SLS Program working on accelerating EUS development timeline

[MoaMem]

Do you have the source for that diagram?

I would assume that you'd get all the bells and whistles possible in the reworking of the EUS that's currently ongoing, and they'd show up in the first Block 1B.  If you can really do a 13t co-manifest, that changes a lot of things.

A "study" made by some Boeing dudes to prompt SLS, it gives never seen before high figures about SLS, paint other launchers under the worst possible light and totally ignores Starship, see for yourself :
https://www.researchgate.net/publication/335212999_The_Space_Launch_System's_Enablement_of_Crewed_Lunar_Missions_and_Architectures

In mid-2018 NASA was showing:

Payload to TLI/Moon for Block 1B Cargo - "37-40 t (74k-81k lbs)

Has the EUS really changed that much in just a year and a half?

It hasn't, SLS proponents have been flooding the spaceflight internet with this "study" (Reddit has a thread dedicated to every single diagram in this study) because it's so biased toward SLS even for Boeing standards.

[dglow]

A 13 metric ton co-manifest would allow the Orion to bring with it a new Transfer stage each time, or a Tanker module to top up either a Transfer stage or Ascent stage. A separate Commercial launch would have to bring a propellant load for an Ascent or Transfer stage, or a fresh descent stage if the Lander design is three-segment. Which I think would be wise; to avoid another $2 billion dollar, schedule-pushing SLS launch of an integrated 2 stage, 40+plus ton Monster LM.

Prediction: if HLS flies on SLS first then it will never fly on another LV.

[MATTBLAK]

Yes, probably

[hektor]

So in the dual-launch, Orion-on-ICPS + HLS-on-EUS, the two will meet up in NRHO, even sans Gateway. Whereas if both launches were on Block 1B they could/would meet in LLO.
Is that correct?

EUS isn't designed to survive 3-4 day trip from TLI to LLO. Has DV but not life. It may e possible upgrade.

Even if you could extend the stage life of the EUS, it and Orion together still can get less than 3t of co-manifested payload to LLO and leave enough prop for Orion to get back to TEI.

The Universal Stage Adapter is heavy.  Assuming a 400 kg PAF, it lops off almost 4.8t from what you can co-manifest.  If you could find a way to get rid of it before TLI, things would be better, but then you'd be flying Orion eyeballs-out and relying on the PAF, the co-manifest, and the NDS to keep the Orion stable during the burn.  Not gonna happen.

Interesting, and thank you both. So EUS only solves Orion's 'LLO problem' by enabling it to be paired with a beefier ESM. Where the current ESM's size/capability has been driven as a function of Orion's mass and ICPS's limitations. Yes?

So we can expect an ESM XL at some point ?

[MATTBLAK]

One hopes so. Orion needs at least 60% more propellant to get itself both into and out of low lunar orbit; unlike the Apollo CSM. The Orion's low delta-v is a hangover from the Ares 1 and Constellation. But redesigning or 'stetching' the Service Module is not likely in the plan or the budget.

[hektor]

One hopes so. Orion needs at least 60% more propellant to get itself both into and out of low lunar orbit; unlike the Apollo CSM. The Orion's low delta-v is a hangover from the Ares 1 and Constellation. But redesigning or 'stetching' the Service Module is not likely in the plan or the budget.

I can see happening two ways :

1) NASA rapatriates the SM to the US

2) NASA offers ESA an attractive package, i.e. European astronauts on the Lunar surface

[jadebenn]

Do you have the source for that diagram?

I would assume that you'd get all the bells and whistles possible in the reworking of the EUS that's currently ongoing, and they'd show up in the first Block 1B.  If you can really do a 13t co-manifest, that changes a lot of things.

MoaMem posted the source upthread (love you too), but I'll provide another link.

To clarify, I mean that I'm assuming those numbers are with the RS-25Es and/or BOLE SRBs.

While I'm not going to go full tinfoil hat and act like the numbers are a fabrication, they are a ton or two over what I'd been hearing prior to this graphic, so I think it's a safe assumption that it's at least assuming RS-25E (which should just barely be available in 2024). Not 100% sure about BOLE considering the context of the paper. Point is, they are juicing it a ton or two higher than before somehow.

Another theory might be that there's some mass reductions for the core in the pipeline and/or this is accounting for updated figures. I remember reading that CS-1 came in underweight - maybe that explains it?

Is the Orion adapter for SLS going to be a lightest possible composite structure? I admit to not knowing much about it. The Apollo LM adapter weighed more than 4,000 pounds - 1,840 kgs and was made of aluminum.

It's composite.

[TheRadicalModerate]

A "study" made by some Boeing dudes to prompt SLS, it gives never seen before high figures about SLS, paint other launchers under the worst possible light and totally ignores Starship, see for yourself :
https://www.researchgate.net/publication/335212999_The_Space_Launch_System's_Enablement_of_Crewed_Lunar_Missions_and_Architectures

In mid-2018 NASA was showing:

Payload to TLI/Moon for Block 1B Cargo - "37-40 t (74k-81k lbs)

Has the EUS really changed that much in just a year and a half?

It hasn't, SLS proponents have been flooding the spaceflight internet with this "study" (Reddit has a thread dedicated to every single diagram in this study) because it's so biased toward SLS even for Boeing standards.

Thanks for the link.

The top-level thing to note is that, while the diagram jadebenn referenced (fig. 9 in the doc) shows the EUS getting 44.8t to TLI, fig. 1 shows it putting between 39t and 43t to TLI.  Note that the Block 1 numbers are also different.  So at least one of these is wrong.  Given that none of the reviewers had fallen asleep by the first paragraph, I'd put my money on fig. 1 being correct.

The next question:  Why the range?  The most obvious answer is that different missions will require different flight performance reserves.  The 43t number is likely at 0% FPR.  39t would therefore represent 2.6% FPR. This is probably the most conservative number for a crewed flight, but it yields a really low co-manifest value.  TLI under-peformance isn't an LOC event, or usually even a LOM event, given that Orion has a fair amount of extra delta-v.  (Update:  2.6% is probably pretty close for a science mission with little delta-v in the payload itself.)

Let's say that the Brown Trouser Brigade will let them get away with 0.5% FPR.  That's a payload to EUS of 42.2t.

What to use for Orion's mass in the parking orbit?  My old numbers implied that a crewed Orion would be about 26.2t without the OSA (which I accidentally included in the previous post).  Fig. 1 and paragraph 1 say 27.5t.  Fig. 9 implies just a tad under 25t.  I say we average them!  26.2t it is.  So:

Total to EUS: 42.2t
Orion: -26.2t
USA: -4.4t
PAF: -0.4t
-------------------------
Co-manifested payload: 11.2t

That's definitely better than my first stab at this.

It's composite.

Here's the Dynetics fact sheet.

[jadebenn]

The 43t is the usable payload. You'll note that's actually common between both figures if you ignore the payload reserve.

[MATTBLAK]

When NASA moved to the 'J-Series' more advanced Apollo missions, the initial parking orbit used on the earlier missions went from about 118 nautical miles down to about 93 for missions 15 to 17. This was to help slightly increase the Saturn V's payload into LEO. And since the parking orbit was temporary before TLI; the increase in atmospheric drag was deemed negligible. Can we assume that the Lunar-bound Artemis missions will also adopt a similarly low parking orbit?

[TheRadicalModerate]

When NASA moved to the 'J-Series' more advanced Apollo missions, the initial parking orbit used on the earlier missions went from about 118 nautical miles down to about 93 for missions 15 to 17. This was to help slightly increase the Saturn V's payload into LEO. And since the parking orbit was temporary before TLI; the increase in atmospheric drag was deemed negligible. Can we assume that the Lunar-bound Artemis missions will also adopt a similarly low parking orbit?

That's certainly not what they're planning for the Block 1 missions.  Unless something changed dramatically, for Artemis I, the core inserts into 1806x41 km, and the ICPS is only used to raise the perigee up to 1806x185 km.  I'd expect an EUS profile to be substantially different, but I'm not sure what that means.

[jadebenn]

The ICPS doesn't just raise the perigee; It performs the TLI burn as well. That's why the SLS core throws it into such a lopsided orbit. Needs the extra delta-V.

[TheRadicalModerate]

The ICPS doesn't just raise the perigee; It performs the TLI burn as well. That's why the SLS core throws it into such a lopsided orbit. Needs the extra delta-V.

Yes.  I was only addressing mattblak's question about the parking orbit.

Have you seen anything on what the Block 1B ascent trajectory would look like?  I'd assume that the 4 RL10's would significantly reduce the second stage gravity drag, but the larger EUS and payloads will increase it for the core.

[jadebenn]

I don't have any unique insights there, just the obvious, "It'll stage lower in the atmosphere and at a lower speed."

[yg1968]

So lets get back to something on topic (like the part where you made an assertion directly contradictory to the facts laid out in the article.)

1. An Artemis manifest leaked by my favorite space reporter a while back pointed at this exact possibility, and I have independent confirmation that the leak was legitimate

2. Loverro has made multiple statements (such as the one quoted by ncb1397) that point to a preference for a simpler SLS-launched architecture.

Why did Jim Bridenstine say it wasn't the plan when Eric Berger tweeted the manifest? I'm confused.

One possible explanation could be that Bridenstine and Loverro are having a bit of a disagreement.

Knowing what we know now, this seems very likely. That was a good (educated) guess!

[Aeneas]

Why don't they just scale ACES up a bit?

[Khadgars]

Are those TLI numbers for Block 2 coming from Congress or from the options being considered (the advanced boosters) (also, which advanced boosters)

I just grabbed Ed Kyle's numbers, which seem to be from the 2014-vintage SRBs.

I'm viewing Block 2 as science fiction, pretty much.  I'll be very interested to see what tweaks they make to EUS, though.  Fairly minor increases in co-manifesting capability make big differences to potential HLS architectures.

Block II is pretty much guaranteed, since the casings for the 5 seg SRB's will eventually run out.  I believe there are enough for 10 flights

[meberbs]

Block II is pretty much guaranteed,

Not even close, even Block 1B isn't. The only real reason for SLS to get greater than 0 flights is political inertia, and that isn't guaranteed to see the first flight through.

The obselesence of SLS was demonstrable a while back and is only becoming more blatant with time.

[Coastal Ron]

Are those TLI numbers for Block 2 coming from Congress or from the options being considered (the advanced boosters) (also, which advanced boosters)

I just grabbed Ed Kyle's numbers, which seem to be from the 2014-vintage SRBs.

I'm viewing Block 2 as science fiction, pretty much.  I'll be very interested to see what tweaks they make to EUS, though.  Fairly minor increases in co-manifesting capability make big differences to potential HLS architectures.

Block II is pretty much guaranteed, since the casings for the 5 seg SRB's will eventually run out. I believe there are enough for 10 flights

Enough for eight flights, according to a story here on NSF just last year.

Throw that in with all the other considerations for what it would take to keep flying the SLS...

[envy887]

Why don't they just scale ACES up a bit?

EUS is more or less just a DCSS/iCPS scaled up a bit. Starting with ACES or Centaur 5 might result in a higher performance stage, but probably would not be significantly faster or cheaper.