NASA's Artemis Program Updates and Discussion Thread 4

[DanClemmensen]

you do realize all these utopian dreams of being able to quickly replace SLS and orion is a once in a generation move. There is no way that it will be politically possible given that so much money has been spent and to download the entire marquee project from nasa onto musk will be un paliable to the lawmakers. Not to mention the time it will take to do so even if approved. say goodbye to a manned launch until late 2030s if not longer if we flip flop.

also dont forget cancellation isnt free. who will pay boeing, esa and others the termination fee? it would cost just as much to compensate for the cancellation than to build it. you think lex musker will pay for it?

My vision (or maybe, my fantasy):
SLS/Orion cannot be abruptly cancelled. Instead, a parallel system will evolve, and SLS/Orion will plod along at the minimum barely-sustainable rate, maybe reaching one mission every 18 months. The parallel system will eventually reach a rate that supports a continuously-inhabited moonbase: at least 4 missions per year and probably more. SLS/Orion will not be cancelled, there will just not be any new orders.

[Khadgars]

The whole SLS/Orion should be cancelled in favor of my personal favorite architecture should really be in either of the following two threads.  We really don't need this discussion in every thread that involves SLS/Orion  imho

https://forum.nasaspaceflight.com/index.php?topic=55246.0

https://forum.nasaspaceflight.com/index.php?topic=57014.0

[Coastal Ron]

...By eliminating the SLS+Orion, and replacing them with reusable space-only transportation systems, many limitations are removed, and humanity can finally start expanding out into space. Maybe not quickly, since figuring out an ROI that meets political needs is still a thing, but the cost goes down so much that politicians should be more likely to let NASA experiment with more exploration options.

you do realize all these utopian dreams of being able to quickly replace SLS and orion is a once in a generation move.

1. There is no "National Imperative" to return to the Moon quickly. If anything, that haste is leading to waste.

2. Replacing a fully expendable transportation system with a partially or fully reusable transportation system would be significant, and if the generational shift is to FINALLY eliminate fully expendable transportation systems, then I think that would be a good choice. Why wouldn't it be?

There is no way that it will be politically possible given that so much money has been spent and to download the entire marquee project from nasa onto musk will be un paliable to the lawmakers.

Whoa there. You are trotting out that old false choice that you either have to fully support the SLS+Orion, or you have to turn over all space exploration to Elon Musk. I've never mentioned Elon Musk or SpaceX, and in fact I want competition and redundancy - something which the SLS+Orion do not provide. Don't you want competition and redundancy?

Not to mention the time it will take to do so even if approved. say goodbye to a manned launch until late 2030s if not longer if we flip flop.

Addressed in a prior post - it has been 50 years since we last set foot on the Moon, what is the rush to return using the most expensive transportation system? And at most it would only add a few years, but in return it would allow far more Artemis missions per year, which our partners would appreciate. And isn't that the better metric, how many missions you can do per year?

also dont forget cancellation isnt free. who will pay boeing, esa and others the termination fee?

Who has paid for the $40B+ we have spent so far without a single person being moved to space?

If anything you are arguing FOR the cancellation of the SLS and Orion, because they have been the biggest waste of taxpayer money in the history of NASA.

...it would cost just as much to compensate for the cancellation than to build it. you think lex musker will pay for it?

Relying on the sunk cost fallacy never won an argument... 

[TheRadicalModerate]

The whole SLS/Orion should be cancelled in favor of my personal favorite architecture should really be in either of the following two threads.  We really don't need this discussion in every thread that involves SLS/Orion  imho :o

https://forum.nasaspaceflight.com/index.php?topic=55246.0

https://forum.nasaspaceflight.com/index.php?topic=57014.0

SLS/Orion hating for its own sake isn't on-topic, but speculation about what Artemis is or isn't in the presence or absence of SLS/Orion should be on-topic.

I compare Artemis to whatever comes after it in the same way Gemini was to Apollo:  It's a period of deliberate accumulation of technologies and capabilities that will be necessary to go to Mars.  There's a long list:

1) Best logistical practices for keeping a base at the bottom of a gravity well supplied--including propellant logistics.

2) Construction, management, and maintenance of long-term surface habitats.

3) A zillion ECLSS details.

4) Medical information about living in partial gravity and radiation outside the magnetosphere.

5) Construction techniques using regolith.

6) Water ISRU.  Possibly LUNOX and the beginnings of metals ISRU.

7) Large-scale power and thermal systems management.

8) Surface transport, potentially including point-to-point exploration hops.

9) Broader base architecture, including figuring out how to partner with other agencies to fill in the architecture with actual hardware.

10) A zillion things I couldn't think of off the top of my head.

Putting my SLS/Orion hater hat back on, none of this is going to happen if NASA continues to be forced to pile $5B a year into a big heap and set it on fire.  So the (more on-topic) question is:  Once you have a minimal capability to get crews to and from the lunar surface, how do you evolve that capability while reallocating funds to start ticking items off this list?  If you never phase out SLS/Orion, is there a path forward?  If you let SLS/Orion slowly fade away, what does that mean?  If you take it out back and shoot it tomorrow, what does that mean?

It'd be lovely to be able to discuss architecture in the absence of politics, but that's not realistic.  You have to structure the program with some level of political realism baked in, or it'll just turn out to be yet another paper program that never happens.

[TheRadicalModerate]

My vision (or maybe, my fantasy):
SLS/Orion cannot be abruptly cancelled. Instead, a parallel system will evolve, and SLS/Orion will plod along at the minimum barely-sustainable rate, maybe reaching one mission every 18 months. The parallel system will eventually reach a rate that supports a continuously-inhabited moonbase: at least 4 missions per year and probably more. SLS/Orion will not be cancelled, there will just not be any new orders.

So, in keeping with my rant just above:  What does that mean for the actual program?  Is there enough budget to do what you're describing?  My guess is the answer to that question is "no".

FWIW, I think this is the best we can hope for:

1) EPOC and OPOC both get trimmed back to build about three SLS/Orion pairs after Artemis III.

2) NASA loses $2B/year from its human exploration budget.

3) Operations that used to cost $4B-$5B a year now cost $1B-$2B a year, which leaves a new $1B/year available for doing stuff beyond just moving flags-n-footprints crews back and forth.

But I can think of a lot of very good science, tech, and capability maturation we could do with $1B/year.  And, best of all, the general public would think it was fun.

[yg1968]

The purpose of government space programs is to do the things that don't have an ROI right now, but likely enable private ventures to have an ROI in the future.  It's basically the same argument we used to build the interstate highway system.  Creating infrastructure is important.

If this is actually true, then NASA should absolutely, catagorically, NOT be using a single government-owned and operated launch system for this purpose. They should be enabling multiple fully commercially owned and operated launch systems. At some point the commercial ventures will need to take ownership of the ENTIRE program. With Orion/SLS as THE critical path item on the program, the entire program is utterly doomed to failure. What are the commercial entities going to do when it's time to take ownership, start over from scratch to design, build, test and certify a new, commercial launch system? The entire concept of using Orion/SLS as the launch system for Artemis is an oxymoronic undertaking.

You're still preaching to the choir. 

I would add one quibble that, right now, there isn't a proven commercial launcher that can accomplish all the requirements Artemis needs for translunar transport.  As of last week, it's fair to say that the government behemoth is more-or-less proven.  Hopefully, six months from now, there will be a commercial alternative.  Until that happens, there's no tactical solution for assaulting the plan of record.  And even then, there won't be an alternative solution for the crew transit portion.

The good news/bad news is that this is solely dependent on how well SpaceX executes.  Only SpaceX will be in a position to have an alternative crew transit system (LSS, serviced by D2).  But that can't happen before refueling works, and before the LSS crew system is certified.  If that goes smoothly, then there's a good chance that by 2025 all the pieces will be in place to make the case for a second transit system.

However, 2025 is late enough that even more EPOC and OPOC stuff will have been cast into concrete.

So this is kind of a race:  The sooner SpaceX can demonstrate a D2+LSS translunar mission (it would likely have to be private, but well worth footing the bill), the less established the SLS and Orion supply chain will be.  As a practical matter, I doubt this can happen before the Option A test mission, and that's going to be too late to ward off the worst effects of SLS and Orion purchasing.

I'm of the opinion that the moment that this is demonstrated, SLS and Orion begin to die of embarrassment.  But that's my political opinion.  And even if I'm right, the question then becomes how to save all the current Artemis funding for the interesting parts of Artemis:  learning how to manage a logistical chain to the lunar surface (and Gateway, I guess), and how to develop technology that takes us from cislunar space to Mars and beyond.

If Congress was interested in going to the lunar surface twice a year (a big if), an extra Artemis mission with Dragon/F9 and HLS-Starship could allow Artemis to achieve such a cadence. But I suspect that NASA would only order one such mission per year (the other one would still use SLS and Orion). In such a scenario, NASA could arguably still justify keeping SLS and Orion for redundancy purposes.

[DanClemmensen]

My vision (or maybe, my fantasy):
SLS/Orion cannot be abruptly cancelled. Instead, a parallel system will evolve, and SLS/Orion will plod along at the minimum barely-sustainable rate, maybe reaching one mission every 18 months. The parallel system will eventually reach a rate that supports a continuously-inhabited moonbase: at least 4 missions per year and probably more. SLS/Orion will not be cancelled, there will just not be any new orders.

So, in keeping with my rant just above:  What does that mean for the actual program?  Is there enough budget to do what you're describing?  My guess is the answer to that question is "no".

FWIW, I think this is the best we can hope for:

1) EPOC and OPOC both get trimmed back to build about three SLS/Orion pairs after Artemis III.

2) NASA loses $2B/year from its human exploration budget.

3) Operations that used to cost $4B-$5B a year now cost $1B-$2B a year, which leaves a new $1B/year available for doing stuff beyond just moving flags-n-footprints crews back and forth.

But I can think of a lot of very good science, tech, and capability maturation we could do with $1B/year.  And, best of all, the general public would think it was fun.

My assumption is that there will be budget for SLS/Orion for many years. This is independent of any other portions of the NASA budget and will continue until is becomes so evident taht SLS/Orion is worthless that congress is shamed into cutting it back. My hope is that NASA will cajole congress into funding the parallel program at an adequate level, initially by justifying it as an adjunct to SLS/Orion, just as they are doing now. NASA inadvertently stared on this with Starship HLS (which includes Depot and Tanker) and continued with Starship HLS Option B.

[Khadgars]

The whole SLS/Orion should be cancelled in favor of my personal favorite architecture should really be in either of the following two threads.  We really don't need this discussion in every thread that involves SLS/Orion  imho

https://forum.nasaspaceflight.com/index.php?topic=55246.0

https://forum.nasaspaceflight.com/index.php?topic=57014.0

SLS/Orion hating for its own sake isn't on-topic, but speculation about what Artemis is or isn't in the presence or absence of SLS/Orion should be on-topic.

I compare Artemis to whatever comes after it in the same way Gemini was to Apollo:  It's a period of deliberate accumulation of technologies and capabilities that will be necessary to go to Mars.  There's a long list:

1) Best logistical practices for keeping a base at the bottom of a gravity well supplied--including propellant logistics.

2) Construction, management, and maintenance of long-term surface habitats.

3) A zillion ECLSS details.

4) Medical information about living in partial gravity and radiation outside the magnetosphere.

5) Construction techniques using regolith.

6) Water ISRU.  Possibly LUNOX and the beginnings of metals ISRU.

7) Large-scale power and thermal systems management.

Surface transport, potentially including point-to-point exploration hops.

9) Broader base architecture, including figuring out how to partner with other agencies to fill in the architecture with actual hardware.

10) A zillion things I couldn't think of off the top of my head.

Putting my SLS/Orion hater hat back on, none of this is going to happen if NASA continues to be forced to pile $5B a year into a big heap and set it on fire.  So the (more on-topic) question is:  Once you have a minimal capability to get crews to and from the lunar surface, how do you evolve that capability while reallocating funds to start ticking items off this list?  If you never phase out SLS/Orion, is there a path forward?  If you let SLS/Orion slowly fade away, what does that mean?  If you take it out back and shoot it tomorrow, what does that mean?

It'd be lovely to be able to discuss architecture in the absence of politics, but that's not realistic.  You have to structure the program with some level of political realism baked in, or it'll just turn out to be yet another paper program that never happens.

I'm not saying those discussions or opinions shouldn't be expressed, I'm saying we don't need them in every thread that happens to be related to SLS/Orion.  There are better threads for that.

[TheRadicalModerate]

My assumption is that there will be budget for SLS/Orion for many years. This is independent of any other portions of the NASA budget and will continue until is becomes so evident taht SLS/Orion is worthless that congress is shamed into cutting it back. My hope is that NASA will cajole congress into funding the parallel program at an adequate level, initially by justifying it as an adjunct to SLS/Orion, just as they are doing now. NASA inadvertently stared on this with Starship HLS (which includes Depot and Tanker) and continued with Starship HLS Option B.

Budget for SLS/Orion vs. budget for cadence and surface architecture are locked in a zero-sum game.  NASA gets the budget that Congress will tolerate.  If it's being spent for big dumb launchers and capsules without enough delta-v, then it's not being spent on more useful stuff.

Note that dropping SLS/Orion cadence to once every three years instead of once every 18 months doesn't help as much as you think, because you have workforce maintenance expenses no matter what.  But at least it would free up some money.

[jadebenn]

Note that dropping SLS/Orion cadence to once every three years instead of once every 18 months doesn't help as much as you think, because you have workforce maintenance expenses no matter what.  But at least it would free up some money.

...Are you for real? The diseconomies of scale alone would eat up any such "savings."

Thankfully it's a pointless idea that's completely divorced from a reality where we already have five vehicles in the procurement and production flow and you know it.

[DanClemmensen]

My assumption is that there will be budget for SLS/Orion for many years. This is independent of any other portions of the NASA budget and will continue until is becomes so evident taht SLS/Orion is worthless that congress is shamed into cutting it back. My hope is that NASA will cajole congress into funding the parallel program at an adequate level, initially by justifying it as an adjunct to SLS/Orion, just as they are doing now. NASA inadvertently stared on this with Starship HLS (which includes Depot and Tanker) and continued with Starship HLS Option B.

Budget for SLS/Orion vs. budget for cadence and surface architecture are locked in a zero-sum game.  NASA gets the budget that Congress will tolerate.  If it's being spent for big dumb launchers and capsules without enough delta-v, then it's not being spent on more useful stuff.

Note that dropping SLS/Orion cadence to once every three years instead of once every 18 months doesn't help as much as you think, because you have workforce maintenance expenses no matter what.  But at least it would free up some money.

Launch cadence is completely irrelevant: Congress does not care. It can remain  zero has it did for 15 years, or it can be once every three years, or once every six months. The only thing that matters to congress is how much money per year is funneled to the SLS/Orion pork machine. NASA must figure out how to turn this into a reasonable-sounding program, and maybe even into an actual worthwhile lunar program.

[jadebenn]

The cadence he's suggesting would actively make the program cost more as well.

[VSECOTSPE]

The whole SLS/Orion should be cancelled in favor of my personal favorite architecture should really be in either of the following two threads.  We really don't need this discussion in every thread that involves SLS/Orion  imho

https://forum.nasaspaceflight.com/index.php?topic=55246.0

https://forum.nasaspaceflight.com/index.php?topic=57014.0

I'm not saying those discussions or opinions shouldn't be expressed, I'm saying we don't need them in every thread that happens to be related to SLS/Orion.  There are better threads for that.

No one is proposing “favorite personal architectures”.  Almost everyone is expressing deep concern about the sustainability of Orion/SLS and Artemis.

Even if there was an ongoing discussion of “personal architectures”, it belongs better in the general Artemis thread here than in the politics thread or the SLS discussion thread.

...Are you for real? The diseconomies of scale alone would eat up any such "savings."

Thankfully it's a pointless idea that's completely divorced from a reality where we already have five vehicles in the procurement and production flow and you know it.

This is the problem:

                Annual Orion/SLS/EGS Budget Requests ($B)

              FY17     FY18     FY19     FY20     FY21     FY22     FY23

FY19      3.9         3.9         3.7        3.8         3.8        3.7         3.8

FY20                    4.4         4.1        3.4         3.4        3.5         3.8

FY21                                  4.1        4.6         4.0        4.0         4.1

FY22                                               4.5         4.5        4.5         4.4

FY23                                                             4.5        4.5         4.7

These are the total budgets for Orion/SLS/EGS in NASA’s annual budget requests to Congress.  This is contract direct spending.  If I added estimates for indirect and overhead spending, the figures would be higher.

The dollars keep going up request after request (vertical axis).  The crest was $3.9B in the FY19 budget, then $4.4B in the FY20 budget, $4.6B in the FY21 budget, and it’s now $4.7B in the FY23 budget.

The crest also keeps moving further into the future (horizontal axis).  First it was in FY18, then FY20, now it’s in FY23.

If this continues — and there’s no evidence from budget data that it won’t — Orion/SLS will eat up the budget for Artemis from the inside.  The program already projects a sub-Apollo mission rate, and it will just get worse from there.

As the IG points out, this is unsustainable.  At some point, there will be a reckoning.  The key to Artemis’s survival is that it needs another way to get crew to/from lunar orbit either online or coming online before that reckoning occurs.

And that takes money — not nearly as much as Orion/SLS but some — and it has to start as soon as possible.  Even if there was a supplier ready today (and there’s not), it will take NASA years to qualify them.

That money has to come from somewhere.  One could hope for a sustained, multi-year plus-up to NASA’s topline but that seems unlikely.  One could take it out of other Artemis elements besides Orion/SLS, but that’s eating the very things that we’re trying to enable.  The logical place to take the offsets is Orion/SLS.  Orion/SLS is causing the problem.  Orion/SLS should pay to fix it.

If that causes the Orion/SLS flight rate to go down, so what?  It’s already sub-Apollo and headed lower given these budget realities.  It’s better for Artemis to have a sub-sub-Apollo mission rate for awhile than to let Orion/SLS drive Artemis over the cliff.

The cadence he's suggesting would actively make the program cost more as well.

No, cutting Orion/SLS content — minimizing buys, pushing out contracts — will reduce the overall Orion/SLS budget.  It will increase the per unit cost of the remaining content, but with the cost of each Orion/SLS launch already at $4B+ to $8B+, that doesn’t matter.  The key is finding some savings to create an alternate means of getting astronauts to/from lunar orbit that doesn’t cost $1B+ to $2B+ per astronaut.

[clongton]

As the IG points out, this is unsustainable.  At some point, there will be a reckoning.  The key to Artemis’s survival is that it needs another way to get crew to/from lunar orbit either online or coming online before that reckoning occurs.

And that takes money — not nearly as much as Orion/SLS but some — and it has to start as soon as possible.  Even if there was a supplier ready today (and there’s not), it will take NASA years to qualify them.

That money has to come from somewhere.  One could hope for a sustained, multi-year plus-up to NASA’s topline but that seems unlikely.  One could take it out of other Artemis elements besides Orion/SLS, but that’s eating the very things that we’re trying to enable.  The logical place to take the offsets is Orion/SLS.  Orion/SLS is causing the problem.  Orion/SLS should pay to fix it.

If that causes the Orion/SLS flight rate to go down, so what?  It’s already sub-Apollo and headed lower given these budget realities.  It’s better for Artemis to have a sub-sub-Apollo mission rate for awhile than to let Orion/SLS drive Artemis over the cliff.

The goal should be to increase the Artemis mission rate by adding an alternative a supplimental ride, as VSECOTSPE indicated, to lunar orbit and back, initially at once per year to suppliment the Orion/SLS ride. At this point in time the only company that has any chance at all of doing that is SpaceX. No one else can do it in a reasonable amount of time and for a reasonable cost. Eventually, I think Starship may ultimately be that ride, but not for some time yet, so I'll take that option right off the table. In the mean time, as I indicated earlier upthread, the easiest and least expensive way to do this is to pay SpaceX to (1) create a propulsive service module based on the Dragon's trunk and (2) certify the Dragon heat shield for lunar return velocity, which it was already designed from the beginning to be able to do. In that way, Dragon becomes the supplimental ride while everything else in Artemis remains exactly the same, including the 12-18 month cadence of the Orion/SLS ride uphill. And VSECOTSPE is correct. Orion/SLS should pay for it from their existing budget. The way SpaceX does things, it would not suprise me to see the supplimental ride certified for NASA use in 18 to 24 months, well before Artemis III. Nobody else could touch that, nobody. In this way, Orion/SLS can continue on for as long as the Congress is able to stomach the embarrasement of funding the pork barrel of a 2nd best ride uphill.

[oldAtlas_Eguy]

As budgets go up so does resistance to pass them. This is evident by the HLS budget where even less than half was passed for 2021 and 2022. To get more for HLS is an uphill struggle in Congress already.

To also significantly increase any spending for SLS/Orion is likely to run into significant resistance. The risk for Artemis is that if Congress get's the impression that NASA is on a spending trip far beyond the need. Artemis could see cuts in the budget not increases.

NASA is unlikely to get hardly any increase for 2023 beyond the increase for inflation and a few already running programs scheduled increases that Congress has already seen.

Most of these new Artemis project contract work because of new designs and little to none previous spending by gov or private to develop. Will be over a period of currently in this environment 8 years to field. Expect these new projects under Artemis to be chocked back and slowed down at best. At worst approved but unfunded to wait for next year. An instant 1 year slip to the Artemis schedules out 8 years from now.

[TheRadicalModerate]

Note that dropping SLS/Orion cadence to once every three years instead of once every 18 months doesn't help as much as you think, because you have workforce maintenance expenses no matter what.  But at least it would free up some money.

...Are you for real? The diseconomies of scale alone would eat up any such "savings."

Thankfully it's a pointless idea that's completely divorced from a reality where we already have five vehicles in the procurement and production flow and you know it.

If you halve the number of SLS/Orion pairs you need and halve the cadence, you won't save half the money.  But even if each pair costs 50% more as a result, you'll still save 25% of the money.

See VSECOTSPE's table of budget estimates for Orion/SLS/EGS.  Even if we assume that we see outlays average $4.5B/year through 2024 and then decline to $2.5B/year after that (which is wildly optimistic), 8 additional missions at a cadence of one every 18 months will cost $34B.  Saving 25% (by doing only four of them) will free up $8.5B.

4 additional transit missions need to come out of that $8.5B from another provider.  So you only get more money for non-transport parts of Artemis if each mission can be accomplished for less than $2.125B apiece.

[sdsds]

No one is proposing “favorite personal architectures”.

Ah, but in a metaphoric sense, you are doing just that. Not literally; you're not defining alternate vehicles or specifying specific system performance capabilities; but in a more general sense. To wit:

[Artemis] needs another way to get crew to/from lunar orbit

You essentially propose more inclusion in the Artemis meta-architecture of "public/private partnerships" (my term, not necessarily quoting you) funded from the US Federal budget.

Obi-Wan: "That boy is our last hope."
Yoda: "No, there is another."

Humanity includes more than just US nationals. There are others.

[Coastal Ron]

[Artemis] needs another way to get crew to/from lunar orbit

You essentially propose more inclusion in the Artemis meta-architecture of "public/private partnerships" (my term, not necessarily quoting you) funded from the US Federal budget.

The U.S. Government is leading the Artemis program, and the U.S. Government is funded 100% by the U.S. Taxpayer. And so far the U.S. Taxpayer has spent over $40B on the Single-Point-Of-Failure (SPOF) SLS+Orion combo.

Do you think that the more money spent on something, the less likely it is to fail? Because I can point you to the Shuttle program if you need evidence regarding how that is not true.

So are you against having redundancy on the crew transportation segment of Artemis?

Obi-Wan: "That boy is our last hope."
Yoda: "No, there is another."

Humanity includes more than just US nationals. There are others.

Not sure if you realize that the Artemis Accords give non-"US nationals" (i.e. other countries from the U.S. perspective) the ability to spend their own money and join in on the Artemis program. But Artemis is a U.S. Government program, so of course the U.S. is the lead entity, and largest contributor.

What is your point?

[sdsds]

I am aware of the Artemis Accords, and cognizant of how many nations have joined in that wonderfully collaborative effort. Certain notable nations seem to feel ... unwelcome.

I have in another post proposed a specific route to getting NASA funding for an alternative crew transport mechanism between the cis-lunar region and Earth: https://forum.nasaspaceflight.com/index.php?topic=57437.msg2441052#msg2441052

I am aware of many programs in diverse domains where adding additional funding did not increase the availability or reliability of the system under development.

At a meta level, I sincerely hope none of these responses triggers in any reader some sense of animosity. They were composed in an effort to build community here, if not actually help achieve a consensus understanding of the topic.

[TheRadicalModerate]

I am aware of the Artemis Accords, and cognizant of how many nations have joined in that wonderfully collaborative effort. Certain notable nations seem to feel ... unwelcome.

I have in another post proposed a specific route to getting NASA funding for an alternative crew transport mechanism between the cis-lunar region and Earth: https://forum.nasaspaceflight.com/index.php?topic=57437.msg2441052#msg2441052

I am aware of many programs in diverse domains where adding additional funding did not increase the availability or reliability of the system under development.

At a meta level, I sincerely hope none of these responses triggers in any reader some sense of animosity. They were composed in an effort to build community here, if not actually help achieve a consensus understanding of the topic.

The short answer is that there's only one spacecraft that is likely to be crew-rated for directly EDL from translunar speeds, and that's Orion.  So you either build a brand new vehicle, adapt an existing one, or find a way to return to LEO propulsively.  Once you're in LEO, you can use CCP spacecraft to bring the crew home.

One kinda crazy kludge that might be worth bearing in mind:  While D2 doesn't have the delta-v to do the NRHO insertion and return to TEI, LSS does--and D2 can dock on its nose.  This is similar to Chuck's "service module" idea in some ways, except the service module is an entire LSS.

This doesn't necessarily involve certifying the LSS as a crewed spacecraft itself, but it does involve certifying it to be safe enough to use as an orbital transfer vehicle.  The D2 could be the crew spacecraft and the LSS could simply provide the delta-v for TLI and the NRHO maneuvers.  Then the D2 jettisons the LSS just before entry interface and takes it from there.

It probably doesn't require that refueling is working.  An expendable SH/SS can get a 14t D2 to NRHO, and it can probably get it back from NRHO to TEI.  (If it can't, the D2 likely has enough prop for just the lunar flyby.)

Three hefty problems:

1) You have to certify the D2 heat shield for translunar speeds.

2) You need a lot of consumables, and a lot more mission life.  I don't know whether that would require D2 redesign, or whether it's easy to put stuff into the trunk.

3) The crew is receiving a lot of acceleration "eyeballs-out", i.e., they're dangling from their seat harnesses at 1.1g.¹


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¹That assumes a 14t D2, a 95t LSS, and one R2SL throttled to 50%, with the LSS tanks dry.  One way to reduce this is to load the LSS up with prop as ballast.  The LSS could then be disposed of, do a propulsive insert back into LEO, or it could do a very-high-altitude, multi-pass aerobrake to return to LEO.