Author Topic: Are Commercial Crew Vehicles Usable/Upgradeable for Beyond-LEO Needs?  (Read 45320 times)

Offline Coastal Ron

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This question came up on a different thread, so I thought I would start a specific one to collect everyones thoughts.

The subject came up when I responded to a statement from Robotbeat:

I will say one thing: since both designs chosen were capsules, they are both relevant for any future BLEO missions and should be considered for inclusion by mission planners.

None of these vehicles will be evolved for BLEO - they are too small.  Be glad to talk on another thread about it if you want...

A number of people agreed with Robotbeat, or at least with the idea that Commercial Crew vehicles could be adapted for beyond LEO needs.

My reasons for saying that Commercial Crew vehicles are too small is that I think we have learned that for humans to stay healthy in space that they need a lot of room, so future human space travelers are not going to be spending most of their time in a capsule like the Dragon or CST-100.  Plus, capsules are really only designed for transporting humans to/from a planet with an atmosphere, so at most my view is that if we take them BEO it's only for use as a lifeboat and for the "last mile" of getting humans down onto a planet.  And currently the only planet we know we can land them as currently designed is Earth, so why not leave them orbiting in LEO and just plan to meet back up with them in Earth orbit on the way back?

If you think Commercial Crew vehicles will be adaptable for BEO applications, please state what those applications are.  For instance, would you envision using a CST-100 for visiting an asteroid or only for trips to the Moon?

And if you don't think they are applicable, go ahead and state what your alternative would be.
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Offline Lars-J

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Yes. But there is limited use in taking them with you past some kind of L1/2 gateway station.

Offline TomH

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Yes. But there is limited use in taking them with you past some kind of L1/2 gateway station.

That does reduce deep space mission mass. It also means, however, that upon return to Earth, the hab must be decelerated to orbital V prior to rendezvous with a taxi, which means taking the prop with you to deep space and back, or you rendezvous with a tanker prior to Earth arrival. The other choice is a taxi must rendezvous with the hab as it approaches Earth, and you lose the hab.

All three of these involve increased risk. Aerobraking takes too much time with a crew aboard.

Online Robotbeat

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My point was that Dragon and CST-100 and Orion and Apollo command module, etc, all would need an extra module, so all are big enough with a module and none are big enough without a module, assuming beyond short trips to and from an EML gateway or something. And they are big enough for a few days.

I mean Gemini was cartoonish lot small for 2 guys (WAY smaller than CST-100, Dragon, etc), and they spent 2 weeks in it. Dragon or CST-100 are like mansions compared to Gemini.
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Offline Coastal Ron

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Aerobraking takes too much time with a crew aboard.

If a crew is coming back from a 6-month mission to an asteroid, or a 2-years mission to Mars, is spending a week or two decelerating into LEO "too much time"?

To me it simplifies the system architecture by relying on LEO-only vehicles for transport to/from Earth, and space-only vehicles for the mission.
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Online QuantumG

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It believe it's passing through the radiation belts too many times that TomH may have been thinking about.
« Last Edit: 10/06/2014 02:08 AM by QuantumG »
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Online Robotbeat

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Doesn't take much to thicken heatshields for faster reentry if they already use ablatives.
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Offline llanitedave

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If the habitat is launched/built separately and put in a permanent cycling orbit, then the capsule could rendevous with it during Earth approach, go along with it on the mission, then separate and return to Earth on the return leg.  That way you only have to expend the energy to accelerate the habitat once.  The capsule may still be dormant, but at least you wouldn't have to launch a new habitat along with it for each mission.
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Offline TomH

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It believe it's passing through the radiation belts too many times that TomH may have been thinking about.

That's true also, however a habitat returning from Mars would need dozens of passes through the very upper atmosphere on a very high apogee ellipse. It would have no TPS at all and could incur very little -ΔV on each pass. I am no expert in orbital mechanics, however I believe it would take much more than the 2 weeks max you believe it would. That means more mass for food, O2, etc., and you have astronauts watching the Earth go by over and over while they cannot land, likely enduring psychological stress from being so near physically, while still so far away temporally.

Offline TomH

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My point was that Dragon and CST-100 and Orion and Apollo command module, etc, all would need an extra module, so all are big enough with a module and none are big enough without a module, assuming beyond short trips to and from an EML gateway or something. And they are big enough for a few days.

I mean Gemini was cartoonish lot small for 2 guys (WAY smaller than CST-100, Dragon, etc), and they spent 2 weeks in it. Dragon or CST-100 are like mansions compared to Gemini.

Yea, this was the main point in the other thread, and Chris is spot on with this. For lunar missions, you only need something slightly larger/more massive than Apollo CM. For beyond lunar, you need something with much more volume than Orion. Orion is perfectly suited for.....absolutely no mission, and it is too massive for its parachutes. Something the mass of CST-100 would be fine on lunar missions. For asteroids, Mars, Phobos a hab is needed. The capsule needs to be nothing more than a taxi to either Luna or LEO and from Luna or a deeper space habitat for reentry. Either it is dormant the rest of the time or (for deeper space) it doesn't go at all.

@IIanitedave, yes an Aldrin cycler is another possibility. Much more complex mechanics are involved though. Aldrin was (is) a genius in that field. That's why he was a good #2 with Neil. Despite his ego, he was most equipped to run LOR calculations had navigational aids gone down.

Offline Coastal Ron

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If the habitat is launched/built separately and put in a permanent cycling orbit, then the capsule could rendevous with it during Earth approach, go along with it on the mission, then separate and return to Earth on the return leg.

I would imagine this would require a powerful upper stage to do this, and let's say it's possible.

But is this the type of transportation system what we want to use for enabling us to send more humans beyond LEO?  It doesn't seem very scaleable to me.

I would think that what we should be shooting for is a transportation system that is broken up into the following segments:

1.  Earth to LEO and back - this would be covered by Commercial Crew vehicles, and any others that come along.  Essentially this will already be paid for by NASA because of their ISS support needs.

2.  LEO to the region of the Moon and back - this would be a reusable vehicle, likely refueling and refurbishing in LEO.  Getting to the Moon is pretty straight forward, but returning to LEO requires perfecting new techniques.  But if we can't figure this part out then we're not going to be able to afford to send many people BEO.

3.  Transportation to/from Earth's orbit - this too should be a reusable vehicle, although refueling and refurbishing may need to take place near the region of the Moon.  Lots of options for this, including the cycler-type vehicle, or one that slows down by spending time dipping down into Earth's gravity well.

Now maybe this is an ideal transportation system, and certainly we're only just getting close to getting the transportation segment to LEO and back put in place.

But if we're going to spend money on ways to leave LEO, I would hope we take the long view.  That doesn't always happen with government programs, and NASA certainly isn't funded for doing that today.  And that's a topic of it's own...

Anyways, that's part of the reason why I don't think today's Commercial Crew capsules are part of the evolutionary line of vehicles that we'll need in the future - I just don't see how they help us scale up the number of people leaving LEO.  And isn't that really the goal?
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Offline Coastal Ron

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...and you have astronauts watching the Earth go by over and over while they cannot land, likely enduring psychological stress from being so near physically, while still so far away temporally.

Isn't that what the crew on LEO space stations experience all the time, watching the Earth go by?

Look, if being able to see the Earth close-by after being gone for potentially years doesn't bring comfort to the crew, then I think we would have chosen the wrong people...
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Offline sdsds

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Orion is perfectly suited for.....absolutely no mission

To the contrary I think Orion is the right size to taxi a crew of four between Earth and a space station in the lunar vicinity, e.g EML1, EML2, or DRO.

The current design is too heavy for this (due to the parachute issue), and no one who knows why seems willing to say. I've expressed my guess that it's the result of structural mass left over from CxP mission requirements that is not required in this taxi role. That mass could be taken out by redesigning the structure. Alternately, EFT-1 may show a way to reduce mass, if it indicates the heat shield is over-built.
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Offline enkarha

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I though Orion was pretty good for journeys to/from L-point gateways for all the reasons Baldusi mentioned in the other thread.
But having BEO rated avionics, heat transfer through heat plates, high distance comm system, long term ECLSS, BEO astrogation capabilities, limited radiation protection for crew, etc. those thing are the hard part.
Orion is just about capable of a 8 day journey out and 4 days back(~350 m/s outbound and ~1200 return) or the reverse. For those long journeys to/from those points a nice roomy spacecraft is doubtlessly better. What I'm unsure of is that adding these various capabilities to the CC vehicles can be done without adding back mass and cost.

However, if Dragon V2 is something like the vehicle the DragonFly EIS describes, it might be capable of doing 8 day trips both ways to L2 if they launch on falcon heavy and use the upper stage for the moon swingby burn, or even without that if they slim it down a few hundred kilos.
« Last Edit: 10/06/2014 06:33 AM by enkarha »
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Offline R7

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To the OP: Whose BLEO needs?

The Chief Designer: obviously Dragon is on it's path to fulfill his.

NASA: BLEO CCVs would give Orion severe existential crisis. Might have to consider building a lander instead  :o

Inspiration Mars: too late for their window?

Mars One: *giggle*
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Offline MATTBLAK

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Orion is perfectly suited for.....absolutely no mission

To the contrary I think Orion is the right size to taxi a crew of four between Earth and a space station in the lunar vicinity, e.g EML1, EML2, or DRO.

The current design is too heavy for this (due to the parachute issue), and no one who knows why seems willing to say. I've expressed my guess that it's the result of structural mass left over from CxP mission requirements that is not required in this taxi role. That mass could be taken out by redesigning the structure. Alternately, EFT-1 may show a way to reduce mass, if it indicates the heat shield is over-built.

Because it's 5 meter diameter has always made it a bit too large to have credibly light mass - with the original 5.5 meter spec was even sillier. In my opinion (for what it's worth) Orion should have been largely composite in structure, much like the ATK Liberty proposal which I also think might have been a 'mere' 4.5 meters in diameter and possibly lighter than Orion's large aluminium/lithium etc structures. And I'm thinking if CST-100 (wish they'd give it a name) was given Orion's Service Module and other upgrades (life support, rad-shielding, flight software, heatshield  ::) ) then could it be a substitute for Orion if it were ever cancelled?!
« Last Edit: 10/07/2014 06:11 AM by MATTBLAK »
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Offline MP99



In my opinion (for what it's worth) Orion should have been largely composite in structure, much like the ATK Liberty proposal which I also think might have been a 'mere' 4.5 meters in diameter and doubtlessly thousands of kilos lighter than Orion's large aluminium/lithium etc structures.

They did build a composite version of Orion, to see what the issues were.

It wasn't any lighter.

Ironically, that composite version of Orion then BECAME Liberty. :-)

Cheers, Martin

Offline newpylong

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Of course they could, but after modifications they are no longer the commercial crew vehicles we know of today, they are bigger, and bulkier like Orion.

Offline Rocket Science

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Add Cygnus as a Hab to CST-100 (with heat shield upgrade to BEO) and the Orion SM and you're good to go...
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Offline Coastal Ron

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So are people thinking that Commercial Crew capsule vehicles (i.e. CST-100 and Dragon V2) could be an interim solution for short duration exploration?  For non-NASA missions, or if for some reason the Orion is not available?

Or that they could be used more expansively than that?
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Offline baldusi

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In my opinion (for what it's worth) Orion should have been largely composite in structure, much like the ATK Liberty proposal which I also think might have been a 'mere' 4.5 meters in diameter and doubtlessly thousands of kilos lighter than Orion's large aluminium/lithium etc structures.

They did build a composite version of Orion, to see what the issues were.

It wasn't any lighter.

Ironically, that composite version of Orion then BECAME Liberty. :-)

Cheers, Martin
There's a paper at NSTR. First, let's remember that we are talking only about the pressure vessel. The short story is that the margins needed to cover for integration accidents, and the cost and difficulty of repairing it meant that it wasn't lighter than the metal PV, it was more expensive, and the integration was quite more difficult because attaching things is very difficult. You can't weld spot, for screws you need to make an insert and then attach. And the thermal expansion is so different.

Offline Rocket Science

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So are people thinking that Commercial Crew capsule vehicles (i.e. CST-100 and Dragon V2) could be an interim solution for short duration exploration?  For non-NASA missions, or if for some reason the Orion is not available?

Or that they could be used more expansively than that?
Golden Spike to the Moon is an example thats still out there for Dragon. Musk seems to be open to mission options if someone wants to pay for it, he'll supply the hardware.
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Online AncientU

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It believe it's passing through the radiation belts too many times that TomH may have been thinking about.

That's true also, however a habitat returning from Mars would need dozens of passes through the very upper atmosphere on a very high apogee ellipse. It would have no TPS at all and could incur very little -ΔV on each pass. I am no expert in orbital mechanics, however I believe it would take much more than the 2 weeks max you believe it would. That means more mass for food, O2, etc., and you have astronauts watching the Earth go by over and over while they cannot land, likely enduring psychological stress from being so near physically, while still so far away temporally.

This is a good argument for taking the capsule with you... separate the capsule with crew a day or two out and return the crew directly through the atmosphere.  Let the uninhabited hab spend the weeks/months aerobraking.  Becomes a trade between amount of fuel needed to decelerate the hab for rendezvous vs mass of the capsule.
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Online Robotbeat

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IMHO, NASA should be building landers, either for Moon, Mars, or both (preferably Moon) which could double as craft to visit asteroids or Phobos/Deimos. Maybe also a deep space gateway in cislunar space or near Mars, perhaps also Mars habitats and infrastructure, maybe a SEP-based transit vehicle. Launch vehicles and now capsules are totally doable by commercial entities. It's a much better use of restores for NASA to be building landers and such, just buying the services for launch or even now crew taxis and logistics from the likes of Boeing, SpaceX, ULA, Orbital/ATK, Sierra Nevada, and Blue Origin.
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Offline Rocket Science

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IMHO, NASA should be building landers, either for Moon, Mars, or both (preferably Moon) which could double as craft to visit asteroids or Phobos/Deimos. Maybe also a deep space gateway in cislunar space or near Mars, perhaps also Mars habitats and infrastructure, maybe a SEP-based transit vehicle. Launch vehicles and now capsules are totally doable by commercial entities. It's a much better use of restores for NASA to be building landers and such, just buying the services for launch or even now crew taxis and logistics from the likes of Boeing, SpaceX, ULA, Orbital/ATK, Sierra Nevada, and Blue Origin.
I agree with all you said Chris except the "building" part... ;) Let industry do it...
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Offline mmeijeri

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That does reduce deep space mission mass. It also means, however, that upon return to Earth, the hab must be decelerated to orbital V prior to rendezvous with a taxi, which means taking the prop with you to deep space and back, or you rendezvous with a tanker prior to Earth arrival. The other choice is a taxi must rendezvous with the hab as it approaches Earth, and you lose the hab.

Braking shouldn't be too much of a problem, if it means inserting into a high earth orbit rather than LEO. The most obvious option would be L1/L2, especially if you have a gateway station there.
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Offline baldusi

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Look at the threads about commercial ISS replacements. There I state some of the things NASA should be working on if they actually wanted to go to BEO. And they could spur a commercial LEO industry. My guess is that if CCtCap is successful and CRS-2 gets at least as good prices as CRS-1, then commercial approach will be validated for HMD. Then we might see some plan for procuring commercially an ISS follow on. But that would be a 2018/19 initiative. That's why the extension to 2028 is so critical. To enable a smooth transition to commercial.
But that can only happen if they don't spend 3B/yr on cargo and crew to the ISS. Else, they simply will not have enough budget. They should get the full commercial services for that amount of nominal money.

Offline mmeijeri

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2.  LEO to the region of the Moon and back - this would be a reusable vehicle, likely refueling and refurbishing in LEO.  Getting to the Moon is pretty straight forward, but returning to LEO requires perfecting new techniques.  But if we can't figure this part out then we're not going to be able to afford to send many people BEO.

Things become a lot easier if you give up on symmetry. There is no pressing need to return to LEO, returning from Moon/Mars to L1/L2 and then returning from L1/L2 to Earth without stopping in LEO is much easier.
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Offline ngilmore

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If you think Commercial Crew vehicles will be adaptable for BEO applications, please state what those applications are.

I would say that to be fair, we should assume that the Commercial Crew adapted solution can be as heavy as Orion. Whatever could launch Orion could launch the adapted solution.

Wikipedia says the dry Orion capsule mass is 8,913 kg and the service Module mass 12,337 kg, and propellant 7,907 kg. Habitable volume 8.95 cubic meters.

It says Dragon v2 dry is about 4,200 kg.
Just by way of example of a structure that could be the base of a mission module, the Leonardo MPM is/was 4,082 kilograms and habitable volume 31 cubic meters.

Is 11,962 kg enough mass margin for adding radiation shielding and ECLSS to a mission module and coming in at or below the total Orion mass? And the MPLM is an oversized example, you could cut it in half and still have more room than Orion.

Adding a requirement that the mission module be re-usable is a separate constraint. If the difference in designing a re-usable mission module meant you have to launch on SLS instead of Falcon Heavy, then the total system cost would be lower to not have a re-usable mission module, correct?


Online AncientU

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Need to add LAS mass
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Offline enkarha

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It says Dragon v2 dry is about 4,200 kg.

I'm pretty sure that's just an unsourced copy-paste from the Dragon v1 mass - it should be significantly higher than that with Superdracos/extra tanks, ECLSS, windows &c. Probably more like 6+ tons dry.
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Offline baldusi

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It says Dragon v2 dry is about 4,200 kg.

I'm pretty sure that's just an unsourced copy-paste from the Dragon v1 mass - it should be significantly higher than that with Superdracos/extra tanks, ECLSS, windows &c. Probably more like 6+ tons dry.
Let's not forget the habitat's power generation, heat rejection, cooling, thermal/radiation insulation and comms. And then the fuel for all that. rocket equation applies just as much (assume 35% of stack should be fuel for Orion's equivalent delta-v).

Offline ngilmore

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Need to add LAS mass

Yes, thank you, even more margin. NASA says the gross liftoff weight of the LAS is 7,314 kg.
http://www.nasa.gov/pdf/617408main_fs_2011-12-058-jsc_orion_quickfacts.pdf

The same NASA fact sheet says the total Orion system gross liftoff weight is 31,380 kg.

So that should be top line comparison when asking if commercial crew vehicles could be adapted for BEO.

Online AncientU

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Need to add LAS mass

Yes, thank you, even more margin. NASA says the gross liftoff weight of the LAS is 7,314 kg.
http://www.nasa.gov/pdf/617408main_fs_2011-12-058-jsc_orion_quickfacts.pdf

The same NASA fact sheet says the total Orion system gross liftoff weight is 31,380 kg.

So that should be top line comparison when asking if commercial crew vehicles could be adapted for BEO.
A BA-330 is supposed to 20mT, plus some if shielding for BEO missions is added. That's a lot of room for a crew of six. First BA-330 flight is scheduled for a couple years from now (2016 or 2017, I believe).
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Offline TrevorMonty

Both Dragon and CST100 would be ideal for transport to a EML1 way station. The capsules should be able support 3-4 crew for 3.5 days. Both company's have LVs capable of delivering the capsules.


Offline raketa

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Dragon 2 will be probably able to land on Mars, but will be not able to launch back LMO.
1/Dragon 2 landing on Mars - confirm ability to land on Marrs
2/Dragon 2 + Second stage Falcon 9
- will land on Mars I>IIIIIIIIII something like that. Dragon heat shield will slow down and 2 stage will land on Mars with Dargon on top
-refueling methan and launch back to orbit to interplanetary vehicle
-Dargon heat shield will slow down inflatbale at Mars and at Earth, interplanetary vehicle will stay on Mars orbit or  earth orbit. Dragon will slow it just to keep it on the orbit.

Offline pathfinder_01

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2.  LEO to the region of the Moon and back - this would be a reusable vehicle, likely refueling and refurbishing in LEO.  Getting to the Moon is pretty straight forward, but returning to LEO requires perfecting new techniques.  But if we can't figure this part out then we're not going to be able to afford to send many people BEO.


Anyways, that's part of the reason why I don't think today's Commercial Crew capsules are part of the evolutionary line of vehicles that we'll need in the future - I just don't see how they help us scale up the number of people leaving LEO.  And isn't that really the goal?

In terms of going to and from the region of the moon direct reentry to earth would probably be the best bet. It costs less in delta V and you get your vehicle back on the ground where it can be inspected and reused(in theory). I think Dragon at least is perfect for this role. It has enough space that with an smaller crew it could make it to L1/L2 with some upgrades and because it also has an role in LEO should be capable of both missions.

Offline Coastal Ron

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In terms of going to and from the region of the moon direct reentry to earth would probably be the best bet. It costs less in delta V and you get your vehicle back on the ground where it can be inspected and reused(in theory).

To me that's like saying all Boeing aircraft would have to land in Everett WA to be inspected and refueled after every flight.  It's hard to scale a transportation system like that.

If we want to expand humanity out into space, then fuel has to become a commodity in space, just like it is here on Earth.  And with that fuel you don't have to worry as much about delta V, because that just becomes part of your fuel budget.  Breaking transportation routes into segments also allows you to build vehicles that are optimized for each route segment, as well as reusable.

We have to get past the Apollo paradigm if we want to do more in space.
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Offline guckyfan

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To me that's like saying all Boeing aircraft would have to land in Everett WA to be inspected and refueled after every flight.  It's hard to scale a transportation system like that.

I disagree. Landing back on earth is the operationally simplest and cheapest method once you have reduced launch cost through reusability. What you are suggesting is another airport somewhere out in the desert to go to instead of flying between two destinations. With that airport in the desert being out of the way and needing a lot of additional facilities that are only needed because you chose to build that extra airport.

Offline mmeijeri

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We have to get past the Apollo paradigm if we want to do more in space.

Sure, but that doesn't mean choosing direct return to Earth is an example of the Apollo paradigm.

I see the most promising path as commercial transport to a commercially operated LEO way station, followed by commercial transport to a waiting NASA MTV based at L1/L2 (using as many commercially available components as possible, such as Bigelow habs) which is supplied by commercially operated tankers at L1/L2, Sun Mars L1/L2 and Phobos / Deimos / LMO. Eventually, there could also be commercially operated way stations at L1/L2, Sun Mars L1/L2 and Phobos / Deimos / LMO.

Aerobraking back to LEO is very difficult, propulsive return to LEO is expensive, while propulsive return to L1/L2 and direct return from L1/L2 to Earth are both cheap and straightforward. I don't see much benefit from changing to a separate LEO capsule for return, especially since the return capsule from L1/L2 can be a properly modified Dragon or CST-100.
« Last Edit: 10/07/2014 05:58 PM by mmeijeri »
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Offline Brovane

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My reasons for saying that Commercial Crew vehicles are too small is that I think we have learned that for humans to stay healthy in space that they need a lot of room, so future human space travelers are not going to be spending most of their time in a capsule like the Dragon or CST-100.  Plus, capsules are really only designed for transporting humans to/from a planet with an atmosphere, so at most my view is that if we take them BEO it's only for use as a lifeboat and for the "last mile" of getting humans down onto a planet.  And currently the only planet we know we can land them as currently designed is Earth, so why not leave them orbiting in LEO and just plan to meet back up with them in Earth orbit on the way back?


I envision for Commercial Capsule's some type of mission module that the capsule will dock to after launch similar to how the Apollo CSM docked to the LM after TLI.  The mission module will be fairly light structurally since it isn't intended for re-entry.  Could be even a Bigelow inflatable.  The module will be discarded shortly before re-entry into Earth’s atmosphere. 
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My reasons for saying that Commercial Crew vehicles are too small is that I think we have learned that for humans to stay healthy in space that they need a lot of room, so future human space travelers are not going to be spending most of their time in a capsule like the Dragon or CST-100.  Plus, capsules are really only designed for transporting humans to/from a planet with an atmosphere, so at most my view is that if we take them BEO it's only for use as a lifeboat and for the "last mile" of getting humans down onto a planet.  And currently the only planet we know we can land them as currently designed is Earth, so why not leave them orbiting in LEO and just plan to meet back up with them in Earth orbit on the way back?


I envision for Commercial Capsule's some type of mission module that the capsule will dock to after launch similar to how the Apollo CSM docked to the LM after TLI.  The mission module will be fairly light structurally since it isn't intended for re-entry.  Could be even a Bigelow inflatable.  The module will be discarded shortly before re-entry into Earth’s atmosphere.

Need to get over the 'discard after use' concept... is there any reason that an inflatable could not autonomously aero-break into a HEO and await reuse?  The capsule could be separated and reenter while the aero-breaking of the mission module begins.  We're not going anywhere if we cannot get past leaving debris trails along each mission's flight path.
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Offline Brovane

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Need to get over the 'discard after use' concept... is there any reason that an inflatable could not autonomously aero-break into a HEO and await reuse?  The capsule could be separated and reenter while the aero-breaking of the mission module begins.  We're not going anywhere if we cannot get past leaving debris trails along each mission's flight path.

I would think a careful look at cost would be in order.  What would be the additional mass required to have a "mission module or inflatable" be able to aero-break in a HEO while coming back from a BEO manned mission considering the velocities involved.  Not saying it is impossible but this needs to be looked at.  Also the "mission module or inflatable" if it was going to be re-used for another mission would have to refurbished and re-stocked with supplies.  It might be cheaper to just create a disposable mission module for each BEO mission especially if the price per kg to orbit continues to drop.  The disposal might also depend on the mission.  For a lunar mission the "mission module or inflatable" might be re-usable since it doesn't need to be occupied for very long.  For a Mars mission you might want to dispose of it after use.  You could very well have new forms of mold etc. growing inside. :)

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Offline Coastal Ron

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I would think a careful look at cost would be in order.  What would be the additional mass required to have a "mission module or inflatable" be able to aero-break in a HEO while coming back from a BEO manned mission considering the velocities involved.  Not saying it is impossible but this needs to be looked at.

Now doubt there is a lot that we still need to work out to implement a reusable transportation system.  NASA has been wanting to invest in some of technologies we'll need, and some is being done in private industry, but it certainly needs more work.

So in the near-term the cheaper solution will likely involve throwing away perfectly good hardware, and that is going to barrier to doing more in space because we are not able to lower the costs fast enough.

To change this is going to require a change in mindset, and the willingness of Congress to allow NASA to help perfect a number of needed technologies.  But based on the spending priorities Congress currently has I'm not sure when NASA will be able to help with this challenge, so that leaves it up to the private sector.
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Offline Coastal Ron

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Sure, but that doesn't mean choosing direct return to Earth is an example of the Apollo paradigm.

To me Apollo was an example of a completely disposable architecture, which makes it hard to scale up.

Quote
I see the most promising path as commercial transport to a commercially operated LEO way station, followed by commercial transport to a waiting NASA MTV based at L1/L2 (using as many commercially available components as possible, such as Bigelow habs) which is supplied by commercially operated tankers at L1/L2, Sun Mars L1/L2 and Phobos / Deimos / LMO. Eventually, there could also be commercially operated way stations at L1/L2, Sun Mars L1/L2 and Phobos / Deimos / LMO.

Aerobraking back to LEO is very difficult...

Today, sure.  But we also haven't been trying very hard to solve this.  I know Jon Goff has some insight into possible technologies that could help solve this, which I think include Magnetic Aerobraking.  But this does need attention and funding to figure out what the best solution is.

Quote
...propulsive return to LEO is expensive...

Again, today, sure.  But if a certain space transportation company is able to perfect some form of reusability, then in-space fuel costs will be able to drop significantly.  So really the solution for this one is based on supply & demand costs for fuel, because once they get down low enough then we can start reusing spacecraft.

Quote
...while propulsive return to L1/L2 and direct return from L1/L2 to Earth are both cheap and straightforward. I don't see much benefit from changing to a separate LEO capsule for return, especially since the return capsule from L1/L2 can be a properly modified Dragon or CST-100.

Today that works, and for a limited number of people.  The challenge is that such a system doesn't scale well, and if we're not scaling then we are not going to be able to do all the things we'd all like humanity to do in space.
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Offline Brovane

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Now doubt there is a lot that we still need to work out to implement a reusable transportation system.  NASA has been wanting to invest in some of technologies we'll need, and some is being done in private industry, but it certainly needs more work.

So in the near-term the cheaper solution will likely involve throwing away perfectly good hardware, and that is going to barrier to doing more in space because we are not able to lower the costs fast enough.

To change this is going to require a change in mindset, and the willingness of Congress to allow NASA to help perfect a number of needed technologies.  But based on the spending priorities Congress currently has I'm not sure when NASA will be able to help with this challenge, so that leaves it up to the private sector.

I think people would be surprised at how much lower the costs would be for some type of standard production "Mission Module".  Most of the expensive parts stay in the capsule and the "Mission Module could be fairly simplified.  What really gets costs cranking for NASA is that they have to do a one-off design and getting the mass into orbit.  If you had to design a new mission module from scratch every time you flew one then the costs would be fairly high.  However if you designed a standard module and then just kept building to that standard design your costs come down a lot.  You then place that with lower costs to orbit you get something that could dramatically lower prices.  Not enough to get into the 1/2 Million dollars to Mars cost that Musk wants but enough to be a good start until more re-usability is figured out. 
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Offline mmeijeri

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Today that works, and for a limited number of people.  The challenge is that such a system doesn't scale well, and if we're not scaling then we are not going to be able to do all the things we'd all like humanity to do in space.

I think the only part that wouldn't be reusable would be the SM of the capsule. I suspect that could be made reusable later, and that aerobraking just a SM is easier than a whole capsule. But I wouldn't like it to be the first step, since I think it's too ambitious. As for a very ambitious long-term plan, I think NASA's OASIS architecture was very nice, except for the fact that it saw all in-space elements as traditional NASA projects, rather than commercial-crew-like competitive procurement of resupply services.
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Offline JasonAW3

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Ok, this is a bit off topic, but...

Anybody know if anything has been done about using a generated magnetic field on a ship, interacting with Earth's magnetic field, to act as a sort of magnetic aerobraking system?

If possible, it sure would save on the TPS materials on Crew Return Vehicles.
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Offline Coastal Ron

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Ok, this is a bit off topic, but...

Anybody know if anything has been done about using a generated magnetic field on a ship, interacting with Earth's magnetic field, to act as a sort of magnetic aerobraking system?

If possible, it sure would save on the TPS materials on Crew Return Vehicles.

Jon Goff has talked about possible solutions that involve magnetic fields.  I should PM him about this.

He also wrote an article about the subject back in 2010 on his website:

MHD Aerobraking and Thermal Protection Part III: Aerobraking and Aerocapture
http://selenianboondocks.com/2010/02/mhd-aerobraking-and-thermal-protection-part-iii-aerobraking-and-aerocapture/
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Offline A_M_Swallow

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Need to get over the 'discard after use' concept... is there any reason that an inflatable could not autonomously aero-break into a HEO and await reuse?  The capsule could be separated and reenter while the aero-breaking of the mission module begins.  We're not going anywhere if we cannot get past leaving debris trails along each mission's flight path.

If we are not too worried about return time we could use an ion thruster.  Low thrust EML-1 to LEO is a delta-v of 7.0 km/s using an Isp of 5000s.

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Today that works, and for a limited number of people.  The challenge is that such a system doesn't scale well, and if we're not scaling then we are not going to be able to do all the things we'd all like humanity to do in space.

I think the only part that wouldn't be reusable would be the SM of the capsule. I suspect that could be made reusable later, and that aerobraking just a SM is easier than a whole capsule. But I wouldn't like it to be the first step, since I think it's too ambitious. As for a very ambitious long-term plan, I think NASA's OASIS architecture was very nice, except for the fact that it saw all in-space elements as traditional NASA projects, rather than commercial-crew-like competitive procurement of resupply services.
Dragon shouldn't need a service module just for entering and exiting EML1/2. All you'd have is the trunk, and even that could be gotten rid o with a clever folding solar array (and/or small radiator) in the nose and/or better Li-S batteries (which are just as good as fuel cells).
« Last Edit: 10/08/2014 12:48 AM by Robotbeat »
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Offline pathfinder_01

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In terms of going to and from the region of the moon direct reentry to earth would probably be the best bet. It costs less in delta V and you get your vehicle back on the ground where it can be inspected and reused(in theory).

To me that's like saying all Boeing aircraft would have to land in Everett WA to be inspected and refueled after every flight.  It's hard to scale a transportation system like that.



Sure breaking it into segments is what happens here on earth but not everything needs to be carried the same way. On earth the jet’s fuel could be a carried by pipeline, tanker, rail car and truck to the airport and the Jet carrying passengers could fly in deposit passengers pick up some more passengers refuel and fly further. In fact moving fuel by air is not cost effective and used only when there is no other option to do so.

The problem with transporting people in space vs. cargo is that the first needs a fast trip while the latter could benefit from slower trips. The problem is that returning to LEO with a crew is very hard. Some methods like SEP and aero braking are just too slow or in the case of aero braking too many passes through the Van Allan belts for crew.  And some cargo like fuel is time insensitive and you could send more by slower trips.

The crew really could travel in something like a capsule or a lifting body designed to be deposited in LEO, transferred to L1/L2 and renter to earth. A transfer stage could be used to push the capsule out. It could be fueled in LEO and push the capsule or other cargo that needs a fast trip to L1/L2. It would be returned to LEO unmanned by some hopefully cost effective means like SEP and refueled there by some cost effective means.  The capsule would reenter from L1/L2.

If we can get reusability up to LEO then the rest could follow. At the moment part of the problem is being worked on Dragon and first stage reuse. Something like Dragon could cover LEO to L1/L2. It is really only when you start to leave earth orbit that direct reentry or carrying the capsule with you becomes debatable.
« Last Edit: 10/08/2014 02:54 AM by pathfinder_01 »

Offline Brovane

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Dragon shouldn't need a service module just for entering and exiting EML1/2. All you'd have is the trunk, and even that could be gotten rid o with a clever folding solar array (and/or small radiator) in the nose and/or better Li-S batteries (which are just as good as fuel cells).

What is type of engine is providing the Delta-V change for entering/exiting EML1/2?
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Offline A_M_Swallow

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Dragon shouldn't need a service module just for entering and exiting EML1/2. All you'd have is the trunk, and even that could be gotten rid o with a clever folding solar array (and/or small radiator) in the nose and/or better Li-S batteries (which are just as good as fuel cells).

What is type of engine is providing the Delta-V change for entering/exiting EML1/2?

The Falcon Heavy can throw the Dragon to EML-1/2, so the RCS can do the docking.

The CST-100 (Mark 2) would need a transfer stage to go fro LEO to EML-1/2.  As the spacecraft is in orbit a medium thrust vacuum engine is sufficient.  Candidates include the hydrogen/LOX RL10 engines on the Centaur or the methane/LOX Morpheus HD5 engines or the monomethylhydrazine Space Shuttle OMS engines.  Possibly modified for a longer burn.

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Quote from: RobotbeatNotCoastalRonMakeSureToEditProperlyPlease

Dragon shouldn't need a service module just for entering and exiting EML1/2. All you'd have is the trunk, and even that could be gotten rid o with a clever folding solar array (and/or small radiator) in the nose and/or better Li-S batteries (which are just as good as fuel cells).

What is type of engine is providing the Delta-V change for entering/exiting EML1/2?
Dracos, of course. Remember, Orion had thrusters as backup to its OMS engine, and that was for lunar orbit. Certainly not Superdracos. Remember, Dragon launches with all that abort propellant which it could use (if it doesn't have enough prop for full vertical landing back on Earth, it may still have enough for parachute assist), and one could imagine a slight increase in propellant. You'd need about 500m/s or so, depending on just how fast of a transit you want. If you can afford to wait, you need a lot less propellant.
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Offline jongoff

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Ok, this is a bit off topic, but...

Anybody know if anything has been done about using a generated magnetic field on a ship, interacting with Earth's magnetic field, to act as a sort of magnetic aerobraking system?

If possible, it sure would save on the TPS materials on Crew Return Vehicles.

Jon Goff has talked about possible solutions that involve magnetic fields.  I should PM him about this.

He also wrote an article about the subject back in 2010 on his website:

MHD Aerobraking and Thermal Protection Part III: Aerobraking and Aerocapture
http://selenianboondocks.com/2010/02/mhd-aerobraking-and-thermal-protection-part-iii-aerobraking-and-aerocapture/

Short answer, there are two classes of approaches to using magnets and plasmas for aerobraking or aerocapture. The one linked to above uses plasma generated due to the bow shock created while your spacecraft passes through the atmosphere. With a strong enough magnet, as the partially ionized gas flows around your vehicle, the conductivity of the gas and the magnetic field interact to create a current loop in front of the vehicle, which pushes the bow shock back away from your vehicle. The magnetic pushback enhances your drag force, and reduces the plasma density in the bowshock (lowering dynamic pressure and heating). But it requires a pretty strong magnet, and only works when you're going fast enough to ionize enough of the incoming air.

The other approach is the stuff we're working on with MSNW. In this approach, you get create a low-density seed plasma and capture it with a weaker electromagnet around your spacecraft. As neutral gas passes into the plasma, charge exchange collisions ionize the neutrals, which are then captured by the electromagnet.

Of the two, I'm more of a fan of the MSNW approach, as it requires less exotic magnets, works at a wider velocity range, and operates at a higher altitude range with lower effective ballistic coefficients.

But one of the key things about either of these technologies, is that they enable you to now start non-propulsively recovering and reusing spacecraft in LEO. If MAC works and scales up, you should be able to brake or capture something that is completely unaerodynamic (Bigelow module, Centaur stage, space station, etc) into LEO with a fairly low mass hit, and no propellant required. If it's easy to stop in LEO like that, you no longer really need to lug a capsule around, and you can start reusing in space hardware.

Did that answer your question Ron?

~Jon

Offline mmeijeri

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Dragon shouldn't need a service module just for entering and exiting EML1/2. All you'd have is the trunk, and even that could be gotten rid o with a clever folding solar array (and/or small radiator) in the nose and/or better Li-S batteries (which are just as good as fuel cells).

That's a very good point!
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Offline JasonAW3

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First, not Ron, Jason.

Second, I didn't entirely make myself clear, so let my clarify.

As I understand it, it is possible to create a Magnetic Sail that would allow a craft to lift itself out of Earth orbit, via the planet's magnetic field.  (I read one article that suggested it may be possible to launch from teh Earth's surface with a Magnetic sail, but I think thats a bit far fetched).

     What I was suggestion was, as a craft is returing to Earth, use a magnetic sail as a sort of "deep space parachute" to bleed off eneough velocity of the entire craft, (Mars mission craft, habitats, engines, etc.) so that the entire craft can make orbit around the Earth and teh ERV Capsule would only have to resist the reentry from LEO rather fronm a high velocity BEO return.

      Obviously, using susch a system to achieve Mars orbit would be impossible, due to teh practically complete absense of a Martian magnetic field, therefor aero braking becomes a necessity.

   It also occures to me that a craft using a nuclear rocket is likely to also be suing some sort of Magnetic shielding to protect teh crew from solar and nuclear radiation.  If so, it may be possible to use this shield as a Magnetic sail to give the craft an additional boost via Earth's Magnetic field.
« Last Edit: 10/08/2014 04:21 PM by JasonAW3 »
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Offline jongoff

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First, not Ron, Jason.

Second, I didn't entirely make myself clear, so let my clarify.

As I understand it, it is possible to create a Magnetic Sail that would allow a craft to lift itself out of Earth orbit, via the planet's magnetic field.  (I read one article that suggested it may be possible to launch from teh Earth's surface with a Magnetic sail, but I think thats a bit far fetched).

     What I was suggestion was, as a craft is returing to Earth, use a magnetic sail as a sort of "deep space parachute" to bleed off eneough velocity of the entire craft, (Mars mission craft, habitats, engines, etc.) so that the entire craft can make orbit around the Earth and teh ERV Capsule would only have to resist the reentry from LEO rather fronm a high velocity BEO return.

      Obviously, using susch a system to achieve Mars orbit would be impossible, due to teh practically complete absense of a Martian magnetic field, therefor aero braking becomes a necessity.

   It also occures to me that a craft using a nuclear rocket is likely to also be suing some sort of Magnetic shielding to protect teh crew from solar and nuclear radiation.  If so, it may be possible to use this shield as a Magnetic sail to give the craft an additional boost via Earth's Magnetic field.

Jason,

I was replying to both of you (Ron PM'd me to see if I would jump into the conversation).

Re: magnetic sails...I don't know what you're talking about. Earth's magnetic field force is way too weak to push against to perform capture maneuvers. Maybe you're thinking of the theoretical work done on "M2P2" magnetosphere sails that deflect the solar wind as way of generating tiny amounts of thrust--comparable to a solar sail. Maybe you're thinking of that? You might be able to very gradually capture into a high orbit around earth, but spiraling in would take forever. And M2P2 requires very high magnetic field strengths, superconducting electromagnets, etc.

You could achieve the end you're talking about (capturing an interplanetary exploration "vehicle"/assembly into LEO) much easier with the Magnetoshell Aerocapture technology I described above. The MSNW guys working on MAC work with some of the UW guys who did M2P2, but MAC is a much simpler technology that I think is a lot closer to being flight ready. It would allow you to brake an entire mission stack into LEO (likely you'd do a capture pass than 2-10 braking passes to keep the delta-V you need in a given pass to a reasonable level), and you would only need an electromagnet (preferably on a deployable structure of some sort), some batteries, and the plasma generator.

~Jon

Offline ncb1397

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I think what you are looking for is here:

Quote
Electrodynamic tethers (EDTs) are long conducting wires, such as one deployed from a tether satellite, which can operate on electromagnetic principles as generators, by converting their kinetic energy to electrical energy, or as motors, converting electrical energy to kinetic energy.[1] Electric potential is generated across a conductive tether by its motion through a planet's magnetic field.
http://en.wikipedia.org/wiki/Electrodynamic_tether

Offline jtrame

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Now doubt there is a lot that we still need to work out to implement a reusable transportation system.  NASA has been wanting to invest in some of technologies we'll need, and some is being done in private industry, but it certainly needs more work.

So in the near-term the cheaper solution will likely involve throwing away perfectly good hardware, and that is going to barrier to doing more in space because we are not able to lower the costs fast enough.

To change this is going to require a change in mindset, and the willingness of Congress to allow NASA to help perfect a number of needed technologies.  But based on the spending priorities Congress currently has I'm not sure when NASA will be able to help with this challenge, so that leaves it up to the private sector.

I think people would be surprised at how much lower the costs would be for some type of standard production "Mission Module".  Most of the expensive parts stay in the capsule and the "Mission Module could be fairly simplified.  What really gets costs cranking for NASA is that they have to do a one-off design and getting the mass into orbit.  If you had to design a new mission module from scratch every time you flew one then the costs would be fairly high.  However if you designed a standard module and then just kept building to that standard design your costs come down a lot.  You then place that with lower costs to orbit you get something that could dramatically lower prices.  Not enough to get into the 1/2 Million dollars to Mars cost that Musk wants but enough to be a good start until more re-usability is figured out.

If you base it on an already existing design (Cygnus) that is using a pressure vessel still in production (Thales Alenia Space) then you start to get that advantage.  The Thales Alenia modules are available in different lengths as well, so you could choose the amount of volume needed by the mission.

Offline jongoff

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I think what you are looking for is here:

Quote
Electrodynamic tethers (EDTs) are long conducting wires, such as one deployed from a tether satellite, which can operate on electromagnetic principles as generators, by converting their kinetic energy to electrical energy, or as motors, converting electrical energy to kinetic energy.[1] Electric potential is generated across a conductive tether by its motion through a planet's magnetic field.
http://en.wikipedia.org/wiki/Electrodynamic_tether

Yeah, I almost mentioned them, but didn't want to muddy the waters. ED's are useful, but you probably can't realistically use an ED tether to capture a spacecraft into LEO. Not enough thrust over the short amount of time you're low enough to get useful currents (which require plasma to close the circuit). They're great for propellantless reboost in LEO, and even some maneuvers around in LEO, but not something that scales well for capture (which I believe is what the original question was about--capturing spacecraft stacks back into LEO so you could use them again, and so the return vehicle only had to be LEO-rated).

~Jon
« Last Edit: 10/08/2014 06:22 PM by jongoff »

Offline JasonAW3

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Now doubt there is a lot that we still need to work out to implement a reusable transportation system.  NASA has been wanting to invest in some of technologies we'll need, and some is being done in private industry, but it certainly needs more work.

So in the near-term the cheaper solution will likely involve throwing away perfectly good hardware, and that is going to barrier to doing more in space because we are not able to lower the costs fast enough.

To change this is going to require a change in mindset, and the willingness of Congress to allow NASA to help perfect a number of needed technologies.  But based on the spending priorities Congress currently has I'm not sure when NASA will be able to help with this challenge, so that leaves it up to the private sector.

I think people would be surprised at how much lower the costs would be for some type of standard production "Mission Module".  Most of the expensive parts stay in the capsule and the "Mission Module could be fairly simplified.  What really gets costs cranking for NASA is that they have to do a one-off design and getting the mass into orbit.  If you had to design a new mission module from scratch every time you flew one then the costs would be fairly high.  However if you designed a standard module and then just kept building to that standard design your costs come down a lot.  You then place that with lower costs to orbit you get something that could dramatically lower prices.  Not enough to get into the 1/2 Million dollars to Mars cost that Musk wants but enough to be a good start until more re-usability is figured out.

If you base it on an already existing design (Cygnus) that is using a pressure vessel still in production (Thales Alenia Space) then you start to get that advantage.  The Thales Alenia modules are available in different lengths as well, so you could choose the amount of volume needed by the mission.

Essentially you'd assemble them kind of like a space going Winnabego RV.  Start with a basic can and internal layout.  Pre run the wiring harnes and assemble internal components and plumbing as needed.

  Orbital itself has suggested a number of different exterior designs including both short and stretch can designs with both docking ports on the ends and in the middle, and even a design with a cupola similar to the one on the ISS already.
They've even done art with one of their cans using an Inflatable Hypersonic Decelerator heat shield as a life boat.

At least they're thinking ahead.  If the Russians DO splash the ISS, with Orbital's modules, we could have a new oner ihn place in a couple of years.
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Offline Brovane

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Dracos, of course. Remember, Orion had thrusters as backup to its OMS engine, and that was for lunar orbit. Certainly not Superdracos. Remember, Dragon launches with all that abort propellant which it could use (if it doesn't have enough prop for full vertical landing back on Earth, it may still have enough for parachute assist), and one could imagine a slight increase in propellant. You'd need about 500m/s or so, depending on just how fast of a transit you want. If you can afford to wait, you need a lot less propellant.

You want to use a 400N Draco engine to move between EML-1/EML-2 and LEO? 
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Offline mmeijeri

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You want to use a 400N Draco engine to move between EML-1/EML-2 and LEO?

Not between LEO and L1/L2, but from L1/L2 back to Earth.
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Offline Brovane

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Not between LEO and L1/L2, but from L1/L2 back to Earth.

Ok the question still applies going from EML1/2 back to Earth.   You are going to need to apply some Delta-V to the vehicle.   
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Offline mmeijeri

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Ok the question still applies going from EML1/2 back to Earth.   You are going to need to apply some Delta-V to the vehicle.   

Only a couple of hundred m/s. That's part of why returning straight to Earth is so much easier than returning to LEO.
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Offline Brovane

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Only a couple of hundred m/s. That's part of why returning straight to Earth is so much easier than returning to LEO.

I guess it is doable.  However some consideration will have to given to modifying the current Draco thrusters to support vastly increased propellant tanks.  You are probably looking at 1000-1500 kg of propellant.  However this is all dependant on the wet mass of the DragonV2.

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Offline mmeijeri

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It's very similar to what your typical apogee thruster is expected to do.
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The low thrust of Draco isn't a concern for capturing at EML1/2.
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Offline Lars-J

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The low thrust of Draco isn't a concern for capturing at EML1/2.

Indeed. If it has enough kick to deorbit from LEO in a reasonable time, then it sure as heck won't be a problem to use regular Draco thrusters to enter and leave EML1/2.

The only concern will be the amount of propellant, but for that purpose it should have enough. (assuming a FH launches it on a EML1/2 transfer trajectory)

People seem to have this concern that thrust is needed once you get beyond LEO. But unless you are propulsively being captured in (or departing from) low orbit around a planetary body or major moon, that simply isn't the case. Efficiency will beat out thrust.
« Last Edit: 10/09/2014 06:55 AM by Lars-J »

Offline MP99

The low thrust of Draco isn't a concern for capturing at EML1/2.

Indeed. If it has enough kick to deorbit from LEO in a reasonable time, then it sure as heck won't be a problem to use regular Draco thrusters to enter and leave EML1/2.

The only concern will be the amount of propellant, but for that purpose it should have enough. (assuming a FH launches it on a EML1/2 transfer trajectory)

People seem to have this concern that thrust is needed once you get beyond LEO. But unless you are propulsively being captured in (or departing from) low orbit around a planetary body or major moon, that simply isn't the case. Efficiency will beat out thrust.
I'm told that when two large ships need to rendezvous at sea, then a single man tugging on a rope is sufficient to draw them together.

Similarly, in space, as long as there is no time pressure (usually due to being deep in a gravity well), then the amount of thrust doesn't really matter, within reason. If your thruster has 1/100th the thrust, then just operate it 100x as long, and you'll end up with the same total impulse. It's only when you get to ridiculously low thrust (EG SEP), that the acceleration time becomes a major issue.

Cheers, Martin

Offline Lars-J

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Only a couple of hundred m/s. That's part of why returning straight to Earth is so much easier than returning to LEO.

I guess it is doable.  However some consideration will have to given to modifying the current Draco thrusters to support vastly increased propellant tanks.  You are probably looking at 1000-1500 kg of propellant.  However this is all dependant on the wet mass of the DragonV2.

How is does a couple of hundred m/s imply the need for a "vastly increased propellant tanks"?

What kind of mission profile are you imagining?

Offline WindyCity

Forgive me if this has been already discussed.

Could a BA330 be mated with a Dragon 2 for BEO missions? I don't know what additional ECLSS would have to be added, but from what I've read, the radiation and meteorite shielding of the hab would appear to be adequate for travel in deep space. Also, the BA330 has a propulsion system. Could the hab be stationed in LEO and then hooked up to the crew capsule and then boosted onto an interplanetary trajectory?

Online AncientU

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Forgive me if this has been already discussed.

Could a BA330 be mated with a Dragon 2 for BEO missions? I don't know what additional ECLSS would have to be added, but from what I've read, the radiation and meteorite shielding of the hab would appear to be adequate for travel in deep space. Also, the BA330 has a propulsion system. Could the hab be stationed in LEO and then hooked up to the crew capsule and then boosted onto an interplanetary trajectory?

That is basically what the BA-330 is designed for... and the propulsion system is a 'tug' that moves the entire bit beyond LEO... or beyond whatever location (EML-1/2 for instance).  I've not actually heard mention or seen written text that showed docked vehicle like Dragon 2 being accelerated with the BA-330, so the stresses at docking mechanism may be be limiting.

Great Article on the topic:
http://www.nasaspaceflight.com/2014/02/affordable-habitats-more-buck-rogers-less-money-bigelow/

Quote
Family of Tugs:

The documentation also portrays a family of tugs that could be used in conjunction with Bigelow habitats for use beyond Low Earth Orbit.

The fleet consists of the Standard Transit Tug, the Solar Generator Tug, the Docking Node Transporter and the Spacecraft Capture Tug.

These tugs could be used to push the various Bigelow Habitats – and other payloads – to specific destinations in LEO, L2, Cislunar space and beyond.

The four tugs are designed to be grouped together in various combinations, depending on the mission requirements. Notably, they are sized for launch on SpaceX’s Falcon Heavy rocket.

The tugs could be launched independently, prior to rendezvous with other elements in LEO to form a complete transport system. Each of these tugs share propulsion, docking and avionic systems.

Quote
The BA 330-DS:

The documentation also offers NASA a deep space version of its habitat, the BA 330-DS, for use beyond Low Earth Orbit. The BA 330-DS could be used by NASA, for example, at a Lagrange point or in lunar orbit.

The BA 330-DS would be very similar to its LEO version. The main difference would be related to radiation shielding.
« Last Edit: 10/10/2014 06:44 PM by AncientU »
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The enhanced shielding is likely the water bags that have been talked about since forever. I've been wondering of they also contain soluble boron compounds for neutrons, if the water "bags" are boron-silicone, or both?

Anyhow, the core looks strong enough to handle axial loads from thrust,
« Last Edit: 10/11/2014 01:57 AM by docmordrid »
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There you go.
Room for twelve crew, six per BA-330.
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Offline mmeijeri

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How is does a couple of hundred m/s imply the need for a "vastly increased propellant tanks"?

Roughly 700 m/s @ 320s Isp should require about 25% of the Dragon's dry mass in propellant.
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How is does a couple of hundred m/s imply the need for a "vastly increased propellant tanks"?

Roughly 700 m/s @ 320s Isp should require about 25% of the Dragon's dry mass in propellant.
Soyuz's 390m/s delta-v (195m/s each way) would be sufficient if you use 16-day traverses.
« Last Edit: 10/11/2014 06:05 PM by Robotbeat »
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Offline mmeijeri

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In that case you'd need roughly 13% of the dry mass in propellant. And additional consumables of course.
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Offline manboy

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This question came up on a different thread, so I thought I would start a specific one to collect everyones thoughts.

The subject came up when I responded to a statement from Robotbeat:

I will say one thing: since both designs chosen were capsules, they are both relevant for any future BLEO missions and should be considered for inclusion by mission planners.

None of these vehicles will be evolved for BLEO - they are too small.  Be glad to talk on another thread about it if you want...

A number of people agreed with Robotbeat, or at least with the idea that Commercial Crew vehicles could be adapted for beyond LEO needs.

My reasons for saying that Commercial Crew vehicles are too small is that I think we have learned that for humans to stay healthy in space that they need a lot of room, so future human space travelers are not going to be spending most of their time in a capsule like the Dragon or CST-100.  Plus, capsules are really only designed for transporting humans to/from a planet with an atmosphere, so at most my view is that if we take them BEO it's only for use as a lifeboat and for the "last mile" of getting humans down onto a planet.  And currently the only planet we know we can land them as currently designed is Earth, so why not leave them orbiting in LEO and just plan to meet back up with them in Earth orbit on the way back?

If you think Commercial Crew vehicles will be adaptable for BEO applications, please state what those applications are.  For instance, would you envision using a CST-100 for visiting an asteroid or only for trips to the Moon?

And if you don't think they are applicable, go ahead and state what your alternative would be.
They probably would need new avionics if you send them BEO. Heat shield may need to be modified.
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Offline mmeijeri

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Beyond LEO is not the same as beyond earth orbit (BEO). I think the commercial crew vehicles are mostly useful for near Earth space and the last mile, but unlike Ron I think an important part of the action will be at L1/L2, in support of lunar and BEO missions, without actually going there. That is beyond LEO, but not BEO.

Then again, Red Dragon suggests there might be a role for Dragons on Mars too.

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A lot of Mars architectures nowadays (that I've seen internal at NASA, plus that one Boeing proposal at FISO) propose leaving Orion at EML1/2 or some high lunar (or Earth, I suppose) orbit, just like where you'd leave Dragon or CST-100.
« Last Edit: 10/12/2014 09:13 PM by Robotbeat »
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Offline WindyCity

Forgive me if this has been already discussed.

Could a BA330 be mated with a Dragon 2 for BEO missions? I don't know what additional ECLSS would have to be added, but from what I've read, the radiation and meteorite shielding of the hab would appear to be adequate for travel in deep space. Also, the BA330 has a propulsion system. Could the hab be stationed in LEO and then hooked up to the crew capsule and then boosted onto an interplanetary trajectory?

That is basically what the BA-330 is designed for... and the propulsion system is a 'tug' that moves the entire bit beyond LEO... or beyond whatever location (EML-1/2 for instance).  I've not actually heard mention or seen written text that showed docked vehicle like Dragon 2 being accelerated with the BA-330, so the stresses at docking mechanism may be be limiting.

Great Article on the topic:
http://www.nasaspaceflight.com/2014/02/affordable-habitats-more-buck-rogers-less-money-bigelow/

Thanks!

Quote
Family of Tugs:

The documentation also portrays a family of tugs that could be used in conjunction with Bigelow habitats for use beyond Low Earth Orbit.

The fleet consists of the Standard Transit Tug, the Solar Generator Tug, the Docking Node Transporter and the Spacecraft Capture Tug.

These tugs could be used to push the various Bigelow Habitats – and other payloads – to specific destinations in LEO, L2, Cislunar space and beyond.

The four tugs are designed to be grouped together in various combinations, depending on the mission requirements. Notably, they are sized for launch on SpaceX’s Falcon Heavy rocket.

The tugs could be launched independently, prior to rendezvous with other elements in LEO to form a complete transport system. Each of these tugs share propulsion, docking and avionic systems.

Could they be parked in LEO and refueled as needed?

Quote
The BA 330-DS:

The documentation also offers NASA a deep space version of its habitat, the BA 330-DS, for use beyond Low Earth Orbit. The BA 330-DS could be used by NASA, for example, at a Lagrange point or in lunar orbit.

The BA 330-DS would be very similar to its LEO version. The main difference would be related to radiation shielding.

What additional shielding would it need. It already has a water jacket to protect against cosmic rays and solar radiation.

Online docmordrid

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>
What additional shielding would it need. It already has a water jacket to protect against cosmic rays and solar radiation.

Bigelow has always said peripheral water containers, which would be a good shield.  A few extra points if you add soluble boron compounds (boric acid is soluble to 57g/l @25°C) as they'd enhance neutron protection, at the cost of potability.
« Last Edit: 10/13/2014 08:38 AM by docmordrid »
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Online AncientU

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Could they be parked in LEO and refueled as needed?


What additional shielding would it need. It already has a water jacket to protect against cosmic rays and solar radiation.

'Tugs' has usually referred to in-space vehicles that are repeatedly refueled and reused.  I suspect this is the operational intent here.

The BA-330 radiation shielding may already contain a thermal neutron absorber, if one is actually needed.  Borated poly layers or boron in solution as proposed by docmordrid should be simple additions.  Bigelow statements have commented on the reduced amount of secondary radiation resulting from their soft-sided designs over aluminum cans.  Since free neutrons are mostly secondary radiation (cosmic rays, even from the sun, allow sufficient time for free neutrons --'primary radiation' -- to radioactively decay, even accounting for the relativistic effects of solar plasmas), and the rad dose from neutrons on ISS isn't too high, I suspect that this is mostly a solvable problem.  More empirical data is needed from operations beyond the Van Allen radiation belts.  An outpost at EML-2 would do nicely...

Here's an ISS experiment that showed neutron rad exposure to be (only) 10x the normal ground dose at sea level.  (This is about what moving to Denver from sea level also contributes.)
Quote
The average dose-equivalent rate observed through the investigation was about 10 times the average exposure on Earth.

http://www.nasa.gov/mission_pages/station/research/experiments/227.html
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Offline metaphor

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It takes about 600 m/s to capture at L1, or to leave L1 for Earth, with a travel time of about 5 days each way.  So any capsule will have to carry an additional 1200 m/s of delta-v over what it receives from the launch vehicle.  At 320s Isp, that means about 50% extra mass in propellant.

For L2 it takes about 350 m/s one-way with a ~9 day travel time.  So that's an extra 700 m/s, which at 320s Isp means about 25% extra mass in propellant.

That's a significant amount of extra mass needed if going to a Lagrangian point and back.

Offline A_M_Swallow

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It takes about 600 m/s to capture at L1, or to leave L1 for Earth, with a travel time of about 5 days each way.  So any capsule will have to carry an additional 1200 m/s of delta-v over what it receives from the launch vehicle.  At 320s Isp, that means about 50% extra mass in propellant.

For L2 it takes about 350 m/s one-way with a ~9 day travel time.  So that's an extra 700 m/s, which at 320s Isp means about 25% extra mass in propellant.

That's a significant amount of extra mass needed if going to a Lagrangian point and back.

The mass is propellant so it can become the cost of propellant in LEO V. cost of a new spacecraft in LEO.
Reusable launch vehicles can make a big price difference to that trade.

Offline mmeijeri

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That's a significant amount of extra mass needed if going to a Lagrangian point and back.

Orion is supposed to have ~1.6 km/s in delta-v, so I don't see any problem with that.
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Offline metaphor

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That's a significant amount of extra mass needed if going to a Lagrangian point and back.

Orion is supposed to have ~1.6 km/s in delta-v, so I don't see any problem with that.

Well yeah, that's why the service module is there.  A commercial crew vehicle would need upgrades like that, that would make it heavier and costlier, in order to go BLEO.  In the end it would probably end up somewhat similar to Orion.

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Given that NASA is using ESA to build the service module for Orion, I rather doubt they would be as bad as Orion esp.  as they could do LEO runs as well as BEO trips.

Offline MP99



It takes about 600 m/s to capture at L1, or to leave L1 for Earth, with a travel time of about 5 days each way.  So any capsule will have to carry an additional 1200 m/s of delta-v over what it receives from the launch vehicle.  At 320s Isp, that means about 50% extra mass in propellant.

For L2 it takes about 350 m/s one-way with a ~9 day travel time.  So that's an extra 700 m/s, which at 320s Isp means about 25% extra mass in propellant.

That's a significant amount of extra mass needed if going to a Lagrangian point and back.

Imagine a SpaceX architecture which uses EML2 as a terminus for an MTV.

If you can line everything up on the return from Mars, you only need an Oberth-assisted ~1 km/s burn at perigee to capture in Earth's gravity and "TLI" towards the Moon. (With MAC you can possibly do it almost prop free via aerocapture.) Another 350 m/s at EML2, and you're done.

For the next outgoing trip to Mars, the MTV only needs a 350 m/s departure burn + ~1 km/s Oberth-assisted TMI, to achieve a TMI that would need a 4.2 km/s burn from LEO.

I suspect that an architecture that needs ~1.7 km/s for the complete Earth turnaround compares fairly well with a cycler. It's like putting an airport at the top of a mountain. Plane lands on an uphill runway, and stops without needing brakes, then takes off downhill without needing engines to reach takeoff speed. The Moon stores a lot of dV.



So, then, what's the cost of getting people & cargo to EML2, then on to Mars?

A 4.2 km/s TMI can either be done in one burn from LEO, or ~3.2 km/s TLI + ~1 km/s post-EML. No advantage here, but no disadvantage, either.

For MTV prop and other "storables", a three-month "slow-boat" / WSB trajectory gets you to EML for ~3.2 km/s. The total dV to get from Earth surface to TMI is about 400 m/s more than the simple launch / LEO / TMI.



Tl;dr - yes, crew and time-critical cargo needs ~700 m/s more dV to reach TMI if you stage from EML2, but the overall architecture gains a lot of mass advantages, such as MTV prop tanks being nearly 3 km/s smaller, and prop delivered in high mass fraction tankers.

Cheers, Martin

Offline mmeijeri

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Given that NASA is using ESA to build the service module for Orion, I rather doubt they would be as bad as Orion esp.  as they could do LEO runs as well as BEO trips.

Yeah, and that's why it would have made more sense for NASA to drop the capsule and to "outsource" it to commercial crew and to continue work on the SM, rather than outsourcing that to ESA.
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That's a significant amount of extra mass needed if going to a Lagrangian point and back.

Orion is supposed to have ~1.6 km/s in delta-v, so I don't see any problem with that.

Well yeah, that's why the service module is there.  A commercial crew vehicle would need upgrades like that, that would make it heavier and costlier, in order to go BLEO.  In the end it would probably end up somewhat similar to Orion.
SINCERELY doubt it could be as expensive as Orion. The capsule dry mass is far less for Dragon and cst100, just to name one thing.

Besides, if you take a 16 day trip instead of 5, the capture delta-v drops to ~195m/s, 390 total. Both probably have that capability just from abort propellent.
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Offline mmeijeri

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SINCERELY doubt it could be as expensive as Orion. The capsule dry mass is far less for Dragon and cst100, just to name one thing.

Even if it were as expensive as Orion, it would still be cheaper than having two commercial crew capsules plus Orion. It would also be cheaper for LEO operations and available to commercial clients. More bang for fewer bucks.
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Offline TomH

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It's like putting an airport at the top of a mountain. Plane lands on an uphill runway, and stops without needing brakes, then takes off downhill without needing engines to reach takeoff speed.

Hey, I know that airport. Never been there, but as a former backpacking/climbing fanatic, I've read about it a number of times:

http://www.weather.com/travel/mount-everest-airport-will-terrify-you-photos-20130618

Had several daredevil pilots in the family too. Flew in and out of some places almost that scary with my dad.
« Last Edit: 10/14/2014 04:21 PM by TomH »

Offline nadreck

It's like putting an airport at the top of a mountain. Plane lands on an uphill runway, and stops without needing brakes, then takes off downhill without needing engines to reach takeoff speed.

Hey, I know that airport. Never been there, but as a former backpacking/climbing fanatic, I've read about it a number of times:

http://www.weather.com/travel/mount-everest-airport-will-terrify-you-photos-20130618

Had several daredevil pilots in the family too. Flew in and out of some places almost that scary with my dad.
I flew into and out of Lukla, note that you do need brakes and the rock wall coming at you as your Twin Otter lands is almost as scary as hoping that the plane actually has enough speed to stay airborne as it goes off the end of the runway on surface effect. Oh and the girl in the pink floppy hat sitting behind you throwing up is just a courtesy detail to make it all seem the more real. About 7 minutes before landing the plane passes between two peaks (not above them).
It is all well and good to quote those things that made it past your confirmation bias that other people wrote, but this is a discussion board damnit! Let us know what you think! And why!

Offline sdsds

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A 4.2 km/s TMI can either be done in one burn from LEO, or ~3.2 km/s TLI + ~1 km/s post-EML. No advantage here, but no disadvantage, either.

Your analysis is spot on, but I think truth is even better than you suggest. There are paths to EML which combine a chemical burn for LEO departure with electric propulsion to transfer onto the EML-bound trajectory. So looking at required IMLEO, utilizing the amazingly high isp of electric propulsion for a portion of the transfer to EML can be a meaningful win.

I believe this is less true for DRO, but haven't myself done the required math.  :D

In either case, rendezvous in the cis-lunar vicinity before departure for Mars has huge mission safety advantages, because abort modes are more accessible. (With classic TMI, you have to look at each moment of a long Earth departure burn and verify there's a safe abort in case of a propulsion failure. With TMI post-EML, the burn -- and thus the vulnerability -- is shorter.)

This all leads to the conclusion that EML (or DRO) rendezvous will be the Mars mission mode that one day is actually selected. Commercial crew and cargo to that rendezvous point are in the cards ... sooner or later depending on the stubbornness of those who refuse to admit it.
« Last Edit: 10/15/2014 03:40 AM by sdsds »
-- sdsds --

Offline MP99



A 4.2 km/s TMI can either be done in one burn from LEO, or ~3.2 km/s TLI + ~1 km/s post-EML. No advantage here, but no disadvantage, either.

Your analysis is spot on, but I think truth is even better than you suggest. There are paths to EML which combine a chemical burn for LEO departure with electric propulsion to transfer onto the EML-bound trajectory. So looking at required IMLEO, utilizing the amazingly high isp of electric propulsion for a portion of the transfer to EML can be a meaningful win.

Thanks.

With a Weak Stability Boundary (slow boat) trajectory, you need no propulsion to slow into EML - interaction of Earth / Moon / Sun does it for free (at expense of a three month transit).

Note that those dVs assume a full Oberth benefit. The two TMI burns totalling ~1.4 km/s give you ~4.7 km/s transit velocity, which eats into the SEP advantage.

Alternatively, such an "almost at escape already" orbit is far and away the best location from which to launch SEP, if you're going to use that for the transit.

I believe this is less true for DRO, but haven't myself done the required math.  :D

In either case, rendezvous in the cis-lunar vicinity before departure for Mars has huge mission safety advantages, because abort modes are more accessible. (With classic TMI, you have to look at each moment of a long Earth departure burn and verify there's a safe abort in case of a propulsion failure. With TMI post-EML, the burn -- and thus the vulnerability -- is shorter.)

This all leads to the conclusion that EML (or DRO) rendezvous will be the Mars mission mode that one day is actually selected. Commercial crew and cargo to that rendezvous point are in the cards ... sooner or later depending on the stubbornness of those who refuse to admit it.

The dV stuff is rather off topic, except insofar as I was using the above to justify why the relatively small dVs to enter / exit EML are well worth including in the baseline for any BLEO version of a LEO capsule, as an integrated part of a wider architecture.

Cheers, Martin

Offline mmeijeri

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So looking at required IMLEO, utilizing the amazingly high isp of electric propulsion for a portion of the transfer to EML can be a meaningful win.

Not only that, but transport of propellant (and eventually cargo) from L1/L2 to HMO and LMO can also be done with SEP, and that's easier given that it doesn't involve crossing the van Allen belts.
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As long as a fuel distribution network is established first, commercial crew vehicles plus in-space habs/tugs can do it all.  This is likely the reason the anti-depot crowd is adamant in opposition.
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I don't know I agree. People are still very skeptical about commercial crew, think that ONLY the "big boys" can do it, and at ridiculous cost and about half a century's worth of time.
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Offline mmeijeri

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As long as a fuel distribution network is established first, commercial crew vehicles plus in-space habs/tugs can do it all.  This is likely the reason the anti-depot crowd is adamant in opposition.

You don't need to establish depots first, a spacecraft can act as it own depot just as ISS and Russian stations before it have been doing for decades.
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As long as a fuel distribution network is established first, commercial crew vehicles plus in-space habs/tugs can do it all.  This is likely the reason the anti-depot crowd is adamant in opposition.

You don't need to establish depots first, a spacecraft can act as it own depot just as ISS and Russian stations before it have been doing for decades.

Doesn't really matter what you call it... when you have refueling technology on the (reusable) vehicles and the means to distribute fuel/refuel where and when you need it, you're good to go.  Anywhere.

The opposite is the concept that every drop of fuel for the entire mission needs to go into the stack before someone lights the fuse.  Expendable is a corollary concept.  I think we're finally ready to drive stakes through the heart of these undead beings.

Not everyone yet has the word...

Quote
There is still no significant move within NASA towards reusable spacecraft, or even boosters, while other institutions like the Air Force and DARPA are now pushing rapidly in that direction. Funding for propellant depots is virtually nonexistent, and any refueling efforts are aimed primarily at refueling and servicing existing satellites that were never designed to be refueled. Taking another look at this document, five years after its initial release, can give us a precautionary view of where not to go in space (and Mars) mission design.
emphasis mine

http://www.thespacereview.com/article/2618/1
« Last Edit: 10/15/2014 04:39 PM by AncientU »
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Offline mmeijeri

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Doesn't really matter what you call it... when you have refueling technology on the (reusable) vehicles and the means to distribute fuel/refuel where and when you need it, you're good to go.  Anywhere.

Exactly, but my point is that we've had the necessary technology for years. If NASA wants to build a transfer stage, let them start with a refuelable SM and leave launch vehicles and capsules to the market by buying services competitively. Later that SM can be enlarged to a storable L1/L2 based pump-fed transfer stage for manned exploration.
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Doesn't really matter what you call it... when you have refueling technology on the (reusable) vehicles and the means to distribute fuel/refuel where and when you need it, you're good to go.  Anywhere.

Exactly, but my point is that we've had the necessary technology for years. If NASA wants to build a transfer stage, let them start with a refuelable SM and leave launch vehicles and capsules to the market by buying services competitively. Later that SM can be enlarged to a storable L1/L2 based pump-fed transfer stage for manned exploration.

Yup. Couldn't have said it better.

It's not a technology but a turf issue.
« Last Edit: 10/15/2014 05:00 PM by AncientU »
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Offline RanulfC

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I don't know I agree. People are still very skeptical about commercial crew, think that ONLY the "big boys" can do it, and at ridiculous cost and about half a century's worth of time.

My take is that most people are 'skeptical' about commercial crew for the same reason; If "commercial" can do orbital travel then why is NASA insisiting on building the SLS?

Which to me pretty much hits spot on why Congress both encourages that thinking and why Commercial Crew is having such a hard time being taken seriously.

IF (and again there is that huge two letter word) you understand the facts its pretty clear that once you have an ongoing ability to transfer crew and supplies TO Low Earth Orbit on a regular basis while you still have incentive to build and operate an HLV you don't REQUIRE the ability to do so on a regular basis. I do NOT want to decend into that debate however and am simply pointing out that what is mostly being said is that SLS is "required" while CC is not and that's actually just the opposite of what it true. SLS is in fact "required" because its a government program while CC is "required" for lower cost, regular access to space by people. There's justification for both but instead both are being played off against each other.

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Offline guckyfan

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Can Dragon 2 do a lunar orbit mission without modified propulsion?

We know a lunar flyby with Dragon and FH is possible. The upper stage even would have enough delta-v for LOI but it won't last long enough without significant modification if at all. The idea is finding a TLI trajectory that minimizes LOI delta-v at expense of more delta-v for TLI. I am sure some modifications are possible but is it enough? It would not need a circularized lunar orbit. Just an elliptical orbit that would be easy to leave for trans earth injection too. It is not something one can take out of a delta-v map. But with plenty of abort fuel and a not so heavy Dragon is it achieavable? Ideally with enough fuel for a propulsively assisted parachute land landing.

Such an orbit may not be suitable for research but would be appreciated as a tourist flight.

Edit: The idea behind this is that SpaceX may not be willing to do major engineering for a modified Dragon but willing to sell a flight for a tourist operator.
« Last Edit: 11/24/2014 09:28 AM by guckyfan »

Offline baldusi

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You not only need Delta-v to get to a lunar orbit, but you also need to get back. Both Orion and PTK-L have 1,500m/s of delta-v. You can't get to. LLO without some serious burn close to the Moon. Now, if you wanted to do something like the orbit you get when you move from EML1 towards the moon, that might be different. You'd still need astrogation, long range coms, ECLSS, heat management and radiation resistance and mitigation for the crew.

Offline Zed_Noir

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Can Dragon 2 do a lunar orbit mission without modified propulsion?

We know a lunar flyby with Dragon and FH is possible. The upper stage even would have enough delta-v for LOI but it won't last long enough without significant modification if at all. The idea is finding a TLI trajectory that minimizes LOI delta-v at expense of more delta-v for TLI. I am sure some modifications are possible but is it enough? It would not need a circularized lunar orbit. Just an elliptical orbit that would be easy to leave for trans earth injection too. It is not something one can take out of a delta-v map. But with plenty of abort fuel and a not so heavy Dragon is it achieavable? Ideally with enough fuel for a propulsively assisted parachute land landing.

Such an orbit may not be suitable for research but would be appreciated as a tourist flight.

Edit: The idea behind this is that SpaceX may not be willing to do major engineering for a modified Dragon but willing to sell a flight for a tourist operator.

Just stick a Super Draco and lots of hypergolic tanks in the trunk. But like Baldusi posted. you need longer duration ECLSS, long range communication, navigation and ground tracking & Communication network (NASA is not going to provide the DSN time).

For tourism, think a free return orbit like Apollo 8 is all that is required initially.

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A really, really high lunar orbit (or EML2) is probably feasible without extra propulsion (may need some light-weighting, however), if you're willing to do a week or two trip time to the Moon's vicinity.

There's no "just" about adding a hypergolic stage or service module. (and you wouldn't use Superdracos, they have really crappy Isp and far more thrust than needed... instead, use an array of regular Dracos). It'd be a significant endeavor. Of course it could be done, but it wouldn't be free.
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Offline TrevorMonty

The CST100 modular design means they could use a large propulsion/service module for BLEO missions.
« Last Edit: 11/25/2014 02:31 AM by TrevorMonty »

Offline Patchouli

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Just stick a Super Draco and lots of hypergolic tanks in the trunk. But like Baldusi posted. you need longer duration ECLSS, long range communication, navigation and ground tracking & Communication network (NASA is not going to provide the DSN time).

For tourism, think a free return orbit like Apollo 8 is all that is required initially.


Instead of a Super Draco you'd probably be better off modifying the Kestrel engine from Falcon 1 to be hypergolic.
 This is not as crazy as it sounds as Aerojet did just that with the LR-87.
The Kestrel is a simple pressure fed engine and would be easy to modify for a different  propellant.


As for the CST-100 and Dream Chaser I'd look into just using the AJ-10 and a stage derived from the Delta-K or better yet the Titan Transtage.

A really, really high lunar orbit (or EML2) is probably feasible without extra propulsion (may need some light-weighting, however), if you're willing to do a week or two trip time to the Moon's vicinity.

There's no "just" about adding a hypergolic stage or service module. (and you wouldn't use Superdracos, they have really crappy Isp and far more thrust than needed... instead, use an array of regular Dracos). It'd be a significant endeavor. Of course it could be done, but it wouldn't be free.

True but you'll either need a resource module or to cut the crew size down.

« Last Edit: 11/25/2014 03:04 AM by Patchouli »

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I'm CONFIDENT that this is at least the tenth time this has been discussed.
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Offline guckyfan

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I'm CONFIDENT that this is at least the tenth time this has been discussed.

I believe you are right. I tried to avoid that by very specifically stating I am looking for a solution without modifications of propulsion. And if that is not possible just forget about it.

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I'm CONFIDENT that this is at least the tenth time this has been discussed.

I believe you are right. I tried to avoid that by very specifically stating I am looking for a solution without modifications of propulsion. And if that is not possible just forget about it.
It is possible.
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Offline Vultur

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For tourism, think a free return orbit like Apollo 8 is all that is required initially.

I agree.


Space Adventures is trying to sell a circumlunar trip at $150 million/seat. I wonder how cheaply SpaceX could provide that, assuming successful first stage reuse and reuse of the Dragonv2?


What would have to be modified to make Dragon capable of a lunar free return?

Offline A_M_Swallow

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I'm CONFIDENT that this is at least the tenth time this has been discussed.

July 2017. Now for the 11th time.

The transfer stage used to go from a LEO spacestation to the lunar orbit spacestation could be launched on a second launch vehicle. The capsule and transfer stage would be docked at the LEO spacestation.

Unless it can reenter with the capsule the transfer stage would probably be expendable, return to LEO requires too much propellant.

Offline GWH

How anyone GETS to the lander though is anyone's guess.

Some Dragon or CST-100 type vehicle?

Yeah one would probably be better off discussing that in more detail here: https://forum.nasaspaceflight.com/index.php?topic=35787.100

Probably wouldn't be quick and easy. Starliner is limited to 60 hour free flight, Dragon at least lacks the dV, and is a tight ride.  ....
False, on both accounts. And yeah, you should have discussed it in that thread.

Moving this over to the proper thread. 

Please elaborate on your "Jim-esque" reply, as it is contrary to information that I have seen and would like to know more.

Regarding Starliner:
Quote from: Nasaspaceflight.com
At most, Mr. Ferguson stated his desire for Starliner to employ 24-hour launch to docking profiles – due in part to the vehicle’s design, which limits its free flight capability (from launch to docking and then undocking to landing) for an entire mission to just 60 hours.
https://www.nasaspaceflight.com/2017/07/starliner-milestones-ula-switches-atlas-booster-maiden-flight/

Dragon 2, from information I have found, has a dry mass of 6,350 kg and carries a total prop mass of 1815 kg including the abort propellant. 
At an ISP of 300s for the Draco thrusters that's 0.74 km/s bone dry no payload.  Well short of returning from anywhere other than L2.
Now adding a kick stage of sorts or trunk based propulsion is well within possibility, but not within the scope of the vehicle as designed.
« Last Edit: 07/28/2017 06:10 PM by GWH »

Online Robotbeat

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And why not stage from L2? The gateway will be in a similar energy orbit.

Just because Apollo used LLO doesn't mean that we should or that it's ideal. Even Orion cannot use LLO unless it leaves LEO with a lander (or similar) attached, which tends to necessitate an expendable lander.

I think EML1,2, or a similar energy orbit would be more appropriate for staging as we already have multiple current or near-term vehicles that would be capable of reaching it with minimal modifications (Orion, Dragon, Starliner, Soyuz, possibly even Shenzhou, on top of SLS, Falcon Heavy, Vulcan Heavy or Vulcan with distributed lift, New Glenn, two launch Delta IV Heavy, Proton/Angara, Long March 5, etc).

As far as having enough room, Gemini was tiny and the two astronauts spent 2 weeks in LEO. 3 or so days transit (longer for a more efficient trajectory) is not a huge constraint. Dragon has much more room per crew than Gemini. Plenty for cislunar. Same with Starliner.

Also, LLO is terrible for staging anywhere but the Moon.
« Last Edit: 07/28/2017 11:48 PM by Robotbeat »
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Offline A_M_Swallow

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Dragon 2, from information I have found, has a dry mass of 6,350 kg and carries a total prop mass of 1815 kg including the abort propellant. 
At an ISP of 300s for the Draco thrusters that's 0.74 km/s bone dry no payload.  Well short of returning from anywhere other than L2.
Now adding a kick stage of sorts or trunk based propulsion is well within possibility, but not within the scope of the vehicle as designed.



And why not stage from L2? The gateway will be in a similar energy orbit.

Just because Apollo used LLO doesn't mean that we should or that it's ideal. Even Orion cannot use LLO unless it leaves LEO with a lander (or similar) attached, which tends to necessitate an expendable lander.

I think EML1,2, or a similar energy orbit would be more appropriate for staging as we already have multiple current or near-term vehicles that would be capable of reaching it with minimal modifications (Orion, Dragon, Starliner, Soyuz, possibly even Shenzhou, on top of SLS, Falcon Heavy, Vulcan Heavy or Vulcan with distributed lift, New Glenn, two launch Delta IV Heavy, Proton/Angara, Long March 5, etc).

As far as having enough room, Gemini was tiny and the two astronauts spent 2 weeks in LEO. 3 or so days transit (longer for a more efficient trajectory) is not a huge constraint. Dragon has much more room per crew than Gemini. Plenty for cislunar. Same with Starliner.

Also, LLO is terrible for staging anywhere but the Moon.

According to Wikipedia high thrust:
Delta-v LEO to L1 is 3.77 km/s
Delta-v L1 to LLO is 0.64 km/s
Delta-v LLO to Earth reentry is 1.31 km/s
Delta-v L1 to Moon surface is 2.52 km/s
Delta-v LLO to Moon surface is 1.87 km/s

If the Dragon 2 refuelled at a depot in L1 (or L2) it could fly to a spacestation in LLO. This is a good place to transfer to a lunar lander.

Cargo vehicles can move the propellant to the depot and spacestation without the high over head of having several tons of life support.

Offline yg1968

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And why not stage from L2? The gateway will be in a similar energy orbit.

Just because Apollo used LLO doesn't mean that we should or that it's ideal. Even Orion cannot use LLO unless it leaves LEO with a lander (or similar) attached, which tends to necessitate an expendable lander.

I think EML1,2, or a similar energy orbit would be more appropriate for staging as we already have multiple current or near-term vehicles that would be capable of reaching it with minimal modifications (Orion, Dragon, Starliner, Soyuz, possibly even Shenzhou, on top of SLS, Falcon Heavy, Vulcan Heavy or Vulcan with distributed lift, New Glenn, two launch Delta IV Heavy, Proton/Angara, Long March 5, etc).

As far as having enough room, Gemini was tiny and the two astronauts spent 2 weeks in LEO. 3 or so days transit (longer for a more efficient trajectory) is not a huge constraint. Dragon has much more room per crew than Gemini. Plenty for cislunar. Same with Starliner.

Also, LLO is terrible for staging anywhere but the Moon.

What about DC and Cygnus? Would they be able to make it to EML1,2 with minimal modifications?

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Cygnus, definitely. Dream chaser... I think so, with some work.
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Offline Coastal Ron

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As far as having enough room, Gemini was tiny and the two astronauts spent 2 weeks in LEO. 3 or so days transit (longer for a more efficient trajectory) is not a huge constraint. Dragon has much more room per crew than Gemini. Plenty for cislunar. Same with Starliner.

We were discussing the merits of LEO vehicles going beyond LEO on a different topic, and I don't disagree that it's possible for people to transport between LEO and the region of the Moon in Commercial Crew vehicles. If there are no other options, then I'm sure we can find some qualified people to go on those trips.

But the Gemini and Apollo flights were done by professionals that had trained for literally years for their flights. At some point going to space has to transition from "highly trained" to "lightly trained" individuals, otherwise cost will still be too high of a barrier to allow the private sector to help push humanity out into space - and I just don't see how we expand out into space without the private sector helping.

Based on that my view is that even if vehicles like Dragon Crew could be used for BLEO transportation, we shouldn't depend on them. Ignoring what SpaceX is doing, what everyone else should focus on is to build dedicated transportation segments that are serviced by vehicles designed for each segment.

For instance:

Earth-to-LEO = Commercial Crew vehicles and the like

LEO-to-Moon local = Reusable space-only vehicles, which obviously requires fuel depots and the ability to return to LEO (propulsively, use atmosphere to slow down, etc.)

Moon-local = Reusable landers

Beyond Earth Local Space = Reusable vehicles for expanding out beyond Earth local space, such as the Nautilus-X and NASA had suggested.

Now if the SpaceX ITS vehicles get perfected then maybe these plans change, but if the ITS do get perfected then we won't need Commercial Crew vehicles for leaving LEO anyways, so I'm not sure there's much merit in trying to modify Commercial Crew vehicles for going beyond LEO.

My $0.02
If we don't continuously lower the cost to access space, how are we ever going to afford to expand humanity out into space?

Offline Patchouli

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Cygnus, definitely. Dream chaser... I think so, with some work.

Cygnus is probably the easiest commercial vehicle to modify for BLEO use for various reasons including not needing to worry about beefing up the TPS.

Though I think DC does have more delta V than Dragon V2 or at least the crewed version did.
More room for propellant and less cosine losses.
« Last Edit: 08/01/2017 06:42 PM by Patchouli »

Offline envy887

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Cygnus, definitely. Dream chaser... I think so, with some work.

Cygnus is probably the easiest commercial vehicle to modify for BLEO use.

For cargo only and no Earth return, yes. Those are significant limitations for some applications.

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