totm dec 2023 Artemis Discussion Thread

[Exoscientist]

 

SpaceX Starship delays could shift Artemis III away from moon landing, official says
Richard Tribou - Orlando Sentinel (TNS) Aug 9, 2023 
https://www.gazettextra.com/news/nation_world/spacex-starship-delays-could-shift-artemis-iii-away-from-moon-landing-official-says/article_bce178db-d801-5bf0-b20b-b6989b498891.html

 An alternative approach to an Artemis landing would not need the Starship HLS so would save NASA $3 billion. In fact, NASA would  not have to pay for the lander at all:

Possibilities for a single launch architecture of the Artemis missions, Page 2: using the Boeing Exploration Upper Stage. https://exoscientist.blogspot.com/2023/08/possibilities-for-single-launch.html

Possibilities for a single launch architecture of the Artemis missions, Page 3: Saving the lander mission for Artemis III.
http://exoscientist.blogspot.com/2023/08/possibilities-for-single-launch_11.html

 

  Bob Clark

Edited August 12, 2023 by Exoscientist
Left out the “not” in the “not have to pay”

[tater]

SLS is useless by itself, and they also don’t have suits yet, so…

There is no single launch mission possible with SLS to the lunar surface of it includes Orion.

Any change to SLS at all, or even requiring EUS means it’s also delayed, since EUS and the MLP don’t exist, either. The idea of any Frankenrocket using not ICPS/EUS would likely involve another decade of dev.

Any proposal for “not Starship,” or “not BO lander” has to start next Monday, and be good to fly a test mission in maybe a year or two.

That seems unlikely.

[RCgothic]

The closest alternative lander is the NT lander, which is even further away from ready and depends on a launch vehicle that has had zero test flights and an engine that has zero hours of flight time.

Lunar Starship will be done when it's done, and if it's not NT will overtake it and SpaceX won't get paid.

There is no magic alternative that can do it faster, or that could have done it faster if started at the same time.

NASA should have started the lander program earlier, should have started the space suit program earlier, and if it needed cash maybe it should have focused on those things that were actually definitely needed for a landing instead of a lot of things that weren't like monolithic launchers, upgrades for that launcher, additional launch towers for that launcher, and space stations in the cheeks end of nowhere.

[tater]

It's buried somewhere in this forum, but numerous calculations have been done on the minimum TLI throw required for SLS to enable a single-stack surface mission. It's around 70t.

So in addition to years for EUS, and the MLP, you then want a Centaur V added on top—I'll ignore the fact that this might not fit in the VAB—which also means a third MLP. That's several years and another billion or two dollars. Assuming they literally start tomorrow—and of course any such plan at earliest starts next fiscal year.

Note that a super light lander is not a thing given the goal of more sustained surface missions. The current min mission is ~6 days because of the NRHO requirement (an orbital period of Gateway is ~6.5 days), but also because they don't want to be rushed. They also want some actual room. Making a lesser Apollo LEM seems like admitting defeat.

 

[Exoscientist]

5 hours ago, tater said:

It's buried somewhere in this forum, but numerous calculations have been done on the minimum TLI throw required for SLS to enable a single-stack surface mission. It's around 70t.

…

 That can’t be right because Apollo was able to do it at a 52 ton payload to TLI, which is about the same as the payload to TLI needed in this alternative proposal.

   Bob Clark

[Geonovast]

Overlapping threads have been merged.

[tater]

Where did my reply go?

[tater]

Guess I need to retype it, as it got disappeared into the ether as I hit reply.

ffffff

11 minutes ago, Exoscientist said:

 That can’t be right because Apollo was able to do it at a 52 ton payload to TLI, which is about the same as the payload to TLI needed in this alternative proposal.

49.5 t can maybe work (depends on SM tank mass)—but SLS cannot throw 49.5 t to TLI. Not ever. There is no proposed variant capable of this. Adding a stage 3 does not help, the S3 in this case is as about big as EUS. Even if it did, this is adding another... decade? More?

All this for a 13t lander. 3.4t lighter than the LM. So another flags and footprints, is it? How is this sustainable in 2033 (cause adding a stage, designing a new lander, and building a new MLP is gonna be 10 years)?

All to be on the surface for a couple days, living in a small closet.

 

[Exoscientist]

12 hours ago, RCgothic said:

The closest alternative lander is the NT lander, which is even further away from ready and depends on a launch vehicle that has had zero test flights and an engine that has zero hours of flight time.

Lunar Starship will be done when it's done, and if it's not NT will overtake it and SpaceX won't get paid.

There is no magic alternative that can do it faster, or that could have done it faster if started at the same time.

NASA should have started the lander program earlier, should have started the space suit program earlier, and if it needed cash maybe it should have focused on those things that were actually definitely needed for a landing instead of a lot of things that weren't like monolithic launchers, upgrades for that launcher, additional launch towers for that launcher, and space stations in the cheeks end of nowhere.

 

 The alternative lunar lander would be faster and cheaper because it would use already existing components. The propulsion system would use the Ariane 5 EPS storable propellant upper stage:

 

 Note for this stage the astronauts would only have to climb down 3 meters  like the Apollo LEM and unlike the 25 meters for the Starship.

 For the lunar landers crew module use the Cygnus capsule:

ORBITAL PROPOSES FUTURE DEEP SPACE APPLICATIONS FOR CYGNUS.
SPACEFLIGHT INSIDER
MAY 1ST, 2014

Orbital’s proposal, outlined in this PDF, involves docking a Cygnus spacecraft with Orion to serve as a habitation and logistics module on longer flights. For these missions, the re-purposed Cygnus would be called the Exploration Augmentation Module (EAM). With its current life support systems used to transport pressurized cargo and experiments to the ISS, Cygnus is stated as being already suitable for the long term support of a crew. While berthed to Orion, Cygnus could support a crew of four for up to 60 days. Cygnus also has the capability of storing food, water, oxygen, and waste and features its own power and propulsion systems. The EAM would utilize the enhanced configuration Cygnus, which will begin flying larger cargoes to the ISS beginning with CRS-4 in 2015. An even larger version is also being proposed, featuring a 4-segment pressurized cargo module.

https://www.spaceflightinsider.com/missions/commercial/orbital-proposes-future-deep-space-applications-cygnus/

 The Cygnus is already used as an unmanned cargo supply module to the ISS. I assumed it would have to be added life support to act as an independent crew module for a lunar lander, but this article seems to suggest it already has it. I know it contains air as it would have to when the ISS crew retrieves supplies from it. But life support is beyond just that. It has to have CO2 scrubbers for when humans are contained in an air-tight confined space for days. And it has to have thermal control systems. In any case if needed, the life-support systems can be added.

 Note the Apollo LEM had an internal volume of 6.7 cubic meters, while the Cygnus has an internal volume 18.9, nearly 3 times larger, and the enhanced version has an internal volume nearly 4 times larger than the LEM.

 Note the Cygnus is actually built in Italy by Thales Alenia Space. So ESA could pay for the lander with no expenditures for a lunar lander from NASA.

  Bob Clark

Edited August 12, 2023 by Exoscientist

[Ultimate Steve]

4 minutes ago, Exoscientist said:

snip

A few issues:

• The last EPS flew in I think 2018, it has been out of production for a while
• Aestus cannot throttle, you might need a separate propulsion system for landing to be safe
• Does the EPS have RCS?
  • If it does, it is likely rotation only as there is no normal need for the EPS to translate, so to dock, upgraded RCS would be needed
    • Just now noticed that you do account for RCS from the Phoenix concept but then pivot to Cygnus and assume everything still applies so I'm not sure how to count this one
• More minor things that aren't that consequential on their own but the mass adds up:
  • Landing gear
  • Deep space navigation capabilities
  • Deep space communication capabilities
  • A budget for surface science experiments
  • A budget for samples to be returned
  • The surface stays Artemis wants may be longer than the life support that was planned for
  • An airlock, or modifications to allow exiting the forward hatch
    • If the entire spacecraft is depressurized, ensure everything inside is vacuum stable
    • Budget for the gas that will be vented overboard that has to be resupplied for every EVA
  • A ladder
• EPS was not designed to last weeks on its own and was designed for LEO, not deep space and the lunar surface, some form of thermal protection is likely needed, and it is likely that other design changes are needed for it to function this long in this environment
• I did a whole paragraph or two about how the numbers don't close for a NRHO landing but then I read your other blog post describing a LLO landing.
  • Under your plan this would require a heavily modified SLS to house the Centaur. At that point this is no longer a cheap quick mission. The VAB would have to be reconfigured, the ML would have to be redesigned, maybe new fairings (which add mass), etc.
  • I will say that given the excess Delta-V the lander has (assuming the above items and the ones I did not list do not eat it up), it might be possible to get away without the Centaur, by using an elliptical Lunar orbit to make the most of the lander's fuel capacity, or underfueling the lander so EUS can push the stack farther, but this is more math than I want to do right now. This, however, leaves us uncomfortably low on fuel, and to be frank, your proposal, at 200m/s remaining, already has me a bit wary.
• As you noted on the blog, it was later found out that the 1500kg number does not include the service module. As you had previously subtracted the mass of the service module from this 1500kg number, this will increase the mass by a lot, and the service module also has the solar panels on it, so those will need to be added back in.
  • The Cygnus RCS was probably partially or mostly or entirely on the service module, so there's going to be some  mass associated with adding it back in or upgrading the EPS RCS
• The Apolo LM Ascent Stage was about 2150kg alltogether. We have made some advances in lightweight structures since then, and this includes the empty tanks, so I am inclined to believe that your 2 ton 3 man crew section is probably possible, but only if the 2150kg number means "without fuel" and not "without astronauts, suits, and any other consumables." I fear the latter is more likely. 2 tons is incredibly light for something that has to provide that much. There's also higher safety standards to keep in mind, the LM would not fly with today's safety culture.
• Assuming that ESA would foot the entire bill if they were selected is probably unrealistic.

The biggest one: Reusing stuff for situations they were not designed for, and integrating stuff with stuff it wasn't designed for, is hard. Very hard. I used to hear people say that and think they were exaggerating. "Rockets aren't Lego!" they'd say. I couldn't think of why they wouldn't be.

But then I joined my university's cubesat team. About half of the satellite is subsystems from the same manufacturer. Integrating those and deciphering the documentation so we can figure out how to get them to work properly has been a multi year long ordeal. To be fair though, a great deal of that is the fact that the team has been all undergraduates, who have maybe a year and a half of programming competence at best before they graduate, assuming they even stay on the team for that long, so brain drain and covid have been huge obstacles.

I'm tearing my hair out over stuff that by space standards is as close to Lego as you can get. I can guaruntee you that creating a lunar module out of an upper stage and an ISS resupply craft is not going to be simple. It will not be an integration, it will be a derivation if not practically a redesign. Possibly still better than a clean sheet design, but not by the huge margins that you seem to imply.

And even then, as Tater said, this lander is not going to be suited for the lofty ambitions of Artemis.

 

Last note: You can probably look back in my post history and see me doing the same thing talking about Dragon missions to the Moon, an X-37 derived moon mission, and countless other flights of fancy. I was younger and more naieve and I officially apologise for these.

[RCgothic]

In the same way SLS would be faster and cheaper for using existing components? Orbital ATK and Thales didn't even bid on HLS. They don't have HLS designs ready to go, and even if they did ESA doesn't provide components to NASA for free it's at best a quid pro quo.

NASA currently claims 46t to TLI for SLS block 2 cargo (I know some users who'll swear up and down it's higher, there's currently no public proof), but only 43t for the non-cargo version, of which Orion/ESM eats at least 26.5t, leaving just 16.5t from NRHO.

The smallest lander NASA studied from NRHO to the lunar surface is 36t minimum for a 3-stage, so it's 19.5t short of a total 62.5t crew variant to TLI. 36t comanifest payload is also long way beyond what Orion/ESM can even brake into NRHO (roughly 13t if expecting to manoeuvre in NRHO and return without any moon rock samples).

The mass budget of 43t *maybe* closes direct to LLO if the ESM is stretched 50% and the lander can be brought in under 11.5t.

But that lander would be absolutely skeletal, doesn't exist, would have to wait for a new space suits, MLP, ESM and EUS even if it did, only gives a few surface days maybe once a year on average, could land no significant surface payloads, probably only 1 astronaut, has no upgrade path, almost certainly wouldn't meet NASA's safety standards, and is with 100% certainty getting cancelled faster than Apollo did and would deserve to be.

1 astronaut and no payload would be embarrassing. Nowhere even close to sustainable. 

 

 

I have some sympathy for the view that the landing should be delayed until we can do it properly: 4+ times per year and/or with crews of 4-20 in a permanently inhabited and steadily growing surface base.

Zero sympathy for tearing up two fantastic lander systems that could support that in order to try and stick to a landing date that has always been impossible without an alternate history with an earlier start date.

TLDR: The dates wouldn't close for a new lander even if the mass and cash budgets did, which they don't, and a skeletal lander absolutely couldn't acheive the programme goals of sustainable lunar missions.

 

 

Edit:

Once more for absolute clarity the medium-long term problem with Artemis is Orion ESM SLS, which are genuinely terrible, and to a lesser extent Gateway which is merely useless. The BO or SpaceX lander systems are genuinely the best parts of Artemis and are worth waiting for even if they cause a bit of a delay.

The HLS landers can fly often, carry huge payloads, and if we can bypass SLS Orion and Gateway then a permanently inhabited lunar colony is possible. The depot architectures further enable missions beyond the earth-moon system.

If we cancel HLS to depend only on SLS Orion and whatever skeletal lander a stretched ESM can limp into LLO we might as well give up and let China take the lead, because whilst China might not get back there first, you can guarantee that when they do they'll arrive with a plan for more than just flags and footprints.

I genuinely cannot grok looking at Artemis and wanting to scrap the best bits whilst keeping the worst.

Edited August 13, 2023 by RCgothic

[tater]

6 hours ago, RCgothic said:

I genuinely cannot grok looking at Artemis and wanting to scrap the best bits whilst keeping the worst.

This. (and everything above)

 

[Exoscientist]

12 hours ago, Ultimate Steve said:

The biggest one: Reusing stuff for situations they were not designed for, and integrating stuff with stuff it wasn't designed for, is hard. Very hard. I used to hear people say that and think they were exaggerating. "Rockets aren't Lego!" they'd say. I couldn't think of why they wouldn't be.

 

  Actually, its done by rocket engineers all the time who know what they’re doing:

 For instance it was done for the ESA’s ATV cargo supply vehicle to the ISS in turning it into the Service Module for the Orion. And it was done to the Delta IV Heavy’s upper stage in turning it into the Interim Cryogenic Propulsion Stage(ICPS) for the SLS.

 Note also that prior to the SLS use, the ATV was last used in 2015. 

Bob Clark

 

 

Edited August 12, 2023 by Exoscientist

[tater]

No one disagrees that different stages can be combined, and parts reused for other uses. SLS/Orion do exactly this. That said, it's exactly why SLS is garbage. Course DIRECT would have reused parts and been much better.

The reality is that the program is too entrenched for major changes, and any such changes would take many years to manifest themselves.

So talking about changes to SLS/Orion to make different mission profiles is fine, but proposing them as a way to beat HLS or the BO lander are nonstarters. They'd have to propose, then some white paper is paid for at the trivial cost of a few hundred million (like Dynetics got to do a white paper proposing a lander that did not even have the dv to complete the base mission). Then that gets accepted, then maybe funding starts, and since the players are the same ole same ole, it takes 10 years nominally, then goes over schedule and over budget.

[RCgothic]

Some combinations are easier than others.

Stick an existing spacecraft on top of  an expendable Starship? They could knock out a new adaptor from stainless steel and GSE to support it in 6-12 months.

Different stage on top of SLS? It'd be over 5 years to get through the design studies contracting and infrastructure mods.

Building a new stage from parts? 5+1d6 years probably.

Edited August 13, 2023 by RCgothic

[Ultimate Steve]

1 hour ago, Exoscientist said:

 

  Actually, its done by rocket engineers all the time who know what they’re doing:

 For instance it was done for the ESA’s ATV cargo supply vehicle to the ISS in turning it into the Service Module for the Orion. And it was done to the Delta IV Heavy’s upper stage in turning it into the Interim Cryogenic Propulsion Stage(ICPS) for the SLS.

 Note also that prior to the SLS use, the ATV was last used in 2015. 

Bob Clark

 

 

ESM for Orion was announced in 2013 and was thrown around earlier, production lines and staff were almost certainly continuous.

As the others have said, anything can be made to work together eventually, but certain integrations are far easier than others. Adapting existing spacecraft is not necessarily the fastest option.

Heavily modifying a long term LEO service module into a long term Lunar service module is doable although not ideal, especially when given eight years to do it, and starting work before the production line is shut down.

Swapping a Boeing built short duration high energy upper stage from one Boeing built core stage to another Boeing built core stage,  that all share propellant commonality,  is also on the easier end of such transformations, especially as the role the upper stage plays does not change much (delta IV even carried Orion at one point). This has even happened before with this stage, as it had previously been on the Delta III. The hard part is making the GSE for this new combination, which, again, they had several years to do. In this case the production periods also overlapped. I would argue this is pretty much ideal Lego territory if such a thing exists.

You are proposing to take a Thales Alenia pressurized module, designed to work with a Northrop Grumman service module, for LEO station resupply, and redesign it into a viable Lunar lander by combining it with an out of production EADS medium duration LEO/MEO upper stage designed with only Ariane 5 in mind.

That is very possible, but there is very little that won't have to be modified, redesigned, or created from scratch. A pressure vessel and a rocket stage are important parts of a Lunar lander, but far from the whole thing. The point of this is to save time, if I read you correctly,  and sure, started at the same time as a purpose built design it may finish a little faster, but even then I'd rather have something far more capable even if it takes a little longer.

Centaur on SLS, sure, Centaur has been adapted enough times that it could be done. Propellant commonality is another bonus. Building yet another mobile launcher and reconfiguring the VAB again, and recertification of the new stack for crew, and hopefully an unmanned test flight in that configuration... those are the parts that I'm worried about.

[Barzon]

On 8/12/2023 at 9:07 PM, Exoscientist said:

 For instance it was done for the ESA’s ATV cargo supply vehicle to the ISS in turning it into the Service Module for the Orion. And it was done to the Delta IV Heavy’s upper stage in turning it into the Interim Cryogenic Propulsion Stage(ICPS) for the SLS.

 

except ESM was significantly redesigned and shares more heritage with Lockheed's SM design than it does ATV

[Exoscientist]

8 hours ago, Barzon said:

except ESM was significantly redesigned and shares more heritage with Lockheed's SM design than it does ATV

 I haven’t heard of a Lockheed design for the Orion service module. Do you have a reference for that?

  Robert Clark

[sevenperforce]

On 8/11/2023 at 2:42 PM, Exoscientist said:

Possibilities for a single launch architecture of the Artemis missions, Page 2: using the Boeing Exploration Upper Stage. https://exoscientist.blogspot.com/2023/08/possibilities-for-single-launch.html

Just glancing through this thread but I spotted right out of the gate that you're adding 10 tonnes of propellant to the Orion service module, but you're not adding any dry mass or different geometry to the Orion service module. Where would you propose these 10 tonnes of hypergolics hang out? Ziplock bags?

[RCgothic]

When I calculated mods for taking a skeletal 11.5t lander to LLO Orion needed ~4.7t extra fuel (over and above 9t currently) for which I gave it 410kg extra dry mass assuming an optimistic mass fraction of 8%.

Edited August 14, 2023 by RCgothic

[SunlitZelkova]

23 hours ago, Exoscientist said:

 I haven’t heard of a Lockheed design for the Orion service module. Do you have a reference for that?

  Robert Clark

It comes from when Orion itself was all American as part of the Constellation program.

I don’t know how detailed the design got.

[Exoscientist]

22 hours ago, RCgothic said:

When I calculated mods for taking a skeletal 11.5t lander to LLO Orion needed ~4.7t extra fuel (over and above 9t currently) for which I gave it 410kg extra dry mass assuming an optimistic mass fraction of 8%.

 But you would also need some fuel left over to bring the Orion and service module back to Earth. So calculate how much prop needed to get Orion/SM/lander plus return prop to LLO. I estimated this return prop as ~7 tons. 

  Bob Clark

[RCgothic]

Yes, I've calculated each phase of flight separately.

It takes ~8.5t of propellant to get Orion/ESM/lander through LLOI starting from 43t wet (SLS B2 Crew's max advertised TLI throw).

Orion/ESM needs some margin for free flight, docking, rendezvous, mid course corrections (both ways). Call it ~100m/s and that uses 0.7t of prop.

4.4t is needed to get Orion/ESM through TEI.

That's 13.6t in total, which is an 4.6t extra the ESM needs to carry above its 9t design value. An extra 4.6t of propellant needs ~400kg extra tank mass to support that, and that's been added to the 17.5t original dry mass to give 17.9t, the figure I've used in each phase of flight.

And there's also some sums to make sure a 11.5t 2-stage lander can land and return. Lander gets ~2t of non-engine & propellant tank mass to support comms, power, and a single astronaut.

Landing needs more margin than SSTO and rendezvous/docking which nominally takes 1730m/s each way.

For safety either Orion or the lander ascent stage should be capable of being the active vehicle during rendezvous and docking.

Edited August 16, 2023 by RCgothic

[tater]

On 8/15/2023 at 2:23 PM, RCgothic said:

And there's also some sums to make sure a 11.5t 2-stage lander can land and return. Lander gets ~2t of non-engine & propellant tank mass to support comms, power, and a single astronaut.

So meets zero Artemis standards.

As we worked through way up thread, the minimum TLI throw for an acceptable surface mission (decent duration for crew on surface, and at least 2 astronauts, possibly more) is pushing 70 tonnes.

A single-stack sortie lander is an option where a habitat is landed ahead of time, so consumables and crew volume can be small. Land, shut down vehicle, EVA to habitat, then reverse to leave.

[Exoscientist]

On 8/15/2023 at 4:23 PM, RCgothic said:

Yes, I've calculated each phase of flight separately.

It takes ~8.5t of propellant to get Orion/ESM/lander through LLOI starting from 43t wet (SLS B2 Crew's max advertised TLI throw).

Orion/ESM needs some margin for free flight, docking, rendezvous, mid course corrections (both ways). Call it ~100m/s and that uses 0.7t of prop.

4.4t is needed to get Orion/ESM through TEI.

That's 13.6t in total, which is an 4.6t extra the ESM needs to carry above its 9t design value. An extra 4.6t of propellant needs ~400kg extra tank mass to support that, and that's been added to the 17.5t original dry mass to give 17.9t, the figure I've used in each phase of flight.

And there's also some sums to make sure a 11.5t 2-stage lander can land and return. Lander gets ~2t of non-engine & propellant tank mass to support comms, power, and a single astronaut.

Landing needs more margin than SSTO and rendezvous/docking which nominally takes 1730m/s each way.

For safety either Orion or the lander ascent stage should be capable of being the active vehicle during rendezvous and docking.

I’ll take a look at your calculations and let you know what I think.

You appear to be someone who likes delta-v calculations.  In that case, take a look at the two cases considered here, the two Vulcain case and the three Vulcain case:

 

  Bob Clark