[New] Space Launch System / Orion Discussion Thread

[Kerb24]

Scrub. 

[intelliCom]

Scrubbed. Well, that was an interesting wet dress rehearsal No. 6, everyone!

[Beccab]

Alright, let's look at the future options:

- 5th September: the launch window is just like this one, but it's only 54 hours after this scrub was called; recycling and preparing for launch again will have an extremely tight window, which they may miss if there's problems. Launch team will also probably be quite fatigued as well by 5 days of nearly continuous launch operations, all of this very close to another failed launch attempt

- 6th September: the recycling schedule is more realistic here, but there's another problem; in fact the launch window is only 24 minutes, when the previous launch attempts couldn't succeed with two hours allowed. Unlikely this will end with a launch if it is pursued at all

- late September/early October: the last official news we had on this is that this launch period is out; the time needed to roll back SLS, reset everything, install a new FTS battery and roll out again would take too long making this a non starter. NASA may try to squeeze out some time and try to reach this launch period, but we've heard nothing about that and it seems unlikely to be workable

- late October: this is likely the first launch period that can be reached safely by Artemis I, launching around halloween with the issues solved

 

My personal bet is the last one given all the issues they've been having, however I'm not going to count the 5th out just yet. Not very likely, but not impossible either

[DDE]

Their attempted solution to the leak is... rather hair-raising.

[RCgothic]

The clean pad decision is looking like a bad one, given 39B will have no other users for the foreseeable.

No on-pad servicing options a related bad call.

No trickle-chargers for FTS and and secondary payloads is a complete WTAF decision.

And ICPS does seem to be severely handicapping for launch windows, which makes all the above even worse. Good article link @tater

[Beccab]

2 minutes ago, DDE said:

Their attempted solution to the leak is... rather hair-raising.

"Have you tried turning it on and off? Oh you have? Try it again please"

[kerbiloid]

They should smoke and see where the smoke flows.

Then attach a wet cloth to make an ice patch.

[SunlitZelkova]

37 minutes ago, intelliCom said:

Apollo IV didn't go to the moon on its first launching; why should SLS?

Because it is a test of Orion too, and Orion in LEO doesn’t make sense since Commercial Crew became a thing.

21 minutes ago, intelliCom said:

You know, I've just realised something; SLS is the absolute antithesis to Sea Dragon.

Sea Dragon would have had:

• Partial reusability (First stage with chutes and airbags)
• Simplistic launch infrastructure ("Ocean 'n go" system)
• Low RnD cost (Big dumb booster)
• Huge payload capacity
• Lower cost per payload mass

On top of all of this, NASA took a funding hit due to Congress wanting to fund the Vietnam war (which they lost lmao)

SLS needs to:

• Be completely expended (despite reusing refurbishable shuttle parts)
• Have completely reworked launch infrastructure (despite reusing shuttle parts)
• Heavily overpriced RnD (despite reusing space shuttle parts)
• Less payload capacity than Saturn V (despite being the "most powerful rocket ever built", and a "modern-day Saturn V")
• Only launches once a year (despite being a "modern-day Saturn V")

On top of all of this, this was going to be built three goddamn times. The third of which is notable for having a lot of political meddling.

I somehow did not expect venting of the problems of SLS to arise as a result of the delays 

Sea Dragon was never realistic because nobody needed it. NASA did not lose funding because of Vietnam, but because no one in the US government really cared about space beyond maintaining a token presence there after Apollo. War or no war NASA was doomed once Apollo landed a man on the Moon.

SLS is directly related to politics. Even the Space Shuttle itself was largely approved because of the jobs it would create in California, and while after the Columbia disaster a completely “clean sheet” call for proposals was issued for a post-Shuttle vehicle, in all likelihood a desire to keep those Shuttle jobs alive is what has driven all Shuttle derived launch vehicles which replaced that concept a mere year after it was revealed.

I think the real travesty was not utilizing the Saturn IB and CSMs + smaller modular space stations to do a space station program along the lines of what happened with Soyuz in the USSR. It would have cost just as much as the Shuttle and actually done stuff, while being “incapable” enough to give a clean slate when people got around to wanting to go further again, instead of chaining the government and industry to the hugely expensive and messy Shuttle industrial complex.

But the ultimate tragedy was that the delay in Artemis 1 as a result of all of those problems means I will never get to eat a Krispy Kreme Artemis doughnut!!! (I bet they would put in on sale again for the next attempt and it is gone) 

[kerbiloid]

It's a test of SRB for Orion, that's why Orion.

Spoiler

 

 

[tater]

Gonna vent on the EUS issue. ICPS was always dumb. It was clear from the start that this required 2 MLPs, and the delay was as I recall almost 2 years just from ICPS to EUS MLP issues. That delay (from 2016) is already long gone. Proper program planning/management would have long ago established a more reasonable EM-1 date (the original designation for the first SLS flight), and seeing it was far enough in the future, they could have just gone straight to what is now Block 1B. Block 1 should never have been a thing.

[tater]

I guess they have access once in the VAB (human platforms at the attachment point)

 

[Pthigrivi]

Im sure this has been talked about but what do you all think about the fundamental decision to stick with hydrolox over methalox or RP1?

[GuessingEveryDay]

2 minutes ago, Pthigrivi said:

Im sure this has been talked about but what do you all think about the fundamental decision to stick with hydrolox over methalox or RP1?

I think they wanted to re-use everything from STS, so they copied the hydrolox too.

[tater]

9 minutes ago, Pthigrivi said:

Im sure this has been talked about but what do you all think about the fundamental decision to stick with hydrolox over methalox or RP1?

LOL.

Horse very, very dead

Suffice it to say that at the time SLS became a thing, the alternative would have been RP-1 (no methalox engines around)—but that would have been clean sheet. SLS of course is functionally a clean sheet, as any similarity to Shuttle components is nonsense.

The SRBs are—except they changed them to 5 segment, so they started from scratch.

The main tank is! Except they scrapped the External tank tooling, and completely redid it (at great cost), so they might as well have picked a tank diameter that was optimal.

The SSMEs are Shuttle! Except they were reworked at a cost for each that greatly exceeded their cost NEW.

Literally nothing on SLS is so Shuttle derived it was used "off the shelf." As a result, they should have simply stated lift/TLI/whatever requirements, and gone clean sheet—in which case yeah, RP-1 all the way, sustainer architectures are lousy.

Edited September 3, 2022 by tater

[Pthigrivi]

21 minutes ago, tater said:

RP-1 all the way, sustainer architectures are lousy.

And RP-1 over hydrolox because of tank volume and hydrogen being so leaky?

[Beccab]

1 minute ago, Pthigrivi said:

And RP-1 over hydrolox because of tank volume and hydrogen being so leaky?

And easier to get a higher thrust too, so that you don't need SRBs like every hydrolox first stage except some Delta IV variants (which in turn were still extremely expensive because of it)

[RCgothic]

Yeah, an RP-1 rocket is just more powerful than a Hydrogen rocket of the same size. Constrained by the size of the VAB, the most powerful rocket NASA could build would be RP-1.

It's also much lighter on the pad prior to fuelling than anything with SRBs, so less constraint on the crawler.

[tater]

14 minutes ago, Pthigrivi said:

And RP-1 over hydrolox because of tank volume and hydrogen being so leaky?

Hydrogen is awesome from an Isp standpoint, but for a launch vehicle thrust dominates initially (hence the SRBs). For Shuttle the idea was to save the expensive engines for reuse, and since the spacecraft definitionally reaches orbit, they want the vac engines there. Trouble is the SSME can't air start, so they had to light them on the ground. Big, fluffy tanks? Not a huge issue, nor are leaks I suppose, but a more normal RP-1 system would have been better, maybe dump the SRBs. With a crew vehicle, the LES has to be pretty powerful to pull the capsule off the stack with SRBs, because those are potentially lethal. Think of Challenger. After the RUD, the SRBs kept flying. If this happened with SLS, Orion needs to pull away faster than bare SRBS are capable of going no longer connected to the core. Going with RP-1 could have gotten the thrust to have no boosters—but solid boosters are made in a different district, so we can't remove those!

Edited September 3, 2022 by tater

[Beccab]

Looks like an October launch (17th October?) Is very likely by now

[tater]

Given the known launch constraints (thanks, ICPS!) shown on the calendar above, roll out needs to be optimally timed to maximize the possible launch dates before putting new batteries in the FTS. Why they don't trickle charge—I don't understand.

The should maybe roll out a few days before the 17th, aiming for the 17th, giving them maybe 3 possible attempts with reasonable times between (4 if they could do 4 days between). 17th, 22nd, 27th (plus 31st if they can do a 4 day turn around).

 

 

[Beccab]

3 minutes ago, tater said:

Given the known launch constraints (thanks, ICPS!) shown on the calendar above, roll out needs to be optimally timed to maximize the possible launch dates before putting new batteries in the FTS. Why they don't trickle charge—I don't understand.

The should maybe roll out a few days before the 17th, aiming for the 17th, giving them maybe 3 possible attempts with reasonable times between (4 if they could do 4 days between). 17th, 22nd, 27th (plus 31st if they can do a 4 day turn around).

 

 

If they are faster than literally 50 days they could even attempt a WDR this time, but i doubt the schedule allows it

Edited September 3, 2022 by Beccab

[tater]

6 minutes ago, Beccab said:

If they are faster than literally 50 days they could even attempt a WDR this time, but i doubt the schedule allows it

At this point they know the QD is a problem at some level. Not even sure if they can really test it in the VAB. They can use He, but the issue might relate to a temperature gradient and it might need LH2 to see the issue (presumably the QD system was tested in isolation long before this).

[Cuky]

At this moment I have so little faith in Artemis program and contractors that make hardware for it that I sincerely doubt they will launch before 2023.

If I am not mistaken first stage is made by Boeing which in last few years hasn't really proven itself with reliably building stuff. They are facing delays and are over budget in rockets, space crafts and airplanes. That doesn't give confidence in the company.

And mobile launch platform is made by Bechtel, and from what experience I have on that company (they built a large part of highways here in Croatia) they also like to go over budget and face delays after delays.

 

And guess what, both scrubbed launch attempts were due to equipment built and delivered by those two companies.

[tater]

It's a new vehicle, was bound to have some teething problems. Would not have been a real issue had it truly been Shuttle-derived, and done quickly. Sticking to Shuttle-derived it should have used minimally altered infrastructure, etc. Shuttle-C to start, work on Direct, etc, in the background.

The issue is that is is so far behind schedule that there is a sort of gottagetthereitis going on. If it was 2017? Meh, take their time, work it out, they're ready when they're ready. 6 years late? Everything seems like it needs to happen yesterday.

[CBase]

9 minutes ago, tater said:

It's a new vehicle, was bound to have some teething problems.

The problem ist really more about slow turn around: failing is painfully slow until they are ready for another attempt.

WDR or ground problems pushed the schedule by months. And because they do, they try to skip some only to later learn that it was needed. pushing it even further. I mean the WDR tests did not any alignment with launch windows if they were planned as it.

Being on schedule on any innovative project is really a lot about failing softly.