrogen/oxygen engined lander capable of aerobraking.

At the other, you've got large, thick, preassembled habs housing a dozen people in a structure that can be assembled from near off-the-shelf parts. Start with 9m aluminium tank rated to 150PSI, and stop once you hit a hundred tons weight including water shielding.

This almost makes discussion pointless, though reasonable assumptions can probably be made that the first system is not going to cost under ten billion dollars - without shipping.

The absolute first step IMO should be risk/cost reduction.

Getting propellant transfer cost in orbit to a reasonable TRL would allow all sorts of things that have previously been impractical.
Similarly, rendevous in orbit, obviously required for the first helps.

Proper operations challenges that can be entered into with little investment.

For example, strip down and reassemble a VW Bug engine using a 3s delay link to a standard industrial robot arm in under a week for $1M.

Similarly, a test of standard industrial arms, lightly modified for vacuum, in orbit.

Any solution to potential problems that might take a hundred million dollars of engineering to get 100% assurance will work, but there are semi-plausible off-the-shelf options for must be investigated first.

Contracts must be structured so that going to Walmart and buying something that works adequately is more profitable than engineering a complex solution. (probably not actually Walmart in most cases.)

This is all largely launcher agnostic, and would help everyone.

Trying to do LOPG where every element is likely to cost a billion dollars, when there is risk reduction that could be done that would significantly reduce the cost of every element, without being willing to invest a half billion in say five test launches is just insane.

Nomatter if you're launching it on Rocketlabs or SLS.




Title: Re: Lunar Gateway Debate
Post by: TripleSeven on 08/02/2018 11:35 am
Speeddevil

I actually think a lunar base is very premature...

one of the two reasons I would be for a lunar gateway is if the gateway was in an orbit and configured to support a reusable lander so that serious and repeated crewed exploration (and uncrewed) could be executed from it

this argues for uncrewed and crewed reusable vehicles that can be serviced from the gateway...and that of course includes refueling
Title: Re: Lunar Gateway Debate
Post by: envy887 on 08/02/2018 02:24 pm
Speeddevil

I actually think a lunar base is very premature...

one of the two reasons I would be for a lunar gateway is if the gateway was in an orbit and configured to support a reusable lander so that serious and repeated crewed exploration (and uncrewed) could be executed from it

this argues for uncrewed and crewed reusable vehicles that can be serviced from the gateway...and that of course includes refueling

But if you do orbital refueling and reuse then the Gateway doesn't need to be in lunar orbit; in fact you don't necessarily need a Gateway at all.

So the question to be answered is "Is the lunar orbit Gateway the optimal concept for promoting exploration"? And is that optimization technical or political.
Title: Re: Lunar Gateway Debate
Post by: envy887 on 08/02/2018 02:26 pm
its not completely clear what the answer to the first part is.  they have resued a first stage, but no one outside the company really knows the economics of that, how much assets it took to "reuse it"

You saying this doesn't make it true.
Title: Re: Lunar Gateway Debate
Post by: TripleSeven on 08/02/2018 03:11 pm
its not completely clear what the answer to the first part is.  they have resued a first stage, but no one outside the company really knows the economics of that, how much assets it took to "reuse it"

You saying this doesn't make it true.

OK so you know what it took in terms of dollars to reuse the Block IV's?

Title: Re: Lunar Gateway Debate
Post by: TripleSeven on 08/02/2018 03:13 pm
Speeddevil

I actually think a lunar base is very premature...

one of the two reasons I would be for a lunar gateway is if the gateway was in an orbit and configured to support a reusable lander so that serious and repeated crewed exploration (and uncrewed) could be executed from it

this argues for uncrewed and crewed reusable vehicles that can be serviced from the gateway...and that of course includes refueling

But if you do orbital refueling and reuse then the Gateway doesn't need to be in lunar orbit; in fact you don't necessarily need a Gateway at all.

So the question to be answered is "Is the lunar orbit Gateway the optimal concept for promoting exploration"? And is that optimization technical or political.

if the lunar gateway is at a libration point the fuel needed for a two way trip is less than if the drop off point is anywhere else...
Title: Re: Lunar Gateway Debate
Post by: envy887 on 08/02/2018 04:34 pm
its not completely clear what the answer to the first part is.  they have resued a first stage, but no one outside the company really knows the economics of that, how much assets it took to "reuse it"

You saying this doesn't make it true.

OK so you know what it took in terms of dollars to reuse the Block IV's?

On average less than substantially less than half the dollars of a new one. Many people here could give you na educated estimate of the actual dollar amount, but it really doesn't matter to the economics of reuse. The only thing that matters is "is it significantly cheaper than a new one", and the answer to that is indisputable.
Title: Re: Lunar Gateway Debate
Post by: envy887 on 08/02/2018 04:37 pm
Speeddevil

I actually think a lunar base is very premature...

one of the two reasons I would be for a lunar gateway is if the gateway was in an orbit and configured to support a reusable lander so that serious and repeated crewed exploration (and uncrewed) could be executed from it

this argues for uncrewed and crewed reusable vehicles that can be serviced from the gateway...and that of course includes refueling

But if you do orbital refueling and reuse then the Gateway doesn't need to be in lunar orbit; in fact you don't necessarily need a Gateway at all.

So the question to be answered is "Is the lunar orbit Gateway the optimal concept for promoting exploration"? And is that optimization technical or political.

if the lunar gateway is at a libration point the fuel needed for a two way trip is less than if the drop off point is anywhere else...

Is it, though? You still have to spend ~700 m/s each way stopping into and out of the libration point. They are more convenient in terms of trip time and launch windows, but not necessarily easier to get to. Which is probably why they aren't the proposed location for LOP-G.
Title: Re: Lunar Gateway Debate
Post by: philw1776 on 08/05/2018 06:27 pm
In the late 90s or early in the first decade of this century, I would have enthused about ANY next step to get us out of the LEO squirrel cage.  But now as we approach the 2020s, we know that far, far less expensive, much more affordable and therefore sustainable access to space technologies will be viable in the 2020s.

The Lunar Gateway is a fish trap.  The fish enter happily for one reason, food, but can't get out for a different reason.

If LG gets funded and $ contracts let, the trap springs despite any momentum building to cancel the unaffordable to fly SLS/ORION. Even if BO or SpaceX by then has a demonstrable, less expensive HLV, the refrain will be, "But SLS and ORION are built into the LG architecture.  It will be too expensive and time wasting to switch the entire LG access architecture now at this late date!  And we must continue LG because of all the science, etc."

I do not see substantive scientific or other compelling reasons for constructing a LG as proposed.
Title: Re: Lunar Gateway Debate
Post by: speedevil on 08/05/2018 07:56 pm
Even if BO or SpaceX by then has a demonstrable, less expensive HLV, the refrain will be, "But SLS and ORION are built into the LG architecture.  It will be too expensive and time wasting to switch the entire LG access architecture now at this late date!  And we must continue LG because of all the science, etc."

I do not see substantive scientific or other compelling reasons for constructing a LG as proposed.
It depends on the costs.
If commercial alternatives pop up where the cost of replacing the whole station is substantially less than completing one more module, ...
Title: Re: Lunar Gateway Debate
Post by: TripleSeven on 08/05/2018 08:13 pm
Speeddevil

I actually think a lunar base is very premature...

one of the two reasons I would be for a lunar gateway is if the gateway was in an orbit and configured to support a reusable lander so that serious and repeated crewed exploration (and uncrewed) could be executed from it

this argues for uncrewed and crewed reusable vehicles that can be serviced from the gateway...and that of course includes refueling

But if you do orbital refueling and reuse then the Gateway doesn't need to be in lunar orbit; in fact you don't necessarily need a Gateway at all.

So the question to be answered is "Is the lunar orbit Gateway the optimal concept for promoting exploration"? And is that optimization technical or political.

if the lunar gateway is at a libration point the fuel needed for a two way trip is less than if the drop off point is anywhere else...

Is it, though? You still have to spend ~700 m/s each way stopping into and out of the libration point. They are more convenient in terms of trip time and launch windows, but not necessarily easier to get to. Which is probably why they aren't the proposed location for LOP-G.

I think that the proposed location has more to do with what SLS can do than anything else

I recognize the m/s but the ability to fly anytime is essential unless one is going to equip the lander with the ability to abort to Earth at any time. 

the poles are still a problem for comm etc but a couple of sats fix that pretty quick..

as for Falcon...I hope those numbers are correct. 
Title: Re: Lunar Gateway Debate
Post by: A_M_Swallow on 08/05/2018 08:18 pm
Even if BO or SpaceX by then has a demonstrable, less expensive HLV, the refrain will be, "But SLS and ORION are built into the LG architecture.  It will be too expensive and time wasting to switch the entire LG access architecture now at this late date!  And we must continue LG because of all the science, etc."

I do not see substantive scientific or other compelling reasons for constructing a LG as proposed.
It depends on the costs.
If commercial alternatives pop up where the cost of replacing the whole station is substantially less than completing one more module, ...

The Orion, Dragon 2 and CST-100 all implement the NASA Docking Standard. That means they can all support a lunar spacestation (given a launch vehicle that can get them there).
Title: Re: Lunar Gateway Debate
Post by: ThereIWas3 on 08/05/2018 09:12 pm
Saturn V was designed to meet the goal of delivering X tons to the Moon.   LOP-G and other NASA plans are being designed to be something that SLS can accomplish, and ignoring other missions that might be possible using a different launcher - exactly backwards.

I have not seen any particular science goals that would be met by either temporary or permanent visits to the Lunar surface in the time frames being discussed for LOP-G.
Title: Re: Lunar Gateway Debate
Post by: ncb1397 on 08/05/2018 10:41 pm
Saturn V was designed to meet the goal of delivering X tons to the Moon.   LOP-G and other NASA plans are being designed to be something that SLS can accomplish, and ignoring other missions that might be possible using a different launcher - exactly backwards.

It was more fluid than that. The Moon mission was designed around the limitations of the Saturn V. The Apollo service module was sized to lift the crew module off the lunar surface, but NASA didn't have a reasonable launch vehicle that could put the fueled CSM on the surface. LOR is portrayed as some kind of stroke of genius, but NASA was basically a cornered rat and had to use it. It was probably for the best though. Just as there is a mass penalty in taking the re-entry vehicle to the lunar surface, there is a somewhat smaller mass penalty in taking your re-entry vehicle to low lunar orbit. The heat shield, parachutes, aeroshell, flotation devices and whatever else don't have any use in LLO. They have some use in burning off energy from a high energy return, but you don't get any more of that from LLO vs. other possible lunar orbits.
Title: Re: Lunar Gateway Debate
Post by: TripleSeven on 08/05/2018 11:01 pm
Saturn V was designed to meet the goal of delivering X tons to the Moon.   LOP-G and other NASA plans are being designed to be something that SLS can accomplish, and ignoring other missions that might be possible using a different launcher - exactly backwards.

It was more fluid than that. The Moon mission was designed around the limitations of the Saturn V. The Apollo service module was sized to lift the crew module off the lunar surface, but NASA didn't have a reasonable launch vehicle that could put the fueled CSM on the surface. LOR is portrayed as some kind of stroke of genius, but NASA was basically a cornered rat and had to use it. It was probably for the best though. Just as there is a mass penalty in taking the re-entry vehicle to the lunar surface, there is a somewhat smaller mass penalty in taking your re-entry vehicle to low lunar orbit. The heat shield, parachutes, aeroshell, flotation devices and whatever else don't have any use in LLO. They have some use in burning off energy from a high energy return, but you don't get any more of that from LLO vs. other possible lunar orbits.

Hmm I dont agree with much of that.  LOR is all about making a Saturn V sized vehicle capable of doing the limited job that Apollo was tasked with.  the Service module was "oversized" but the "direct to the lunar surface" requires a far larger booster...they called it NOVA
Title: Lunar Gateway Debate
Post by: Markstark on 08/08/2018 04:38 pm
https://twitter.com/spacebrendan/status/1026990492800757765?s=21

Recent Bridenstine interview discussing the Gateway. He discusses desire to use reusable elements for all aspects of the lunar architecture. He also notes that the PPE will be able to change orbits from NRHO to Lagrange points as needed.
Title: Re: Lunar Gateway Debate
Post by: theinternetftw on 08/08/2018 08:45 pm
Recent Bridenstine interview discussing the Gateway.

Quick transcript of this for those who'd like it: https://gist.github.com/theinternetftw/8cbb257253221f06a7bf593d2808f55f
Title: Re: Lunar Gateway Debate
Post by: Archibald on 08/09/2018 04:56 am
https://twitter.com/spacebrendan/status/1026990492800757765?s=21

Recent Bridenstine interview discussing the Gateway. He discusses desire to use reusable elements for all aspects of the lunar architecture. He also notes that the PPE will be able to change orbits from NRHO to Lagrange points as needed.

Quote
but with Solar Electric Propulsion, it's not just going to be in an orbit around the moon, it's going to actually go to L2 and L1 and give us more access to more parts of the moon than ever before.

I wish Robert Farquhar had lived long enough to read these lines. Also thinking about  Harley Thronson, who spent the last two decades hammering the idea of a Gateway  at a libration point (see his FISO group).

(https://media.tenor.com/images/939895eeadd796565d3ef07b7a7169f3/tenor.gif)

Title: Re: Lunar Gateway Debate
Post by: Proponent on 08/09/2018 01:30 pm
It was more fluid than that. The Moon mission was designed around the limitations of the Saturn V. The Apollo service module was sized to lift the crew module off the lunar surface, but NASA didn't have a reasonable launch vehicle that could put the fueled CSM on the surface. LOR is portrayed as some kind of stroke of genius, but NASA was basically a cornered rat and had to use it. It was probably for the best though.

It's true that the SM's propulsion system was sized to propel the CSM from the lunar surface back to Earth.  That's because the contract was let before the mode decision had been made*.  At the time, almost all architectures under consideration (Earth-orbit rendezvous, direct, lunar surface rendezvous, the Army's Project Horizon, the Air Force's Lunex) envisioned the return of the crew directly from the lunar surface.

There was an extensive debate among NASA's and its contractors' engineers as to the best architecture for reaching the moon -- you can read about it in great detail in documents on NTRS (https://ntrs.nasa.gov).  Firstly the politicians set the goal, and then the engineers chose the best way of doing it.  What's happening now is, as ThereWasI3 says, is "backward":  the politicians, not the engineers, have chosen the hardware.  Imagine that the politicians had usurped the engineers' role in 1961 as well, when JFK announced the moon goal.  They almost certainly would not have selected LOR, because few had even heard of it then:  it was an idea out of left field.  As a result, Apollo would have been much more expensive (relying on either two Saturn V's or a single Nova for each mission) and would likely have missed the end-of-decade deadline.



*An illustration, incidentally, of the hazards of building your hardware before you've decided what you're going to do with it.  That's happening on a much larger scale with Orion/SLS.
Title: Re: Lunar Gateway Debate
Post by: Lunadyne on 08/09/2018 08:09 pm
Quote
He also notes that the PPE will be able to change orbits from NRHO to Lagrange points as needed.

Do we have a paper we can cite for that?  Or is it just the NASA Administrator trying to minimize the effects of the obnoxious EML-1 crowd?  What would be the purpose in moving it back and forth from NRHO to EML-1?  Why complicate the overall architecture that way?  What would it do at EML-1?  I'm just trying to picture SLS delivering to LOP-G in NRHO, and then the LOP-G changing its orbit with SEP to deliver a crew to EML-1 (or EML-2 for that matter for the dV purists) for...something.  What kinds of timeframes are we talking about here?

Sorry, but the comment strikes me more as political image management (don't worry EML-1 nerds; we're thinking of you) than actual strategic thinking about cislunar architectures.

And I am serious, I would like to see a paper on what the Administrator is describing.  I'm a bit of an orbital mechanics geek and so would be interested in what they're envisioning.
Title: Re: Lunar Gateway Debate
Post by: Markstark on 08/09/2018 08:38 pm
Recent Bridenstine interview discussing the Gateway.

Quick transcript of this for those who'd like it: https://gist.github.com/theinternetftw/8cbb257253221f06a7bf593d2808f55f

Awesome! Thanks!
Title: Re: Lunar Gateway Debate
Post by: Markstark on 08/09/2018 08:40 pm
Quote
He also notes that the PPE will be able to change orbits from NRHO to Lagrange points as needed.

Do we have a paper we can cite for that?  Or is it just the NASA Administrator trying to minimize the effects of the obnoxious EML-1 crowd?  What would be the purpose in moving it back and forth from NRHO to EML-1?  Why complicate the overall architecture that way?  What would it do at EML-1?  I'm just trying to picture SLS delivering to LOP-G in NRHO, and then the LOP-G changing its orbit with SEP to deliver a crew to EML-1 (or EML-2 for that matter for the dV purists) for...something.  What kinds of timeframes are we talking about here?

Sorry, but the comment strikes me more as political image management (don't worry EML-1 nerds; we're thinking of you) than actual strategic thinking about cislunar architectures.

And I am serious, I would like to see a paper on what the Administrator is describing.  I'm a bit of an orbital mechanics geek and so would be interested in what they're envisioning.

I believe I saw a reference to using the PPE to change orbits in a Gateway presentation on the  public NASA Tech Reports Server. I’ll look for it and get back to you. However, I don’t think it elaborated on why.
Title: Re: Lunar Gateway Debate
Post by: ThereIWas3 on 08/09/2018 08:55 pm
It might just be the usual NASA tendency to try to keep all the different "center" factions happy.  Next thing you know, they'll throw a VASIMR on it.
Title: Re: Lunar Gateway Debate
Post by: A_M_Swallow on 08/10/2018 12:20 am
It might just be the usual NASA tendency to try to keep all the different "center" factions happy.  Next thing you know, they'll throw a VASIMR on it.

LOP-G does not need an engine as powerful as a VASIMR but Mars transfer vehicles could use VASIMR thrusters.

NRHO is a viable orbit for a lunar spacestation because only a little station keeping fuel is needed. The LOP-G could be used as a staging and refuelling depot for the lunar lander.

EML-1 (or EML-2) makes a good staging point for trips to Mars. A solar electric vehicle can take months spinning out from LEO to EML-1 where the crew join them using chemical rockets. Two spacestations can be used - one each at NRHO and EML-1 - but moving the station between the two locations may be cheaper (double check).
Title: Re: Lunar Gateway Debate
Post by: TrevorMonty on 08/10/2018 01:16 am
Quote
He also notes that the PPE will be able to change orbits from NRHO to Lagrange points as needed.

Do we have a paper we can cite for that?  Or is it just the NASA Administrator trying to minimize the effects of the obnoxious EML-1 crowd?  What would be the purpose in moving it back and forth from NRHO to EML-1?  Why complicate the overall architecture that way?  What would it do at EML-1?  I'm just trying to picture SLS delivering to LOP-G in NRHO, and then the LOP-G changing its orbit with SEP to deliver a crew to EML-1 (or EML-2 for that matter for the dV purists) for...something.  What kinds of timeframes are we talking about here?

Sorry, but the comment strikes me more as political image management (don't worry EML-1 nerds; we're thinking of you) than actual strategic thinking about cislunar architectures.

And I am serious, I would like to see a paper on what the Administrator is describing.  I'm a bit of an orbital mechanics geek and so would be interested in what they're envisioning.

I believe I saw a reference to using the PPE to change orbits in a Gateway presentation on the  public NASA Tech Reports Server. I’ll look for it and get back to you. However, I don’t think it elaborated on why.
Being able to move between cislunar locations is primary requirement of Gateway.
Title: Re: Lunar Gateway Debate
Post by: Markstark on 08/10/2018 02:22 am
Quote
He also notes that the PPE will be able to change orbits from NRHO to Lagrange points as needed.

Do we have a paper we can cite for that?  Or is it just the NASA Administrator trying to minimize the effects of the obnoxious EML-1 crowd?  What would be the purpose in moving it back and forth from NRHO to EML-1?  Why complicate the overall architecture that way?  What would it do at EML-1?  I'm just trying to picture SLS delivering to LOP-G in NRHO, and then the LOP-G changing its orbit with SEP to deliver a crew to EML-1 (or EML-2 for that matter for the dV purists) for...something.  What kinds of timeframes are we talking about here?

Sorry, but the comment strikes me more as political image management (don't worry EML-1 nerds; we're thinking of you) than actual strategic thinking about cislunar architectures.

And I am serious, I would like to see a paper on what the Administrator is describing.  I'm a bit of an orbital mechanics geek and so would be interested in what they're envisioning.

Hey Lunadyne,

Check out this presentation from the PPE Industry Day that took place four weeks ago. Slide 23 addresses using SEP for changing orbits but isn't as explicit as Mr. Bridenstine.

Side note: I was surprise to see SpaceX send four people to this event considering this project is strictly electric propulsion.

https://govtribe.com/project/spaceflight-demonstration-of-a-power-and-propulsion-element-ppe/activity

Title: Re: Lunar Gateway Debate
Post by: Markstark on 08/10/2018 02:31 am
Also this from the Q&A that's also publicly available. Again, not as explicitly stated as the Administrator.
Title: Lunar Gateway Debate
Post by: Markstark on 08/10/2018 12:49 pm
Quote
He also notes that the PPE will be able to change orbits from NRHO to Lagrange points as needed.

Do we have a paper we can cite for that?  Or is it just the NASA Administrator trying to minimize the effects of the obnoxious EML-1 crowd?  What would be the purpose in moving it back and forth from NRHO to EML-1?  Why complicate the overall architecture that way?  What would it do at EML-1?  I'm just trying to picture SLS delivering to LOP-G in NRHO, and then the LOP-G changing its orbit with SEP to deliver a crew to EML-1 (or EML-2 for that matter for the dV purists) for...something.  What kinds of timeframes are we talking about here?

Sorry, but the comment strikes me more as political image management (don't worry EML-1 nerds; we're thinking of you) than actual strategic thinking about cislunar architectures.

And I am serious, I would like to see a paper on what the Administrator is describing.  I'm a bit of an orbital mechanics geek and so would be interested in what they're envisioning.

Also found this in a recent Gateway commercialization RFI:
Quote
The Gateway will be located in a Near-Rectilinear Halo Orbit (NRHO) around the Moon and can be relocated in cislunar

Source: https://govtribe.com/project/gateway-commercial-opportunities-request-for-information/activity
Title: Re: Lunar Gateway Debate
Post by: Archibald on 08/11/2018 03:08 pm
Delta-v between NRHO and EML-1 / EML-2 are barely 100 m/s. I'd be surprise if the PPE and its electric thrusters couldn't handle that.
Title: Re: Lunar Gateway Debate
Post by: Lunadyne on 08/11/2018 06:14 pm
Okay, so I looked through the PPE Industry Day slides, which I admit make many assertions that the LOP-G will be able to maneuver to various Lagrange points, especially EML-1 and EML-2, as part of its functionality.

So I looked through the Attachment D to the BAA, which covers the NASA Unique Requirements, and while I do see references to the PPE being able to put itself into an NRHO, station keep, and slew for various functions like docking and keeping Orion's butt towards the Sun while docked, what I don't see are references to PPE being able to propulse the LOP-G stack to other destinations in cislunar space.  Maybe I just missed it.

I'm pretty sure I saw a reference to an orbital summaries doc buried somewhere in the many slides of administrivia, so I'm going to see if I can refind that, although from what I remember you have to contact NASA to get a copy as it's considered export-sensitive, and since I'm not actually associated with the BAA process it's unlikely I'll be able to get one.

This isn't my first rodeo, so I know how these things work.  Any contractor looking to win a contract is going to look to the formal documents for the requirements to be met.  Any pretty powerpoint platitudes mean absolutely zero.  Zilch.  Nada.  All I'm seeing so far are promises, allegations and blarney. 

I'm also having a hard time buying into the 09/2022 launch window.  If Orion and SLS is any indication of the rate of progress in the industry, I would expect that four-year timeframe to double or more.  Ample time for things like cislunar maneuverability to be scrapped to get to the end product.

So I'm still sticking with my original position, which is that this whole emphasis of maneuverability to EML-1 is just a last-minute add-on to try to get the Lagrange nerds on board with the iffy LOP-G project.  Political consensus building, and not a real thing to which we can actually look forward.
Title: Re: Lunar Gateway Debate
Post by: speedevil on 08/11/2018 08:00 pm
This isn't my first rodeo, so I know how these things work.  Any contractor looking to win a contract is going to look to the formal documents for the requirements to be met.  Any pretty powerpoint platitudes mean absolutely zero.  Zilch.  Nada.  All I'm seeing so far are promises, allegations and blarney. 
It might be plausible that it is impractical to meet for reasonable designs 'put itself into NHRO', station-keep for x years at y m/s*kgs - without also having the capacity to switch orbits of the whole stack - if supplied with enough Xenon.

If the ion engine has sufficient life, and is run directly off solar panels, and has enough fuel, it doesn't care if it's run for a couple of months at a time, or twenty minutes once every two weeks for stationkeeping.
Title: Re: Lunar Gateway Debate
Post by: DreamyPickle on 08/11/2018 09:07 pm
A more interesting application of PPE-derived craft would be to shuttle payloads from Earth to Lunar orbit. Is there any indication NASA is looking at this? The trip would take many months through the Van Allen belts but could deliver 10-20 ton modules from LEO launchers.
Title: Re: Lunar Gateway Debate
Post by: Endeavour_01 on 08/13/2018 06:48 pm
So I'm still sticking with my original position, which is that this whole emphasis of maneuverability to EML-1 is just a last-minute add-on to try to get the Lagrange nerds on board with the iffy LOP-G project.  Political consensus building, and not a real thing to which we can actually look forward.

I'm gonna stick with what is in the RFI and what has been reiterated multiple times by the NASA administrator and others. The current plan is for the LOP-G to be capable of changing orbits, including from NRHO to EML-1 and EML-2. Like Archibald said its not that difficult to do from a delta-V perspective.

You may think LOP-G is a terrible idea but argue against it on the merits of what is being proposed, not your belief that NASA is just pretending to want this orbit-changing capability.
Title: Re: Lunar Gateway Debate
Post by: Markstark on 08/13/2018 09:28 pm
He just emphasized it again twice today at an all hands in Michoud. I’m going to assume it’s more than a talking-point at this point.
Title: Re: Lunar Gateway Debate
Post by: DreamyPickle on 08/13/2018 11:08 pm
This is a more basic question: How exactly is the PPE going to perform station keeping? The simplest way to do attitude control on a spacecraft is to have many small thrusters all around and use them to rotate, however the PPE seems to have a single large engine and multiple modules assembled on one side.

Will the PPE rotate the entire station before firing the main engine? In this case "orbital changes" and reboost would be it's main capability.
Title: Lunar Gateway Debate
Post by: Markstark on 08/13/2018 11:28 pm
This is a more basic question: How exactly is the PPE going to perform station keeping? The simplest way to do attitude control on a spacecraft is to have many small thrusters all around and use them to rotate, however the PPE seems to have a single large engine and multiple modules assembled on one side.

Will the PPE rotate the entire station before firing the main engine? In this case "orbital changes" and reboost would be it's main capability.

Note sure if this answers the mail, but here’s what I found from public available documents found in the link I included above: (https://uploads.tapatalk-cdn.com/20180813/904878126e451135aa01c5d9e228d4eb.png)(https://uploads.tapatalk-cdn.com/20180813/b15f8e38ae2641adbd2fcfba2f51f831.png)

p.s. mods please let me know if all this orbit stuff is off-topic!
Title: Re: Lunar Gateway Debate
Post by: Lunadyne on 08/13/2018 11:55 pm
Quote
argue against it on the merits of what is being proposed

That's exactly what I'm trying to do.  I looked at the BAA for the PPE, and as noted did not see any references to visiting other destinations in cislunar space like EML-1. 

Quote
I'm gonna stick with what is in the RFI

I looked at the RFI, and the only thing I could find was:

"3A PPE Propulsion Capability - The PPE will be capable of providing orbit transfers for a stack of TBD mass with a center of gravity of TBD."

Not a whole lot of guidance there.  Orbit transfer can mean a lot of things and is very ambiguous.  Now, if it said something along the lines of:

"The PPE will be capable of transferring the DSG/LOP-G stack from NRHO to other destinations of interest in cislunar space such as EML-1 or EML-2"

then I would be much more convinced.  So, looking at the Synopsis for NextSTEP BAA Appendix-C: Power and Propulsion Element Studies, we can see that the priorities are as follows:

"Studies intend to address key drivers for PPE development such as but not limited to potential approaches to:
-meeting the intent of human rating requirements;
-concept and layout development;
-attitude control;
-propulsive maneuverability;
-power generation;
-power interface standards;
-power transfer to other Gateway Elements;
-hosting multiple International Docking System Standard (IDSS) compatible docking systems;
-batteries/eclipse duration;
-15 year lifetime;
-communications;
-avionics, assembly integration and test approaches;
-extensibility;
-accommodations of potential (international or domestic partner provided) hardware such as robotic fixtures, science and technology utilization and other possible elements; and
-options for cost share/cost contributions.

Sure, one might get excited about "propulsive maneuverability", but it has to demonstrate that to get into the NRHO, so I'm having a hard time reading too much into that.

See, I was trained that documents are everything.  If it's not in the document, then you can't rely on it.  People can make all the shiny promises they like, and politicians really like to make promises, but again, if it's not in the documentation, then you cannot rely on it.  Documents are what you take into the courts, and are legally binding.  "But he said..." is not.

Please, show me where this information is documented.  Where does it say in the BAA, or the RFI for that matter, that the DSG/LOP-G stack has to be capable of getting to EML-1 or EML-2 or other destinations of interest in cislunar space, be it GEO, L-5, or wherever?  I'd like to take what the Administrator says on faith, but my science/engineering background is telling me to see the facts and the evidence.  I do not see it as being unreasonable to ask for such.  Maybe I'm not looking in the right place.  That's why I keep asking for cites.  I'm not trying to be obstreperous, just trying to get some real data.

Because if they do intend what they're saying, the next logical question is why?  Why is this capability being built into the system?  What are their intentions?  I mean, I do already know, they're going to utilize the capabilities of the LOP-G to stage the MARS mission from EML-2.  In theory.  But as someone who has an interest in cislunar development (q.v. Cislunar Econosphere at The Space Review) that doesn't really float my boat.  If it can get to EML-1, why not just park it there and start taking advantage of all that it has to offer (q.v. EML-1: The Next Logical Destination at The Space Review) instead of backing into it for some unknown reason(s).  Are they proposing these transfers while crewed?  What kind of timeframes are we talking about here, because I've seen the math in Vallado and electric propulsion is not fast. Something's just not adding up...

[Edit: And, yup, MarkStark found the smoking gun.  EML-2.  To MARS!  Ares! uber alles!  Because yeah, it makes sense to park hardware over the radio-quietest spot in the Solar system...] 
Title: Re: Lunar Gateway Debate
Post by: Markstark on 08/14/2018 12:25 am
Happy to help Luna!

I wonder if this requirement/capability moves the needle for some of the Gateway critics. Not saying it should, just wondering if does. 
Title: Re: Lunar Gateway Debate
Post by: Archibald on 08/14/2018 07:03 pm
http://www.thespacereview.com/article/2027/1

http://www.thespacereview.com/article/1764/1

Are you Ken Murphy or just a fan of him ? (just asking !)

The second article I linked is pretty good. By the way, if you look at the comment section, you can see "Ann Onymous" - it's me !!!!

I've closely followed the development of the Gateway station since 2008 (when I joined this forum). Tracked down libration points history since Bob Farquhar. I crammed my HD with a boatload of related documents. If anybody interested, I can link some of them.
Title: Re: Lunar Gateway Debate
Post by: A_M_Swallow on 08/15/2018 12:40 am
How viable is it to move a spacestation from a near-rectilinear halo orbit (NRHO) to Earth-Moon Lagrange Point 2 (EML-2) and back again every couple of years?

The spacestation is likely to mass 40-50tonne and have 40kW available for electric ion propulsion. I do not know what the delta-v from NRHO is but Low Lunar Orbit to EML-2 is about 0.65km/s. Ion thrusters are slow so travel time is important.
Title: Re: Lunar Gateway Debate
Post by: Eric Hedman on 08/15/2018 06:07 am
How viable is it to move a spacestation from a near-rectilinear halo orbit (NRHO) to Earth-Moon Lagrange Point 2 (EML-2) and back again every couple of years?

The spacestation is likely to mass 40-50tonne and have 40kW available for electric ion propulsion. I do not know what the delta-v from NRHO is but Low Lunar Orbit to EML-2 is about 0.65km/s. Ion thrusters are slow so travel time is important.
According to Archibald's post earlier in the thread:

"Delta-v between NRHO and EML-1 / EML-2 are barely 100 m/s. I'd be surprise if the PPE and its electric thrusters couldn't handle that."
Title: Re: Lunar Gateway Debate
Post by: Archibald on 08/15/2018 10:14 am
The way I see the entire thing... when I say "cislunar space" to me it is a very large, broad zone that starts from GEO and extends to SEL-1 / SEL-2, basically Earth sphere of influence.

As far as distances go: 36 500 km to 1.5 million km.
As far as delta-v goes, it starts at Earth escape, more or less 3.1 km/s (although GEO is a very peculiar, counter-intuitive case, related to satellites and their 24 hour orbit).

It is easier to over-simplify a little and just ask yourself "well, 3.1 km/s, Earth escape, now WHAT and WHERE ? Which destination ?"

From Earth escape into that broad "cislunar space" I mentionned, there are plenty of orbits or locations to go.

To be fully honest, DRO and NHRO were completely unknown to me before ARM and LOP-G. I thought it was either "GEO, LLO, libration points, or burst". Then again, I'm no astrodynamicist by any mean, and there are probably an infinity of different orbits high there - halo orbits and DRO aplenty.

The basic numbers are as follow (from LEO)
- Earth escape: 3.1 km/s
- Low Lunar Orbit (LLO) 4.1 km/s
- Lunar surface: +2.5 km/s, one way, from LLO.

What is kind of interesting is that...

- "exit-from-GEO-to-cislunar"
-  all ten Earth-Moon / Sun-Earth libration points (EML and SEL)
- LLO
- and those new DRO and NHRO orbits

...are all stuck between 3.1 km/s (Earth escape) and 4.1 km/s (LLO).

The entire thing, the entire "cislunar sphere" merely spans 1 km/s of delta-v, which is not a lot (when compared to those daunting SSTO numbers, Earth surface to LEO, a whopping 10 km/s).

What is really interesting is that 1 km/s of delta-v is small enough to be handled by either chemical or electric propulsion or both (think PPE vs Orion Service Module) at reasonable weight of propellants.

EDIT

According to this thread... https://forum.nasaspaceflight.com/index.php?topic=34858.0

Earth escape to DRO seems to be 300 m/s (so that would be 3400 m/s from LEO), close from EML-2 "best case" as found by Bob Farquhar and mentionned by Kirk Sorensen in the thread "An alternative lunar architecture" (the one that made a libration point groupie in the first place)
Title: Re: Lunar Gateway Debate
Post by: Lunadyne on 08/15/2018 05:36 pm
Yes, I am that Ken Murphy.  Lunadyne, or a unit of Moon force, is one of my noms de plume, murphydyne is another.

I stumbled into what I call the cislunar econosphere concept when I read Human SMAD from cover to cover while pursuing a Masters degree at ISU.  I further explored the concept during my internship at Boeing's HSF&E.  Once I got a briefing on the same basic concepts from the NExT team during a NASA Academy field trip to KSC I realized that there was really something of value here.  Coupled with my background in international business and economics, and training as an economist, it became obvious that any kind of near-future human commercial expansion into space is bounded by the Moon as an 'anchor tenant' of the market space, and is already happening in cislunar space at GEO mainly but also LEO.

I am very careful about my use of the term cislunar.  While Archibald gives a rather broad definition, a prima facie reading (cis-: bounded by or on the near side of; lunar: of or relating to the Moon) would delimit the space to:
-Suborbital
-LEO
-MEO/HEO
-GEO
-EML1
-EML3, 4, 5
-Moon
-EML2 as a courtesy

Then rotate into a sphere because space is 3-D and voila, cislunar econosphere.  I do often see people exclude cis-GEO space which is odd given that LEO is obviously in the volume of space bounded by the Moon's orbit.  Moving out to the Sun-Earth lagrange points you're still in Earth's gravity well but beyond the Moon (translunar space).  So some combination of cis, terra, fons and gravitas?

Taking the stricter definition of cislunar space, IF you have gas stations in LEO, EML-1 and on the Moon, then you can get everywhere you want to go or at least to a place to gas and go for <4 km/s of delta-V.  The exception is LEO to GEO, which has always been a bear because deep gravity wells suck.  Once you're staging at EML-1, the bulk of GEO operations will likely shift there to become the logistics point for work at GEO (and most other places).  Plus you can get to EML-1 from any LEO orbital inclination which is a huge plus transportation logistics-wise.

As Archibald notes, DRO and NRHO are relatively recent inventions, and arose from the desire to bring back an asteroid to near-Earth space but not so near as to scare the crap out of everyone, so hey, let's park it around the Moon!  Well, them pesky mascons make stable orbits difficult, and so a search was undertaken to find something, anything that was a stable orbit around the Moon.  Much number-crunching later a number of orbits fell out of the mix, which generally followed the way I described it previously - stay far away (DRO) or use a Molniya-type orbit to not stay long (NR[H]O).  Given the risks, I would much rather have anyone trying to bring a big rock back to near-Earth space park it at SEL-4 or SEL-5 to demonstrate that they can control it, and then move it closer.  While orbital mechanics is a beautiful and well-night perfect math, engineering is not and there have been fiction stories about people trying to bring an asteroid to Earth and some engineering cock-up leaves it on an uncontrolled collision course.

What would be far more interesting to me would be if the PPE was proposed as part of a modular orbital transfer vehicle (OTV, to use the SEI parlance) for cargo in cislunar space.  As a station-keeping element it would seem to be most applicable in situations where you need constant orbit adjustments, like a space station in LEO to keep it aloft.  Would a facility at EML-1 need constant orbital station-keeping adjustments, or would periodic bursts suffice?  For the LOP-G, it would seem that it is currently envisioned as a way to move the stack to EML-2 to act as a staging point for a journey to MARS! 

Meh...
Title: Re: Lunar Gateway Debate
Post by: Proponent on 08/16/2018 01:49 am
Would a facility at EML-1 need constant orbital station-keeping adjustments, or would periodic bursts suffice?

The attached JSC presentation (see p. 11), foresees station-keeping burns of about a meter per second once a week or so.  But the answer to your question must depend on the tolerable excursions.

Quote
For the LOP-G, it would seem that it is currently envisioned as a way to move the stack to EML-2 to act as a staging point for a journey to MARS!

But is it obvious that a permanent facility is needed at the staging point?  NASA's Evolvable Mars Campaign, for example, foresees staging in lunar DRO but places no permanent infrastructure there.  Given that just maintaining LOP-G is likely to cost over $3 billion per year (just to send one Orion/SLS there annually), it's really not clear to me that LOP-G wouldn't hinder a Mars effort more than it would help.

EDIT:  "place" -> "places"
Title: Re: Lunar Gateway Debate
Post by: Archibald on 08/16/2018 07:06 pm
Quote
While orbital mechanics is a beautiful and well-night perfect math, engineering is not and there have been fiction stories about people trying to bring an asteroid to Earth and some engineering cock-up leaves it on an uncontrolled collision course.

Stephen Baxter Titan (which is as bad as Voyage was good) has the chinese making such a mistake... oops, kaboom, there goes Earth civilization !

Quote
What would be far more interesting to me would be if the PPE was proposed as part of a modular orbital transfer vehicle (OTV, to use the SEI parlance) for cargo in cislunar space.

A while back was the OASIS study, which had a pretty clever Earth-Moon OTV, called the hybrid propulsion module. It had both chemical and SEP, to try and get the best of both worlds, notaly high thrust to cut those looooooooong SEP transit times of months...
https://spacecraft.ssl.umd.edu/old_site/academics/484S03/oasis_docs/OASIS_FY01_FINAL.PDF

I'm not a great fan of xenon and LH2, and felt ammonia could do both jobs of chemical and SEP, with a single tank of propellant.
Title: Re: Lunar Gateway Debate
Post by: speedevil on 08/16/2018 07:20 pm
But is it obvious that a permanent facility is needed at the staging point?  NASA's Evolvable Mars Campaign, for example, foresees staging in lunar DRO but place no permanent infrastructure there.  Given that just maintaining LOP-G is likely to cost over $3 billion per year (just to send one Orion/SLS there annually), it's really not clear to me that LOP-G wouldn't hinder a Mars effort more than it would help.
For it to be cheaper, ISRU really needs to have kicked off in a massive way, so that lunar fuel makes it worthwhile.

At three billion a year, commercial launch (todays prices) can get some 1000 tons of propellant to orbit, in off-the-shelf tanks that will last three years before boiloff without shading. They will need to be spun very lightly, as they are designed for earth.
(LOX/methane, hydrogen is more annoying)

Title: Lunar Gateway Debate
Post by: Markstark on 08/25/2018 03:29 pm
Gateway Debate. Live and in color. Going to watch it now.

https://www.youtube.com/watch?v=5f6fMI5DiOA

Edit: Okay I watched the video. First, I’ll make my bias clear and state that I’m for the Gateway. Anyhow, I didn’t think either made a great case but the case against from Dr. Zubrin was a bit more clear. I thought Mr. Mankins’ Eminem 8 mile approach where he says self deprecating things first kinda back fired. I appreciate Dr. Zubrin not making a Mars vs Moon debate and instead focusing on lunar surface vs orbit. I also appreciate Mr. Mankins willingness to go into the lions den.
Title: Re: Lunar Gateway Debate
Post by: QuantumG on 08/26/2018 02:22 am
Neither speaker wants to accept the political reality. LOP-G is modelled on the ISS because the ISS has proven uncancellable. Mankins' concluding remarks are the closest either got to saying that. The goal of LOP-G is to ratchet up the sustainable funding of in-space architecture. If you're a fan of government expenditure on uncancellable space projects, you should be cheering LOP-G, or presenting an alternative that is equally as uncancellable. Zubrin's suggestion of a lunar village as an international project (with Mankins nodding on) doesn't cut the mustard.
Title: Re: Lunar Gateway Debate
Post by: su27k on 08/26/2018 03:51 am
Neither speaker wants to accept the political reality. LOP-G is modelled on the ISS because the ISS has proven uncancellable. Mankins' concluding remarks are the closest either got to saying that. The goal of LOP-G is to ratchet up the sustainable funding of in-space architecture. If you're a fan of government expenditure on uncancellable space projects, you should be cheering LOP-G, or presenting an alternative that is equally as uncancellable. Zubrin's suggestion of a lunar village as an international project (with Mankins nodding on) doesn't cut the mustard.

Why is an international lunar village more cancellable than LOP-G?
Title: Re: Lunar Gateway Debate
Post by: RonM on 08/26/2018 04:39 am
Neither speaker wants to accept the political reality. LOP-G is modelled on the ISS because the ISS has proven uncancellable. Mankins' concluding remarks are the closest either got to saying that. The goal of LOP-G is to ratchet up the sustainable funding of in-space architecture. If you're a fan of government expenditure on uncancellable space projects, you should be cheering LOP-G, or presenting an alternative that is equally as uncancellable. Zubrin's suggestion of a lunar village as an international project (with Mankins nodding on) doesn't cut the mustard.

Why is an international lunar village more cancellable than LOP-G?

Because LOP-G gives SLS/Orion something to do. Congress is willing to fund that and can get international partners to chip in with some of the modules. An international lunar village would require an expensive crewed lunar lander and not necessarily need SLS/Orion. LOP-G fits in with current NASA plans and will be cheaper than a lunar village.

Don't worry about lunar exploration. Ten years from now both BFR and NA should be flying. Reusable large payload rockets should make a lunar village more affordable.
Title: Re: Lunar Gateway Debate
Post by: QuantumG on 08/26/2018 06:23 am
"lunar village" to me means robotic. Crew landers are the next administration's problem (and always will be?)


Title: Re: Lunar Gateway Debate
Post by: su27k on 08/26/2018 08:02 am
Neither speaker wants to accept the political reality. LOP-G is modelled on the ISS because the ISS has proven uncancellable. Mankins' concluding remarks are the closest either got to saying that. The goal of LOP-G is to ratchet up the sustainable funding of in-space architecture. If you're a fan of government expenditure on uncancellable space projects, you should be cheering LOP-G, or presenting an alternative that is equally as uncancellable. Zubrin's suggestion of a lunar village as an international project (with Mankins nodding on) doesn't cut the mustard.

Why is an international lunar village more cancellable than LOP-G?

Because LOP-G gives SLS/Orion something to do. Congress is willing to fund that and can get international partners to chip in with some of the modules. An international lunar village would require an expensive crewed lunar lander and not necessarily need SLS/Orion. LOP-G fits in with current NASA plans and will be cheaper than a lunar village.

LOL, you just stated all the wrong reasons for supporting LOP-G, according to John Mankins (the debater for the LOP-G).

Anyway, I guess Zubrin really did have a hard time finding someone who can defend LOP-G, since John Mankins seems to be a supporter for lunar village himself. His version of LOP-G ($5B to $10B, 5 years, advanced technology) is pretty detached from what NASA is actually doing, so the whole debate is kind of misleading.

A good question by the audience is the artificial gravity one, very much to the point: If LOP-G is supposed to be a prototype inter-planetary spaceship, the foundation for human expansion to the solar system, then it must have artificial gravity (and long term radiation protection). The fact that none of these is even discussed means LOP-G is nothing of the sort.
Title: Re: Lunar Gateway Debate
Post by: ncb1397 on 08/26/2018 08:03 am
How viable is it to move a spacestation from a near-rectilinear halo orbit (NRHO) to Earth-Moon Lagrange Point 2 (EML-2) and back again every couple of years?

The spacestation is likely to mass 40-50tonne and have 40kW available for electric ion propulsion. I do not know what the delta-v from NRHO is but Low Lunar Orbit to EML-2 is about 0.65km/s. Ion thrusters are slow so travel time is important.
According to Archibald's post earlier in the thread:

"Delta-v between NRHO and EML-1 / EML-2 are barely 100 m/s. I'd be surprise if the PPE and its electric thrusters couldn't handle that."

More like 60 m/s for EML-2 consuming 56 kg of propellant transporting a mass of ~25,000 kg.

Quote
The third cislunar transfer type designed is from the 9:2 NRHO to an EML2 halo orbit. Trajectories
between the NRHO and the two different EML2 Halo orbits, a flat halo and a more traditional halo orbit
described earlier are presented in this section.
The first cislunar transfer to the Option 1 flat halo takes a total of 214 days, with 16 days of thrust and
198 days of coast. This trajectory is shown in Figure 9. Using 2 thruster strings operating at their full power
of 26.6 kW total EP system power, 56 kg of Xe are needed to perform the 60 m/s total mission DV for this
transfer. The NRHO starting orbit is colored in green, and the final EM-L2 halo orbit is shown in red

https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20170009215.pdf

Trip time is long, but presumably it would start after one crew leaves and end before the next crew arrives.
Title: Re: Lunar Gateway Debate
Post by: su27k on 08/26/2018 08:21 am
"lunar village" to me means robotic. Crew landers are the next administration's problem (and always will be?)

What's wrong with robotics? Their funding is stable and long lasting, just look at Cassini or Opportunity. Besides, LOP-G itself will be a robot 11 months per year.
Title: Re: Lunar Gateway Debate
Post by: TrevorMonty on 08/26/2018 10:16 am



A good question by the audience is the artificial gravity one, very much to the point: If LOP-G is supposed to be a prototype inter-planetary spaceship, the foundation for human expansion to the solar system, then it must have artificial gravity (and long term radiation protection). The fact that none of these is even discussed means LOP-G is nothing of the sort.

The fiso podcast  discusses artifical gravity at Gateway (new name for it).

A lunar base would let us know where to start with artifical gravity. At this stage no knows if 1/10 or 9/10 is good enough.
Title: Re: Lunar Gateway Debate
Post by: RonM on 08/26/2018 03:22 pm
Because LOP-G gives SLS/Orion something to do. Congress is willing to fund that and can get international partners to chip in with some of the modules. An international lunar village would require an expensive crewed lunar lander and not necessarily need SLS/Orion. LOP-G fits in with current NASA plans and will be cheaper than a lunar village.
LOL, you just stated all the wrong reasons for supporting LOP-G, according to John Mankins (the debater for the LOP-G).

I'm not defending LOP-G. NASA came up with the idea to give SLS/Orion something to do. It's political reality. If NASA could get funding for practical lunar exploration, it would be for robotic landers.
Title: Re: Lunar Gateway Debate
Post by: A_M_Swallow on 08/26/2018 05:14 pm
"lunar village" to me means robotic. Crew landers are the next administration's problem (and always will be?)




A reusable lander based at the LOP-G with a 10 tonne payload will give you manned landings. Some aeronautical engineer will work out how to insert an ECLSS into a metal box with a docking port and door. There is sufficient mass budget for luxuries like an oven, manual controls and toilet.
Title: Re: Lunar Gateway Debate
Post by: Archibald on 08/26/2018 06:07 pm
Quote
More like 60 m/s for EML-2 consuming 56 kg of propellant transporting a mass of ~25,000 kg.

Amen to that, brother !
Title: Re: Lunar Gateway Debate
Post by: Coastal Ron on 08/26/2018 06:07 pm



A good question by the audience is the artificial gravity one, very much to the point: If LOP-G is supposed to be a prototype inter-planetary spaceship, the foundation for human expansion to the solar system, then it must have artificial gravity (and long term radiation protection). The fact that none of these is even discussed means LOP-G is nothing of the sort.

The fiso podcast  discusses artifical gravity at Gateway (new name for it).

A lunar base would let us know where to start with artifical gravity. At this stage no knows if 1/10 or 9/10 is good enough.

We certainly should not spend any money to test the effects of artificial lunar gravity while in orbit around our Moon. That makes no sense at all.

If there is a desire to create spaceships or space stations with artificial gravity (which would be nice), the least expensive place to build and test them will be in Low Earth Orbit, not Low Lunar Orbit.
Title: Re: Lunar Gateway Debate
Post by: QuantumG on 08/27/2018 05:59 am
What's wrong with robotics? Their funding is stable and long lasting, just look at Cassini or Opportunity. Besides, LOP-G itself will be a robot 11 months per year.

There's no support for robotic exploration of the Moon in the decadal.

Again, political reality.
Title: Re: Lunar Gateway Debate
Post by: DreamyPickle on 08/27/2018 07:53 am
Both debaters were somewhat dismissive of refueling at the Gateway and Zubrin said that going from Earth to the Gateway to the lunar surface adds to your delta-v requirement.

Can't the gateway be placed in an orbit that's optimized for rendezvous after TLI? The initial proposal called for placing the gateway in NRHO but perhaps that could be adjusted. Since it has a lot of electric propulsion capability there is no need to optimize for low station keeping requirements.
Title: Re: Lunar Gateway Debate
Post by: geza on 08/27/2018 09:34 am
Both debaters were somewhat dismissive of refueling at the Gateway and Zubrin said that going from Earth to the Gateway to the lunar surface adds to your delta-v requirement.

Can't the gateway be placed in an orbit that's optimized for rendezvous after TLI? The initial proposal called for placing the gateway in NRHO but perhaps that could be adjusted. Since it has a lot of electric propulsion capability there is no need to optimize for low station keeping requirements.
Sure, but design the surface mission first, decide when do you want it, how frequently and who will pay for it. Probably it will require cislunar rendezvous. Decide, if a permanent structure is useful at the staging orbit, or not. The contraindications are the added complexity, cost and constraints. I guess staging outpost could be useful and economic in case of very high-volume traffic. Certainly, it is meaningless in a world, where SLS can fly once a year and a lander is unaffordable.
Title: Re: Lunar Gateway Debate
Post by: A_M_Swallow on 08/27/2018 09:18 pm
Both debaters were somewhat dismissive of refueling at the Gateway and Zubrin said that going from Earth to the Gateway to the lunar surface adds to your delta-v requirement.

Can't the gateway be placed in an orbit that's optimized for rendezvous after TLI? The initial proposal called for placing the gateway in NRHO but perhaps that could be adjusted. Since it has a lot of electric propulsion capability there is no need to optimize for low station keeping requirements.
Sure, but design the surface mission first, decide when do you want it, how frequently and who will pay for it. Probably it will require cislunar rendezvous. Decide, if a permanent structure is useful at the staging orbit, or not. The contraindications are the added complexity, cost and constraints. I guess staging outpost could be useful and economic in case of very high-volume traffic. Certainly, it is meaningless in a world, where SLS can fly once a year and a lander is unaffordable.

Cost and function are two separate but related requirements. For reusable equipment calculating and comparing the cost effectiveness over 10 missions is valid - assuming that 10 missions are a genuine possibility, a mission may include multiple launches.

A lunar spacestation such as the LOP-G means that the SLS's maximum payload to the lunar surface is the same as its payload to lunar orbit. The lander and propellant going up on separate launches. (I have lost count of the SLS's payload to NRHO but it is something like 25-40 tonne.)

Other launch vehicles can also use the LOP-G (and smaller landers). I suspect spacestation staging will considerably increase the lunar payload of the Atlas V and Falcon 9.

edit: max payload
Title: Re: Lunar Gateway Debate
Post by: su27k on 08/28/2018 04:48 am
Because LOP-G gives SLS/Orion something to do. Congress is willing to fund that and can get international partners to chip in with some of the modules. An international lunar village would require an expensive crewed lunar lander and not necessarily need SLS/Orion. LOP-G fits in with current NASA plans and will be cheaper than a lunar village.
LOL, you just stated all the wrong reasons for supporting LOP-G, according to John Mankins (the debater for the LOP-G).

I'm not defending LOP-G. NASA came up with the idea to give SLS/Orion something to do. It's political reality. If NASA could get funding for practical lunar exploration, it would be for robotic landers.

Ok, then the debate is not for you. The problem is there're still people who do not want to admit LOP-G is a political creation, they still cling to the illusion that LOP-G is necessary or even a good idea, the debate is for them.
Title: Re: Lunar Gateway Debate
Post by: su27k on 08/28/2018 04:51 am
What's wrong with robotics? Their funding is stable and long lasting, just look at Cassini or Opportunity. Besides, LOP-G itself will be a robot 11 months per year.

There's no support for robotic exploration of the Moon in the decadal.

Again, political reality.

Any robotics for lunar village would be for survey of resources, preparation of ISRU and human landing, they would not be run from SMD thus can ignore decadal. An example is the Lunar Reconnaissance Orbiter, which was run under ESMD.
Title: Re: Lunar Gateway Debate
Post by: su27k on 08/28/2018 05:07 am



A good question by the audience is the artificial gravity one, very much to the point: If LOP-G is supposed to be a prototype inter-planetary spaceship, the foundation for human expansion to the solar system, then it must have artificial gravity (and long term radiation protection). The fact that none of these is even discussed means LOP-G is nothing of the sort.

The fiso podcast  discusses artifical gravity at Gateway (new name for it).

A lunar base would let us know where to start with artifical gravity. At this stage no knows if 1/10 or 9/10 is good enough.

There're two recent podcast for AG, not sure which one you're referring to. The one from James Engle and Torin Clark has the following summary:

Quote
* AG is currently in the Global Exploration Roadmap
   * Not integrated in to Industry and NASA’s Cis-lunar exploration architecture.
...
* Human space centrifuge in LEO, near the ISS, would allow for:
   * Fundamental scientific and validation experiments,
   * Demonstrate necessary technologies

The conclusion I got from this:
1. NASA is not planning on AG for LOP-G
2. AG testing can be done in LEO, in fact I think notional plan is to use Dragon's trunk to transport it.
Title: Re: Lunar Gateway Debate
Post by: QuantumG on 08/28/2018 06:00 am
Any robotics for lunar village would be for survey of resources, preparation of ISRU and human landing, they would not be run from SMD thus can ignore decadal. An example is the Lunar Reconnaissance Orbiter, which was run under ESMD.

That's not what the partners are interested in... LRO barely survived and the other precursor missions were axed. When your budget can be legally raided for human spaceflight, it will be.
Title: Re: Lunar Gateway Debate
Post by: jongoff on 08/28/2018 06:09 am
Ok, then the debate is not for you. The problem is there're still people who do not want to admit LOP-G is a political creation, they still cling to the illusion that LOP-G is necessary or even a good idea, the debate is for them.

I don't think it's mutually exclusive to believe that LOP-G is a political creation to make work for SLS/Orion, while still thinking that it might be done in a way that creates at least some net benefit, and that a platonically ideal Gateway (not LOP-G) could actually be quite beneficial.

~Jon
Title: Re: Lunar Gateway Debate
Post by: envy887 on 08/28/2018 12:37 pm
Both debaters were somewhat dismissive of refueling at the Gateway and Zubrin said that going from Earth to the Gateway to the lunar surface adds to your delta-v requirement.

Can't the gateway be placed in an orbit that's optimized for rendezvous after TLI? The initial proposal called for placing the gateway in NRHO but perhaps that could be adjusted. Since it has a lot of electric propulsion capability there is no need to optimize for low station keeping requirements.
Sure, but design the surface mission first, decide when do you want it, how frequently and who will pay for it. Probably it will require cislunar rendezvous. Decide, if a permanent structure is useful at the staging orbit, or not. The contraindications are the added complexity, cost and constraints. I guess staging outpost could be useful and economic in case of very high-volume traffic. Certainly, it is meaningless in a world, where SLS can fly once a year and a lander is unaffordable.

Cost and function are two separate but related requirements. For reusable equipment calculating and comparing the cost effectiveness over 10 missions is valid - assuming that 10 missions are a genuine possibility, a mission may include multiple launches.

A lunar spacestation such as the LOP-G means that the SLS's maximum payload to the lunar surface is the same as its payload to lunar orbit. The lander and propellant going up on separate launches. (I have lost count of the SLS's payload to NRHO but it is something like 25-40 tonne.)

Other launch vehicles can also use the LOP-G (and smaller landers). I suspect spacestation staging will considerably increase the lunar payload of the Atlas V and Falcon 9.

edit: max payload

That is the SLS payload to TLI, not to DHRO. The difference is a 500-700 m/s LOI burn with a lower performance propulsion system such as the Orion SM which is not nearly as efficient as the ICPS or EUS.
Title: Re: Lunar Gateway Debate
Post by: RonM on 08/28/2018 02:02 pm
Ok, then the debate is not for you. The problem is there're still people who do not want to admit LOP-G is a political creation, they still cling to the illusion that LOP-G is necessary or even a good idea, the debate is for them.

I don't think it's mutually exclusive to believe that LOP-G is a political creation to make work for SLS/Orion, while still thinking that it might be done in a way that creates at least some net benefit, and that a platonically ideal Gateway (not LOP-G) could actually be quite beneficial.

~Jon

When life gives you lemons, make lemonade.

Looks like we're getting LOP-G whether we like it or not. Might as well figure out what to do with it.

Of course, Congress could decide not to fund LOP-G, but continue SLS/Orion with nothing to do.  ???
Title: Re: Lunar Gateway Debate
Post by: Archibald on 08/28/2018 03:28 pm
Ok, then the debate is not for you. The problem is there're still people who do not want to admit LOP-G is a political creation, they still cling to the illusion that LOP-G is necessary or even a good idea, the debate is for them.

I don't think it's mutually exclusive to believe that LOP-G is a political creation to make work for SLS/Orion, while still thinking that it might be done in a way that creates at least some net benefit, and that a platonically ideal Gateway (not LOP-G) could actually be quite beneficial.

~Jon

Bingo ! We have a winner here.
Title: Re: Lunar Gateway Debate
Post by: envy887 on 08/28/2018 06:18 pm
Quote
NASA’S ROAD TO THE MOON’S SURFACE IS UNCLEAR

NASA officials presented their latest goals yesterday for human space exploration over the next decade, detailing the agency’s plans to build a space station in orbit around the Moon and then send humans to and from the lunar surface.
...
Getting people to the Gateway by the 2024 deadline is contingent on a lot of new technology being created within very aggressive timeframes. And the timelines are incredibly optimistic given that the SLS program has suffered from numerous delays over the last decade. A lot of complicated elements will need to come together quickly without any further scheduling issues.
...
But based on charts shown at yesterday’s meeting, it seems that 2026 is the earliest any human landers will touch down on the Moon.

https://www.theverge.com/2018/8/28/17790374/nasa-moon-surface-astronauts-lunar-space-station-2024
Title: Re: Lunar Gateway Debate
Post by: Lar on 08/28/2018 09:58 pm
Quote
...
But based on charts shown at yesterday’s meeting, it seems that 2026 is the earliest any non SpaceX human landers will touch down on the Moon.

https://www.theverge.com/2018/8/28/17790374/nasa-moon-surface-astronauts-lunar-space-station-2024
Fixed that for them (bold text inserted by me)...  Earlier than 2026 for a manned BFS landing on Luna is not guaranteed (some say unlikely), but not impossible.

(that said, extended discussion of SpaceX or BFS is off topic... I was merely pointing out that some statements aren't necessarily taking all possibilities into account)
Title: Re: Lunar Gateway Debate
Post by: DreamyPickle on 08/28/2018 10:51 pm
How about building a storable bipropellant depot at the Gateway? This was landers could launch with partially empty tanks, refuel before landing and deliver bigger payloads to the lunar surface. This would also be useful for refueling Orion or a hypothetical very large lander that stretches the capability of SLS but it wouldn't be tied to that program.

Propellant would be mostly delivered with commercial launchers, perhaps as part of a competitive "Commercial Fuel" program. This would be technically simpler to setup that cargo and crew because the interfaces are less complex.

The first users could be participants in the new commercial lunar payload services program but fuel could also be made available to partners like ESA. NASA could subsidize the fuel significantly in the interest of making the moon's surface more accessible.
Title: Re: Lunar Gateway Debate
Post by: su27k on 08/29/2018 07:58 am
Ok, then the debate is not for you. The problem is there're still people who do not want to admit LOP-G is a political creation, they still cling to the illusion that LOP-G is necessary or even a good idea, the debate is for them.

I don't think it's mutually exclusive to believe that LOP-G is a political creation to make work for SLS/Orion, while still thinking that it might be done in a way that creates at least some net benefit

So? You can always extract benefit from any disastrous situation, as long as you're creative enough. That's not what the debate is about. The debate is about whether LOP-G is a lemon (Or to use the Mars Society event title: Breakthrough or Boondoggle?), it's a simple Yes or No question. It's not about how we can make lemonade.

Quote
and that a platonically ideal Gateway (not LOP-G) could actually be quite beneficial.

If the ideal version is not LOP-G, then it's off topic for the debate (and this thread).
Title: Re: Lunar Gateway Debate
Post by: Steven Pietrobon on 08/29/2018 09:32 am
I believe 2026 is possible, but only if LOP-G is cancelled, NASA concentrates of development on EUS and a Lunar Lander, and NASA's budget is increased by $3B a year. A two mission profile is used. First mission takes lander to low Lunar orbit using EUS which can last the three day journey to the Moon. Second mission takes Orion for rendezvous with lander. After landing, Orion performs TEI. Following the current plan could easily put the landing in 2036.
Title: Re: Lunar Gateway Debate
Post by: speedevil on 08/29/2018 10:38 am
How about building a storable bipropellant depot at the Gateway? This was landers could launch with partially empty tanks, refuel before landing and deliver bigger payloads to the lunar surface. This would also be useful for refueling Orion or a hypothetical very large lander that stretches the capability of SLS but it wouldn't be tied to that program.

Propellant would be mostly delivered with commercial launchers, perhaps as part of a competitive "Commercial Fuel" program. This would be technically simpler to setup that cargo and crew because the interfaces are less complex.
Assuming for the moment that propellant transfer in orbit has been demonstrated, along with a heavy payload adaptor for FH.

Using the figures upthread, NHRO is some 700m/s from TLI.
Falcon heavy, in partially reusable mode can throw some 55 tons into LEO. (10% under the nominal mass.)
Payload to TLI is some 22 tons. (assuming 4 ton S2).
Assuming a Dragon 1 with extended trunk and a tank inside is the payload, as well as a very small hypergolic thruster for LHRO insertion, this would reasonably end up with some 15 tons of propellant in NHRO for $200M or so. Post fuel transfer, a small burn would allow Dragon to return.
(this assumes a contract allowing multiple deliveries, once may not be worth it)

This would set a reasonable first cut at a aggressive but reachable propellant cost (for several launches) at of the order of $13M/ton.

This would put the propellant cost for a 5km/s visit to the lunar surface with ISP of 290, no staging on the surface, and crewed mass of 10 tons, using some 50 tons of fuel at some $650M. (much more payload with staging)

An Apollo class lander would be $130M or so.

LOX/CH4 or H2 only make sense if your overall system becomes cheaper, and especially if you use a disposable surface stage, hypergolics are easily good enough for lunar surface.

If crew is going up on SLS, commercial fuel would not be the dominant cost for any crewed mission, and vastly expand capability.

The program would have to be carefully written to provide commercial certainty, and allow any entrant, but to prevent 'Eleven thousand tons of fuel, sign here' type events.
Title: Re: Lunar Gateway Debate
Post by: LMT on 08/29/2018 01:49 pm
Quote from: NasaWatch
Jason Crusan (https://www.nasa.gov/directorates/heo/aes/jason-crusan) is trying to be cute saying that Gateway is not a space station (to thwart some criticism that it is) because it has an engine and moves around.

Apparently Jason does not know that ISS has engines and that it moves around...

(https://media.giphy.com/media/NJZMSqRY3rG9i/200.gif)

--

If LOP-G is supposed to be a prototype inter-planetary spaceship, the foundation for human expansion to the solar system, then it must have artificial gravity (and long term radiation protection). The fact that none of these is even discussed means LOP-G is nothing of the sort.

Pinned just for comparison: some achievable SpaceX options for their own DSG with artificial gravity and full radiation protection (https://forum.nasaspaceflight.com/index.php?topic=34036.msg1838262#msg1838262), circa 2022.  Richie-2 (https://forum.nasaspaceflight.com/index.php?topic=34036.msg1842424#msg1842424) to Richie-5 (https://forum.nasaspaceflight.com/index.php?topic=34036.msg1842904#msg1842904).
Title: Re: Lunar Gateway Debate
Post by: TripleSeven on 08/29/2018 02:11 pm
I believe 2026 is possible, but only if LOP-G is cancelled, NASA concentrates of development on EUS and a Lunar Lander, and NASA's budget is increased by $3B a year. A two mission profile is used. First mission takes lander to low Lunar orbit using EUS which can last the three day journey to the Moon. Second mission takes Orion for rendezvous with lander. After landing, Orion performs TEI. Following the current plan could easily put the landing in 2036.

2026 is possible if 1) NASA cancelled SLS and LOP G...and farmed out the development of a lander much as it did commercial crew...and FUNDED IT on a SLS level.

They would have to use Earth orbit rendezvous but the station is a neat place (outside of the orbit) to do the assemblying and vehicle keep alive...

its technically possible...its just not politically likely
Title: Re: Lunar Gateway Debate
Post by: A_M_Swallow on 08/29/2018 03:59 pm
Both debaters were somewhat dismissive of refueling at the Gateway and Zubrin said that going from Earth to the Gateway to the lunar surface adds to your delta-v requirement.

Can't the gateway be placed in an orbit that's optimized for rendezvous after TLI? The initial proposal called for placing the gateway in NRHO but perhaps that could be adjusted. Since it has a lot of electric propulsion capability there is no need to optimize for low station keeping requirements.
Sure, but design the surface mission first, decide when do you want it, how frequently and who will pay for it. Probably it will require cislunar rendezvous. Decide, if a permanent structure is useful at the staging orbit, or not. The contraindications are the added complexity, cost and constraints. I guess staging outpost could be useful and economic in case of very high-volume traffic. Certainly, it is meaningless in a world, where SLS can fly once a year and a lander is unaffordable.

Cost and function are two separate but related requirements. For reusable equipment calculating and comparing the cost effectiveness over 10 missions is valid - assuming that 10 missions are a genuine possibility, a mission may include multiple launches.

A lunar spacestation such as the LOP-G means that the SLS's maximum payload to the lunar surface is the same as its payload to lunar orbit. The lander and propellant going up on separate launches. (I have lost count of the SLS's payload to NRHO but it is something like 25-40 tonne.)

Other launch vehicles can also use the LOP-G (and smaller landers). I suspect spacestation staging will considerably increase the lunar payload of the Atlas V and Falcon 9.

edit: max payload

That is the SLS payload to TLI, not to DHRO. The difference is a 500-700 m/s LOI burn with a lower performance propulsion system such as the Orion SM which is not nearly as efficient as the ICPS or EUS.

Allowing for a delta-v of 700 m/s to enter NRHO using the hypergolic propellant MXP-351 with 322 Isp.
m1=m0*exp(deltav/(Isp*g))
m0=m1/exp(deltav/(isp*g))

m0=40/exp(700/(322*9.81)) = 32 tonne - 10% = 28.8 tonne

The SLS getting 28 tonne to LOp-G would be useful.

Note. I chose MXP-351 as the propellant because it is being developed for lunar landers so there is likely to be some at the lunar orbit propellant depot.
Title: Re: Lunar Gateway Debate
Post by: ncb1397 on 08/29/2018 05:43 pm
I believe 2026 is possible, but only if LOP-G is cancelled, NASA concentrates of development on EUS and a Lunar Lander, and NASA's budget is increased by $3B a year. A two mission profile is used. First mission takes lander to low Lunar orbit using EUS which can last the three day journey to the Moon. Second mission takes Orion for rendezvous with lander. After landing, Orion performs TEI. Following the current plan could easily put the landing in 2036.

Why are you taking a 15,000 kg dry mass capsule/SM to low lunar orbit? The Apollo LEM only has a 4,000 kg dry mass. You should stage from a lunar orbit that requires the least insertion dV. And it should be noted that the average LM budget between 1963 and 1970 was $2.1 billion, but it had 4 flights in 1969 which would map to 2025 if the start of funding(1963) maps to 2019. Given that payments to Russia for crew rotation will stop at ~500 million per year soon and you could reprogram a couple hundred million from other HSF programs to what is now the agencies #1 priority, the actual budget increase for Apollo like funding levels of a lunar lander could easily average less than $1.3 billion per year.
Title: Re: Lunar Gateway Debate
Post by: Joseph Peterson on 08/29/2018 10:28 pm
How about building a storable bipropellant depot at the Gateway? This was landers could launch with partially empty tanks, refuel before landing and deliver bigger payloads to the lunar surface. This would also be useful for refueling Orion or a hypothetical very large lander that stretches the capability of SLS but it wouldn't be tied to that program.

Propellant would be mostly delivered with commercial launchers, perhaps as part of a competitive "Commercial Fuel" program. This would be technically simpler to setup that cargo and crew because the interfaces are less complex.

The first users could be participants in the new commercial lunar payload services program but fuel could also be made available to partners like ESA. NASA could subsidize the fuel significantly in the interest of making the moon's surface more accessible.

If we design a Gateway that can transition to, and operate in, low Lunar orbit, I might be able to accept it.  A fuel tank in 86° LLO gives us windows to polar locations every two hours, using fast transits, on a fully reusable 4.5 km/s lander.  Week long equatorial sorties are possible when orbits align roughly every other week.  The Moon provides nearly 50% of our radiation shielding through the entire flight, and few microgravity facilities are requires.  In other words, we get a fairly simple lander design.  A Gateway remaining in NRHO puts us in the position where we want 6 m/s, radiation shielding, and going without a microgravity toilet is cruel and unusual punishment.  A refuelable Orion extends Orion's range enough so the capsule could return from LLO, meaning this isn't an automatic threat to SLS/Orion.  Storable propellants such as MMH/NTO(Orion's propellant) don't care about transit times, so using SEP(solar electric propulsion) for the transit from Earth orbit to LLO negates most of the launched mass savings of using chemical propellant from Earth to NRHO.

I do have several concerns.  As far as I am aware the Gateway is not being designed to operate in the thermal environment in LLO.  Retrofitting appropriate radiators could carry significant expense.  Modifying Gateway design requirements would best be done sooner rather than later.  I'm afraid to ask how many years and billions will be required to design a refuelable Orion.  Human operators are virtually unnecessary for propellant transfer, so there is little justification for a Gateway when a far cheaper tanker will suffice.

While I am a fan of storable propellants for Lunar landers, we want the high test stuff for our "Ferrari" NRHO based landers.  "Regular unleaded" is better used for the "Civic" LLO lander which doesn't need as much acceleration.  Barring unexpected Gateway capability, my fear is we are boxing ourselves into being reliant on the development pace of long-term hydrolox storage.

Then again the "Roadster" might beat both options to the surface at lower cost, making the entire discussion moot.
Title: Re: Lunar Gateway Debate
Post by: ThereIWas3 on 08/29/2018 11:43 pm
Making it into a propellant storage facility would greatly increase it's mass (not being all that big to start) and probably make orbital changes less feasible.
Title: Re: Lunar Gateway Debate
Post by: Joseph Peterson on 08/30/2018 03:08 am
Making it into a propellant storage facility would greatly increase it's mass (not being all that big to start) and probably make orbital changes less feasible.

Agreed .

That said, running down the propellant stock prior to major maneuvers is a relatively straightforward procedure at current projected flight rates.  I project a 99.9% chance that we will not use the Gateway to concurrently build a Moon base while reviving ARM and/or dispatching crewed Martian missions during the next decade.  Instead, I find it more likely the Gateway will spend a number of years in an orbit which is proper for whatever task it finally ends up doing.

Alternatively, we could draw inspiration from NCC-1701-D and design the habitat section be detachable from the propellant section. 
Title: Re: Lunar Gateway Debate
Post by: Steven Pietrobon on 08/30/2018 10:12 am
Why are you taking a 15,000 kg dry mass capsule/SM to low lunar orbit? The Apollo LEM only has a 4,000 kg dry mass. You should stage from a lunar orbit that requires the least insertion dV.

Orion dry mass with three crew is actually 17,120 kg. :-) As we're using hydrolox to perform LOI and the lander is using storable propellants (since it has to stay in LLO for several months, waiting for Orion to arrive), its more efficient to place the lander in LLO then in a higher orbit. The second SLS has the performance to send Orion to LLO, so we might as well use that capability. Not sure what you're implying with the 4 t dry mass of the Apollo LM. The Apollo 17 LM dry mass was 4,937 kg. I assumed a larger lander, having a dry mass of 7,758 kg and propellant mass of 18,090 kg.

Quote
And it should be noted that the average LM budget between 1963 and 1970 was $2.1 billion, but it had 4 flights in 1969 which would map to 2025 if the start of funding(1963) maps to 2019. Given that payments to Russia for crew rotation will stop at ~500 million per year soon and you could reprogram a couple hundred million from other HSF programs to what is now the agencies #1 priority, the actual budget increase for Apollo like funding levels of a lunar lander could easily average less than $1.3 billion per year.

Total LM funding was $2,241M in then year dollars or $16,670M today. Over eight years, that works out to $2.1B a year, but I don't expect the LM to cost that much, so we'll use your value of $1.3B a year, similar to what NASA is spending on Orion at $1.35B. NASA is spending $2.15B a year on SLS. That might need to increase to $2.85B with the added development of EUS and Dark Knight boosters to replace RSRMV when they run out. Operations and "other stuff" that NASA invariably spends money on is currently $1.3B. So total spending is $1.3+$1.35+$2.85+$1.3 = $6.8B, compared to $4.8 being spent today. So that would be an extra $2B. I pulled $3B out of the air in my first post, so I wasn't that far off, only by a billion. :-) NASA might need that extra billion anyway, considering how they've blown the budget on previous projects.
Title: Re: Lunar Gateway Debate
Post by: ncb1397 on 08/30/2018 02:40 pm
Why are you taking a 15,000 kg dry mass capsule/SM to low lunar orbit? The Apollo LEM only has a 4,000 kg dry mass. You should stage from a lunar orbit that requires the least insertion dV.

Not sure what you're implying with the 4 t dry mass of the Apollo LM. The Apollo 17 LM dry mass was 4,937 kg. I assumed a larger lander, having a dry mass of 7,758 kg and propellant mass of 18,090 kg.

I was rounding to the nearest 1000 kg.

Quote
The dry mass of the ascent stage was 2445 kg and it held 2376 kg of propellant. The descent stage dry mass (including stowed surface equipment) was 2034 kg and 8248 kg of propellant were onboard initially.
https://nssdc.gsfc.nasa.gov/nmc/spacecraftDisplay.do?id=1969-059C

2445 + 2034 = 4478 kg.

vs. Apollo 17

Quote
The dry mass of the ascent stage was 2260 kg and it held 2387 kg of propellant. The descent stage dry mass (including stowed surface equipment) was 2935 kg and 8874 kg of propellant were onboard initially.
https://nssdc.gsfc.nasa.gov/nmc/spacecraftDisplay.do?id=1972-096C

2260 + 2935 = 5195 kg

That might need to increase to $2.85B with the added development of EUS and Dark Knight boosters to replace RSRMV when they run out.]

The 2.15 billion already includes cutouts for the Exploration Upper Stage. $300 million in 2018 alone. If there was a hydrolox booster with the GLOW of the EUS, it would put about 5,000 kg into LEO. As such, 15% of the funding for 5% of the scale should be plenty and additional money should not need to be allocated.
Title: Re: Lunar Gateway Debate
Post by: catdlr on 09/08/2018 03:01 am
Designing a tiny home to orbit the Moon

The Verge
Published on Sep 7, 2018

NASA wants to build another space station — except this one won’t live in a close orbit around Earth. Instead, it will be sent into deep space to orbit around the moon and then someday…Mars. Within the last year, NASA has begun planning for a much smaller astronaut outpost, a new destination dubbed the Gateway. The idea is for this space station to serve as a place for astronauts to live and train for excursions to and from the lunar surface. In this episode of Space Craft, Loren Grush heads to Lockheed Martin to visit a mockup of one of these space habitats and see what living in it might actually feel like.

https://www.youtube.com/watch?v=BXjP7kWpuZw?t=001

https://www.youtube.com/watch?v=BXjP7kWpuZw

Title: Re: Lunar Gateway Debate
Post by: Coastal Ron on 09/08/2018 03:33 am
Eric Berger with an article on Ars Technica:

NASA says it’s building a gateway to the Moon—critics say it’s just a gate (https://arstechnica.com/science/2018/09/nasa-says-its-building-a-gateway-to-the-moon-critics-say-its-just-a-gate/) | Ars Technica

A quote from the article:

Quote
This has not left much oxygen in the room for dissenters—publicly, at least. However, a few critics persist, and they raise valid questions about the lunar Gateway. Robert Zubrin, a high-profile aerospace engineer outside of NASA’s policymaking process, has emerged as a chief antagonist.

“It is the next giant leap into quicksand,” Zubrin argued during a recent meeting of The Mars Society. “If you wanted to send people to the Moon or Mars, would you take some of your money to build a lunar orbit space station on the way? You would not.”

Interesting fact:

Quote
Put another way, a spacecraft could leave LEO, reach the surface of the Moon, and return directly to Earth for a total delta-v cost of 9.1km/s. To do the same mission through the Gateway, both coming and going, requires a delta-v of 10.65km/s, a 17 percent increase. This is one reason why Zubrin has taken to calling the lunar Gateway a “toll booth,” because it adds significantly to the energies needed to reach the Moon (or Mars, if spacecraft first went to the Gateway and then on to the Red Planet).

Other nuggets in their too, so make sure to read the article and then come back with comments or observations...
Title: Re: Lunar Gateway Debate
Post by: ncb1397 on 09/08/2018 03:43 am
Yeah, I posted a comment on there trying to correct their delta-v numbers. I also emailed Eric Berger directly. No response either re-affirming that their numbers are correct or accepting my numbers (well, NASA's numbers really). The correction is the following:

Quote
You significantly overstate the delta-v penalty of going through the gateway.

https://ntrs.nasa.gov/search.jsp?R=20180003324&hterms=nrho&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchallany%26Ntt%3Dnrho

Based on that, it is 9110 m/s to go through the gateway and 8600 m/s to go through low lunar orbit(i.e. Apollo). This is an increase of ~6%.

It is 425 m/s + 730 m/s or 1155 m/s to get into LLO through the NRHO vs 900 m/s going directly. This is a one way penalty of 255 m/s. Round trip is double that. Your estimate of a penalty of 1550 m/s is off by a factor of 3.

Their result shouldn't even pass the gut check as it is greater than Orion's total delta-v capability meaning either Orion couldn't reach the gateway and leave or it was less expensive to reach LLO from a trans lunar trajectory than the elliptical NRHO which is already a lunar orbit.

It seems the claims get more extreme over time. First Zubrin says it is 1 km/s more. Now it is 1.5 km/s + more.
Title: Re: Lunar Gateway Debate
Post by: Archibald on 09/08/2018 10:56 am
this is pretty bizarre indeed. First there is Earth escape, 3.1 km/s. Then, where do we go from there ?
- entering LLO takes 1 km/s to get in, and 1 km/s to get out. That's what Apollo SPS did ! And it has 2.5 km/s of delta-v. Nearly twice as much as Orion, thank Ares 1 for that.  >:(
- now the case of libration points. I will dug Vanilla / Sorensen old thread and numbers, but from memory, it took less than LLO, which make some sense (300 m/s to 700 m/s, one way, so X2, and even then, 600 m/s to 1400 m/s is still less than LLO)
- Farquhar, Belbruno and Sorensen (and many others) showed that entering or exiting a libration point (halo) orbit, isn't like LLO: the delta-v I mentionned are not carved in stone, because one can trade transit times for low delta-v insertion.

I would be interesting to know whether DRO / DHRO are closer from LLO or libration points in this respect. Then again, we run into Orion limits: 21 days in space, or burst.
Title: Re: Lunar Gateway Debate
Post by: TrevorMonty on 09/08/2018 02:14 pm
Article says DV round trip is 6.1+3.0kms via LLO  and 6.85 + 3.8kms via Gateway. The only issue is Orion + SLS aren't capable  of first option and neither is Dragon +FH.

Small detail that Zubrin leaves out.
Title: Re: Lunar Gateway Debate
Post by: TripleSeven on 09/08/2018 02:56 pm
Eric Berger with an article on Ars Technica:

NASA says it’s building a gateway to the Moon—critics say it’s just a gate (https://arstechnica.com/science/2018/09/nasa-says-its-building-a-gateway-to-the-moon-critics-say-its-just-a-gate/) | Ars Technica

A quote from the article:

Quote
This has not left much oxygen in the room for dissenters—publicly, at least. However, a few critics persist, and they raise valid questions about the lunar Gateway. Robert Zubrin, a high-profile aerospace engineer outside of NASA’s policymaking process, has emerged as a chief antagonist.

“It is the next giant leap into quicksand,” Zubrin argued during a recent meeting of The Mars Society. “If you wanted to send people to the Moon or Mars, would you take some of your money to build a lunar orbit space station on the way? You would not.”

Interesting fact:

Quote
Put another way, a spacecraft could leave LEO, reach the surface of the Moon, and return directly to Earth for a total delta-v cost of 9.1km/s. To do the same mission through the Gateway, both coming and going, requires a delta-v of 10.65km/s, a 17 percent increase. This is one reason why Zubrin has taken to calling the lunar Gateway a “toll booth,” because it adds significantly to the energies needed to reach the Moon (or Mars, if spacecraft first went to the Gateway and then on to the Red Planet).

Other nuggets in their too, so make sure to read the article and then come back with comments or observations...

the problem with the GAteway is the same problem the space station had in 1980's...it was going to do everything that anyone wanted to be done in space...and yet like the station that emerged...it will do nothing much EXCEPT keep the space industrial complex in a lot of countries...in business

and it will take at least 10 years and at least 50 billion to do nothing
Title: Re: Lunar Gateway Debate
Post by: woods170 on 09/08/2018 04:44 pm
Article says DV round trip is 6.1+3.0kms via LLO  and 6.85 + 3.8kms via Gateway. The only issue is Orion + SLS aren't capable  of first option and neither is Dragon +FH.

Small detail that Zubrin leaves out.

Oh yeah, Zubrin is good at that. Anything to further his own agenda, as usual.
Title: Re: Lunar Gateway Debate
Post by: woods170 on 09/08/2018 04:51 pm
the problem with the GAteway is the same problem the space station had in 1980's...it was going to do everything that anyone wanted to be done in space...and yet like the station that emerged...it will do nothing much EXCEPT keep the space industrial complex in a lot of countries...in business

and it will take at least 10 years and at least 50 billion to do nothing

Yes sir. Hence my post a few months ago: https://forum.nasaspaceflight.com/index.php?topic=43405.msg1826333#msg1826333
Title: Re: Lunar Gateway Debate
Post by: su27k on 09/11/2018 04:25 am
Article says DV round trip is 6.1+3.0kms via LLO  and 6.85 + 3.8kms via Gateway. The only issue is Orion + SLS aren't capable  of first option and neither is Dragon +FH.

Small detail that Zubrin leaves out.

Remember he proposed Moon Direct as a plausible way of returning to the Moon without LOP-G and using existing launch vehicles, so I don't see any omission here.
Title: Re: Lunar Gateway Debate
Post by: ncb1397 on 09/11/2018 04:54 am
Article says DV round trip is 6.1+3.0kms via LLO  and 6.85 + 3.8kms via Gateway. The only issue is Orion + SLS aren't capable  of first option and neither is Dragon +FH.

Small detail that Zubrin leaves out.

Remember he proposed Moon Direct as a plausible way of returning to the Moon without LOP-G and using existing launch vehicles, so I don't see any omission here.

It really wasn't that plausible. It required a 3,000 kg crew vehicle that carries 9000 kg of storable low density deep cryo hydrolox propellants. Yes, it is a true that the LEM ascent module massed a similar amount(2150 kg), but it only carried more like 2,500 kg of hypergolics. So, you have about 850 kg of mass growth to accomplish quite a few miracles including quadrupling the propellant mass load while increasing insulation and increasing the tank sizes by 8x+. Previously in this thread, I proposed a 4,200 kg vehicle that carries 10,000 kg of hydrolox to go up and down from the gateway and that may still be pushing the mass fractions. Anyways, with this wonder vehicle, you could also easily do crewed lunar missions from the gateway as well using a single SLS 1B launch.
Title: Re: Lunar Gateway Debate
Post by: Eric Hedman on 09/23/2018 06:51 pm
I guess Russia wants out.

https://www.yahoo.com/news/russia-throws-doubt-joint-lunar-space-station-u-105357218--finance.html (https://www.yahoo.com/news/russia-throws-doubt-joint-lunar-space-station-u-105357218--finance.html)
Title: Re: Lunar Gateway Debate
Post by: TripleSeven on 09/23/2018 06:55 pm
I guess Russia wants out.

https://www.yahoo.com/news/russia-throws-doubt-joint-lunar-space-station-u-105357218--finance.html (https://www.yahoo.com/news/russia-throws-doubt-joint-lunar-space-station-u-105357218--finance.html)

the US and Russian partnership is in its "end times" ...if nothing else the politics of it are starting to now work (ie they are running out of money AND we are running out of the need to pay them) and its clear well we are going different ways...

as things are going I would not be surprised to see the Chinese/Russian friendship rekindle...they are already doing heavy joint military excersizes...
Title: Re: Lunar Gateway Debate
Post by: TrevorMonty on 09/24/2018 12:12 am
I guess Russia wants out.

https://www.yahoo.com/news/russia-throws-doubt-joint-lunar-space-station-u-105357218--finance.html (https://www.yahoo.com/news/russia-throws-doubt-joint-lunar-space-station-u-105357218--finance.html)
The Russian part of Gateway was nice to have but not essential. NASA didn't want Russia in critical path for this project.
Title: Re: Lunar Gateway Debate
Post by: ncb1397 on 09/24/2018 01:24 am
It was my impression that JAXA wanted to build their own hab, but it didn't have a ride. This frees up a launch slot for JAXA to build their own module with the caveat it has to double as an airlock. They have some experience in that domain given Kibo has an airlock. The Russian demand for equal partnership when they aren't providing for any construction launches and are providing for a single smaller airlock just doesn't fly.
Title: Re: Lunar Gateway Debate
Post by: MATTBLAK on 09/24/2018 01:51 am
The Kibo Lab module is one of the biggest modules on ISS. If Japan built another and an airlock module, too this would be significant hardware for a gateway station. USA adds another couple of pressurized modules including a docking unit, propulsion bus and Service Module, solar arrays and a Canadarm and they'd be good to go! :) The lot shouldn't cost $20 billion, though :( As I've said - without a reusable Lunar Lander, propellant depot system and the most useful orbit for the Lander... It's hard to justify the whole project.
Title: Re: Lunar Gateway Debate
Post by: A_M_Swallow on 09/24/2018 04:32 pm
With all this science stuff is the lunar spacestation turning into a scientific spacestation probably requiring minimum vibration making it useless as a gateway?
Title: Re: Lunar Gateway Debate
Post by: Lunadyne on 09/24/2018 05:59 pm
Not sure what the situation is at EML-2, but I know that EML-1 is a good spot for freeflyer platforms to do that kind of science.  If you look at the second graphic on this page: http://www.thespacereview.com/article/2033/1, you will see an example of how a freeflyer platform can be launched from the region of EML-1, and after a period of time it will return to the same vicinity.

(http://www.thespacereview.com/archive/2033a.jpg)

[Sorry about the Chinese, I haven't found the equivalent in any of the English-language books in the Lunar Library.]

Basically you're taking advantage of the fact that EML-1 and EML-2 are at slightly different energy levels in the Earth's gravity well.  By controlling the energy (C) imparted to your freeflyer platform you can pinch off EML-2 and constrain the craft to an orbit within the Moon's sphere of influence, the only exit being a kind of throat that passes through the EML-1 point to emerge into the Earth's gravity well and sphere of influence.  It is in this throat area that the freeflyer is captured for return to facilities at EML-1.

(https://i.stack.imgur.com/eXWhr.jpg)

Looking at the graphics, it would seem that if you want to do the equivalent from EML-2 you'd have to send your freeflyer on a big loop out around past EML-3.

This again highlights why I think NASA is misguided (and unstrategic) in their focus on EML-2.  Sure it offers a very slight delta-V advantage to get to MARS!, but you lose most of the logistical advantages offered by EML-1, with a side order of opportunity cost and unintended consequences.  I think back to an old post at the Selenian Boondocks (https://selenianboondocks.com/2005/12/were-on-a-road-to-nowhere/), and realize that we're still on that road...
Title: Re: Lunar Gateway Debate
Post by: faramund on 09/24/2018 09:32 pm
With all this science stuff is the lunar spacestation turning into a scientific spacestation probably requiring minimum vibration making it useless as a gateway?

Although, will it? I'm thinking, if an experiment needed minimum vibration, couldn't it be done more cheaply, on say ISS - or some successor LEO station. Specifically, what would need minimum vibration - and also have a preference for lunar, versus Earth orbit?

Granted, if ISS is gone and there's no follow on station, then that would make the lunar station the only man-tended option.
Title: Re: Lunar Gateway Debate
Post by: Propylox on 10/20/2018 04:47 am
In engineering form follows function. The prime mission of the spacestation in lunar orbit needs agreeing. Then we can write the requirements.
Well said. If the purpose is to explore the Lunar surface, a low orbit is required to efficiently downmass and/or return regularly. If the purpose is Lunar Orbital science (engine duration tests, telescopes/imaging, etc) than a low orbit is required. If the purpose is to float around in empty space doing nothing but spend money and pat ourselves on the back, than NRHO or EML are adept orbits - though ones costing significantly more than ISS to tend.

The Gateway is not locked into an orbit for life, it can move around cislunar space. Thats main reason for such capable propulsion module. -&- Being able to move between cislunar locations is primary requirement of Gateway.
That's interesting .. if you're not interested in Lunar science. Deep space orbits have arguably many uses (almost all etherial notions based on future speculations), but Lunar science ain't one. While station keeping is a requirement, the diminutive power proposed for Gateway based on a defunct asteroid mission is useless in Low Orbit. If this is about science, and not just spending money, the propulsion system and orbital requirements proposed are irrelevant wastes.

It might just be the usual NASA tendency to try to keep all the different "center" factions happy.  Next thing you know, they'll throw a VASIMR on it.
A more interesting application of PPE-derived craft would be to shuttle payloads from Earth to Lunar orbit. Is there any indication NASA is looking at this? The trip would take many months through the Van Allen belts but could deliver 10-20 ton modules from LEO launchers.
PPE is significantly too small for anything other than meandering about in empty space and though VASIMR begins approaching the power requirement for a SEP cycler (if engines were clustered) it's not a good solution. Any cycler will wear each use from aforementioned Belts, refueling, high amperage operation, thermal fatigue, battery degradation, etc. The performance of VASIMR for cycling doesn't exceed other ion systems other than in complexity, cost, weight and an exceptional service life. Similarily, high-end solar panels could last 30 trips over 15yrs, but the rest of the craft can't match that service life. Better to keep it light, cheap, disposable and powerful - like any other stage.

A 'Lunar Gateway' would only be a 'success' or useful if it included a small/medium propellant depot for a reusable, crewed Lander that was based there. And because of the Lander; it would have to have the right orbit to allow good access and coverage to much of the Lunar surface for useful periods of time - could someone nail down for me/us what type of orbit that would be?

Without a Lander based there, I'd say the Gateway serves little purpose...
A refueling station is needed for a reusable lander.  Agreed.  The station would also have to support the lander in other ways.  Cargo transfer.  Human transfer and temporary habitation.  Maintenance and testing.  Is this what the current gateway design reflects?  Could the gateway be somewhere else?

 - Ed Kyle
This is what I've looked at and worked through - a transportation infrastructure from LEO to the Moon's surface and back. It requires a weighpoint in LLO to deliver supplies (propellant, equipment, modules, landers, etc), to outfit landers per mission, to temporarily provide and extend human occupation and the added feature of enabling and conducting Lunar Orbital science including rendezvous/repair/inspection of orbital testbeds (nuclear engines anyone?).

If we design a Gateway that can transition to, and operate in, low Lunar orbit, I might be able to accept it.  A fuel tank in 86° LLO gives us windows to polar locations every two hours, using fast transits, on a fully reusable 4.5 km/s lander.  Week long equatorial sorties are possible when orbits align roughly every other week. ..
Will I get banned if I say I'm a fan of the PLO - Polar Lunar Orbit, that is. I've proposed and outlined here before an 86* orbit, but synchronous so it's apogee is toward Earth while zipping low over the far side. This doesn't provide the "good access and coverage to much of the Lunar surface" requested by MattBlak, but instead endless access to the poles, equatorial meridians near and far, and rapid Earth-return. Basically the interesting points, everywhere 15* or so from them and the safety of getting home in a hurry.

the least useful comparison of the gateway are comparisons to the current station. The space station is in all respects a failure. .. the "gateway" will exactly the same trap, because in the end the same mistakes will be made...the difference is that instead of permanently crewed, it will only have "guest" every so often, who might as well be as far from the moon as ISS is ..
You might be fishing, and I might just tug that hook. The ISS hasn't been a failure, it merely achieved goals other than science and exploration. In this way, the Gateway as proposed will have the same successes as ISS in all but one: ISS allowed the continued development, refinement and expertise of Russia's ECLASS that began with Salyut and carried through Mir to today. Their over half-century of perfecting the ability to live in space is completely unique in the political and scientific community. But the end of ISS appears to be a return to political divergence and an opportunity wasted for NASA's ECLASS development.

How long has NASA been in space, including with ISS, and perishable ECLASS that only last a few weeks is all we got? Pathetic, especially compared to regenerative systems lasting years that would be required at a Lunar Station - thus required that Russia be a primary tenant to again keep our American butts alive. Or we can nix the requirement for spacefairing and just float a can around empty space, briefly visit once a year (until the air runs out) while accomplishing nothing except trying to justify spending $billions on feeding an industrial institution clamoring for regular projects and via a tragically-misengineered Congressional rocket = Just Like ISS
Title: Re: Lunar Gateway Debate
Post by: Eric Hedman on 10/20/2018 05:21 am
Will I get banned if I say I'm a fan of the PLO - Polar Lunar Orbit, that is. I've proposed and outlined here before an 86* orbit, but synchronous so it's apogee is toward Earth while zipping low over the far side. This doesn't provide the "good access and coverage to much of the Lunar surface" requested by MattBlak, but instead endless access to the poles, equatorial meridians near and far, and rapid Earth-return. Basically the interesting points, everywhere 15* or so from them and the safety of getting home in a hurry.
You won't get banned for being a fan of a Polar Lunar Orbit.  The reason for the NRHO orbit is simply because the Orion Service module doesn't have the delta V for anything else.  If you want to fix the orbit, you have to either convince NASA or ESA to fund a bigger service module or use other vehicles.  Good luck with that battle.
Title: Re: Lunar Gateway Debate
Post by: Propylox on 10/20/2018 06:06 pm
.. The reason for the NRHO orbit is simply because the Orion Service module doesn't have the delta V for anything else.  If you want to fix the orbit, you have to either convince NASA or ESA to fund a bigger service module or use other vehicles.  Good luck with that battle.
My car has a busted transmission. That defines everything I do as it can only make it from my house to the edge of town. Where I go, what I plan, how I invest and limits I impose.
I can only buy enough groceries to carry by hand because anything interesting is distant to my car's range and if I need to get something big I must arrange alternative transport. I would fix the tranny, but I have mandated to keep it broken under the excuse it's been broken for so long and so much has been spent working around its shortcomings it should be kept it that way. I've considered investing in upgrading the engine and axle for slightly better performance, but that doesn't address the problem - only wastes time and money. By all measures, I'm a fool and this was a metaphor for SLS.

If a Lunar Gateway is defined by a Congressional rocket with its inept core stage design, than the Gateway will be equally inept. If the rocket is designed to complete a desired task, rather than vice versa, than we can explore Lunar space, surface, advance propulsion technology, habitation, bolster both gov and private participation and actually accomplish NASA's mandate of science and exploration. But as-is, the Gateway and SLS designs/proposals are useless and should either be corrected or cancelled so NASA can pursue actual science and exploration.
Title: Re: Lunar Gateway Debate
Post by: Eric Hedman on 10/20/2018 07:13 pm
.. The reason for the NRHO orbit is simply because the Orion Service module doesn't have the delta V for anything else.  If you want to fix the orbit, you have to either convince NASA or ESA to fund a bigger service module or use other vehicles.  Good luck with that battle.
My car has a busted transmission. That defines everything I do as it can only make it from my house to the edge of town. Where I go, what I plan, how I invest and limits I impose.
I can only buy enough groceries to carry by hand because anything interesting is distant to my car's range and if I need to get something big I must arrange alternative transport. I would fix the tranny, but I have mandated to keep it broken under the excuse it's been broken for so long and so much has been spent working around its shortcomings it should be kept it that way. I've considered investing in upgrading the engine and axle for slightly better performance, but that doesn't address the problem - only wastes time and money. By all measures, I'm a fool and this was a metaphor for SLS.

If a Lunar Gateway is defined by a Congressional rocket with its inept core stage design, than the Gateway will be equally inept. If the rocket is designed to complete a desired task, rather than vice versa, than we can explore Lunar space, surface, advance propulsion technology, habitation, bolster both gov and private participation and actually accomplish NASA's mandate of science and exploration. But as-is, the Gateway and SLS designs/proposals are useless and should either be corrected or cancelled so NASA can pursue actual science and exploration.
I see that you understand what's going on.  It would be funny if it wasn't so sad.
Title: Re: Lunar Gateway Debate
Post by: Markstark on 11/12/2018 05:05 pm
Hello all. Based on information in this publicly available FOIA response https://www.muckrock.com/foi/united-states-of-america-10/nasa-space-force-59278/#file-228649 (https://www.muckrock.com/foi/united-states-of-america-10/nasa-space-force-59278/#file-228649), it appears that there's a parallel effort underway to develop a partially reusable lunar human lander to be used with the Gateway in the 2020's

I included some relevant snips but the document is searchable if you want to look yourself.

The information in that document appears to line up with Anatoly's reporting here https://www.popularmechanics.com/space/moon-mars/a24115130/nasa-reusable-lander/ (https://www.popularmechanics.com/space/moon-mars/a24115130/nasa-reusable-lander/) & herehttp://www.russianspaceweb.com/ (http://www.russianspaceweb.com/).

I'm curious if the combination of Lander + Gateway changes any opinions.
Title: Re: Lunar Gateway Debate
Post by: speedevil on 11/12/2018 06:37 pm
I need to read the document fully.
Quote from: Markstak
I'm curious if the combination of Lander + Gateway changes any opinions.
Quote from: NASA
Humans on the surface no later than 2029.

I wholly do not support any efforts to get to the moon which is happy to spend $50B on getting 50 tons of stuff around the moon, and perhaps tens of astronauts in the 2030s.
I might have supported it twenty years ago.

Getting to the moon with $1M/kg teaches us nothing at all about living and working on the moon.
It teaches us how to spend murderous amounts of money on tiny amounts of hardware for political and institutional gain.
Getting ISRU working on the moon at $1M/kg does not help at all - it may drop your costs to $100K/kg - this is not actually helping.

If 'ridiculous' but cheap solutions end up cheaper than the boutique ones, then you're on the wrong path.

Take for example the concerns about 'fuels that can cope with the cold' raised in the above document - well - great, you have a fuel that can cope with the cold.

If you are going to claim this meaningfully helps, you need to show that simply extending the vehicle thermal envelope over the tanks, perhaps making it ten times larger is not cheaper.

There are reasonable arguments why earth launch rockets are not Lego.

However, these arguments get a lot weaker for cislunar operations, where you have no aerodynamic forces, all needed accelerations are below 1/2g, and you don't care so much about mass fraction.

We need something like Lego.

(https://images-na.ssl-images-amazon.com/images/I/61JocjT-R5L._SX466_.jpg)From Amazon. (https://www.amazon.com/Unlimited-Creation-Centimeter-Interlocking-Building/dp/B07CH9X2TL)


As a semi-serious suggestion.

Mass produce these at 3.6m across, with 5cm average thickness walls, made of aluminium, for a dry weight of 10 tons, with fitments to attach to other cubes in a gas-tight manner at the cheapest price possible.
Order a thousand, for $1M each.

At around a hundred to one launch cost to hardware differential, even before taking into account hardware launched on massively reusable RLV, it is not startlingly clear to me that you can't get more pressurised, shielded, warm, powered, safe volume on the moon or in lunar orbit with this very dumb basis.

And that's a problem for LOPG, as it shoud be very clear there is a massive benefit on spending around a thousand times more a kilo on hardware that is cleverly designed and not based around a childrens toy.


Title: Re: Lunar Gateway Debate
Post by: freddo411 on 11/12/2018 06:42 pm
Hello all. Based on information in this publicly available FOIA response https://www.muckrock.com/foi/united-states-of-america-10/nasa-space-force-59278/#file-228649 (https://www.muckrock.com/foi/united-states-of-america-10/nasa-space-force-59278/#file-228649),
...

I'm curious if the combination of Lander + Gateway changes any opinions.


Does anyone really think that this is a well structured and thought out effort to go to the Moon?  In what way is any of this efficient?  Is it a low cost?  Is it expeditious?  Does it build up facilities and/or techniques that are useful in some way?   I don't see the upside.

LOPG strikes me as another ISS.   ISS never did any meaningful partial gravity work.   Development and testing of meaningful long duration ECLSS concepts didn't happen.   New and improved space suits have not been built, and the existing inventory has been dangerously overused.    Billions of dollar per year are spent to launch handfuls of cube sats.  A animated mannequin with GM logos rounds out the kibuki theatre in space.  It's beyond the pale.  A lot of money and effort has been spent to occupy space but the purpose has been lacking.

Judging by the language and posturing in these documents, I don't see a serious effort at a manned lander.
Title: Re: Lunar Gateway Debate
Post by: saliva_sweet on 12/26/2018 12:45 pm
Does anyone really think that this is a well structured and thought out effort to go to the Moon?  In what way is any of this efficient?  Is it a low cost?  Is it expeditious?  Does it build up facilities and/or techniques that are useful in some way?   I don't see the upside.

I used to think that the LOP-G is a boondoggle for these reasons. Now I think it's vital. Going to the moon is the boondoggle.

LOPG strikes me as another ISS.   ISS never did any meaningful partial gravity work.

ISS reasearch is deceptve. The astronauts are doing experiments that aren't interesting enough to warrant their own satellites, which would do the work better and cheaper. It's real value is to keep them busy. ISS is a vivarium for human subjects in space. The real research is measuring their vital signs, eyeball pressures, bone densities, sequencing their DNA, following every aspect of their lives. It has proven that humans can spend over a year in space and come back fine. This knowledge is priceless. The case for human exploration of space relies on the ISS.

We need to do that now for deep space environment. Prove that we can build the spaceship (vivarium) and the subjects won't die, go mad, or become space mutants. Why not do that around the moon? Could even give them some RC cars to drive on the surface because it's cool. Maybe even a lander, but that's the boondoggle part that detracts from the main mission. The hypothesis and theory says the astronauts will be fine. But we need the proof to move on. Otherwise we'll be stuck in distractions like radiation, psychology, or whatever and never get anywhere.
Title: Re: Lunar Gateway Debate
Post by: freddo411 on 12/26/2018 04:49 pm


LOPG strikes me as another ISS.   ISS never did any meaningful partial gravity work.

ISS reasearch is deceptve. The astronauts are doing experiments that aren't interesting enough to warrant their own satellites, which would do the work better and cheaper. It's real value is to keep them busy. ISS is a vivarium for human subjects in space. The real research is measuring their vital signs, eyeball pressures, bone densities, sequencing their DNA, following every aspect of their lives. It has proven that humans can spend over a year in space and come back fine. This knowledge is priceless. The case for human exploration of space relies on the ISS.

We need to do that now for deep space environment. Prove that we can build the spaceship (vivarium) and the subjects won't die, go mad, or become space mutants. Why not do that around the moon? Could even give them some RC cars to drive on the surface because it's cool. Maybe even a lander, but that's the boondoggle part that detracts from the main mission. The hypothesis and theory says the astronauts will be fine. But we need the proof to move on. Otherwise we'll be stuck in distractions like radiation, psychology, or whatever and never get anywhere.

Granted, ISS does generate some experience and data that is useful.   

I'm disappointed that the 3 or 4 billion dollars per year wasn't utilized to fly a significantly sized centrifuge to enable the study of partial gravity on mammals.   That's an obvious area of study that is sorely needed.    I find the reasonings against such a facility disrupting microgravity experiments unconvincing.
Title: Re: Lunar Gateway Debate
Post by: Proponent on 12/26/2018 06:14 pm
Does anyone really think that this is a well structured and thought out effort to go to the Moon?  In what way is any of this efficient?  Is it a low cost?  Is it expeditious?  Does it build up facilities and/or techniques that are useful in some way?   I don't see the upside.

I used to think that the LOP-G is a boondoggle for these reasons. Now I think it's vital. Going to the moon is the boondoggle.

LOPG strikes me as another ISS.   ISS never did any meaningful partial gravity work.

ISS reasearch is deceptve. The astronauts are doing experiments that aren't interesting enough to warrant their own satellites, which would do the work better and cheaper. It's real value is to keep them busy. ISS is a vivarium for human subjects in space. The real research is measuring their vital signs, eyeball pressures, bone densities, sequencing their DNA, following every aspect of their lives. It has proven that humans can spend over a year in space and come back fine. This knowledge is priceless. The case for human exploration of space relies on the ISS.

We need to do that now for deep space environment. Prove that we can build the spaceship (vivarium) and the subjects won't die, go mad, or become space mutants. Why not do that around the moon? Could even give them some RC cars to drive on the surface because it's cool. Maybe even a lander, but that's the boondoggle part that detracts from the main mission. The hypothesis and theory says the astronauts will be fine. But we need the proof to move on. Otherwise we'll be stuck in distractions like radiation, psychology, or whatever and never get anywhere.

But the Gateway as proposed would host crews only for periods of a few weeks.  A deep-space vivarium is certainly possible and would have the benefit you describe, but that's not what the Gateway is.
Title: Re: Lunar Gateway Debate
Post by: saliva_sweet on 12/26/2018 07:00 pm
But the Gateway as proposed would host crews only for periods of a few weeks.

I think it's a reasonable start that could and should lead to longer tours as systems are validated. Like was done on other stations.
Title: Re: Lunar Gateway Debate
Post by: whitelancer64 on 12/26/2018 07:30 pm
LOPG strikes me as another ISS.   ISS never did any meaningful partial gravity work.   

Partial gravity research isn't the only meaningful research that needs to be done on the ISS.

And in fact, the ISS is doing some partial-g research. The mouse habitat has a section that can be rotated to partial g.

Quote
Development and testing of meaningful long duration ECLSS concepts didn't happen.   
*snip*

The ECLSS on the USOS is one big long duration experiment. Prior to the ISS, the US did not have much experience in long duration life support, and what it did relied heavily on consumables (filters, scrubbers, etc.). NASA has actually learned a lot from its time on the ISS, particularly from the water recycling systems. Lessons learned and improvements to the ECLSS will be incorporated to LOP-G and Orion and any other future space station / capsule / habitat. Part of the reason that NASA wanted an extension to the life of the ISS beyond 2024 was to test out next-gen ECLSS improvements.
Title: Re: Lunar Gateway Debate
Post by: Coastal Ron on 12/26/2018 07:47 pm
Granted, ISS does generate some experience and data that is useful.   

I'm disappointed that the 3 or 4 billion dollars per year wasn't utilized to fly a significantly sized centrifuge to enable the study of partial gravity on mammals.   That's an obvious area of study that is sorely needed.    I find the reasonings against such a facility disrupting microgravity experiments unconvincing.

Artificial gravity is on everyones list of things we'll need in the future, but can't afford today (or that is the assumption).

Also, for the transportation architecture that NASA is planning to use for the LOP-G artificial gravity would be a waste of money since the planned missions don't last any longer than 90 days, and 90 days in space is not long enough for the negative side effects of zero gravity.

We will only need artificial gravity when we intend for humans to spend years in space at a time, and that is not anything NASA is planning right now. Which is why they are not focused on studying it yet.
Title: Re: Lunar Gateway Debate
Post by: freddo411 on 12/26/2018 08:18 pm
It seems that my comment has started to drift this thread away from LOPG.    I acknowledge the positive points folks have made about ISS, without necessarily agreeing that it has accomplished much as a long duration, continuously operated LEO station should have.   The ECLSS system is longer duration than the shuttle, but it really hasn't changed since it was designed in the 1990s -- the ISS program should have flown a couple of versions worth of improvements by now.   I hear rumblings that the CO2 scrubber is problematic to the point of having negative impacts on the astronauts.   Happy to continue that discussion point in a different thread.

My point about LOPG, was that it will end up similar to the ISS program, in that while it is possible to imagine some utility for a lunar station, LOPG almost certainly won't actually do that (see ISS history).    Will LOPG facilitate landing humans on the Moon... not likely.   Will LOPG be a propellent depot? ... almost certainly not.   Will LOPG in result in some sustainable foothold in space/HEO/Lunar orbit? ...   

On the positive side, it's just possible that NASA might use some commercial cargo type arrangements that have a chance of spinning off some lunar capabilities for wider use.

Title: Re: Lunar Gateway Debate
Post by: redliox on 12/26/2018 08:30 pm
A further factor occurs to me I'm unsure if anyone's brought up in the debate...Orion and how many times it can fly.

Presumably Lockheed Martin would be merry to supply numerous capsules for NASA, although like ESA I presume technically they only build what's officially contracted to them...which would be 2 flights currently scheduled. 

The real trouble factor is the service module and SLS (boosters specifically and the Block 1/1B variants); both basically are dependent on shuttle spares.  Including the crewless test, there'll only be 6 Orion flights before alternative parts are required and 8 for SLS.  Even assuming these flights are one a year, maybe one per 2 years, that puts a direct limit on how long the Orion can be depended upon for Gateway servicing; roughly 10 years which might largely be consumed just by assembling Gateway.

While I think the Gateway could be made more functional than the ISS, I'd be concerned how well it could operate empty before becoming unstable like Skylab or 2010's Discovery before crashing into our Moon.

Any thoughts on Orion alternatives for Cislunar space or Gateway's autonomy?
Title: Re: Lunar Gateway Debate
Post by: redliox on 12/26/2018 08:37 pm
The ECLSS system is longer duration than the shuttle, but it really hasn't changed since it was designed in the 1990s -- the ISS program should have flown a couple of versions worth of improvements by now.   I hear rumblings that the CO2 scrubber is problematic to the point of having negative impacts on the astronauts.   

Definitely a problem needing addressing, and the cooling system I recall required numerous EVAs to fix on more than one occasion as another example of ISS exasperations that need to be learned from.

My point about LOPG, was that it will end up similar to the ISS program, in that while it is possible to imagine some utility for a lunar station, LOPG almost certainly won't actually do that (see ISS history).    Will LOPG facilitate landing humans on the Moon... not likely.   Will LOPG be a propellent depot? ... almost certainly not.   Will LOPG in result in some sustainable foothold in space/HEO/Lunar orbit? ...   

On the positive side, it's just possible that NASA might use some commercial cargo type arrangements that have a chance of spinning off some lunar capabilities for wider use.

I agree with both your heavy pessimism and light optimism.  The Gateway needs to be something better than ISS, especially with a clearer purpose and simplified assembly.  Incorporating commerical space would be a good idea both with modules (Bigelow an obvious example) or spacecraft (SpaceX another obvious but not necessarily exclusive option).
Title: Re: Lunar Gateway Debate
Post by: whitelancer64 on 12/26/2018 09:42 pm
It seems that my comment has started to drift this thread away from LOPG.    I acknowledge the positive points folks have made about ISS, without necessarily agreeing that it has accomplished much as a long duration, continuously operated LEO station should have.   The ECLSS system is longer duration than the shuttle, but it really hasn't changed since it was designed in the 1990s -- the ISS program should have flown a couple of versions worth of improvements by now.   
*snip*

First of all, the USOS only got its ECLSS installed in July 2007, so it's only been operating for 10 1/2 years. It has had to deal with several problems. For example, in 2011 it was basically inoperable for several months because the water being input into it was too acidic. Additionally, the water reclaimer (installed in 2008) was designed to recycle 89% of water from urine, it has only been able to get about 70% because of problems with excess calcium sulfate in the system.

Next gen target is 90-95% water reclamation. NASA does want to test that out on the ISS before putting it in LOP-G.
Title: Re: Lunar Gateway Debate
Post by: RonM on 12/26/2018 09:48 pm
Any thoughts on Orion alternatives for Cislunar space or Gateway's autonomy?

Easy, upgraded Starliner and Dragon 2. Just need to have new contracts and throw money at Boeing and SpaceX.
Title: Re: Lunar Gateway Debate
Post by: TrevorMonty on 12/27/2018 12:03 am


A further factor occurs to me I'm unsure if anyone's brought up in the debate...Orion and how many times it can fly.

Presumably Lockheed Martin would be merry to supply numerous capsules for NASA, although like ESA I presume technically they only build what's officially contracted to them...which would be 2 flights currently scheduled. 

The real trouble factor is the service module and SLS (boosters specifically and the Block 1/1B variants); both basically are dependent on shuttle spares.  Including the crewless test, there'll only be 6 Orion flights before alternative parts are required and 8 for SLS.  Even assuming these flights are one a year, maybe one per 2 years, that puts a direct limit on how long the Orion can be depended upon for Gateway servicing; roughly 10 years which might largely be consumed just by assembling Gateway.

While I think the Gateway could be made more functional than the ISS, I'd be concerned how well it could operate empty before becoming unstable like Skylab or 2010's Discovery before crashing into our Moon.

Any thoughts on Orion alternatives for Cislunar space or Gateway's autonomy?

I'd hope in ten years time there will be commercial alternatives to SLS and Orion for HSF to Gateway and moon.

Gateway is quite capable of departing lunar orbit under its own stream, so crashing into moon shouldn't be issue.
Title: Re: Lunar Gateway Debate
Post by: Eric Hedman on 12/27/2018 04:43 am
Any thoughts on Orion alternatives for Cislunar space or Gateway's autonomy?

Easy, upgraded Starliner and Dragon 2. Just need to have new contracts and throw money at Boeing and SpaceX.
Blue Origin may also have a capsule design under way that could fit the bill.  The more options, the merrier.
Title: Re: Lunar Gateway Debate
Post by: A_M_Swallow on 12/27/2018 12:49 pm
{snip}
Any thoughts on Orion alternatives for Cislunar space or Gateway's autonomy?

Dragon 2 can be pushed to LOPG if the Falcon 9's upper stage is refuelled. Same for the CST-100 and Centaur/ACES. The upper stages can then power the return flights if the service modules have insufficient delta-v. The CST-100's heat shield may need some help slowing down the capsule from a propulsive system. Same for the Dream Chaser.
Title: Re: Lunar Gateway Debate
Post by: floss on 01/03/2019 05:44 pm
The way I figure lop G will operate is that it will be small at first and grow over the decades .A high performance crew transfer craft from ISS to lopG IS needed ,a slow tanker to transfer fuel and cargo craft to transfer food and spares .

ISS will  grow as Gateway grows hopefully 50 people in gateway before I die .
Title: Re: Lunar Gateway Debate
Post by: Tulse on 02/28/2019 06:58 pm
It appears we have another name change: Gateway lunar outpost (http://blogs.nasa.gov/bridenstine/2019/02/28/canada-commits-to-joining-nasa-at-the-moon/) (and yes, only "Gateway" seems to be capitalized, but no, it's not just called "Gateway", but "Gateway lunar outpost").
Title: Re: Lunar Gateway Debate
Post by: MATTBLAK on 02/28/2019 07:21 pm
That is a better name. Some will still call it a 'tollbooth' though... ;)
Title: Re: Lunar Gateway Debate
Post by: MATTBLAK on 02/28/2019 07:25 pm
The way I figure lop G will operate is that it will be small at first and grow over the decades .A high performance crew transfer craft from ISS to lopG IS needed ,a slow tanker to transfer fuel and cargo craft to transfer food and spares .

ISS will  grow as Gateway grows hopefully 50 people in gateway before I die .
Highly unlikely to have 50 people at any stage; unless a SpaceX 'Starship' has to dock there for any reason. And the best place for 50 people near the Moon would be actually on the Moon.
Title: Re: Lunar Gateway Debate
Post by: Tulse on 02/28/2019 07:25 pm
I'd prefer just "Gateway", although that name has its own cultural history (https://en.wikipedia.org/wiki/Gateway_(novel)).
Title: Re: Lunar Gateway Debate
Post by: RDoc on 03/10/2019 06:54 pm
Gateway lunar outpost? OK. Are we going to refer to it as Glo?
Title: Re: Lunar Gateway Debate
Post by: A_M_Swallow on 03/11/2019 03:53 am
Gateway lunar outpost? OK. Are we going to refer to it as Glo?

At night will it Glo in the dark?  :P
Title: Re: Lunar Gateway Debate
Post by: Steven Pietrobon on 03/14/2019 12:04 am
It seems that the Gateway is in fact an old idea, but only for Lunar surface access. After watching the MSFC history video of Dr. Margrit von Braun (Werner von Braun's daughter) showing a slide of the August 1969 Mars mission, I found this set of slides given by Werner von Braun in August 1969 to the Space Task Group.

https://www.nasa.gov/sites/default/files/atoms/files/19690804_manned_mars_landing_presentation_to_the_space_task_group_by_dr._wernher_von_braun.pdf

The Mars mission was part of the "Integrated Space Program" which included the following elements:

Saturn V
Space Shuttle
SSM (Space Station Module?, 6.6 m diameter)
Tug (6.6 m diameter)
Nuclear Shuttle (10 m diameter)
Mars Excursion Module (MEM, 10 m diameter)

The SSM is basically an advanced version of Skylab, built to the same dimensions. The SSMs (carrying 6 crew each) would be used in an Earth orbit space station (12 crew), Earth orbit space base (100 crew), geosynchronous orbit space station (25 crew), Lunar orbit station (6 to 25 crew), Lunar surface base (6 to 48 crew), Mars mission module (6 crew), Mars orbit space station (24 crew) and Mars surface base (12 to 48 crew).

In the first slide, after the Apollo extended missions, the plan was to first build a Lunar orbit station with 6 crew using one SSM. Presumably the Tug would be used for Lunar surface access. Sound familiar to anyone? It seems that these types of plans are embedded in NASA's DNA! Just a matter of ticking the boxes one by one.
Title: Re: Lunar Gateway Debate
Post by: RonM on 03/14/2019 01:33 am
The grand plans before computers were powerful enough to replace crew. Seemed like a good idea at the time, except for the cost.
Title: Re: Lunar Gateway Debate
Post by: libra on 03/14/2019 04:38 pm
Gateway lunar outpost? OK. Are we going to refer to it as Glo?

At night will it Glo in the dark?  :P

https://www.flickr.com/groups/[email protected]/

Day-glo !
Title: Re: Lunar Gateway Debate
Post by: theinternetftw on 03/20/2019 08:45 pm
From the human lander Industry Day:

<snipping human lander stuff>

* The preliminary Gateway NRHO is 71,100km x 3,366 km. This is still under review.
Title: Re: Lunar Gateway Debate
Post by: yg1968 on 03/20/2019 10:55 pm
This article from a month ago provides an update on the PPE awards:

Quote from: SN
NASA, which had anticipated awarding contracts [for the PPE] in March, now expects starting work by the end of May. That delay will have a domino effect on the overall PPE project, including when the module will be launched. NASA stated in the procurement filing that it expects “a corresponding shift in the target launch date from September 2022 to no later than December 31, 2022.”

https://spacenews.com/shutdown-to-delay-first-element-of-nasas-lunar-gateway/
Title: Re: Lunar Gateway Debate
Post by: Tywin on 03/21/2019 08:04 pm
The Sierra Nevada module for the Gateway...

https://twitter.com/SierraNevCorp/status/1106239388516794369

https://twitter.com/hashtag/askawaygateway?src=hash
Title: Re: Lunar Gateway Debate
Post by: gosnold on 03/26/2019 08:32 pm
VP Pence just called for a return to the Moon in 2024:
https://mailchi.mp/spacenews/just-in-pence-calls-for-human-return-to-the-moon-by-2024 (https://mailchi.mp/spacenews/just-in-pence-calls-for-human-return-to-the-moon-by-2024)

Already the usual suspects are making their moves (from Chris B's twitter):
Quote
Lockheed Martin talking about scaling down Gateway and "an aggressive but achievable schedule"

These space council meetings should come with their own supply of popcorn...
Title: Re: Lunar Gateway Debate
Post by: catdlr on 03/26/2019 11:47 pm
March 26, 2019
RELEASE 19-022

NASA Administrator Statement on Return to Moon in Next Five Years


The following is a statement from NASA Administrator Jim Bridenstine on Tuesday’s announcement by Vice President Mike Pence, at the fifth meeting of the National Space Council, about putting American astronauts back on the Moon in the next five years:

“Today, I joined leaders from across the country as Vice President Mike Pence chaired the fifth meeting of the National Space Council. Vice President Pence lauded President Donald J. Trump’s bold vision for space exploration and spoke to NASA’s progress on key elements to accomplish the President’s Space Policy Directives.

“Among the many topics discussed during our meeting at the U.S. Space and Rocket Center in Huntsville, Alabama, was to accelerate our return to the Moon:

NASA is charged to get American astronauts to the Moon in the next five years.
We are tasked with landing on the Moon’s South Pole by 2024.
Stay on schedule for flying Exploration Mission-1 with Orion on the Space Launch System (SLS) rocket next year, and for sending the first crewed mission to the lunar vicinity by 2022.
NASA will continue to ‘use all means necessary’ to ensure mission success in moving us forward to the Moon.
“It is the right time for this challenge, and I assured the Vice President that we, the people of NASA, are up to the challenge.

“We will take action in the days and weeks ahead to accomplish these goals. We have laid out a clear plan for NASA’s exploration campaign that cuts across three strategic areas: low-Earth orbit, the Moon, and Mars and deeper into space.

“I have already directed a new alignment within NASA to ensure we effectively support this effort, which includes establishing a new mission directorate to focus on the formulation and execution of exploration development activities. We are calling it the Moon to Mars Mission Directorate.

“Earlier today I was also at Marshall Space Flight Center for an all-hands to reinforce our commitment to SLS with the workforce. We discussed my recent announcement that NASA would consider all options to fly Orion around the Moon on schedule. I shared the analysis we conducted to asses flying the Orion on different commercial options. While some of these alternative vehicles could work, none was capable of achieving our goals to orbit around the Moon for Exploration Mission-1 within our timeline and on budget. The results of this two-week study reaffirmed our commitment to the SLS. More details will be released in the future.

“There’s a lot of excitement about our plans and also a lot of hard work and challenges ahead, but I know the NASA workforce and our partners are up to it. We are now looking at creative approaches to advance SLS manufacturing and testing to ensure Exploration Mission-1 launches in 2020. We will work to ensure we have a safe and reliable launch system that keeps its promise to the American people.

“I know NASA is ready for the challenge of moving forward to the Moon, this time to stay.”

To learn more about NASA’s Moon to Mars plans, visit:

https://www.nasa.gov/moon2mars

-end-
Title: Re: Lunar Gateway Debate
Post by: b0objunior on 03/29/2019 04:20 pm
Seems like NASA will be testing the gateway prototypes to see what's best for astronaut. Can somebody explain what it means? They're saying the won't choose a winner to build the real deal, but wasn't that the whole point of NextSTEP?


Quote
March 27, 2019
NASA Begins Testing Habitation Prototypes

Over the next several months, NASA will conduct a series of ground tests inside five uniquely designed, full-size, deep space habitat prototypes. The mockups, constructed by five American companies, offer different perspectives on how astronauts will live and work aboard the Gateway – the first spaceship designed to stay in orbit around the Moon, providing the critical infrastructure needed for exploration, science and technology demonstrations on the lunar surface.

NASA doesn’t plan to select one habitat prototype to advance to flight – rather, the tests will help NASA evaluate the design standards, common interfaces, and requirements for a future U.S. Gateway habitat module, while reducing risks for eventual flight systems.

“These tests were formulated so that we can do a side-by-side comparison of very different and innovative concepts from U.S. industry,” said Marshall Smith, who leads human lunar exploration programs at NASA Headquarters in Washington. “While we won’t dictate a specific design when we procure the U.S. habitat, we will enter the procurement phase with far less risk because of the knowledge we gain from these tests.”

NASA assembled a team from across the agency and from U.S. industry to conduct these tests. Engineers and technicians will analyze habitat system capabilities and performance proposed by each prototype concept, while human factors teams consider layout and ergonomics to optimize efficiency and performance. During the tests, future Gateway flight operators at NASA’s Johnson Space Center in Houston will collect actual live telemetry streams from each prototype. Flight operators will monitor habitat performance and support realistic mission activities as astronauts conduct “day-in-the-life” procedures within each habitat prototype, providing their perspectives as potential crew members who may one day live and work aboard the Gateway.

In addition to the physical enclosure, each company has outfitted their prototype with the basic necessities to support humans during deep space expeditions—including environmental control and life support systems, avionics, sleeping quarters, exercise equipment, and communal areas.
 

The Prototypes

The NextSTEP Habitation effort began in 2015 with four companies completing year-long concept studies. Those studies set the foundation for prototype development from 2016-2018—this time with five companies submitting concepts. Their prototype approaches are listed below, as well as a concept study outline from a sixth company, NanoRacks:

Lockheed Martin – Testing at NASA’s Kennedy Space Center, Florida

The Lockheed Martin prototype is based on a Multi-Purpose Logistics Module (MPLM), which was originally designed to provide logistics capabilities for the International Space Station. The design leverages the capabilities of Lockheed’s robotic planetary spacecraft and the Orion capsule that will transport astronauts to and from the Gateway. The prototype includes a reconfigurable space that could support a variety of missions, and combines hardware prototyping and software simulation during the test.
NextSTEP Lockheed Martin
Concept image of Lockheed Martin’s Gateway concept featuring their habitat design.
Credits: Lockheed Martin

Northrop Grumman – Testing at NASA’s Johnson Space Center, Texas

Northrop Grumman’s prototype leverages the company’s Cygnus spacecraft that delivers supplies to the International Space Station. The Cygnus took its maiden flight in 2013, and is already human-rated. Northrop Grumman’s habitat mockup focuses on providing a comfortable, efficient living environment as well as different internal configuration possibilities.
 
NextSTEP Northrop Grumman
Concept image of Northrop Grumman’s Gateway concept featuring their habitat design.
Credits: Northrop Grumman

Boeing – Testing at NASA’s Marshall Space Flight Center, Huntsville, Alabama

Proven space station heritage hardware is the key ingredient in Boeing’s Exploration Habitat Demonstrator. Named the prime space station contractor in 1993, the company developed multiple space station elements. Their demonstrator will leverage heritage assets, with a focus on optimizing interior volume, with isolated areas offering the capability to use different atmospheres for payloads without impacting cabin atmosphere.
 
NextSTEP Boeing
Concept image Boeing’s Gateway concept featuring their habitat design.
Credits: Boeing

Sierra Nevada Corporation – Testing at NASA’s Johnson Space Center, Houston, Texas

Sierra Nevada’s Large Inflatable Fabric Environment (LIFE) habitat is designed to launch in a compact, “deflated” configuration, then inflate once it’s in space. The benefit of inflatables (also called expandables) is their final configuration is capable of providing much larger living space than traditional rigid structures, which are limited in size by the payload volume of the rocket used to launch it. The LIFE Prototype inflates to 27 ft in diameter and simulates three floors of living areas.
 
NextSTEP Sierra Nevada Corporation
Concept image of Sierra Nevada’s Gateway concept featuring their habitat design.
Credits: Sierra Nevada Corporation

Bigelow Aerospace – Testing at Bigelow Aerospace, North Las Vegas, Nevada

Bigelow’s B330 prototype is an expandable module that expands in space, as its name suggests, to provide 330 cubic meters of livable area. Bigelow sent a smaller module, the Bigelow Expandable Activity Module (BEAM) to the space station in 2015, where astronauts expanded the structure live on NASA Television with compressed air tanks. The BEAM completed a two-year demonstration aboard the station, proving soft-goods resilience to the harsh space environment. Following its demonstration period, NASA extended BEAM's time aboard the station to become a storage unit.
 
NextSTEP Bigelow Aerospace
Concept image Bigelow’s Gateway concept featuring their habitat design.
Credits: Bigelow Aerospace

NanoRacks – Concept Study

NanoRacks has proposed yet another concept to maximize habitable volume for Gateway astronauts. The company’s idea is to refurbish and repurpose a spent rocket propellant tank, leveraging the natural vacuum of space to flush the tank of residual propellants. The company completed a feasibility study outlining the concept and next plans to develop full-scale prototypes demonstrating robotics development, outfitting and systems integration to convert the tank into a deep space habitat.
 
NextSTEP NanoRacks
Concept image of NanoRack’s habitat concept docked to the International Space Station.
Credits: NanoRacks

Operational - Driven Engineering

“This prototyping approach allows us to design, build, test and refine the habitat long before the final flight version is developed,” said NASA astronaut Mike Gernhardt, principal investigator of the agency's habitation prototype test series. “We are using this operational-driven engineering approach to gain an early understanding of exactly what we need to address the mission, thereby reducing risk and cost."

Using this approach, the builders, operators, and future users of the Gateway work together to evaluate concepts earlier and more completely, which helps NASA move forward to the Moon as early as possible.

The Gateway will be a temporary home and office for astronauts farther in space than humans have ever been before, and will be a home base for astronaut expeditions on surface of the Moon, and for future human missions to Mars. The NextSTEP approach bolsters American leadership in space, and will help drive an open, sustainable and agile lunar architecture.

https://www.nasa.gov/feature/nasa-begins-testing-habitation-prototypes/
Title: Re: Lunar Gateway Debate
Post by: whitelancer64 on 03/29/2019 04:38 pm
Seems like NASA will be testing the gateway prototypes to see what's best for astronaut. Can somebody explain what it means? They're saying the won't choose a winner to build the real deal, but wasn't that the whole point of NextSTEP?


Quote
March 27, 2019
NASA Begins Testing Habitation Prototypes

Over the next several months, NASA will conduct a series of ground tests inside five uniquely designed, full-size, deep space habitat prototypes. The mockups, constructed by five American companies, offer different perspectives on how astronauts will live and work aboard the Gateway – the first spaceship designed to stay in orbit around the Moon, providing the critical infrastructure needed for exploration, science and technology demonstrations on the lunar surface.

NASA doesn’t plan to select one habitat prototype to advance to flight – rather, the tests will help NASA evaluate the design standards, common interfaces, and requirements for a future U.S. Gateway habitat module, while reducing risks for eventual flight systems.

“These tests were formulated so that we can do a side-by-side comparison of very different and innovative concepts from U.S. industry,” said Marshall Smith, who leads human lunar exploration programs at NASA Headquarters in Washington. “While we won’t dictate a specific design when we procure the U.S. habitat, we will enter the procurement phase with far less risk because of the knowledge we gain from these tests.”

*snip*

https://www.nasa.gov/feature/nasa-begins-testing-habitation-prototypes/

NextSTEP is a program to develop technology for human spaceflight / deep space missions. It's not specifically tied to the Gateway, but rather, at least when the program was started, to enable the future Journey to Mars. When all the testing is done, I would expect that NASA will select a couple of these companies for a more detailed design study for the Gateway, then select one to actually build the habitation module.

That said, NASA's really in a state of flux right now. I don't know if anyone is sure what will be funded next year. Gateway might be dramatically scaled back or defunded in favor of a lunar landing.
Title: Re: Lunar Gateway Debate
Post by: theinternetftw on 04/02/2019 03:25 am
A quick quote from the recent Bridentstine town hall: (https://youtube.com/watch?v=o2gz2E-Wrws)

Quote
Certain things will have to be descoped.

We're not building the International Space Station around the moon, as many people would love to do. That's not what we're doing here.

Title: Re: Lunar Gateway Debate
Post by: b0objunior on 04/03/2019 05:10 pm
I'm not sure insulting people is the way to go... can the mod do something?
Title: Re: Lunar Gateway Debate
Post by: Chris Bergin on 04/03/2019 06:10 pm
I'm not sure insulting people is the way to go... can the mod do something?

Concur. Post in question removed. The person who lost their post will appreciate why, per a previous action they requested on different person's undesired actions.
Title: Re: Lunar Gateway Debate
Post by: spacenut on 04/03/2019 06:10 pm
I still think an LL1 or LL2 outpost would be better.  It would be easier to access from earth launch, a little harder for lunar lander.  However, from earth takes a larger rocket and larger amount of fuel.  From lunar surface not as much.  Most existing rockets can reach LL1 from earth with a larger payload than trying to get from earth to low lunar orbit. 
Title: Re: Lunar Gateway Debate
Post by: JohnFornaro on 04/05/2019 06:55 pm
A quick quote from the recent Bridentstine town hall: (https://youtube.com/watch?v=o2gz2E-Wrws)

Quote
Certain things will have to be descoped.

We're not building the International Space Station around the moon, as many people would love to do. That's not what we're doing here.

I think the Gateway is a good idea in principle.  This 73 ton artifact theoretically requires about six SLS launches, along with a number of commercial launches, per the oracle:

https://en.wikipedia.org/wiki/Lunar_Orbital_Platform-Gateway

"Various components of the Gateway would be launched on commercial launch vehicles and on the Space Launch System as Orion co-manifested payloads on the flights EM-3 through EM-8."

No metal has been bent, and six SLS's are not available on any official timeline.  Then there's the lander and the ascent vehicle, yada yada, none of which is ready to go, unless the commercial interests are way further along than is generally publicly known. 

It is hard to think that this is all happening on Trump's short schedule.
Title: Re: Lunar Gateway Debate
Post by: Slarty1080 on 04/05/2019 10:48 pm
Please Mr Musk how quickly could you beef up the Falcon Heavy and what lift capability might we be able to expect in the near future if you did? Ok so lets see if we can make the LOPG modules fit...
Title: Re: Lunar Gateway Debate
Post by: A_M_Swallow on 04/06/2019 12:37 am
Please Mr Musk how quickly could you beef up the Falcon Heavy and what lift capability might we be able to expect in the near future if you did? Ok so lets see if we can make the LOPG modules fit...

Currently the LOP-G modules are sent lunar orbit and attached by using the Orion as a tug. Something(s) else will be needed to do the same job if SLS and Orion are not available.
Title: Re: Lunar Gateway Debate
Post by: Slarty1080 on 04/06/2019 12:59 am
Please Mr Musk how quickly could you beef up the Falcon Heavy and what lift capability might we be able to expect in the near future if you did? Ok so lets see if we can make the LOPG modules fit...

Currently the LOP-G modules are sent lunar orbit and attached by using the Orion as a tug. Something(s) else will be needed to do the same job if SLS and Orion are not available.
Isn't a space tug just another name for a space based booster rocket? If not what's the difference? What additional kit would be required beyond an uprated FH with a smallish hypergolic boost stage and appropriately mass matched LOP-G modules? No doubt there are things but what?
Title: Re: Lunar Gateway Debate
Post by: spacenut on 04/06/2019 02:34 am
Building the lunar gateway with SLS is not going to get the job done.  Most modules will have to be taken there by smaller launchers using tugs, Falcon Heavy, or New Glenn, at least until Starship is operational.  SLS is just too expensive, especially for launching unmanned components. 
Title: Re: Lunar Gateway Debate
Post by: A_M_Swallow on 04/06/2019 03:14 am
Please Mr Musk how quickly could you beef up the Falcon Heavy and what lift capability might we be able to expect in the near future if you did? Ok so lets see if we can make the LOPG modules fit...

Currently the LOP-G modules are sent lunar orbit and attached by using the Orion as a tug. Something(s) else will be needed to do the same job if SLS and Orion are not available.
Isn't a space tug just another name for a space based booster rocket? If not what's the difference? What additional kit would be required beyond an uprated FH with a smallish hypergolic boost stage and appropriately mass matched LOP-G modules? No doubt there are things but what?

It is the parking problem, i.e. getting the last inch right, that upsets this plan. I am sure that with stretched fuel tanks and refuelling a Falcon Heavy could get modules to the LOP-G what it cannot do is accurately dock them. Unlike the Falcon Heavy the Dragon 2 has the small thrusters required to accurately like up docking ports. However I am not certain the Dragon 2 and CST-100 are programmed to dock with 10 tonne masses on the front of the their docking ports.