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[New] Space Launch System / Orion Discussion Thread


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1 hour ago, RCgothic said:

But in positive news: 

 

Because apparently it's hard to stimulate a countdown.

Well a certain NewSpace company is spending quite a bit of time at the moment practicing launchpad procedures for its own very large rocket. So I’m guessing that there’s more to these countdown thingies than checking the staging, counting backwards from ten, and hitting the spacebar. :)

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But eventually you have to light that candle. And be prepared for a fireball and a lot of mess on the stand. Because rocket science is in fact hard. Does ULA have anything they can sacrifice in the name of testing, or the flight article will be the test article at the same time? That is asking for trouble. SpaceX is at their eighth prototype and they are churning out more, fully expecting more losses along the way. ULA seems to be putting all their eggs in one, very expensive basket.

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On 10/5/2020 at 10:39 PM, Scotius said:

But eventually you have to light that candle. And be prepared for a fireball and a lot of mess on the stand. Because rocket science is in fact hard. Does ULA have anything they can sacrifice in the name of testing, or the flight article will be the test article at the same time? That is asking for trouble. SpaceX is at their eighth prototype and they are churning out more, fully expecting more losses along the way. ULA seems to be putting all their eggs in one, very expensive basket.

It's a different way of doing it and, with SRBs, probably the most practical one. Kind of hard to do a hot-fire test with an SRB and when it comes to the actual launch you really, really want them all to fire correctly at once. Otherwise you most definitely will not be going to space today - and they'll probably be naming elementary schools after your crew.

Edited by KSK
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4 hours ago, sevenperforce said:

!!!!! wow that's dark

Yeah.

Lifted directly from an after-dinner speech from Chris Hadfield. As you'll probably guess, the context was sitting in the Shuttle and hoping that both SRBs do light off together.

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  • 2 weeks later...

It's still very likely SLS launches boilerplate Orion to a lunar free return trajectory before SpaceX lands on the Moon with Starship.

2024 is gone for Artemis III, though, all the dates get pushed back.

 

 

 

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It appears there's a serious issue with an LH2 prevalve on the core stage. The prevalve is not a small bit of plumbing, and it looks to me it may be difficult to access without dismounting an engine.

 

There's also some sort of issue with the TVC test, which wasn't reported when they posted their green tick against test 5 all the way back in mid September. Frankly this suggests a culture terrified of reporting further delays. Not sure this is an improvement on "indifferent to constant delay and expense".

 

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To be fair, they were already behind schedule, and with no margin when JB took over, and then were tasked with a mission and an actual timeline. I think it was clear that all the Artemis dates are, to borrow a word from Elon Musk, "aspirational."

If they had schedule margin, then the dates might be more serious, but they've been fully in 1:1 delay mode for a few years now, hitting target dates requires that everything happens on schedule, and that with facilities on the Gulf Coast (always risky).

Another thing I read was that once they stack the SRBs, they have to fire them within a year, else they have to take them apart and redo them (presumably/possibly related to o-ring aging?).

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I’ve been doing some musings on the Orion MPCV lately and thought this might be the best place to get some feedback from the experts. I’m looking for any sort of discussion be it support or counter-points.

At this point in time it seems Orion is being portrayed as a vehicle meant solely for the specific mission architecture of the Artemis program, however for various reasons that have been discussed it is generally understood that Orion is not well optimized for that mission and could be considered underpowered for the task at hand. We know Orion started life as a multi-purpose vehicle (and even carries that as part of it’s name) but unlike the early Ares 1 concept Orion is not currently planned for any LEO missions, when in fact it seems like the vehicle would be highly optimized for this environment, with room to grow.

What is obvious is that SLS would NOT be the launcher to accompany it in this mission. To put it briefly (since it’s been discussed a lot already) SLS has a “weird” distribution of dV, with most of it being in the booster that delivers an upper stage plus payload into a high-energy eccentric parking orbit, where the upper stage is intended to push to TLI. Orion’s mission from there is dictated entirely by what upper stage it flies with, and ranges from “pretty much nothing” to a basic lunar manned mission, as long as the lander and other assets are already in place through other means... 

But for LEO Orion could be a winner. With the right launcher it could deliver a crew of six to the ISS or similar future station, and possibly more. Why not the ULA Vulcan, which is already coming out the gates with the intention of being man-rated for the Starliner? The first upside being that a bridge exists between Orion’s manufacturer and ULA (Lockheed) and that this should entail similar suppliers and contractors, as well as possibly hardware and avionics.

Secondly, the bulkhead diameters are nearly identical, and taking the existing SLS Block 1 stage adapter and fitting it atop a Centaur V would be a relatively light bit of engineering. Third, though I slacked on the calculations since neither vehicles have flown yet, a Vulcan/Centaur V should be plenty of dV to put an Orion into LEO where it’s service module could put it into a number of useful orbits. 

Another hidden benefit I’ve taken note of is the unique design of the Orion. It’s “stepped-up” profile from the service module to the capsule creates an empty void between the vehicle and the aero shroud. Couldn’t a specially shaped payload be comanifested here? This could also provide a space for external instruments, like a light robotic arm that tucks up to the service module, useful maybe for satellite servicing missions or other stations besides the ISS that aren’t equipped with something like the CanadArm.  You’ve also got the stage adapter that could comanifest a small pressurized payload container, whereby Orion could detach, transposition, and dock in the same manner as Apollo.

All I’m saying is, from a drawing board standpoint, Orion seems like a great vehicle to grow and build on for future LEO missions. But, I suspect the reason that isn’t really on the table is political reasons. And the manufacturer/NASA probably doesn’t feel like the cost would be competitive with other commercial options nearing maturity. But on that point I think the capability would justify the added cost.

Thoughts?

 

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7 minutes ago, lemon cup said:

Secondly, the bulkhead diameters are nearly identical, and taking the existing SLS Block 1 stage adapter and fitting it atop a Centaur V would be a relatively light bit of engineering. Third, though I slacked on the calculations since neither vehicles have flown yet, a Vulcan/Centaur V should be plenty of dV to put an Orion into LEO where it’s service module could put it into a number of useful orbits. 

Vulcan Centaur heavy has a LEO payload basically equal to the Orion CSM combo—the problem is that the LAS is another ~7.5t, so I am unsure how much that reduces the LEO throw of Vulcan.

Seems like the only alternative LV would be New Glenn—which can easily put Orion into any LEO orbit.

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24 minutes ago, tater said:

Vulcan Centaur heavy has a LEO payload basically equal to the Orion CSM combo—the problem is that the LAS is another ~7.5t, so I am unsure how much that reduces the LEO throw of Vulcan.

Seems like the only alternative LV would be New Glenn—which can easily put Orion into any LEO orbit.

Much heavier than I remember. So the best way to justify that much mass in an LEO crew  vehicle would be with a reusable booster like New Glenn. That is an even more exciting prospect to me, but the question is, is that remotely likely given the state of the industry?

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State of New Glenn as far as public knows is: Virtual.

We can only assume it's being built, but we have no idea how close to completion it is or what are preliminary capabilities. Presumably NASA knows, and is tailoring their plans accordingly.

Not much else can be said of the situation.

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Orion is too heavy for LEO missions. So it can do 7 crew to LEO? So can Dragon2 and Starliner, for much *much* less money. Dragon2 can also co-manifest cargo in the trunk.

 

For a Lunar architecture, Orion's service module should have been upgraded and SLS should have been straight to Block 1B, which would have had enough TLI throw to support that.

SLS should also have been much cheaper and be able to fly much more often.

 

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19 minutes ago, RCgothic said:

For a Lunar architecture, Orion's service module should have been upgraded and SLS should have been straight to Block 1B, which would have had enough TLI throw to support that.

Doesn't really buy much even then. The Orion capsule is just too heavy. Adding a decent SM could be done, but then you get crew in a useful lunar orbit for surface access... and nothing to do there.

For some reason, SLS proponents seem to think that lunar orbit rendezvous is somehow easy, while Earth orbit rendezvous is impossibly difficult, and harms chances for mission success. Because reasons.

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