Author Topic: "Mission to Mars Using Six 'Not So Easy' Pieces" • Mike Raftery , Boeing  (Read 30742 times)

Offline Robotbeat

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Another interesting presentation on a Boeing approach to Mars exploration that references the NASA 2013 Mars Design Reference Architecture (which I don't think has yet been released?).
May 14th, 2014.

Ancillary files are here, including the mp3 of the FISO talk:
http://spirit.as.utexas.edu/~fiso/telecon/Raftery_5-14-14/

The pieces are Orion, SLS, SEP tug, Transit Hab, Mars Ascent Vehicle, and Mars Lander, focusing on how the total IMLEO for a single manned Mars mission is actually much smaller than all the flights to ISS.
« Last Edit: 07/04/2014 06:17 PM by Robotbeat »
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Online ThereIWas3

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It seems like a lot of steps.  And no artificial gravity.  And they start too late.
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Offline Robotbeat

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Remember Apollo? A lot more steps. Mercury, Gemini, then several flights around Earth and the moon with the Apollo mission stack before the first landing. Listen to the teleconference while following along.

Artificial gravity is not needed for the relatively short transits of ~250 days... There were Mir flights far longer.

This sort of thing is an excellent approach.
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Offline floss

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Nice plan but the funding could be challenging .

Offline Coastal Ron

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It's an interesting proposal.

Let's keep in mind that Boeing is building the SLS, so using only the SLS in the study is not surprising.  And Boeing also has experience in building other types of in-space hardware, so all in all it's kind of an advertisement of sort.  But that said, it looks like something that's doable.

I'm not sure I can infer enough information to understand what the sizes and masses are of each of the elements, but the first question I would have is what are the elements that can lifted using less expensive transportation?  Yes that means more launches, but the SLS itself is a risky platform for a number of reasons (lack of flight heritage, questionable future, etc.) so if this type of mission is deemed as a good idea we should be looking at how to do it in the least costly & risky way.  And the SLS has some challenges on that front.

I'm also glad to see that the study was released through FISO, but I wonder if it will join all the other "looks doable" studies that have come before and gone nowhere?
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Offline Robotbeat

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Nice plan but the funding could be challenging .
You should listen to the teleconference:
http://spirit.as.utexas.edu/~fiso/telecon/Raftery_5-14-14/Raftery.mp3

ISS had many more launches and was a larger scale than a Mars mission would require. The idea of this architecture is that it wouldn't actually need a big increase in funding, just a level of funding growing with inflation and/or the size of the economy.
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Offline DLR

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Why use SEP at all when SLS Block II has the capability to push around 40 to 50 tonnes (or more with advanced LRBs) through TMI.

Offline Robotbeat

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Why use SEP at all when SLS Block II has the capability to push around 40 to 50 tonnes (or more with advanced LRBs) through TMI.
Because they need only up to 2 launches per year to support a continual Mars campaign. The SEP tug is reusable. All chemical would require more IMLEO, probably break the bank.
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Online meekGee

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Nice plan but the funding could be challenging .
You should listen to the teleconference:
http://spirit.as.utexas.edu/~fiso/telecon/Raftery_5-14-14/Raftery.mp3

ISS had many more launches and was a larger scale than a Mars mission would require. The idea of this architecture is that it wouldn't actually need a big increase in funding, just a level of funding growing with inflation and/or the size of the economy.

Well to be precise, they're saying that their *predicted/promised* funding requirement is lower than ISS's *actual/as-it-turned-out* costs.
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Offline Coastal Ron

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Nice plan but the funding could be challenging .
You should listen to the teleconference:
http://spirit.as.utexas.edu/~fiso/telecon/Raftery_5-14-14/Raftery.mp3

ISS had many more launches and was a larger scale than a Mars mission would require. The idea of this architecture is that it wouldn't actually need a big increase in funding, just a level of funding growing with inflation and/or the size of the economy.

The challenge though is that NASA will be funding the development of the even-larger SLS during the rest of the 2020's, so not a lot of funding is going to be available from the SLS budget.  And considering that NASA has to launch the SLS no-less-than once every 12 months in order to have a safe flight cadence (per NASA), that means a lot of NASA's non-development budget will be going just to building and flying the SLS.  And that doesn't even count the budget for the payloads that are supposed to launch no-less-than every 12 months, which likely will include the hugely expensive Orion/MPCV (which ESA is only building one Service Module and the parts for a 2nd).

So to do this mission NASA would still need to fund:

1.  Development, test, and deployment and ongoing support for an EML2 Gateway.  If you think supporting the ISS in LEO is expensive, try supporting a crew 1,000X farther away.

2.  Development, test, and deployment of a Solar Electric Propulsion (SEP) Tug, which likely will have to do some jaunts around local space in order to validate it.

3.  Development, test, and deployment of a Transit Hab.  This can probably be checked out at the ISS, since the EML2 Gateway will have validated any "deep space" technologies by that point.

4.  Development, test, and deployment of a Mars Lander.  This could be done with a precursor robotic rover that is the same size as the anticipated human equipment.  Maybe it can pre-deploy some of the needed equipment, but obviously this would be years in advance of need.  So throw in some more money for the robotic mission.

5.  Development, test, and deployment of a Mars Ascent Vehicle.  I'm thinking this is going to take some iteration in order to get the hardware right, but even with just a single test that would be years in advance of the human version.

6.  More Orion/MPCV vehicles.

So besides the overhead that such a program would need over a period of well over a decade (my guess), that's a lot of development, especially if it all has to be "man-rated".  Within the current budget profile I think it would take multiple decades at the very least, since various experts has stated that prior to this plan that NASA would NEVER make it to Mars within it's current budget profile.  And I'm not sure I see anything in this plan that changes that assessment...
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Offline Robotbeat

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By that logic, anything that doesn't get rid of SLS isn't going to get to Mars. I don't entirely disagree with that.
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Offline Borklund

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The challenge though is that NASA will be funding the development of the even-larger SLS during the rest of the 2020's, so not a lot of funding is going to be available from the SLS budget.  And considering that NASA has to launch the SLS no-less-than once every 12 months in order to have a safe flight cadence (per NASA), that means a lot of NASA's non-development budget will be going just to building and flying the SLS.  And that doesn't even count the budget for the payloads that are supposed to launch no-less-than every 12 months, which likely will include the hugely expensive Orion/MPCV (which ESA is only building one Service Module and the parts for a 2nd).

So to do this mission NASA would still need to fund:

1.  Development, test, and deployment and ongoing support for an EML2 Gateway.  If you think supporting the ISS in LEO is expensive, try supporting a crew 1,000X farther away.

2.  Development, test, and deployment of a Solar Electric Propulsion (SEP) Tug, which likely will have to do some jaunts around local space in order to validate it.

3.  Development, test, and deployment of a Transit Hab.  This can probably be checked out at the ISS, since the EML2 Gateway will have validated any "deep space" technologies by that point.

4.  Development, test, and deployment of a Mars Lander.  This could be done with a precursor robotic rover that is the same size as the anticipated human equipment.  Maybe it can pre-deploy some of the needed equipment, but obviously this would be years in advance of need.  So throw in some more money for the robotic mission.

5.  Development, test, and deployment of a Mars Ascent Vehicle.  I'm thinking this is going to take some iteration in order to get the hardware right, but even with just a single test that would be years in advance of the human version.

6.  More Orion/MPCV vehicles.

So besides the overhead that such a program would need over a period of well over a decade (my guess), that's a lot of development, especially if it all has to be "man-rated".  Within the current budget profile I think it would take multiple decades at the very least, since various experts has stated that prior to this plan that NASA would NEVER make it to Mars within it's current budget profile.  And I'm not sure I see anything in this plan that changes that assessment...
1. Scrap ISS, build EML2 gateway over time with ISS money. Support it with Commercial Lunar Cargo/Crew, which comes out of the already existing Commercial Cargo/Crew budget.

2. EM-2

3. Build the EML2 Gateway with things you could also use for a Mars Transit Hab and then use those parts for the Transit Hab.

4. Planetary science budget. Instead of another two Curiosity clones next decade. Do science missions in tandem.

5. Same as above. MAV can bring back samples as part of development and test program.

6. Higher production rate will lower cost, not drive cost.

Note: I do not claim to have all the right answers, in fact I may be completely wrong, but tell me this doesn't at least sound plausible. But it doesn't matter, because unless the United States of America adopts a unitary state system and rids its politics of hyperpartisanship, then two decades from now NASA is not going to put humans on Mars - or anywhere else.

Offline Robotbeat

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A lot of these things are addressed in the actual telecon audio.
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Offline D_Dom

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My aspirations of witnessing humans on Mars do not include changing the political structure of these United States. At the July 4th parade today I wore shirt with a flag, being saluted by an astronaut standing on the surface of the moon, LEM in the background. If I could find a Boeing shirt that includes the rover I would wear it with pride. Experience matters.
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Offline KelvinZero

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Listening to the mp3 while reading the pdf definitely adds a lot.

Im a fan of the "Exploration augmentation module" tested at ISS, and getting on with the SEP tug. I don't recall them mentioning the asteroid capture but they did mention not going to the full size SEP in one go.

Interesting choice of Methane/LOX should be popular with lots of people though they don't exploit ISRU in this version.

Interesting lander that puts the cargo near the ground with multiple small rockets around the edge, a bit like the Dragon-2 I suppose.

Offline DLR

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Given that this programme requires the establishment of an EML2 gateway and the development and validation of a reusable (!) SEP stage in addition to all the Mars hardware, I don't see how this is more affordable than to use SLS Block II to launch payloads directly to Mars. An ongoing Mars Semi-Direct programme would require three SLS launches per window.

Offline Robotbeat

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It doesn't /require/ the L2 gateway. Listen to the telecon.
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Offline jtrame

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Given that this programme requires the establishment of an EML2 gateway and the development and validation of a reusable (!) SEP stage in addition to all the Mars hardware, I don't see how this is more affordable than to use SLS Block II to launch payloads directly to Mars. An ongoing Mars Semi-Direct programme would require three SLS launches per window.

SEP + EML2 promises reusability and sustainability.   That would be one benefit.  The cost is spread out over  many years. 

An "all up" mission in which the only part left at the end is the Orion spacecraft bobbing in the ocean becomes "flags & footprints."  Doable, repeatable, and not necessarily bad if that's the objective.

Without a roadmap, we don't know what the objective is (except in very general terms). 

Offline muomega0

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Why use SEP at all when SLS Block II has the capability to push around 40 to 50 tonnes (or more with advanced LRBs) through TMI.
That is the hidden agenda.  206 days from LEO to L2..not a robust supplier to L2 but great for Mars trips.

Why SLS?   work on game changing technology instead.

It doesn't /require/ the L2 gateway.
Budget:           It doesn't require SLS and Orion:  >3.2B/year savings
Sole Source:    It doesn't include the existing U.S. and IP fleet  to reduce launch costs:  see Budget.
Depot in LEO:   It doesn't include a LEO gas station to reduce the Budget and maintains sole source.
Amplification:    It doesn't include Boeing's Amplification factor to reduce costs and IMLEO
Architecture:    It doesn't include the trade study...what a surprise  :o
EP-L2-Mars:    The EP LEO to L2 leg is designed to fail - eliminate other options (depots, ..) in the meantime
Mass Budget:  DRM 5 was 900mT, HLV with boiloff raises this to 1200mT, LEO EP back to 900mt (savings?)
Cadence:        Budget limited with no SLS/Orion commonality for decades-sad case for reliability and safety
Days to L2:    206.6 days....designed to limit missions what happened to 2x lunar sorties?
Crew Health:  it doesn't mention the significant number of dedicated SLS/Orion flights likely required to L2 to incrementally demonstrate the crew and hardware can survive the long duration trip to Mars.  LEO SEP to L2 over 206.6 days vs a quarter of that from L2 to Mars.  No mention of GCR mass and power required.

It's another classic example of why outsourcing large integrated programs often results in non-optimal solutions for the government (taxpayer):  Companies (and parts of the government!) will not implement other companies technology if it hurts their bottom line.

Offline mike robel

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Huh.  This is interesting.  Almost provides me as much excitement as Mars Direct did when I first read it.  Looks doable.   And, of some importance to me, a lot of opportunities for building models.  :)

 

Offline Coastal Ron

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6. Higher production rate will lower cost, not drive cost.

My background is manufacturing operations, and building any complex vehicle such as the Orion is not assembly-line type stuff, and certainly not at the low volumes we're talking about here (at best around one per year).  Since virtually everything that are the large cost drivers on the Orion are custom made for the Orion, it's difficult to lower costs without dramatically higher volumes - and that won't happen with the Orion since it's a transition vehicle at best (i.e. NASA would prefer to have a more capable vehicle like Nautilus-X).

Quote
Note: I do not claim to have all the right answers, in fact I may be completely wrong, but tell me this doesn't at least sound plausible.

As a blanket statement, we can do just about anything from a technical standpoint, and this plan looks doable.

However this plan does not solve the real issue that has held us up from leaving LEO in 40 years, which is the amount of money that our politicians want to spend on such a venture.

Quote
But it doesn't matter, because unless the United States of America adopts a unitary state system and rids its politics of hyperpartisanship, then two decades from now NASA is not going to put humans on Mars - or anywhere else.

I don't think that's the only choice.  You seem to assume a NASA-only approach to going to Mars, and I think that is a common false premise that leads to a dead end.  I don't think NASA will ever be funded enough to do all the things BY ITSELF that will get NASA to Mars.  And does it matter if it's NASA that gets there first?

For instance, what if Elon Musk is able to marshall enough resources to get to Mars?  Do we really care if NASA is in the lead or not?  I don't.

So instead of being focused on NASA only, which is very likely to keep getting a smaller and smaller budget, we should be focused on how official or unofficial coalitions of people, companies and countries can get there.  And for that to happen it can't be a NASA-centric architecture like this one.
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 mike robel

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For instance, what if Elon Musk is able to marshall enough resources to get to Mars?  Do we really care if NASA is in the lead or not?  I don't.

So instead of being focused on NASA only, which is very likely to keep getting a smaller and smaller budget, we should be focused on how official or unofficial coalitions of people, companies and countries can get there.  And for that to happen it can't be a NASA-centric architecture like this one.

Musk is clearly a smart guy who knows how to build a team and get things done.  Perhaps I am just short sighted, but I don't think, he, by himself, has enough money to fund this, even if he finds other private partners.  I don't see a payoff strategy here.

What may be workable, is a combination International-Private effort, but while governments can spend money without worrying about return on investment too much, I can't think private investors would do so.

So, what would be the carrot for them? 

Offline RonM

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For instance, what if Elon Musk is able to marshall enough resources to get to Mars?  Do we really care if NASA is in the lead or not?  I don't.

So instead of being focused on NASA only, which is very likely to keep getting a smaller and smaller budget, we should be focused on how official or unofficial coalitions of people, companies and countries can get there.  And for that to happen it can't be a NASA-centric architecture like this one.

Musk is clearly a smart guy who knows how to build a team and get things done.  Perhaps I am just short sighted, but I don't think, he, by himself, has enough money to fund this, even if he finds other private partners.  I don't see a payoff strategy here.

What may be workable, is a combination International-Private effort, but while governments can spend money without worrying about return on investment too much, I can't think private investors would do so.

So, what would be the carrot for them?

Pay them for what they can provide. If NASA got out of the hardware business, as they have in COTS and Commercial Crew, then NASA could pay for systems designed and built by more efficient private industry.

To do this Boeing mission could the components be put into orbit on a Falcon Heavy? Could you replace the Orion with an upgraded CST-100 or Dragon? Would it cost less? My guess as the answer to all of these question is yes.

SpaceX is designing a BFR and the MCT (whatever that really is) to go to Mars. If NASA had a Commercial Mars program, the BFR would be useful.

Offline yg1968

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I noticed that they would use Hall thrusters rated at 50KW for the SEP. NASA intends to use a 40KW thruster for the ARM mission.
« Last Edit: 07/05/2014 04:03 PM by yg1968 »

Offline yg1968

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It doesn't /require/ the L2 gateway. Listen to the telecon.

They say that but Orion is parked at the L2 gateway in their architecture.

Offline DLR

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I don't really understand why the cargo is launched directly to EML-2 to meet an SEP transfer stage there. Launching to EML-2 takes only a few hundred m/s less than launching directly to Mars for aerocapture or direct entry. A single SLS launch should be sufficient to place a habitat for four crew on the surface of Mars.

I like the idea of reusing the transfer stage, but that is a long-term option. Attempting to incorporate it from the outset is an unnecessary addition to the upfront cost. If you wanna do Mars, you have to keep the upfront cost as low as possible. Three SLS launches per window would be able to sustain an ongoing campaign on Mars with minimal orbital assembly and rendezvous operations.

Regarding the crew, whatever happened to the idea to let the crew ride out to Mars in the surface habitat and conduct a surface rendezvous with a pre-positioned and checked-out ascent vehicle? This adds tons of redundancy to the mission without increasing IMLEO. Landing in the MAV, with its limited life support and vital role for the mission seems like a recipe for disaster if the landing is slightly off target or the ascent stage damaged in a hard landing. If you land in the surface hab, the crew will have full life support for at least 500 days available irrespective of where it lands and with the addition of a pressurised rover it could cover a lot of ground to reach the MAV. Pre-positioning the MAV allows for remote checkout before the crew ever commits to launch from Earth. Doing it the way Boeing propose (with a dedicated transfer vehicle and lander/ascender) takes away that redundancy and adds risk, just for the sake of hypotehtical reusability some way down the line.

Online ThereIWas3

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I liked their vision of the Mars entry/landing vehicles, with just an inflatable aeroshell plus rockets, and putting the engines up high like Dragon.

But I do not like just about everything else about this proposal.  The two big challenges I see are (1) doing it cheaper, and (2) doing it quickly (which helps with #1).  It has to be cheap or nobody will even start to fund it, and it has to be fast or nobody will continue to fund it to completion.  This plan does not address those challenges.

Our first trip to Mars does not have to be the ultimate in how we could do it.  We do not have to build infrastructure in advance; that just increases up-front costs.  We should build the infrastructure as we go, so the second trip is cheaper than the first one, etc.

Rather than starting with a grand plan like this, I would like to see an approach starting with "what can we do with the technology we have now?" and build from that.  Imagine that the first launch of the manned Mars exploration program was in 2017 - what should be that payload?
« Last Edit: 07/05/2014 04:25 PM by ThereIWas3 »
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Online A_M_Swallow

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The infrastructure has to be in place for the astronauts to use it.  So it needs to either travel with them or in advance of them.  A second base can arrive later but the first group of astronauts cannot use it.

Unlike the short stays of Apollo the astronauts will be spending months on the planet.  They will need habitation, consumables, mobility and power during the first mission.  ISRU is optional but nice.

Offline gbaikie

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I don't really understand why the cargo is launched directly to EML-2 to meet an SEP transfer stage there. Launching to EML-2 takes only a few hundred m/s less than launching directly to Mars for aerocapture or direct entry. A single SLS launch should be sufficient to place a habitat for four crew on the surface of Mars.
It seems that a SEP transfer stage requires abundant electrical power for propulsion and one could use this  electrical power for things other than just this propulsion. Or the full power needed for highest thrust could be needed for a month of a year of operation. Though perhaps it's as much as 6 months of a year, but seems unlikely it could be 11 months or more of a year of operation.
Or if need full thrust at Mars distance, you will also get twice as much power at Earth distance.
This can be seen as problem or abundance one could imagine one might utilize.
Cargo could have no need of any electrical power, but some cargo might need some electrical power- and crew will certainly will need some.
As far as putting a habitat for four on Mars surface, in general, this seems to be the least of the problem, though it depends what is meant by such a habitat. For example was first couple modules of ISS what it meant by habitat, or is the 500 tons of ISS that is considered the habitat.

As Boeing advertizement indicated, a difficult aspect of Manned Mars, is getting back off the surface and returning to Earth. And therein lies the appeal of idea of one way trip to Mars- in terms of total costs.

I believe putting off return to Earth as long as practical, is generally an approach that NASA should incorporate.
Or I think NASA needs an emergency abort from Mars orbit from the start- but not from Mars surface. Or emergency abort from Mars surface could be too expensive to provide for the crew which first land on Mars. But an emergency or routine way to leave Mars surface should be a priority of the first crews
which land of Mars surface. Or one will use the crew presence in order to build such a capability as soon as possible.
So from that way of looking at it, a crew habitat is needed as part of first step, but getting crew to surface is more costly than just having a habitat. So need abort from Mars orbit, and need the means crew being able to "construct" a way to get off Mars surface, needing supplies for crew to live on surface, and of getting them to Mars surface, alive- happy and healthy.

It could be the entire process of finding where to put a habitat, costs more, then construction, and delivery of such a habitat- though again it depends upon what is meant by a habitat. Such as all that is involved in using Mars environment for getting water and radiation shielding. And landing site and electrical power plant. A greenhouse. A lab/workshop. Another thing is all that is needed for a crew to be able handle the "mission control" from Mars.



Online ThereIWas3

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The infrastructure has to be in place for the astronauts to use it.  So it needs to either travel with them or in advance of them.  A second base can arrive later but the first group of astronauts cannot use it.

Unlike the short stays of Apollo the astronauts will be spending months on the planet.  They will need habitation, consumables, mobility and power during the first mission.  ISRU is optional but nice.

I should clarify.  By 'in advance' I meant we do not need to complete the infrastructure before sending people.  We do it piecemeal.  So the first launch could be the unmanned ERV/ISRU unit that will be used by the second manned launch people to get home.  I would expect the second launch to include a habitat which is used both enroute and on the surface.  I disagree about ISRU. because ISRU greatly reduces the mass required to be delivered to the Mars surface on every trip and therefore reduces cost.
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Online A_M_Swallow

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The EML-2 Gateway and the transfer vehicle's habitat may be able to save money by using the same design for some systems.  the 80:20 rule will probably apply.

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I don't really understand why the cargo is launched directly to EML-2 to meet an SEP transfer stage there. Launching to EML-2 takes only a few hundred m/s less than launching directly to Mars for aerocapture or direct entry. A single SLS launch should be sufficient to place a habitat for four crew on the surface of Mars.

That seems like a response to the proposal that voices meaningful concerns, rather than flying off into discussions of how SpaceX will get there first. So it seems like it deserves to be considered! Could you start by putting some crispness into the numbers? I use 3,188 m/s for LEO to Earth escape, and 4,400 m/s for TMI from LEO. The difference is quite a bit more than "a few hundred m/s"!

Also, about what mass do you believe any single SLS launch will put through TMI? How would that mass capability lead to a surface habitat suitable for a crew of four?
« Last Edit: 07/06/2014 01:33 AM by sdsds »
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Offline Coastal Ron

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For instance, what if Elon Musk is able to marshall enough resources to get to Mars?  Do we really care if NASA is in the lead or not?  I don't.

So instead of being focused on NASA only, which is very likely to keep getting a smaller and smaller budget, we should be focused on how official or unofficial coalitions of people, companies and countries can get there.  And for that to happen it can't be a NASA-centric architecture like this one.

Musk is clearly a smart guy who knows how to build a team and get things done.  Perhaps I am just short sighted, but I don't think, he, by himself, has enough money to fund this, even if he finds other private partners.  I don't see a payoff strategy here.

Definitely part of the conundrum.

So there are at least two ways to address this:

1.  Find sources of funding that are independent of business models and single-nation architectures.

2.  Lower the cost.

As far as lowering the overall cost, I think we are getting closer to the point where private entities can mount such an effort (i.e. go to Mars) and do it in a relatively safe way.  Not completely safe, and in a way that's where the cost savings come from.  But safe enough for non-government efforts.

For instance, the way NASA currently works - and what Congress expects of NASA - is to plan for as many contingencies as possible and create ways to overcome them.  That makes for "safe as possible" type efforts, but it also comes with not only expensive hardware but also expensive on-going NASA overhead.

But I think we could be coming to a point where there is enough knowledge and industry capabilities for hire to create "commercial level" safety in space hardware.  Levels that would not necessarily meet NASA's requirements, but would otherwise be acknowledged as "inherently safe enough".  It would also be far quicker to build and less costly overall.

Thus, instead of a $200-400B tab for a NASA-only mission to Mars, non-NASA architectures could do it for far less.

Still a challenge to fund them though...

Quote
What may be workable, is a combination International-Private effort, but while governments can spend money without worrying about return on investment too much, I can't think private investors would do so.

So, what would be the carrot for them?

We only have what we have today, which is A) The urge to explore, and B) Start working on making humanity multi-planetary.

But in order to get money behind one or both of those, you need someone with a vision and a plan to attract lots of money.  Musk has a vision, but so do others, and no one has a plan yet, so it's hard to tell how much money is waiting in the wings - or when people will start writing checks.  I think it's going to be a while still...
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 Coastal Ron

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I don't really understand why the cargo is launched directly to EML-2 to meet an SEP transfer stage there. Launching to EML-2 takes only a few hundred m/s less than launching directly to Mars for aerocapture or direct entry. A single SLS launch should be sufficient to place a habitat for four crew on the surface of Mars.

That seems like a response to the proposal that voices meaningful concerns...

Though the element could probably be assembled in LEO, if you have an EML2 station anyways (which I think is the next logical step after the ISS), then it makes sense to try and use it as a mission assembly point.
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 guckyfan

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Though the element could probably be assembled in LEO, if you have an EML2 station anyways (which I think is the next logical step after the ISS), then it makes sense to try and use it as a mission assembly point.

This seems a circular argument to me. What is a EML2 station good for except as a staging point? You make the argument to build a station there -  for what purpose? Then you argue it is a logical misison assembly point, good because it is already there.


Offline Robotbeat

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Listen to the telecon. EML station is good as a staging point but isn't strictly necessary. Does provide a convenient interface for commercial logistics and a path towards international cooperation (which is more useful for avoiding cancelation than for reducing cost).

Also, the cargo SEP and transit hab are meant as a demo for the full Mars mission. And spiraling in then releasing the lander reduces the difficulty of designing a heatshield capable of such an entry. Also, the second SEP tug allows redundancy from the start.

The SEP stage and transit hab and EML2 gateway are reusable infrastructure that could foster exploration to many different destinations for decades. Also, the SEP tug technology basically already exists.

All of this stuff is very easily transferable to a more commercially supplied architecture.

The EML gateway helps provide continuity with ISS and confidence with deep space operations and refitting the transfer vehicle for a new mission.
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Though the element could probably be assembled in LEO, if you have an EML2 station anyways (which I think is the next logical step after the ISS), then it makes sense to try and use it as a mission assembly point.

This seems a circular argument to me. What is a EML2 station good for except as a staging point? You make the argument to build a station there -  for what purpose? Then you argue it is a logical misison assembly point, good because it is already there.

Well, EML2 is a good staging point. Or it's a better staging point than LEO- in various aspects.
EML2 is a better staging point IF one is sending a lot of mass to Mars- or if you only needed say a total mass of 100 tons at LEO to get to Mars then it's less of advantage to use EML2, because requires for there to be less launches and less time at LEO.
Or 100 ton at LEO is roughly equal to 50 tons at EML2 and the 100 tons at LEO which equal to 50 at EML-2
has about 1/2 of mass as rocket fuel or propulsion capability to get to L-point in terms of delta-v needed.
Or one is immediately or in short time expending the delta-v to get 1/2 way to Mars, if you stage at EML2, whereas if staging at LEO one needs to store or refuel at point earth departure at LEO.

Now if want more massive chunks of hardware, this is advantage of LEO, but one could this lift the massive chunk to LEO, and within short period of time reboost it to EML2, using a booster from an additional launch.
Or disadvantage of LEO is keeping anything in this orbit for longer time periods [weeks, months, years]. Or ISS is in fairly high orbit in terms, LEO, and it's higher, in order to lower the atmospheric drag.
Or biggest mass which could be lifted would be lower low earth orbit, which could spend a short period of time in this orbit, and which was then, boosted to a higher orbit, from an additional launch or depot refueling.

Or one looking at LEO or L-point with the assumption is can not use one single earth launched rocket to do the Mars mission. Though some parts of Mars Mission could be launched directly from Earth surface to Mars surface with a single rocket.

Part of this discussion involves whether the SLS is going to be 130 tons to LEO, and I assume lot of people do assume NASA does get this launch vehicle. But I am not even certain NASA will get the SLS with 70 ton to LEO.

So if we assume one gets 130 ton lift, then suppose we talk about some sort of Mars Direct. Or with only brief period in LEO before going to Mars.

It seems if the plan involves needed a staging area, and needing time at staging area, and/or having more survivability if any launches are delayed for any significant period of time.
And in terms of program costs, making sure that Mars window can gotten in the year one wants to go to Mars.
Then a L-point makes more sense.
As it seems to me, one could be ready to go to Mars months before the time of getting the point of having Mars launch window, available.

Another aspect would be, where in LEO? And is everything assembled in orbit to going to Mars going be at KSC 28 inclination or is Russia or Europe [or others involved]. As 51 inclination is not optimal for KSC and 28 inclination not really feasible for Russia and not optimal for Europe. Or in terms of international involvement
a L-point is a better place to stage at.
If you want to use ISS, or 51 inclination, one could additionally stage at a L-point, and so have some of stuff first go to 51 inclination and have other parts using other inclinations which later meet up at EML2.
« Last Edit: 07/06/2014 06:25 AM by gbaikie »

Offline manboy

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I liked this rendering.
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Offline RanulfC

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I don't really understand why the cargo is launched directly to EML-2 to meet an SEP transfer stage there. Launching to EML-2 takes only a few hundred m/s less than launching directly to Mars for aerocapture or direct entry. A single SLS launch should be sufficient to place a habitat for four crew on the surface of Mars.

Not sure what you don't understand actually. You're suggesting (as does both the Mars Direct and Semi-Direct) to repeat the mistakes of Apollo without the "justification" that drove the decisions that ended up with a non-sustainable and non-functional "Lunar Exploration" program. The Lunar missions were, it is true, building "up" with time but the entire Apollo structure was not intended nor could it have been significantly "modified" to become an actual extended Lunar Exploration program. The various AAP studies show this to be so, the entire "system" would have needed significant modification to meet longer term goals.

So as you point out:
Quote
I like the idea of reusing the transfer stage, but that is a long-term option. Attempting to incorporate it from the outset is an unnecessary addition to the upfront cost. If you wanna do Mars, you have to keep the upfront cost as low as possible. Three SLS launches per window would be able to sustain an ongoing campaign on Mars with minimal orbital assembly and rendezvous operations.

You suggest then instead of "doing" Mars correctly with a sustainable and reusable ITV we should instead simply push individual "shots" as we did during Apollo so that the entire thing can be more easily "cancled" once the first mission has landed and come back? Throwing away three FULL sets of equipment (and yes the stuff on Mars will NOT be "reusable" by later crews, was any of the Apollo landers? Why "assume" that it won't be cheaper to throw a whole "new" set for each crew if that's the "plan" in the first place?) per "mission" in a similar manner as Apollo simply reduces the arguments to terminate the progrqam as soon as the goal is achieved. Meanwhile having actual "hardware" in orbit tends to make doing so much more difficult. (Apollo/Apollo-AAP versus ISS should be a point here)

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Offline newpylong

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Intense presentation...

Offline metaphor

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I don't really understand why the cargo is launched directly to EML-2 to meet an SEP transfer stage there. Launching to EML-2 takes only a few hundred m/s less than launching directly to Mars for aerocapture or direct entry. A single SLS launch should be sufficient to place a habitat for four crew on the surface of Mars.

That seems like a response to the proposal that voices meaningful concerns, rather than flying off into discussions of how SpaceX will get there first. So it seems like it deserves to be considered! Could you start by putting some crispness into the numbers? I use 3,188 m/s for LEO to Earth escape, and 4,400 m/s for TMI from LEO. The difference is quite a bit more than "a few hundred m/s"!

The lowest transfer windows to Mars are about 3.54 km/s from LEO.  The more difficult launch windows might require up to 3.8 km/s.  Lowering transit time increases that delta-v, but that shouldn't be a concern for cargo launches.  For crew launches, if you want to lower the transit time to less than 7 months, 4.00 km/s is enough for any launch window, while a less than 6-month transit time takes less than 4.15 km/s.  Trajectory Browser

Offline sdsds

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The lowest transfer windows to Mars are about 3.54 km/s from LEO.  The more difficult launch windows might require up to 3.8 km/s.[...] Trajectory Browser

Those clearly exist. I suppose the question is, "Can you count on launching into them?" Attached is a chart from "Cryogenic Propulsive Stage (CPS) Mission Sensitivity Studies - Low Earth Orbit Departure Results - Revision D" dated 4 October 2012 by Mark Schaffer of SpaceWorks Engineering. To get a 30 day launch window on this opportunity required 4400 m/s.
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Offline metaphor

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The lowest transfer windows to Mars are about 3.54 km/s from LEO.  The more difficult launch windows might require up to 3.8 km/s.[...] Trajectory Browser

Those clearly exist. I suppose the question is, "Can you count on launching into them?" Attached is a chart from "Cryogenic Propulsive Stage (CPS) Mission Sensitivity Studies - Low Earth Orbit Departure Results - Revision D" dated 4 October 2012 by Mark Schaffer of SpaceWorks Engineering. To get a 30 day launch window on this opportunity required 4400 m/s.

I'm not sure why the lowest point on that blue line is still higher than 4 km/s.  The 2022 launch window is actually one of the hardest but it should still be less than that.

I was assuming cargo launches land directly on Mars and don't go into orbit first.  In that case, the Mars arrival delta-v does not matter so there's no reason to optimize for it.

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After Apollo 11, each mission was to a different location.  They were exploring, not building.  So none of the equipment was designed to be reused.  And they launched  one or two missions per year.  Maximum stay was 3 days, so they did not need a lot of equipment.

Mars being a lot further away, stays will be longer and more equipment will be required; more than a single launch of any of the proposed vehicles could manage.   So an integration location needs to be chosen.

LEO has advocates, as does EML.  I would like to see both Mars orbit and Mars surface considered as well for rendezvous/integration locations.   It might allow for first launches a few cycles earlier than building up everything at the Earth end first.
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Offline Robotbeat

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Many rendezvous points probably makes sense. EML2 (or EML1 or high Earth orbit... Practically all the same from an energy perspective), in addition to Mars orbit and Mars surface. By having the SEP stage and transit hab be reusable, you have the two biggest pieces (which are also most flexible... SEP could be used as a tug for, say, a depot for lunar propellant and both pieces could be used for a mission to, say, Ceres) which could be used again and again even after we go beyond SLS and Orion. Also, it'd be nice to have a better performance, single-stage reusable Mars lander that could be refueled in orbit or on the surface.
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Offline Rocket Science

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It would be interesting if Habs and Rovers could be repositioned by being refueled and making short “hops” to a new location for the next crew...
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Offline sdsds

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Comparing the two trajectories below seems useful. Both are for the same (2035) opportunity. Raftery's uses SEP; the trajbrowser assumes impulsive (i.e. chemical) TMI. 256 days in transit, versus 112.
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Offline Robotbeat

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The traj isn't optimizing for Mars capture delta-v, not an appropriate comparison. That delta-v isn't free. Appropriate for a flyby, not for an actual Mars mission with Mars-orbit rendezvous (chemical OR SEP-chemical hybrid).
« Last Edit: 07/08/2014 08:21 PM by Robotbeat »
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Offline sdsds

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Right, or if one had sufficient faith in one's direct Mars entry/descent/landing technology, perhaps because it had been tested on prior cargo missions. That would lead to a Mars surface rendezvous approach....
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Offline Robotbeat

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Right, or if one had sufficient faith in one's direct Mars entry/descent/landing technology, perhaps because it had been tested on prior cargo missions. That would lead to a Mars surface rendezvous approach....
That'd be fine except now your lander must be much bigger because it has to be big enough to support the whole transit. The lander/ascent-vehicle is just about the hardest part so you'd want to minimize it.

All in all, the approach by Raftery is more conducive to sustainable, flexible operations.
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Offline sdsds

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All in all, the approach by Raftery is more conducive to sustainable, flexible operations.

This being the Raftery thread, I'll have to agree with that. "Have SEP, will travel!"
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Offline Halidon

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Maybe its artistic license, but the SLS EUS appears to be using different engines for the caro and crew launches. Certainly looks like RL-10s for the crew version, RL-60/RL-X for cargo?

Offline Archibald

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The pictures on that pdf, they were so beautiful, I made a 5 minutes powerpoint animation with them. I added Coldplay "a sky full of stars" as soundtrack. I should post that on YouTube  :o
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Offline Robotbeat

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The pictures on that pdf, they were so beautiful, I made a 5 minutes powerpoint animation with them. I added Coldplay "a sky full of stars" as soundtrack. I should post that on YouTube  :o
That'd be cool.
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Offline metaphor

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This is an ingenious proposal.

But one thing I feel might be a problem is the high orbit rendezvous.  That means that the MAV has to use much more fuel than a low orbit rendezvous, and also an additional engine start.  Compared to the ~3.8 km/s of delta-v to low Mars orbit from the surface, going to areostationary orbit requires an additional two burns of 1.1 km/s and 0.7 km/s.  If the spacecraft has a dry mass of 10 tons, a MAV using LOX/methane would need 20 tons of fuel to get to low orbit, but 40 tons of fuel to get to areostationary orbit.  That might be a problem, especially if not using ISRU and that fuel has to be carried from Earth.

Online ThereIWas3

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This is an ingenious proposal.

But one thing I feel might be a problem is the high orbit rendezvous.  That means that the MAV has to use much more fuel than a low orbit rendezvous, and also an additional engine start.  Compared to the ~3.8 km/s of delta-v to low Mars orbit from the surface, going to areostationary orbit requires an additional two burns of 1.1 km/s and 0.7 km/s.  If the spacecraft has a dry mass of 10 tons, a MAV using LOX/methane would need 20 tons of fuel to get to low orbit, but 40 tons of fuel to get to areostationary orbit.  That might be a problem, especially if not using ISRU and that fuel has to be carried from Earth.

A cynic might say that Boeing would prefer the higher mass solution, as it reinforces the need for SLS.
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Offline Robotbeat

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Cynical: Doesn't make that much sense, really. With refueling, the 30-40mT lander is likely to weigh ~10mT dry.

A higher rendezvous orbit means a smaller SEP tug, and the SEP tug has more need of the volume than the lander.
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Offline yg1968

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All of this stuff is very easily transferable to a more commercially supplied architecture.

In Boeing's proposal, Orion could easily be replaced by an upgraded Dragon since the spacecraft doesn't go further than the L2 Gateway.
« Last Edit: 07/10/2014 08:01 PM by yg1968 »

Offline Robotbeat

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All of this stuff is very easily transferable to a more commercially supplied architecture.

In Boeing's proposal, Orion could easily replaced by an upgraded Dragon since the spacecraft doesn't go further than the L2 Gateway.
Indeed. Raftery also explicitly mentions commercial propellant delivery for the SEP, which could logically be extended to the lander, too (especially if you could manage a single-stage reusable lander).
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Offline Oli

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Awesome. SEP tugs are the real deal.

I have a feeling this might actually happen.
« Last Edit: 07/10/2014 02:58 AM by Oli »

Offline sdsds

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In Boeing's proposal, Orion could easily replaced by an upgraded Dragon since the spacecraft doesn't go further than the L2 Gateway.

What? You're saying Boeing is making a proposal for SLS etc. that doesn't depend on the success of Lockheed-Martin's MPCV development effort? I wonder why they would do that?
« Last Edit: 07/10/2014 04:13 AM by sdsds »
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Offline Oli

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If EML-2 assembly is too difficult for whatever reason, I guess you could assemble both vehicles in LEO and only dock Orion with the crew vehicle at EML-2. Its just that SLS gives you the performance to launch hab+kick stage directly to EML-2, so you do not have to "spiral out" those modules.

Further I do not think SLS Block II is an essential part of this architecture. I suppose SEP tug and the Mars lander could be launched separately.
« Last Edit: 07/10/2014 07:37 AM by Oli »

Offline yg1968

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In Boeing's proposal, Orion could easily replaced by an upgraded Dragon since the spacecraft doesn't go further than the L2 Gateway.

What? You're saying Boeing is making a proposal for SLS etc. that doesn't depend on the success of Lockheed-Martin's MPCV development effort? I wonder why they would do that?

NASA didn't make the same "mistake" in their proposal. In their study, Orion comes back directly from Mars without stopping at the gateway/staging point. However, the habitat returns to the staging point/gateway in order to be refurbished. See slide 11:

http://forum.nasaspaceflight.com/index.php?topic=35122.0
« Last Edit: 07/10/2014 08:23 PM by yg1968 »

Offline Robotbeat

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Yeah, the Raftery proposal keeps Orion at EML2. Good idea, actually. You can really optimize the heck out of the transit hab that way.
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 yg1968

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Yeah, the Raftery proposal keeps Orion at EML2. Good idea, actually. You can really optimize the heck out of the transit hab that way.

Yes but what happens if SpaceX decides to develop an upgraded Dragon that can make it to L2. Wouldn't NASA be forced to use the commercial option (instead of Orion) in such a case? I suspect that is why NASA's study decided to bring Orion all the way to Mars orbit.

P.S. From your sig: "To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers." 
« Last Edit: 07/10/2014 08:58 PM by yg1968 »

Offline Robotbeat

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Yeah, the Raftery proposal keeps Orion at EML2. Good idea, actually. You can really optimize the heck out of the transit hab that way.

Yes but what happens if SpaceX decides to develop an upgraded Dragon that can make it to L2. Wouldn't NASA be forced to use the commercial option (instead of Orion) in such a case? I suspect that is why NASA's study decided to bring Orion all the way to Mars orbit.

P.S. From your sig: "To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers."
Indeed. And actually, SpaceX's heatshield may be better suited to Mars entry than Orion's due to the use of PICA-X instead of Avcoat.

But NASA isn't supposed to plan missions intentionally to avoid commercial space transportation services. Constellation kind of did that, but both Raftery's architecture and NASA's architecture have spots where commercial space transportation services could take over some of the duties now served by Orion and SLS. Heck, NASA's architecture may be better off with Dragon V2 anyway since it's significantly lighter than Orion.
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 Burninate

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For human cargo, an LEO rendezvous with a chemical boost stage which brings the craft to high orbit to rendezvous with the depot / departure stage is a practical way to avoid super-heavy-lift for this sole point.

Offline Robotbeat

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That's unnecessary if you're using either Dragon or Soyuz which can launch on Falcon Heavy and Proton (or Angara) respectively. CST-100 could just about make it on Delta IV Heavy with RS-68A, careful trajectory, and use of abort propellant or could also use Falcon Heavy. You're going to the gateway, which is the logical extension of ISS to beyond LEO so may inherit much of the logistics of ISS. But yeah, it may be possible to launch Orion there Gemini style without SLS.
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 Robotbeat

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For human cargo, an LEO rendezvous with a chemical boost stage which brings the craft to high orbit to rendezvous with the depot / departure stage is a practical way to avoid super-heavy-lift for this sole point.
Just to reiterate, this is a perfectly valid way of beyond-LEO transport. Some of the Gemini missions did this and they went further from Earth than anyone has ever been since 1972. Worked just fine, and this was before our modern automated rendezvous methods were developed.



By my calculations, as long as Orion can be launched manned on D4H to LEO (should be fine), then a Hydrolox upper stage in LEO with a mass of 30t and dry of 3 should be enough to put Orion at EML2 within 20 days, with just a little help from Orion herself. The longer transit also reduces insertion delta-v, leaving more oomph for the return journey. A 2-launch architecture is perfectly doable.
« Last Edit: 07/11/2014 10:27 PM by Robotbeat »
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 Archibald

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The pictures on that pdf, they were so beautiful, I made a 5 minutes powerpoint animation with them. I added Coldplay "a sky full of stars" as soundtrack. I should post that on YouTube  :o
That'd be cool.

I (finally !) did it and hope you'll enjoy the video.

https://www.youtube.com/watch?v=oJcC4SKd16Y&feature=youtu.be

...you have been found guilty by the elders of the forum of a (imaginary) vendetta against Saint Elon - BLAAASPHEMER !

Offline redliox

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Are there any further details about the solar electric tug?  I'm trying to make a better judgement call about it.  I see their details about the trajectory, which is pleasant knowledge to have, and the thrust times required.

So the overall plan, from Boeing, is the slow haul to Mars both crew and humans from EML-2 to Areosynchronous orbit?  I could agree to some points about it, and maybe even live with 45 days to break the crew into orbit.  I think those six pieces could be simplified.

I think there should be a blending of Mars Direct with this; if the main concerns against Direct's straightforward approach is aerocapture and ISRU, having the solar tug allows for a safe arrival and an escape route to mitigate those concerns.
« Last Edit: 04/24/2015 09:15 AM by redliox »
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Offline sdsds

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With the reusable tug it is easy to jump to the (I think erroneous) conclusion that each subsequent Orion can launch with the SEP propellant needed to refuel the tug, and thus the mission cycle can continue as long as the tug lasts, with only launches of the cargo component and the crew component.

But that doesn't work, because it doesn't provide the SEP propellant for the subsequent cargo components. (The first time around the loop this was launched with the tug.) So you need to have another launch with the cargo SEP propellant. And either that needs to include an Orion so you can have its crew do the refueling of the tug, or you need to develop autonomous refueling.

I'm sure many here would say, "The autonomous refueling of the SEP tug is a 'no-brainer' detail." I would gladly dispute that on both technical and political grounds! ;)
-- sdsds --

Offline guckyfan

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I'm sure many here would say, "The autonomous refueling of the SEP tug is a 'no-brainer' detail." I would gladly dispute that on both technical and political grounds! ;)

In the Jupiter concept by LM the next cargo also brings the fuel along. They bring the fuel in a new tank. If that is easier than refuelling then go that way.

Offline Robotbeat

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I'm sure many here would say, "The autonomous refueling of the SEP tug is a 'no-brainer' detail." I would gladly dispute that on both technical and political grounds! ;)

In the Jupiter concept by LM the next cargo also brings the fuel along. They bring the fuel in a new tank. If that is easier than refuelling then go that way.
Jupiter refuels from the Exoliner, it does not swap tanks.
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 guckyfan

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Jupiter refuels from the Exoliner, it does not swap tanks.

Does Jupiter even have tanks? It takes its fuel from the tanks Exoliner brought along. What advantage would transfering fuel have?

Offline Bob Shaw

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Jupiter refuels from the Exoliner, it does not swap tanks.

Does Jupiter even have tanks? It takes its fuel from the tanks Exoliner brought along. What advantage would transfering fuel have?

Weight.

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