[New] Space Launch System / Orion Discussion Thread

[ZooNamedGames]

3 hours ago, sevenperforce said:

Docking in LEO is not harder than docking in cislunar space. What is the difference between staging distributed launch in LEO vs staging distributed launch at LOP-G? We need to develop it regardless.

Europa Clipper is going to be spending years in space anyway. What's the harm in throwing it to LEO a few months early?

Almost everything we’ve docked by  has involved crew in some fashion onboard the vehicle. Soyuz to the ISS, shuttle to Mir, Apollo to Skylab, Gemini to Agena, CSM to LM. We’ve never built a rocket assembly in space. Docking adaptor would have to be new and strong enough to withstand the thrust generated, any slipping action, dampen any movement between the two vehicles- especially enough to protect the onboard instruments, and also devise a guidance system to handle two separate vehicles during burns and maneuvers.

4 hours ago, sevenperforce said:

They really mean "which we pretend requires the use of the SLS" but otherwise.....

Until 2030 (at the soonest SpaceX can compete in lunar space) NASA’s SLS is the only vehicle ready for BEO flight.

[tater]

 

[Barzon]

There are at least two sources saying engine 4 is in aswell. which is interesting.

[sevenperforce]

42 minutes ago, ZooNamedGames said:

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Docking in LEO is not harder than docking in cislunar space. What is the difference between staging distributed launch in LEO vs staging distributed launch at LOP-G? We need to develop it regardless.

Almost everything we’ve docked by  has involved crew in some fashion onboard the vehicle. Soyuz to the ISS, shuttle to Mir, Apollo to Skylab, Gemini to Agena, CSM to LM.

Almost everything? It's 100% the opposite. Unmanned Progress spacecraft autonomously dock themselves to the ISS several times every year without incident. There have been far more unmanned dockings than manned dockings, and Soyuz dockings are automated. 

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We’ve never built a rocket assembly in space.

Apollo would beg to differ, unless docking one vehicle to another and then using the first vehicle's engine to push the connected stack doesn't count as building a rocket assembly in space.

Also, this is exactly what the Artemis plan calls for: building rocket assemblies in space. We need to develop it for Artemis anyway.

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Docking adaptor would have to be new and strong enough to withstand the thrust generated, any slipping action, dampen any movement between the two vehicles- especially enough to protect the onboard instruments

It would have to be newer and stronger, yes. Again, these are things we need to develop.

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and also devise a guidance system to handle two separate vehicles during burns and maneuvers.

If Apollo could devise such a guidance system with less software than a smartwatch, I'm sure we can today. Especially since we have to, because Artemis.

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They really mean "which we pretend requires the use of the SLS" but otherwise.....

Until 2030 (at the soonest SpaceX can compete in lunar space) NASA’s SLS is the only vehicle ready for BEO flight.

SLS is not ready for any flight, let alone sending any competitive payload BEO, and I seem to recall Falcon Heavy sending something BEO two years ago.

If distributed launch with eyeballs-out burns was good enough for Constellation, it should be a no-brainer for sending Orion and crew to the moon now.

Edited November 7, 2019 by sevenperforce

[tater]

45 minutes ago, ZooNamedGames said:

Until 2030 (at the soonest SpaceX can compete in lunar space) NASA’s SLS is the only vehicle ready for BEO flight.

This is just nonsense.

I have no idea when Starship will be capable of BLEO flight with or without crew. Neither do you. 11 years, though? If there isn't something, anything vastly better than SLS in 11 years, we're all going to die of old age before anything even slightly interesting happens in human spaceflight. If SS fails, then SpaceX likely gets into some serious trouble vs BO. Regardless of that competition, anything really interesting in human spaceflight in the next 11 years comes from one or both of those companies, IMO, not SLS.

SLS is what it is, but it's not really great for any human mission. Sorry, that's simply a fact. It might be the best we have for crew in the next 2-3 years, but it's not really good at even that. It gets a capsule out towards the Moon. It is less capable than the rocket that landed people on the Moon 50 years ago, and due to the bloat of the capsule it flies it is substantially less capable in terms of where it can send people. If our cart is tied only to SLS, I see a long period of stagnation, SLS is not some stepping stone to Mars, the idea of a Mars craft built by SLS is comical. If the goal was humans to the lunar surface, and SLS was the LV to enable that goal, would it (and Orion) look the same as it does now? Nope. Because it would have been built to accomplish that mission (higher throw to TLI, and smaller capsule better SM if that was not possible---else lower cost and better flight rate for distributed launch architectures). If SLS was designed to facilitate even the simplest Mars mission architectures like Mars Direct, would it look like it does right now? Nope, don't think so (would have been optimized for bulk cargo to LEO and higher flight rate, lower cost, cause that's what you need to build a Mars spacecraft in orbit).

 

5 minutes ago, sevenperforce said:

It would have to be newer and stronger, yes. Again, these are things we need to develop.

Progress pushes ISS all the time. Cygnus did from the Unity module, as well.

Edited November 7, 2019 by tater

[sevenperforce]

2 minutes ago, tater said:

4 minutes ago, sevenperforce said:

It would have to be newer and stronger, yes. Again, these are things we need to develop.

Progress pushes ISS all the time. Cygnus did from the unity module, as well.

I mean, it was a fair point: you can't just slap an IDA onto the end of Europa Clipper, mate to a half-depleted Falcon Heavy upper stage, and fire up the MVac. It's a little more complicated and we definitely need to develop it.

Especially if Artemis.

[tater]

10 minutes ago, sevenperforce said:

I mean, it was a fair point: you can't just slap an IDA onto the end of Europa Clipper, mate to a half-depleted Falcon Heavy upper stage, and fire up the MVac. It's a little more complicated and we definitely need to develop it.

Especially if Artemis.

True, but the idea that it's a particularly difficult problem is kinda silly.

It's like all the talk of Gateway as a spacecraft. PPE pushes it, and it all docks together. Any Mars craft imagined to be assembled at Gateway (Mars Base Camp from LockMart does this with presumably a zillion SLS launches---some to get empty things to Gateway, then many, many more to tank them up (because math)) needs this capability as well.

Oh, wait, NASA is explicitly seeking landers that are sent in parts then docked together to form a whole lander stack, so there is that docking capability as well (which likely also includes a quick disconnect for abort scenarios on top of that).

Edited November 7, 2019 by tater

[KSK]

2 hours ago, ZooNamedGames said:

Docking adaptor would have to be new and strong enough to withstand the thrust generated, any slipping action, dampen any movement between the two vehicles

So, something like the Common Berthing Mechanism used to join US-side ISS modules? Link here to most of the technical detail you could want. 

Capable of berthing and un-berthing operations (as was shown multiple times during ISS assembly), held together by sixteen damn great motorised bolts and rugged enough to cope with ISS reboosts.

This is not an insurmountable problem. 

Yes, space is hard, but you do seem to make a habit of over-inflating problems which have either been solved previously (guidance systems) or that NASA etc have quite a bit of working experience with (docking bits of spacecraft together)

[tater]

It's funny since SLS based architectures for anything anyone could want to do for human spaceflight require:

1. Distributed launch (no SLS block can do anything useful with crew at all in 1 launch).

2. Because of #1, above: Docking.

If distributed launch and docking are a bridge too far, lets cut our losses and kill SLS, because minus those 2 capabilities it's worse than useless (worse because spending billions for useless is worse than not spending billions for worthless).

[kerbiloid]

10 hours ago, sevenperforce said:

building rocket assemblies in space.

Just a notice: there should be a threshold value of the rocket assembly mass.
Nobody makes 10 t heavy assemblies in orbit. And unlikely a Martian ship (normally ~2000 t heavy) could be ever built by tens of launches.

So, 200...300 t to LEO looks like the natural threshold for orbital rocket assemblies and a desired payload for any perspective heavy rocket.
It can launch a direct ascent Apollo (if not Orion).
It can deliver an assembled long-term base module to the Moon without Kerbal-style assembly, 3d-printing, and other flea hunting.
It can build a Martian ship in 10 launches or less.
It can deliver a Mir/ISS in one piece.

P.S.
If they didn't scrap Nova to build Saturns instead, they would have all of this in 1970s.

Edited November 8, 2019 by kerbiloid

[RCgothic]

It's been said again and again. SLS/Orion isn't the rocket/spacecraft combo we need.

For LEO assembly it's too expensive, flies too infrequently, and has nowhere near enough dwell time with a hydrolox upper stage.

For BEO operations it doesn't have enough throw weight to accomplish anything meaningful in a single mission. Which brings us straight back to too expensive, flies too infrequently, and has nowhere near enough dwell time, because the lack of throw weight makes rendezvous a necessary mission requirement.

You don't need a big man-rated (and therefore expensive) booster for getting a crew to orbit anymore. Rendezvous is a solved problem. Ares absolutely had the right idea (minus the bonkers srb design).

You want a big dumb booster that's payload agnostic, inexpensive, and can fly frequently. 200t to orbit. Then you'd have a range of things you could stick on top of it to suit the mission. It doesn't have to be fancy, or have great BEO performance. That much is handled by the payload. It just needs to get to LEO as cheaply and as often as possible.

[sevenperforce]

7 hours ago, kerbiloid said:

Just a notice: there should be a threshold value of the rocket assembly mass.
Nobody makes 10 t heavy assemblies in orbit. And unlikely a Martian ship (normally ~2000 t heavy) could be ever built by tens of launches.

So, 200...300 t to LEO looks like the natural threshold for orbital rocket assemblies and a desired payload for any perspective heavy rocket.
It can launch a direct ascent Apollo (if not Orion).
It can deliver an assembled long-term base module to the Moon without Kerbal-style assembly, 3d-printing, and other flea hunting.
It can build a Martian ship in 10 launches or less.
It can deliver a Mir/ISS in one piece.

P.S.
If they didn't scrap Nova to build Saturns instead, they would have all of this in 1970s.

50 tonnes to LEO is a good starting point for orbital assembly, though. If we had multiple vehicles with flight heritage throwing 40-50 tonnes to LEO whenever we needed it, we could have a moon base already.

[ZooNamedGames]

19 hours ago, sevenperforce said:

Almost everything? It's 100% the opposite. Unmanned Progress spacecraft autonomously dock themselves to the ISS several times every year without incident. There have been far more unmanned dockings than manned dockings, and Soyuz dockings are automated. 

Apollo would beg to differ, unless docking one vehicle to another and then using the first vehicle's engine to push the connected stack doesn't count as building a rocket assembly in space.

All of those involve crew onboard the vessel being docked. Progress docks to the crewed ISS, Apollo is obviously crewed. Hence why I said docking EU would be trickier than anything we've done before.

17 hours ago, KSK said:

held together by sixteen damn great motorised bolts and rugged enough to cope with ISS reboosts.

And what's the acceleration of an ISS reboost? And what would EU experience when being accelerated by a FH upper stage after being docked together?

Yes it can handle one thing, that doesn't make it universally capable of handling any and all forces thrown at it.

[tater]

28 minutes ago, ZooNamedGames said:

All of those involve crew onboard the vessel being docked. Progress docks to the crewed ISS, Apollo is obviously crewed. Hence why I said docking EU would be trickier than anything we've done before.

Um, no.

The crew being there actually makes it worse, because they have to be more concerned about crew safety with automated docking when headed towards a vehicle with crew aboard. Hyper cautious so that the Progress doesn't slam into something with people on it.

Automated docking is a solved problem. Regardless, Gateway REQUIRES automated docking for literally every single element except Orion. Orion is the only exception only because... Orion CANNOT dock itself, because it's not advanced enough to do that.

You are making a virtue out of yet another problem with Orion. Craft with automated docking can always have the crew dock if needed as a fallback. If the crew was to be disabled somehow, the vessel could bring them to safety at Gateway (say they all got so sick they couldn't dock) if it could dock itself. With Orion? Nope.

29 minutes ago, ZooNamedGames said:

And what's the acceleration of an ISS reboost? And what would EU experience when being accelerated by a FH upper stage after being docked together?

Yes it can handle one thing, that doesn't make it universally capable of handling any and all forces thrown at it.

I just did the math. a 47.8t cargo pushed by FH S2 starts at 7m/s², and at the end of the burn it's 18 m/s². Under a g, to 1.8g max. Not an issue.

Edited November 8, 2019 by tater

[sevenperforce]

1 hour ago, ZooNamedGames said:

21 hours ago, sevenperforce said:

Almost everything? It's 100% the opposite. Unmanned Progress spacecraft autonomously dock themselves to the ISS several times every year without incident. There have been far more unmanned dockings than manned dockings, and Soyuz dockings are automated. 

Apollo would beg to differ, unless docking one vehicle to another and then using the first vehicle's engine to push the connected stack doesn't count as building a rocket assembly in space.

All of those involve crew onboard the vessel being docked. Progress docks to the crewed ISS, Apollo is obviously crewed. Hence why I said docking EU would be trickier than anything we've done before.

You're intentionally conflating the two examples I gave. Progress, Soyuz, Salyut, and Dragon 2 are all examples of autonomous, crew-agnostic dockings, which you seem to think is impossibly challenging. Apollo was an example of building a rocket assembly in space, which you said has never been attempted. The very earliest autonomous dockings (Kosmos 186 + Kosmos 188, Kosmos 1443/Progress 23 + Salyut 7, Progress M1-5 + Mir) were wholly uncrewed, because that is easier and less risky than doing it with people on board.

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And what's the acceleration of an ISS reboost? And what would EU experience when being accelerated by a FH upper stage after being docked together?

Yes it can handle one thing, that doesn't make it universally capable of handling any and all forces thrown at it.

Well, the last time we built a rocket assembly in space, burnout acceleration was 0.3 gees. Given that the Common Berthing Mechanism has a diameter 222% of the Apollo Docking System, I'm sure we could find a way to beef it up to handle 0.74 gees (minimum downthrottle of MVac to 364 kN, total stack burnout mass of 49 tonnes).

Edited November 8, 2019 by sevenperforce

[tater]

 

[tater]

15 minutes ago, sevenperforce said:

Well, the last time we built a rocket assembly in space, burnout acceleration was 0.3 gees. Given that the Common Berthing Mechanism has a diameter 222% of the Apollo Docking System, I'm sure we could find a way to beef it up to handle 0.74 gees (minimum downthrottle of MVac to 364 kN, total stack burnout mass of 49 tonnes).

What's funny is that Orion has been built with the design idea that it sits on front of a spacecraft that goes to Mars and back. Before ARM. Before Artemis.

All the NASA press about Orion was that it was going to go with astronauts to Mars (because it can do a direct entry from  Mars-TEI). So Engine_Mars_ship---docking ports---Orion docking to something with decent thrust was part of what should have been the original design (for years now).

Spoiler

https://abcnews.go.com/Technology/inside-orion-space-capsule-day-astronauts-mars/story?id=27339272

They cannot possibly have spent billions building the spacecraft that will bring astronauts to Mars and stuck a docking port on front that cannot deal with the sort of burn pushing on it that any Mars spacecraft is going to generate. Right? They're not idiots.

Edited November 8, 2019 by tater

[sevenperforce]

10 minutes ago, tater said:

What's funny is that Orion has been built with the design idea that it sits on front of a spacecraft that goes to Mars and back. Before ARM. Before Artemis.

They cannot possibly have spent billions building the spacecraft that will bring astronauts to Mars and stuck a docking port on front that cannot deal with the sort of burn pushing on it that any Mars spacecraft is going to generate. Right? They're not idiots.

We don't even have to guess at the burn, because Constellation. The J2-X on the EDS would have downthrottled to 1,048 kN for the TLI burn, pushing a stack that at burnout would have massed roughly 86 tonnes, for 1.24 gees through the same NDS that Dragon 2 has.

Also keep in mind that the NDS already has pyros for contingency undocking, which mean you already have a "decoupler" option when constructing a lunar descent/ascent vehicle.

[KSK]

2 hours ago, tater said:

Um, no.

The crew being there actually makes it worse, because they have to be more concerned about crew safety with automated docking when headed towards a vehicle with crew aboard. Hyper cautious so that the Progress doesn't slam into something with people on it.

Automated docking is a solved problem. Regardless, Gateway REQUIRES automated docking for literally every single element except Orion. Orion is the only exception only because... Orion CANNOT dock itself, because it's not advanced enough to do that.

You are making a virtue out of yet another problem with Orion. Craft with automated docking can always have the crew dock if needed as a fallback. If the crew was to be disabled somehow, the vessel could bring them to safety at Gateway (say they all got so sick they couldn't dock) if it could dock itself. With Orion? Nope.

I just did the math. a 47.8t cargo pushed by FH S2 starts at 7m/s², and at the end of the burn it's 18 m/s². Under a g, to 1.8g max. Not an issue.

I've been looking at this from a slightly different angle. The EUS will apparently put out about 440KN of thrust. 

Assume that is all in shear, that is, for some mad reason you're attaching an EUS to your spacecraft as a strap-on booster.

From a quick poke around on the internet, a standard M39 stainless steel bolt can have a shear capacity of up to 375 KN. Diameter of an M39 bolt - well the clue is in the name - 39mm. Not  exactly a large piece of metal and actually pretty small as bolts go.

My point is that two modules joined by a Common Berthing Mechanism are effectively joined by a bolted structure. Those are strong.That M39 bolt can't quite take an EUS worth of shear but it's not all that far off the mark either. 

 

Edited November 8, 2019 by KSK

[tater]

 

[jadebenn]

This picture is at a better angle, IMO.

[tater]

25 minutes ago, jadebenn said:

This picture is at a better angle, IMO.

The only improvement would be a person in the frame for scale (you can judge from other stuff, but a human is always good).

For people who have a sense of Falcon 9, the RS-25 bell is 2.4m, or about 2/3 of the diameter of a F9 booster.

[KSK]

Yeah, for all the skepticism on this thread, you can't deny that it's one impressive piece of hardware when you see it like that.

[tater]

34 minutes ago, KSK said:

Yeah, for all the skepticism on this thread, you can't deny that it's one impressive piece of hardware when you see it like that.

It's frickin huge, no question.

The other rocket I see sometimes is a Titan missile here at the National Atomic Museum. Titan is ~3m in dia, or about the size of those white rings where the RS-25 engines are mounted.

Edited November 9, 2019 by tater

[kerbiloid]

10 hours ago, tater said:

The only improvement would be a person in the frame for scale

The stairways.