NASA Artemis I Launch
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They pump it back. But some of it warms and turns to gas while it's being "used", so that part bleeds off.
> While the vehicle is filled with liquid propellant, some of the LH2 is consumed for engine conditioning and some boils off inside the tanks. If a launch attempt was to be scrubbed after waiting through a whole two-hour launch window, and the propellants in the tanks were drained back into the spheres, they would end up being over 280,000 gallons short of the LH2 needed for another attempt.
https://www.nasaspaceflight.com/2021/11/artemis-1-launch-per...
Something that should have been tested during the wet dress rehearsal, but because of a hydrogen leak issue, they never completed the wet dress and this was not tested.
Hmm, skipping tests. SHIP IT.
Does that mean they sent people out to the pad while it was still fueled?
BTW: from a casual point of view it looks suspiciously like a shuttle launch stack without the shuttle.
edit: it looks like it has been scrubbed
It’s probably 100 times cheaper, and 10x faster, to focus on unmanned space projects:
https://www.nybooks.com/articles/2004/04/08/the-wrong-stuff/
In the year 2100, a lot more humans will have gone to space if we iterate quickly with unmanned projects for a few decades then as our capabilities increase, send humans.
Given falcon 9 has been launching crew dragon for a numbe of years, and Starship is the selected lander, and falcon heavy exists for heavy lift, why continue with the SLS?
I for one will enjoy watching the launch, and am excited by humans travelling to space, but would have like to see NASAs stop shovelling good money after bad.
NASA is a political organization created by politicians for political purposes and remains beholden to politicians for its continued existence. The engineering innovation, science, and exploration of NASA programs are wonderful side effects. The bad news is that it’s always primarily political but the good news is that as long as the political purposes remain relevant then the overall budget is reasonably safe. With competition with China, and the burgeoning commercialization of space its relevance is likely to grow.
I think this will be a much more pressing question (if?) after Starship starts flying regularly and finishes its demo mission to the moon as part of its Artemis obligations. It's easy to rationalize SLS with whataboutism while Starship is in development - particularly since SpaceX favors a hardware rich style. I'm not saying that this is good decision making, just that the arguments are plausible - the fig leaf is dense enough to do its job.
But if Starship is able to achieve and/or surpass the flight rate and safety record of Falcon 9, it'll be much more difficult to criticize; and consequently, it'll be much more difficult to support continued SLS development.
> I ... would have like to see NASAs stop shovelling good money after bad.
I too would like to see that. But I'm not particularly optimistic.
SLS is a worse system than Apollo, if anything we have regressed.
All indications point towards the opposite - that he considers low cost and high performance to be more important, and that vertical integration is an important part of achieving both of those goals.
While it's true that SpaceX is doing work in CA, FL, and TX, there's not much indication that they'll be farming out subcomponent work to high-40s number of states ala the Shuttle/SLS.
Thinly veiled welfare or a grandfathered in earmarks depending on your perspective.
Because having your human space program depend on a single launch provider is not great? This is not a SpaceX dig: for years, NASA had to rely exclusively on Roscosmos,and that wasn't ideal either.
NASA can "waste" money now and ensure there's some level of competition across the board later, or be subject to gauging in each specialist niche in the future
IMO, it's just much more effective to do both with the same system - like Falcon 9 which can fly Crew Dragon, but can also do regular cargo to orbit. It's important to improve systems like life support, etc. Launch is not enough.
Architecture becomes toxic when you can only launch with crew ala the Shuttle. SLS is pretty close to that - there is technically a cargo version of the rocket, and there are theoretical plans to launch deep space probes. But with Artemis using 1 (and according to some sources, up to 2) SLSes per year, that doesn't leave many available for cargo missions.
For example, the SpaceX moon lander is likely to use several tankers. And some of the landers might just ship cargo.
“In the year 2100, a lot more humans will have gone to space if we iterate quickly with unmanned projects for a few decades then as our capabilities increase, send humans”
My way gets more humans into the solar system faster. Sending humans to the moon by 2029 with NASA then a few to Mars 10-15 years later is the slow way.
Then, the idea that things would be substantially cheaper without man-rating is also based on shaky assumptions. The fact is large space probes are extremely expensive pieces of hardware and launch windows for certain missions are uncommon, so even if humans aren't on board it is still extremely undesirable to lose a probe to an engineering failure. Indeed while putting a price on human life is extremely taboo, the fact is that in situations where such a price must be determined, it usually comes out to the low tens of millions of USD. Compared to the multibillion dollar costs of many space missions, it makes sense to treat them with the same care as human life.
Finally, the idea that quickly iterating unmanned projects will make human spaceflight safer doesn't make much sense. If you're not using safety systems regularly, and you're not under pressure to improve them, why would one expect to gain useful experience and develop better improved versions? If anything, in the future we should have more capable probes that swing the pendulum further away from human spaceflight.
I think astronaut lives are much more expensive. I don't know how much the launch abort system costs but I suspect the overall budget more than makes up for the value of the lives of the crew if the crew was made of random people.
Astronauts are exceptional people, and their training is awefully expensive. Not only that but they are public figures. If an astronaut dies in a way that could have been prevented, public opinion will not be kind to those who "cheaped out", and since it is a government program and public opinion is everything in politics, the consequences will be huge.
Pricing human lives is taboo, an even more so if we consider that some lives are more valuable than others, but it has to be done, we can't make do risk analysis without doing that, and NASA probably did. I wonder what the number is, but I wouldn't be surprised if it was more than a billion.
I get anxiety just when the DEV pipleline fails after my change.
Learning about problems and solving them were comforting. It increased everyone's confidence that we had built a robust and predicable system. The head of the software test team would have snuck into the capsule if he could!
I help design UAVs for medical deliveries now, and while it's really satisfying work, launching a new UAV prototype is only a small fraction of the adrenaline rush of launching a falcon 9 rocket!
It's also the case that, if you take manned missions of the table into an indefinite future, a lot of the rationale for many unmanned missions goes away too.
Seriously, with a little imagination …
Those voters, by the way, also like jobs.
- "... Engineers are now investigating two other issues. The first is a possible “crack in an intertank flange.” The second is that a hydrogen bleed line to chill one of the four core-stage engines before ignition is not quite working correctly. When the countdown clock reaches T-10 minutes, there is a planned hold. That is when managers will decide a target launch time (Unless the launch is called off before then)."
- "The countdown is paused at T-40 minutes as engineers try to troubleshoot the issue with the hydrogen bleed line."
https://www.nytimes.com/live/2022/08/29/science/nasa-moon-la...
https://blogs.nasa.gov/artemis/2022/08/29/engineers-troubles...
More and more I have to wonder how long they will continue to work on this and just cut their losses?
At some point this isn't just a money sink but is a bad look and I worry can put doubt on space and NASA in general?
Hydrogen leak in one of the H2 lines. Bummer!
Listening to nasa administrator Nelson go on about how effective SLS is - also a bit mind warping. On what measure?
The Biden admin has some bug going on about spaceX - Kathy got demoted / sidelined a bit at NASA after doing commercial crew - she or many others in nasa far better administrators. Instead we get sn old white guy Nelson - and I’m an old white guy. His claim to fame is sls support. Ugh
I think most people who are familiar with rocket launches understand that the countdown is really a time indexed checklist, which can pause or even reverse depending on sensor readings from the rocket.
Admittedly, that can be a bit confusing for the casual observer.
Scrub-a-dub-dub