NASA Delays Artemis II To March (nasa.gov) 49
During tanking, engineers spent several hours troubleshooting a liquid hydrogen leak in an interface used to route the cryogenic propellant into the rocket's core stage, putting them behind in the countdown. Attempts to resolve the issue involved stopping the flow of liquid hydrogen into the core stage, allowing the interface to warm up for the seals to reseat, and adjusting the flow of the propellant.
Teams successfully filled all tanks in both the core stage and interim cryogenic propulsion stage before a team of five was sent to the launch pad to finish Orion closeout operations. Engineers conducted a first run at terminal countdown operations during the test, counting down to approximately 5 minutes left in the countdown, before the ground launch sequencer automatically stopped the countdown due to a spike in the liquid hydrogen leak rate.
Completely Predictable (Score:1)
There's always at least 1 hydrogen valve issue. Perhaps they should redesign their valves?
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It's also a microcosm of the Challenger disaster o-ring failure. :(
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It's also a microcosm of the Challenger disaster o-ring failure. :(
Except this time the hats made the right decision to abort and reschedule.
So...progress?
Re:Completely Predictable (Score:5, Insightful)
There's always at least 1 hydrogen valve issue. Perhaps they should redesign their valves?
There's always at least 1 hydrogen leak issue. Perhaps they should redesign their rocket.
Valves, connectors, o-rings shrinking from cold temperatures, loose pins blowing out at high speed causing tiny nicks in tubing that hydrogen leaks through very easily... these are just a few of the many ways hydrogen can go wrong.
Hydrogen is not the answer. Hydrogen is the question. "H*ll, no" is the answer. In any sane universe, it's far better to have to lift 80% more fuel for your upper stages than to keep canceling or delaying launches for months at a time to avoid blowing up... and still blow up once (Challenger) and almost twice (Columbia in 1999).
IMO, it was a big mistake to go with hydrogen as the main engine fuel, and anyone who studied the history of the shuttle should have reached that conclusion long before Artemis was planned, or even Ares. But it was more important to keep jobs in the districts where the Space Shuttle main engines were manufactured than it was to build something reliable, so we got the best design that a committee of career politicians could produce.
Now we're stuck with it, at least until SpaceX has a human-rated Starship launch vehicle. And at that point, I hope the remaining Artemis hardware will be quietly scrapped as the mistake that it was.
Re:Completely Predictable (Score:5, Informative)
In any sane universe, it's far better to have to lift 80% more fuel for your upper stages than to keep canceling or delaying launches for months at a time to avoid blowing up...
That depends entirely on your goal, so a judgement of sanity isn't really on point.
One could also argue that, in a sane universe, it's far worse to have to lift 80% more fuel for your upper stages (and not to mention the required additional fuel on the lower stages to life the extra fuel for your upper stages) than to delay a launch. Hell, one could argue it's fucking absurd, unless one also gets super excited about it taking a month of orbital refueling to get your rocket.... well, fucking anywhere.
Realistically, we need to get better at handling hydrogen.
I'm aware of its problems, but I think much of the extant problems are because it's too easy to just "work around them", rather than really fix them.
at least until SpaceX has a human-rated Starship launch vehicle.
lol... A human-rated Starship... isn't going *anywhere* fucking close to the moon, unless we've also got a magical fuel depot waiting in orbit for it, itself fueled by a dozen or so launches, waiting for it.
Re:Completely Predictable (Score:4, Interesting)
Part of the reason (not all) that Starship will require so much fuel is because of its size and payload capability, which is FAR greater than any other design has proposed thus far. That's not to say that Hydrogen isn't a more efficient fuel relative to methane. It is, 2x-3x more energy efficient by weight, but not necessarily by Volume which also matters.
I only say this because the details matter. It's not as if swapping Methane for Hydrogen lends itself to an Apples-to-Apples comparison. It's more complicated than that.
Re:Completely Predictable (Score:5, Informative)
Part of the reason (not all) that Starship will require so much fuel is because of its size and payload capability
I'd say more so it's construction from steel. Size doesn't really play a large role, and empty space is quite cheap to launch.
I only say this because the details matter. It's not as if swapping Methane for Hydrogen lends itself to an Apples-to-Apples comparison. It's more complicated than that.
Absolutely- it's not apples-to-apples.
However, the efficiency increase would be enough to turn an Earth-to-Moon Starship mission from "Every trip is an appreciable fraction of the logistical difficulty of building the fucking ISS" to, "alright- that's not bad."
And this is ignoring that both things parent mentioned had nothing to do with hydrogen, anyway.
Musk uses methane because he dreams of refueling the thing on Mars, which is also why it's focus is on its frankly absurd refueling requirement, rather than trying to make the thing actually good at going places locally.
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LOL, what? I don't know what measure of "logistics" are you using, but the only sensible measure is USD
Incorrect.
In fact, that sentence indicates a complete lack of understanding of what that word means.
The logistics involved with getting a Starship from LEO to NRLO, is the fact that you have to launch 20 total Starships to get it there.
Of course nobody has 20 Starships.
This means you'll have to launch x Startships 20/x times, each, hoping they require basically no maintenance between launches.
It's estimated the quickest this could be done, assuming everything magically went perfect, would be ~30 days.
Re:Completely Predictable (Score:5, Informative)
One could also argue that, in a sane universe, it's far worse to have to lift 80% more fuel for your upper stages (and not to mention the required additional fuel on the lower stages to life the extra fuel for your upper stages) than to delay a launch. Hell, one could argue it's fucking absurd, unless one also gets super excited about it taking a month of orbital refueling to get your rocket.... well, fucking anywhere.
A 1.8x increase in fuel consumption is not going to make it take a month unless it was already going to take 18 days with hydrogen. We're not talking about orders of magnitude here. We're talking about a relatively small difference in the amount of energy per unit of mass. And in exchange for that relatively small reduction in payload capacity, launches have to endure constant failures that more traditional launch systems don't.
Even ignoring the risk of embrittlement causing an in-space disaster, I'm pretty sure nobody is seriously considering using hydrogen for orbital refueling because of the leaks alone. There's no way to fix them in space, so you'd have to launch your fuel right before you need it. For that reason alone, I don't think they're even seriously considering it for refueling on Mars. Hydrogen is being used for getting humans into orbit and lifting payloads. The only refueling that I'm aware of is by Starship, whose in-orbit parts are methane-based.
Realistically, we need to get better at handling hydrogen.
Realistically, NASA and its contractors have been struggling to achieve that for more than fifty years and still haven't pulled off. I mean sure, people who don't try again after a failure never succeed, but if you keep trying over and over and still don't succeed, at some point, it makes sense to acknowledge that you're never going to be good enough and stop trying. Insanity is doing the same thing over and over again and expecting different results. And here we are 50 years later, and hydrogen leaks still are repeatedly unmanageable. They're not even trying to stop leaks completely — just keep them below the threshold where the rocket would blow up. Yikes.
For orbital refueling to be possible with hydrogen, you'd need to stop leaks completely, and have the whole system remain leak-free after enduring the shock of getting launched into space. I would not want to place bets on that happening any time soon.
I'm aware of its problems, but I think much of the extant problems are because it's too easy to just "work around them", rather than really fix them.
To some degree, sure. On the flip side, other than the engines themselves, somebody designed this thing from scratch relatively recently. They could have designed it to be slightly bigger with methane for the top stage fuel, and you wouldn't *need* to solve any of those problems, because they would be solved by virtue of the fuel not being such a pain in the a** to work with.
It's one thing to solve problems that have to be solved. It's another to spend huge amounts of money to solve problems primarily because politicians insisted on reusing leftover shuttle parts to keep jobs in their districts. If throwing a little bit more fuel at the problem solves a problem, I say throw more fuel at the problem.
at least until SpaceX has a human-rated Starship launch vehicle.
lol... A human-rated Starship... isn't going *anywhere* fucking close to the moon, unless we've also got a magical fuel depot waiting in orbit for it, itself fueled by a dozen or so launches, waiting for it.
A human-rated Starship is exactly what they're planning to land on the moon. And it uses methane. And yes, they're planning to use multiple refueling launches to get it into the correct orbit.
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A 1.8x increase in fuel consumption is not going to make it take a month unless it was already going to take 18 days with hydrogen. We're not talking about orders of magnitude here. We're talking about a relatively small difference in the amount of energy per unit of mass. And in exchange for that relatively small reduction in payload capacity, launches have to endure constant failures that more traditional launch systems don't.
No- it's a matter of having to refuel, and not.
If you can use non-hydrogen to complete your mission without refuelling, then you're fine and dandy.
If not, you're looking at a Starship-style dumbfuckery.
A human-rated Starship is exactly what they're planning to land on the moon. And it uses methane. And yes, they're planning to use multiple refueling launches to get it into the correct orbit.
That Starship will be in orbit around the moon, and placed there without any humans in it.
In no universe are they launching humans from the Earth in a Starship, and sending them to the moon. The amount of fuel it would take is fucking clown shoes.
I.e., it's a very expensive elevator.
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It will have enough fuel left over after this to do exactly one landing and launch off of the lunary surface, back to LLO. The crew will then be taking Orion back.
It is seriously comically stupid.
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The Starship's payload is a problem they are actively working on. The original goal was 200 tons to LEO, but the Starship v2 was only theoretically capable of ~30 tons (v2 will never actually go into orbit anyways). The v2 that has flown to-date did not have a workable payload for the size of the vehicle. The problem is/was dry mass being too high. Supposedly v3 (set to launch next month) can do 100 tons and v4 (which does not yet exist) sets the original target of 200 tons. Whether they have achieved even
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Given all of that, do we think V3 is going to put 100t into orbit? Na, I don't. Especially since V2 was supposed to.
I know they've got really good engineers over there doing their shit. But they're also working under someone who is quite simply disconnected from reality, and has temper tantrums whe
Re:Completely Predictable (Score:4, Interesting)
That Starship will be in orbit around the moon, and placed there without any humans in it.
That Starship will be in orbit around/near the Earth and the moon, and will be placed there without any humans in it. But what you seem to be missing is that not all of the fuel is required just to get it into that orbit. It has to be in that orbit and still have enough fuel to land on the moon and then return to that orbit.
In no universe are they launching humans from the Earth in a Starship, and sending them to the moon. The amount of fuel it would take is fucking clown shoes.
Starship and Super Heavy are obviously designed to lift a lot more mass to orbit, and are therefore massively overbuilt for the job. But assuming we're just talking purely theoretically in terms of fuel consumption, rather than talking about how much mass you're planning to take into orbit, the approach Starship uses is likely to almost break even with the approach that SLS uses, because the efficiency gains from hydrogen are wiped out by the efficiency losses from the solid rocket boosters.
The SLS's solid rocket boosters have a specific impulse of 269 seconds versus Super Heavy's 327 seconds. I'm not certain precisely how solid versus liquid oxidizer impacts the numbers, but if I understand correctly, then at least in theory, the SRBs use roughly 1,256,000 kg of solid fuel and oxidizer to do what a methane-based rocket like Super Heavy could do with 1,033,223 kg of fuel and oxidizer. That's about 222,777 kg more mass than necessary.
Meanwhile, the hydrogen parts of SLS use 144,000 kg and 129,000 kg of hydrogen, respectively, which is roughly equivalent to about 260,000 kg of methane and 232,000 kg of methane, respectively. or about 218,000 kg of extra mass.
So I'm pretty sure SLS's inefficient solid rocket engines almost perfectly cancel out the efficiency boost they get from using hydrogen instead of methane, to within some reasonable margin of error, ignoring timing differences in when the fuel is used.
Mind you, this is not the whole story, since the inefficient fuel that SLS uses burns off during the first part of the launch, while the less efficient methane that Starship uses would be carried through the entire flight. So it *would* take more fuel to move that extra fuel mass during the upper parts of the flight, but unless I'm missing something major, it would definitely not be "f**king clown shoes" to lift a payload the size of an Orion capsule to a lunar halo orbit (NRHO), or at least not much more so than it already is.
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That Starship will be in orbit around/near the Earth and the moon, and will be placed there without any humans in it. But what you seem to be missing is that not all of the fuel is required just to get it into that orbit. It has to be in that orbit and still have enough fuel to land on the moon and then return to that orbit.
Incorrect. Starship requires complete refueling (1200t) to get to NRHO from LEO.
The mission currently looks like this:
They launch a tanker (or we can skip this and add 2 more Starship launches to the tally).
They launch 18 more Starships to fill that tanker.
They launch HLS. They fill HLS from tanker. They send HLS to LLO, with enough fuel for exactly one descent and ascent.
Starship and Super Heavy are obviously designed to lift a lot more mass to orbit, and are therefore massively overbuilt for the job. But assuming we're just talking purely theoretically in terms of fuel consumption, rather than talking about how much mass you're planning to take into orbit, the approach Starship uses is likely to almost break even with the approach that SLS uses, because the efficiency gains from hydrogen are wiped out by the efficiency losses from the solid rocket boosters.
The problem isn't that they're "overbuilt". It's that they're fucking heavy as fuck, and inefficient as fuck. It takes an absurd amo
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That Starship will be in orbit around/near the Earth and the moon, and will be placed there without any humans in it. But what you seem to be missing is that not all of the fuel is required just to get it into that orbit. It has to be in that orbit and still have enough fuel to land on the moon and then return to that orbit.
Incorrect. Starship requires complete refueling (1200t) to get to NRHO from LEO.
Technically correct — the best kind of correct.
SLS can't reach NRHO, either. It just lifts the Exploration Upper Stage to LEO. The EUS is what goes to NRHO. The only fair comparison is not between Starship and SLS + EUS, but rather between Starship and SLS by itself.
The first three SLS flights (Block 1) have a payload capacity to LEO of 95 metric tons. The fourth flight (the one with the EUS attached) will raise that to 105 tons.
Starship is, of course, still a bit of an open question, because they
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SLS can't reach NRHO, either. It just lifts the Exploration Upper Stage to LEO. The EUS is what goes to NRHO. The only fair comparison is not between Starship and SLS + EUS, but rather between Starship and SLS by itself.
Erm. Yes, SLS is a staged rocket. It's quite silly to say that it "can't make it to NRHO".
Let's flip it around.
Starship couldn't put an EUS into NRHO, in any configuration, until it was fully refueled with another 1200t of propellant.
The first three SLS flights (Block 1) have a payload capacity to LEO of 95 metric tons. The fourth flight (the one with the EUS attached) will raise that to 105 tons.
Don't get caught up on LEO. It's not going to LEO. It's not a good rocket for going to LEO. 1) It's not a reusable rocket. What the hell you gonna stack that thing up just to put 100t in orbit for, when something like Starship exists?
SLS Block 1 can put 27kg into TLI. Starsh
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Ah, the tyranny of the rocket equation strikes again.
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Ah, the tyranny of the rocket equation strikes again.
Not really. Not when the partially solid first stage of SLS is as inefficient as it is. Like I said elsewhere, the total fuel mass is pretty similar. At worst, with methane all the way, you might be lifting more of it slightly farther than you otherwise would have been, but even that part, I'm not so sure about.
The only question is whether methane could realistically be used for the additional stage that transfers from LEO to NRHO. But they haven't even started testing that yet. They're still hopelessl
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The reason they use inefficient fuel on the boosters and not on the upper stages is *because* of the rocket equation.
The difference between hydrogen and methane isn't an order of magnitude for a moon rocket, but it is somewhere in the neighbourhood of 3x the launch mass. Quite a bit more back when NASA was actually making the choice too. You'd have to actually run the numbers but I suspect it is the difference between a direct to the moon launch being just on the edge of practical possibility and requiring
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We're talking about a relatively small difference in the amount of energy per unit of mass.
Yeah, but the rocket equation is a bitch. Small differences matter.
It's not like Artemis, or the Shuttle, were the first rockets to ever use hydrogen. It's been used by multiple launch systems, particularly upper stages, because that added performance is really advantageous. Yup, it's a bitch to work with, but not so much that rocket designers in many places over decades haven't reached for it.
At the opposite extreme are hypergolics. Energetic, store-able, not cryogenic. But also wickedly toxic,
Re:Completely Predictable (Score:4, Informative)
Challenger was a problem with a solid fuel booster. No hydrogen involved. Columbia was an issue with ice, which would be a problem for any cryogenic fuel... basically anything other than solid fuel.
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Challenger was a problem with a solid fuel booster. No hydrogen involved.
Gah. My bad. I mixed up my o-rings.
Scalable vs One-Off, not H2 vs CH4 (Score:2)
Totally agree. Also:
Yes, H2 is very difficult to handle and seal etc. Even harder on a lightweight vehicle. Even harder to make a reusable one as H2 makes structures become brittle over time. But it is the golden child with a high Isp so science heads reach for it always. But....
It is very difficult to mass produce flightweight H2 systems. And if you have a problem that requires scale, then you have squared or cubed the difficulty of the problem: a difficult to handle material, cryo temperatures, lightwei
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Hydrogen is atomically as small as a fuel can get.
It is prone to leak out somewhere and that is why the hydrogen conversion for cars isn't taking off.
Even Edison set a submarine on fire with his hydrogen leaking batteries a century ago.
Deja Vu? (Score:5, Informative)
Freezing temperatures in Florida. Leaking o-rings. Fuel leak.
Why do I have this sense of deja vu?
For the record, I fully expected the launch to be delayed. just Artemis things.
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Freezing temperatures in Florida. Leaking o-rings. Fuel leak.
Why do I have this sense of deja vu?
Yeah, deja view all over again. I saw an article yesterday from a fluff site saying something like "NASA picked the worst week to fly Artemis", and I immediately thought about temps and polar vortices. Not at all. They went on about how the Olympics are starting, Superbowl is Sunday, and Artemis is going to be knocked out of the news/viewing cycle. I thought, "That's it? That's all?".
My last thought leaving the article was wondering if that was a valid conclusion. Tagging in with the world's biggest TV show
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I didn't see the explosion live but I heard about it when I got to work. That day wasn't very productive.
but which (Score:1)
Space is hard. Very hard. (Score:2)
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That's why we deliberately choose hydrogen, one of the most difficult to handle substances we can come up with in order to power our big ass rocket.
And in order to increase the difficulty yet again we choose to use politically picked contractors who are not really competent to do the job in order to build our big ass rocket.
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Heh. Interesting interpretation to "We do not do these things because they are easy, we do these things because they are hard!"
Re: Space is hard. Very hard. (Score:2)
We do these things not because they make sense, but to try to prop up a failing defense contractor
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We do these things not because they make sense, but to try to prop up a failing defense contractor
"We do not do these things because they make cents, we do these things because they make dollars!"
Please consider this suitably modified.
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That's why we deliberately choose hydrogen
Meh. So do the Chinese. So do the Europeans.
Its only downside is density. Its mass efficiency is ridiculously better.
For a traditional staged rocket- that just makes sense.
Lifting methane to space in order to burn it there borders on stupid.
Also, we've had exactly zero hull losses caused by the use of hydrogen. It is more complicated and more expensive, though.
And in order to increase the difficulty yet again we choose to use politically picked contractors who are not really competent to do the job in order to build our big ass rocket.
I think this is probably our primary problem.
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"Its only downside is density."
No, another downside is that it's damned hard to make the fuel system hydrogen-tight. Other fuels are easier for a fuel system to handle. As this incident has just demonstrated.
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Many solved problems were once hard.
This incident doesn't demonstrate that it's hard. It demonstrates that we can no longer handle hard.
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Yes, it has been solved. Yes, the fact that they don't seem to be able to solve it here is an indictment of the project. It doesn't change the fact that it is a difficult problem is a downside to using hydrogen, contrary to the original post.
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Given the newfound incompetence in the use of LH2- it's indeed a downside.
For other Space Agencies run by competent individuals rather than political bureaucrats- it's not a downside.
For ours, which is run by incompetent political bureaucrats, it is indeed a downside.
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I would submit that its a downside even if you *do* have the competence, because you have to devote effort and resources to cope with it, and that cost is a downside.
Boeing again (Score:2)
Kind of disappointing, but not surprising. They had the same issues with Artemis-1, so why are they still having problems? Seems like they didn't solve the problems at all, just "try enough times until you get fuel flow without leaks".
The Shuttle used LH2. The second and third stages of the Saturn-V rocket used LH2. The Centaur upper stage uses LH2 since 1962 and is still in service. A modified version or Centaur is even the upper stage for SLS. Forget all the BS from Boeing about how "LH2 is hard to handle
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Correction. The SLS upper stage "ICPS" is based off of Delta Cryogenic Second Stage, not Centaur. Although it does also use LH2.
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The Chinese are using LH2 for heavy lift. The Europeans are using LH2 for heavy lift.
If you're one of the big boys who can handle an engineering challenge, you are using LH2. Why? Because it's vastly fucking more efficient per gram, and how deeply the rocket equation penetrates you comes down to one thing- that efficiency.
This is definitely a stupid problem to have.
We shouldn't be using rockets... (Score:1)
... to get to orbit. We should have at least one ClarkeTower/Beanstalk up by now. (aka space elevator)
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... to get to orbit. We should have at least one ClarkeTower/Beanstalk up by now. (aka space elevator)
And you have a 100,000-km spool of stronger-than-any-current-bulk-material sitting around? Are you spending your days addressing the technical challenges of making one? Then please stop armchair grousing that somebody else hasn't delivered your pet solution yet.
SLS delayed... again... (Score:3)
hydrogen (Score:2)
Hydrogen is a nightmare to work with. Even though it has the best specific thrust or whatever they call it, for example SpaceX I believe eschiews it as too much of a problem. This Artemis thing will not go well, I fear.