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[New] Space Launch System / Orion Discussion Thread


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1 hour ago, tater said:

The Moon is a goal that can actually be accomplished, and international partners are only contributing chump change, so it's a good deal for them. Get astronauts to the Moon for virtually zero cost.

Well it'd be awkward if they finished their part of the mission and the main mission hasn't started...

56 minutes ago, RCgothic said:

Orion on top of an expendable Starship...?

You mean the booster ? That'd take an even longer time...

50 minutes ago, tater said:

Starship is not, so I'd say that would depend.

I'm not sure about that, but this isn't the thread for it.

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3 minutes ago, YNM said:

I'm not sure about that, but this isn't the thread for it.

From a NASA rating POV.

They tend to require every single part etc meets some arbitrary standard so that they calculate a probability of loss of crew at some value  by combining the problems with parts, etc. This is necessary since each rocket is 100% new, and used once.

SpaceX is heading towards something far closer to airworthiness, and such a path will take longer. And again, there are 2 other LVs coming soon that can loft Orion.

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1 hour ago, YNM said:

Well it'd be awkward if they finished their part of the mission and the main mission hasn't started...

You mean the booster ? That'd take an even longer time...

I'm not sure about that, but this isn't the thread for it.

No, I means Superheavy + an expendable Starship 2nd stage without fairings, legs, fins etc, just an adaptor to fit Orion up top.

Without refuelling Starship can't send any payload to the moon whilst lugging fins, fairing and reserve fuel for landing, but with those stripped away it's comparable to SLS at minimum. It'd be a really easy conversion - with stainless steel it's not like they'd need to hexgrid a new adaptor. And with a capsule with LAS up top and no attempt to reuse the upper stage it shouldn't be harder to crew-rate than F9.

 

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24 minutes ago, RCgothic said:

No, I means Superheavy + an expendable Starship 2nd stage without fairings, legs, fins etc, just an adaptor to fit Orion up top.

Again, I'm not sure how you'd refit a Starship to receive something else on top of it, given the header tanks and whatnot. What you're asking is like taking the TKS spacecraft and adding a capsule on it when it already have one. And again this is not the Starship design-related thread.

1 hour ago, tater said:

From a NASA rating POV.

They tend to require every single part etc meets some arbitrary standard so that they calculate a probability of loss of crew at some value  by combining the problems with parts, etc. This is necessary since each rocket is 100% new, and used once.

SpaceX is heading towards something far closer to airworthiness, and such a path will take longer. And again, there are 2 other LVs coming soon that can loft Orion.

Well I mean if (and if) NASA contracts the Starship as a moon lander, then they'd already be man-rated, at least in space. OFC you can't launch it on itself from the Earth without sacrificing all the payload and the fuel, so in effect it needs the first stage, which is real early in development. That's the one I'm questioning would be man-rated by mid 2020s. But to my understanding they're aiming for man-rating.

Also, NASA might be more open for reused boosters than you might think, given that they're still considering to allow F9 reused booster for Commercial Crew. (although we haven't seen one being manifested so perhaps after two or three years...)

Edited by YNM
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There are a lot of hoops to jump through fro NASA to put Orion on top. I could see a SpaceX tug taking Orion to the Moon, however... Or maybe just providing the dv for a return.

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6 hours ago, tater said:

I could see a SpaceX tug taking Orion to the Moon, however... Or maybe just providing the dv for a return.

Yeah, if they ended up being chosen for HLS then I can see the Orion spacecraft being pushed back to Earth by Starship. That'd be even less propellant needed on the Orion SM.

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Y’all do realize NASA said they have spare engines on site right? Set to take at most a week to perform a swap (if that’s even needed). Which currently does not appear to be the case.

Jim even said that a retest may not be necessary if they got the data they needed.

2 hours ago, YNM said:

Yeah, if they ended up being chosen for HLS then I can see the Orion spacecraft being pushed back to Earth by Starship. That'd be even less propellant needed on the Orion SM.

Everyone realizes the docking port on Orion can’t handle the forces of a tug in a reverse orientation (unless its extremely low thrust). Merlin (much less raptor) generates so much thrust that the docking port would be crushed, who knows what kind of damage the capsule itself would endure as it hasn’t been designed for that (abandoned when Orion become the MPCV in 2011).

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2 minutes ago, ZooNamedGames said:

Jim even said that a retest may not be necessary if they got the data they needed.

Didn't they say that 2 minutes was the minimum acceptable duration though? They got a good ignition and more than a minute of burn, sure, but the engines shut down just before the first gimbal check. Surely if the cause of the early shutdown was, and I quote, a 'major component failure', they'd want to test again to make sure it doesn't fail on an actual flight? A critical engine component failing just over a minute into the flight seems like it'd be an immediate abort.

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11 minutes ago, ZooNamedGames said:

Everyone realizes the docking port on Orion can’t handle the forces of a tug in a reverse orientation (unless its extremely low thrust).

Are the thrust for landing on the Moon that much ?

11 minutes ago, ZooNamedGames said:

Y’all do realize NASA said they have spare engines on site right? Set to take at most a week to perform a swap (if that’s even needed).

Yeah, and it's a good thing they tested the thing (finally !). Only problem now is that even if they can swap the engines they'd need to run up and makes in all the fuel etc. again. Even doing a retest within next month is going to be the fastest they've been moving so far, but I really hope they'd finally gear up.

12 minutes ago, ZooNamedGames said:

Jim even said that a retest may not be necessary if they got the data they needed.

67 seconds vs. 480 seconds is waay too short. Unless if the only data they need is "oh look it can turn on, dunno how we'd do guidance".

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1 hour ago, ZooNamedGames said:

Y’all do realize NASA said they have spare engines on site right? Set to take at most a week to perform a swap (if that’s even needed). Which currently does not appear to be the case.

I read that just resetting the test would take about a month (regardless of any work, just scheduling, planning).

 

1 hour ago, ZooNamedGames said:

Jim even said that a retest may not be necessary if they got the data they needed.

The idea that this was enough data is comical. It was smart to do the green run test they have a rocket that has reusable engine, they can test on the stand as much as they like.

 

1 hour ago, ZooNamedGames said:

Everyone realizes the docking port on Orion can’t handle the forces of a tug in a reverse orientation (unless its extremely low thrust). Merlin (much less raptor) generates so much thrust that the docking port would be crushed, who knows what kind of damage the capsule itself would endure as it hasn’t been designed for that (abandoned when Orion become the MPCV in 2011).

1. You're saying Orion could not do the Constellation style mission originally proposed with Altair doing the LOI burn?

2. Orion has no docking port yet, it's a boilerplate right now, the simple solution is to add a docking port that is not awful. Or was "useless" one of Congress's requirements for a docking port so they go with that?

Were they really that stupid? Design a spacecraft incapable of doing, well, anything useful, then hobble it so that a more capable craft can't push it?

 

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This whole program is a textbook example of why you need to define a mission first, then design and build a vehicle. It doesn't work as well when you do it the other way around and try to design a mission around a vehicle you are already locked into.

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2 minutes ago, mikegarrison said:

This whole program is a textbook example of why you need to define a mission first, then design and build a vehicle. It doesn't work as well when you do it the other way around and try to design a mission around a vehicle you are already locked into.

Exactly.

A prime example of this is how the landers are being forced to make up for SLS and Orion's deficiencies. Orion can only reach a distant retrograde lunar orbit, so the landers have to bring along extra dV to get them where they need to be. If SLS/Orion was capable of reaching LLO, landers could avoid rendezvous in NRHO entirely and get more payload to the surface.

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6 minutes ago, mikegarrison said:

This whole program is a textbook example of why you need to define a mission first, then design and build a vehicle. It doesn't work as well when you do it the other way around and try to design a mission around a vehicle you are already locked into.

Yeah, my real complaint about SLS/Orion was never the cost, timing, etc, it was always that is it a "rocket to nowhere."

Too large for LEO, too small for "not LEO."

The IDSS rev E design dock says the max compressive load is 100,000N (which is about what a single RL-10 does as a reference), but the original concept was for Altair to do the LOI burn... that design was never finalized though, some show 1 engine, most I have seen have multiples. Also, shear and tension forces are lower than compression, see below:

2 hours ago, ZooNamedGames said:

Everyone realizes the docking port on Orion can’t handle the forces of a tug in a reverse orientation (unless its extremely low thrust). Merlin (much less raptor) generates so much thrust that the docking port would be crushed, who knows what kind of damage the capsule itself would endure as it hasn’t been designed for that (abandoned when Orion become the MPCV in 2011).

In addition, Orion has been pitched throughout it's history (including SLS) as the capsule that will go to Mars. How, pray tell, is Orion going to Mars stuck to the front of a transfer vehicle that can push it to TMI, but not one capable of TLI?

NASA image:

Orion_docked_to_Mars_Transfer_Vehicle-e1

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55 minutes ago, tater said:

Were they really that stupid? Design a spacecraft incapable of doing

Do you mean "Ares"?
Well...  :sealed:

***

https://www.internationaldockingstandard.com/download/IDSS_IDD_Revision_E_TAGGED.pdf

Page 3-35 has a table with inertial parameters of the "IDSS-compliant mechanisms".

The IDSS-350T one optimistically hopes on 350 t things attached.

Edited by kerbiloid
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25 minutes ago, kerbiloid said:

Do you mean "Ares"?
Well...  :sealed:

***

https://www.internationaldockingstandard.com/download/IDSS_IDD_Revision_E_TAGGED.pdf

Page 3-35 has a table with inertial parameters of the "IDSS-compliant mechanisms".

The IDSS-350T one optimistically hopes on 350 t things attached.

Yeah, that's where I found the compressive force allowed (100,000 newtons).

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19 hours ago, kerbiloid said:

The IDSS-350T one optimistically hopes on 350 t things attached.

The 350T version is exactly what's used on the ISS. The ISS is 400 tonnes in mass.

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3 hours ago, YNM said:

The 350T version is exactly what's used on the ISS. The ISS is 400 tonnes in mass.

Unlikely, maybe only on the docking modules used for Shuttle.
The ISS modules and trusses are attached with CBM (Common Berthing Mechanism) adaptors.
They are 1.25 times larger and more simple, have nothing common with IDSS.

The "Russian" section modules are attached with a "hybrid" docking port (the hard-capture system is IDSS-compatible, but soft-capture one is a probe/drogue from Mir modules).

IDSS are used only for ships docking, and they are not heavier than 110 t (Shuttle).

Edited by kerbiloid
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https://blogs.nasa.gov/artemis/2021/01/19/green-run-update-data-and-inspections-indicate-core-stage-in-good-condition/

Quote

After analyzing initial data, the team determined that the shutdown after firing the engines for 67.2-seconds on Jan.16 was triggered by test parameters that were intentionally conservative to ensure the safety of the core stage during the test. Initial data indicate the sensor reading for a major component failure, or MCF, that occurred about 1.5 seconds after engine start was not related to the hot fire shutdown. It involved the loss of one leg of redundancy prior to T-0 in the instrumentation for Engine 4, also known as engine number E2060. Data analysis is continuing to help the team determine if a second hot fire test is required

 

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Would have been good messaging to know the constraints on testing, and let people know that this is a campaign of testing, and they will err on the side of protecting the vehicle should there be any concerns. The engines are reusable, which allows as many tests as needed, etc.

They seemed off script as soon as it was not going perfectly.

Edited by tater
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4 hours ago, kerbiloid said:

Unlikely, maybe only on the docking modules used for Shuttle.

Where do you think the current line-up of US crew vehicles are docked to ? They're allowed to re-boost the station as well.

3 hours ago, RealKerbal3x said:
Quote

It involved the loss of one leg of redundancy prior to T-0 in the instrumentation for Engine 4, also known as engine number E2060.

 

37 minutes ago, tater said:

They seemed off script as soon as it was not going perfectly.

At least it's a good thing that it was practically nothing... Although I'd have to wonder why they didn't realize it before the engines were started, given the lengthy hold-up (or maybe it is due to the lengthy hold-up ?).

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22 minutes ago, YNM said:

Where do you think the current line-up of US crew vehicles are docked to ?

IDA on PMA, early version of IDSS or late version of APAS-95. Carrying up to a Shuttle (110 t), but usually up to15 t.

The modules themselves (400+ t in total) are attached to each other with CBM, not with IDSS.

22 minutes ago, YNM said:

They're allowed to re-boost the station as well.

Like the hybrid probe/drogue allows for Progress.

Boosting is not docking. It's hitless, gentle, so may differ.

Edited by kerbiloid
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15 minutes ago, kerbiloid said:

The modules themselves (400+ t in total) are attached to each other with CBM, not with IDSS.

And CBMs aren't hitting each other... There's a reason we'll never see CBMs again after Shuttle due to the loss of the arms (although berthing is still possible for ISS but I question you can do it entirely unmanned). There's actually one APAS being used to connect the ROS with USOS, and I can't see how the other two PMAs would be of a different design. However I'll say that the currently used IDSS/IDA on the crew capsule itself are definitely not the heavy type. Not sure about the APAS to IDA/IDSS adapters itself, there's a chance it's not the heavy type as well.

But yeah in a way we already have one of the docking ports connecting a station together.

Edited by YNM
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