totm dec 2023 Artemis Discussion Thread

[Exoscientist]

18 hours ago, Codraroll said:

"Quick! Shove it out the door before the program is cancelled!"

[tater]

 

[AckSed]

Lockheed Martin slowly getting ready for Artemis with LVSAT:

https://spacenews.com/lockheed-martin-unveils-solar-power-array-for-artemis-program/

[Cracktacular]

On 11/21/2024 at 12:30 AM, Exoscientist said:

There really is no logical reason to use the multiple launch approach with 18 SuperHeavy/Starship launches to accomplish a single mission compared to a single launch approach of a rocket at only 1/3rd the size. It would be like the Apollo engineers running the numbers on the Saturn V and realizing it could do a Moon mission in a single launch, decided to do it instead with 50 launches of the Saturn V for that one single Moon mission.

That's because you seem to be hung up on making another Apollo. Of course we can make some bare-bones craft to do a single-launch mission.

The difference between Apollo and Artemis, is that Apollo was the equivalent of going camping for a few days in a tin can, and Artemis is supposed to be a permanent base that will expand over time. The reason the much higher payload capacity is desired for Artemis vs Apollo is because the individual modules to be transported will likely be heavier than what your 1/3rd size rocket can even lift. The original Lunar Module famously could not support its own weight under Earth's gravity. I think the modules we send to the Moon to process regolith for ISRU, etc. are going to have to be a bit beefier than NASA-grade aluminum foil structures.

This reminds me of an aviation saying: "Nobody cares about how much sky is above you, how much runway is behind you, or how much fuel you left back at the airport." Nobody cares about having "too much" payload capacity. In fact, I posit that the entirety of human spaceflight has been constrained by not enough payload capacity.

 

On 11/23/2024 at 6:57 PM, Codraroll said:

"Quick! Shove it out the door before the program is cancelled!"

My brain is having trouble processing seeing the word "quick" in a thread about SLS

[AckSed]

If I might straddle both camps here, I believe Exoscientist is working off an older, long-held dream of the Apollo Applications Program, and Constellation, and now Artemis: here is something that could lift all the things they dreamed up, right now, if the ones making it deigned to make a simple modification. The frustration is real.

The Starship troopers (sorry, not sorry) have lost their heart to reusable second stages, which seem more real with each flight test that reaches the water, and are more trusting/hopeful that it will pan out. The excitement is real.

Who wins? SpaceX decides.

Myself, I think if it becomes necessary, an expendable booster and Starship would launch in a few months - if they needed it. That's the thing about their workflow: modifications are easier when you have completed ships, and they have the expertise to change software and weld steel to suit.

[tater]

So we'll know more tomorrow on the heatshield issue I assume.

[tater]

https://www.youtube.com/watch?v=mAP-ywsh_HI

 

 

 

[tater]

I've been suggesting that for a while...

[DAL59]

Artemis II Delayed to April 2026 

This is JWST all over again

[AckSed]

NASA have finally told the press how the divots in the Orion heatshield happened: the material was less permeable to gas than the original Apollo Avcoat and the permeability varied across it. As it cooled from the initial heat of the skip trajectory, the gas generated inside in many of these places couldn't escape. When it was heated again with the final re-entry down to the ground, the gases expanded and material broke off in the chunks we see. Engineers found a total of 100 spots where the material broke off in ways that it wasn't supposed to.

[Ultimate Steve]

In addition, the Artemis II heat shield was built in a way that resulted in it being even less permeable. From what I remember they intend to fly it as is with a modified entry trajectory to offset the decreased permeability (and hopefully then some).

[Ultimate Steve]

Given that the future of SLS's involvement in the Artemis program is up in shambles, I'm gonna muse over some various options for what could be done to replace it. From what I've thought of there's three main families of options.

 

Family 1: Distributed Lift.

This usually comes in the form of Orion getting launched on one rocket and a rocket stage getting launched on another rocket. Orion was at least at some point designed to take the force of engines firing through the docking port as it would have been required to back in the Constellation days. I'm unsure if this capability has been retained. Orion masses around 27 tons on its own, 34 tons with the launch escape system. This is beyond the capacity of Vulcan Centaur, but can fit on New Glenn and Falcon Heavy. Both would require a new adapter but it would likely be easier on New Glenn as it is wider, and you could taper down to Orion's diameter rather than having to taper up or do a Starliner style overhang - though Orion's diameter is smaller than the Falcon Fairing diameter so it shouldn't be too wide). Using Falcon Heavy gives you the advantages of flight heritage and having a crew access arm already at the launch pad (though it will likely need modifications to sit at the right height and have an appropriate interface).

A challenge with this approach is that Orion is designed to be vertically integrated. Both Falcon Heavy and New Glenn are horizontally integrated rockets. Orion can be transported horizontally without propellant and without the LAS attached, but sticking it on a Falcon style transporter erector fully fueled and with abort tower is going to take some effort. I'm not sure how much effort, but not zero effort.

The LEO launcher could also be a custom expendable variant of Starship - Starship of course has the performance to lift Orion's mass in reusable mode but it needs to be mounted on top for the LAS to work and Starship can't re-enter without its top. Starship is vertically integrated so it has that going for it, and it has more flight heritage than New Glenn, but SpaceX likely wouldn't want to make a custom expendable variant and changes to their launch towers especially with how much they are iterating right now. There's no clear winner for the launch vehicle IMO.

Then the question is, which launcher launches the space tug?

Vulcan Centaur can't, even if the structure was massless, 27 tons (VC's max payload) of propellant at an RL-10's isp can only just barely push Orion's mass to TLI. Real rockets aren't massless, real rockets have boiloff, and NASA doesn't like pushing rockets to their maximum (NASA's rocket performance calculator lists a maximum payload for reusable Falcon 9 that is below what they regularly do for Starlink, and Vulcan's numbers are lower on NASA's calculator than ULA's website).

Falcon Heavy fully expendable can do it with at least ten tons of margin. However, the timing would be tight without modifying it for long durations. Currently it can only do a few hours. Once you launch you have to commit fully to the other launch at the next launch window (unless you arrange the orbits at just the right way so you get two valid windows in rapid succession, but the odds that it lines up with the orbit you need to get to the moon are rather low). If you launch Falcon Heavy first and there's a problem with Orion, Falcon dies in orbit and the launch campaign is over. If Orion launches first, well, actually that could work. The crew may have to spend a few days hanging out in LEO, and risk having to come home if a showstopper issue delays Falcon more than a week or two. An amusing solution to this is to perform both launches timed simultaneously and with their launch commit criteria wired up to each other.

Falcon Upper Stage's acceleration at burnout would be very high compared to say, Centaur, but if Orion can still handle the forces it was expected to for Constellation, it can probably handle Falcon. If not, big problem, as at a minimum, peak force would be above 1 G.

New Glenn, I'm much less well versed on. BE3U has an isp of 445s, and at New Glenn's maximum payload (reused even) it should be able to do the job (though early versions of New Glenn are reportedly severely missing payload targets), though boiloff is as always a problem. They do want to create a variant of GS2 for refueling Cislunar Transporter so it may end up being a fairly straightforward modification.

Centaur V would be a really good option here as they really want to do zero boil off long duration, and it has a very low thrust, but unless they stick it on a New Glenn, it is not going to happen.

Starship is an option but largely redundant, same talking points as for Orion.

There's also the consideration that you would want to have this happening on two separate vehicles or deal with turning around your launch pad really quickly for 2 launches with the same vehicle (or building 2 launch pads, or doing zero boiloff forever duration upper stage).

 

Family 2: Single Launch Orion

This is a family inhabited solely by expendable Starship and even then only maybe. It is highly dependent on what the dry mass and payload of an expendable Starship would end up being. At one extreme you have a 120 ton vehicle with 100 tons of payload+prop that won't even get to 1500m/s of Delta-V, and at the other extreme you have a 40 ton vehicle with 200 tons of payload+prop which has 4.5km/s (waaaayyyyy more than needed). If you expend Super Heavy I can almost guarantee that the numbers close but SpaceX won't want to do that. Assuming that it does have the required performance it is an attractive option for its simplicity. Vertical integration, no rendezvous, no force through the docking port, and more flight heritage than any other option on the table besides Falcon Heavy. The catches are that for a reasonable timeframe you have to move Orion integration to Texas, you have to create a custom Starship variant, you have to crew rate Starship (and possibly commit to a design freeze) far ahead of schedule, with SpaceX really doesn't want to do, and you have to make modifications to Starship's launch tower.

 

Family 3: No Orion

There are 3 options in this family that immediately come to my mind as credible.

Option 1: Whatever Blue Origin is cooking up with Cislunar Transporter and their crew vehicle. Can't say much about that as it is still very much a mystery.

Option 2: Lunar Dragon. I don't think this is going to pan out as SpaceX doesn't want to invest in a system they hope to make obsolete in the same timeframe. New service module for Dragon, somehow maintaining abort capability, upgrading the heat shield. Dragon is ~12 tons, it needs ~8 tons of propellant to have as much Delta-V as Orion (though that may be a bit high as that doesn't take into account the propellant Dragon already carries), misc upgrades and service module mass, let's say it comes out to 1 more ton. The stack is 21 tons, and Falcon Heavy Expendable's TLI capacity is, well, unknown. Most estimates place it somewhere in the 21-23 ton range. On paper it fits, and SpaceX may do something funky with propellant utilization and a draco nozzle extension to reduce Lunar Dragon's mass, or not take as much Delta-V as Orion, so it wouldn't surprise me if it could work. But again, NASA does not like pushing its launch vehicles to their limits, so I have a hard time seeing this being selected.

Option 3: Lunar Starship, but not in the way you think

Depending on your chosen performance characteristics, Starship is maybe capable of going from LEO to the Lunar surface and back. Probably not. This requires a lot of optimism and no payload. However, I recently saw another option making its rounds online. The idea of using two Starships. HLS Starship is expended as normal. A crew Starship is refueled in LEO and goes to the Moon, transfers its crew to HLS, HLS lands and ascends, and crew Starship takes them back, and - crucially - propulsively brakes into LEO. It has the performance to do this, this saves the necessity to develop a Lunar rated heat shield if that becomes a significant barrier. Of course then you have to commit to putting crew on Starship through ascent and landing sooner than you otherwise would have, which is probably not the best idea.

Expanding upon this idea, depending on the masses involved, you might also be able to use crew ship to refuel HLS ship and reuse HLS ship, though it would probably require a Lunar rated heat shield if the refilling was to be done all at once, and delivery of heavy cargo to the Lunar surface would require some way to transfer that cargo from crew ship to HLS ship.

 

And then there's doubtless more options of various practicality that I haven't listed here or haven't thought of. The next few years will certainly be interesting. We may see a request for proposals for commercial Lunar crew transportation within the next few months. Reading the source selection statement for that is going to be interesting.

[RCgothic]

I think expendable Superheavy is just a case of making SpaceX an offer, plus a bit of time. How much time?

Probably not more than any other option. 

[tater]

SH doesn't even need to be expended, just a SS as upper stage. At 173t residuals (200 minus Orion at 27), and 57t dry for the upper stage "Starship" it can not only put Orion to TLI, it can place the stack in LLO. It TLI is the only goal it's trivial.

 

[tater]

That said, domestically, Artemis is about politics (pork), not exploring the Moon. So I would expect any solution that includes Orion (sans the useless SLS) uses "not SpaceX" as much as possible since SpaceX has the HLS. Once BO gets their landing system operational, this could flip, with SpaceX being another Orion launch provider (assuming Orion is even still a thing at that point).

[StrandedonEarth]

An expendable Starship as a launch vehicle for Orion has the advantage of also being the space tug by simply meeting up with a depot and refilling, So not really expendable, just not landable. 

[darthgently]

1 hour ago, StrandedonEarth said:

An expendable Starship as a launch vehicle for Orion has the advantage of also being the space tug by simply meeting up with a depot and refilling, So not really expendable, just not landable. 

This is the image I got also.  SS truncated to have Orion as the nose for launch.  If refill prior to TLI is required Orion can separate and standoff during refill then reattach as nose and head for Moon.  Standoff in Orion again if HLS needs refill.  Orion fore docking port is used to transfer to HLS which does its thing then redock and transfer back into Orion.  Return and brake into LEO, park SSTug and meteor down in Orion.

So the Orion and SSTug would need the ability to separate and reconnect  with Orion as SSTug nose.  This is for orienting  g force on crew during launch and braking.  A small emergency escape segment module could be in between tug and capsule that would give Orion with the module the ability to return to LEO from any point 

 

[StrandedonEarth]

58 minutes ago, darthgently said:

This is the image I got also.  SS truncated to have Orion as the nose for launch.  If refill prior to TLI is required Orion can separate and standoff during refill then reattach as nose and head for Moon.  Standoff in Orion again if HLS needs refill.  Orion fore docking port is used to transfer to HLS which does its thing then redock and transfer back into Orion.  Return and brake into LEO, park SSTug and meteor down in Orion.

So the Orion and SSTug would need the ability to separate and reconnect  with Orion as SSTug nose.  This is for orienting  g force on crew during launch and braking.  A small emergency escape segment module could be in between tug and capsule that would give Orion with the module the ability to return to LEO from any point 

 

I see it more as replacing the current Euro service module with a Starship-based SM, with refilling not requiring separation of Orion

[darthgently]

31 minutes ago, StrandedonEarth said:

I see it more as replacing the current Euro service module with a Starship-based SM, with refilling not requiring separation of Orion

I threw the separation in because we likely won’t have refilling with human presence, at least initially, is my guess.

Edited December 15, 2024 by darthgently

[RCgothic]

It's a sensible idea. Movements of large quantities of propellant are risky, and the ability to stand the crewed module off at a safe distance might be a useful safety feature. They undock and return dragons to the ISS with crew on with moderate frequency, this would be similar.

[AckSed]

Small Business Innovation Research/Small Business Technology Transfer (SBIR/STTR) grants may play a larger part in getting and staying on the Moon:

https://payloadspace.com/nasa-cozies-up-to-industry-with-2025-sbir-plans/

Quote

While 2024 was another successful year for the Phase I SBIR and STTR programs, funding nearly 250 companies for a total investment just shy of $45M, Kessler said the main success for the program was in building up the ecosystem to help more awardees stand on their own.

So, though the awardees typically display the "valley of death" where after stage 2 funding finishes, about 1 in 6 reach Stage 3 (commercialisation), this says (hopes) that they have a better idea how this year.

One of them is outright propping up entrepreneurs and commercial companies with SBIR Ignite. Now, it's no free ride, they have to reach certain benchmarks, but this lets companies access NASA technology and patents when they are just starting. This year it's:

• Aviation-Ready Electrical Energy Storage for All-Electric or Hybrid Electric Aircraft (heavy drones and certification for such)
• Leak-Free Cryogenic Valves and Quick Disconnects (valves and disconnects that will work on the ground and in space)
• Decision Support Tools Leveraging NASA Earth Science Data (processing all the data under the Earth Science To Action initiative)

[tater]

 

[darthgently]

6 hours ago, tater said:

 

I’m wondering how much NRHO for Gateway may be questioned now.  Or Gateway as it is currently conceived even

[tater]

2 hours ago, darthgently said:

I’m wondering how much NRHO for Gateway may be questioned now.  Or Gateway as it is currently conceived even

Gateway only exists because SLS/Orion is so awful. Canada might be annoyed because we won't have a need for a grossly overpriced robot arm.

[darthgently]

27 minutes ago, tater said:

Gateway only exists because SLS/Orion is so awful. Canada might be annoyed because we won't have a need for a grossly overpriced robot arm.

I could see having something habitable in lunar orbit to serve the same purpose as emergency cabins in the alps.  A small pressurized shelter with emergency consumables perhaps.  Maybe even a dedicated often manned research station just for supporting lunar research.  But the “gateway to mars” thing never rang right.