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NASA finally admits what everyone already knows: SLS is unaffordable
(arstechnica.com)
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this post was submitted on 08 Sep 2023
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It doesn't have potential. It's possible, but not practical. Using hydrogen for transport is snake oil - there are plenty of other industrial uses that should have much higher priority.
In order to meet the global industrial demand with green hydrogen, we would need to dedicate 3x the global renewable generation capacity from 2019 entirely to hydrogen production. That simply isn't going to happen - and that's just trying to deal with demand where there are no other options but hydrogen. If you start adding transport the demand will sky rocket. This is great for those in the business of selling hydrogen, terrible for everyone else.
Hydrogen is also an incredibly inefficient fuel, both in terms of burning it and in terms of energy cost to produce.
Methane is also not exclusively extracted through fracking. You're minimising the negatives of hydrogen and sensationalising the competition.
Yes because Boeing are totally a company for the people, they never take advantage of government contracts and always stay within budget.
Say what you will about SpaceX and the issues with the private sector and publicly traded businesses, SpaceX have revolutionised the rocket industry and driven costs down.
Remind me again, where is SLS taking off from? Who's the one not being honest in their argument here?
Wow. You're not worth speaking to.
Not going to lie, I found your back and forth interesting (and mostly sided with the other person), but the argument was lost for me when they attacked you directly.
You are right, SpaceX brought down costs (in dollars) to move mass into space which has opened many new doors. We can argue and disagree about what the broader and long term costs and outcomes of that change might be, but I didn’t get the feeling you were being a fanboy or unreasonably lavish in your praise.
Kudos for walking away from the conversation.
The other person was just wrong.
Large scale Hydrogen generation isn't generated in a fossil free way, Hydrogen can be generated is a green way but the infrastructure isn't there to support SLS.
Hydrogen is high ISP (miles per gallon) by rubbish thrust (engine torque).
This means SLS only works with Solid Rocket Boosters, these are highly toxic and release green house contributing material into the upper atmosphere. I suspect you would find Falcon 9/Starship are less polluting as a result.
Lastly the person implies SLS could be fueled by space sources (e.g. the moon).
SLS is a 2.5 stage rocket, the boosters are ditched in Earths Atmosphere and the first stage ditched at the edge of space. The current second stage doesn't quite make low earth orbit.
So someone would have to mine materials on the moon and ship them back. This would be far more expensive than producing hydrogen on Earth.
Hydrogen on the moon makes sense if your in lunar orbit, not from Earth.
Thank you for writing this response. My general thoughts on hydrogen for rocketry have been that it doesn't seem worth the trouble (temps, leaks, storage, etc), but I hadn't considered the environmental or future angles. I'm not convinced that it's the right choice now, but thanks for giving me something to think about.
The really annoying thing about hydrogen is that it's most useful once you're already in space, where the density and thrust of the fuel doesn't matter so much and insulation is generally easier. Since all our rockets so far are built and launched from Earth's surface hydrogen ends up being a thing that'd be really nice in concept but not so good in practice.
I wouldn't be terribly concerned with the environmental impact of methane rocket fuel, personally. Although currently Starbase gets is methane shipped in by trucks from elsewhere, SpaceX's ultimate goal with Starship is to land and return from Mars and they'll need to refuel on Mars for that to work. So the long-term plan for Starbase is to build a Sabatier process methane production plant powered by solar panels, much like they'll be building on Mars, to convert CO2 into methane. Once that's up and running Starship will be a carbon-neutral launch vehicle.
No worries. Tbh I kind of jumped on a hydrogen rant, that was all I wanted to talk about, rather than SLS as a whole. I agree we need NASA making things for space, we definitely don't want SpaceX to be the only player. However it bears mentioning that NASA have also contracted SpaceX to make their moon rockets, in exactly the same way they contract Boeing and others (the only difference is SpaceX already had a suitable rocket in development). So there is no sign of NASA rockets going away, if anything they have more suppliers to choose from.
Hydrogen also does have its place in combustion, and it's good that there's some development in this area. However, as someone who works in the electricity industry, adjacent to hydrogen ballooning into the energy markets, I'm intentionally wary of development as much of it seems to be pushed by those looking to sell more hydrogen using disengenuous claims about the reality of it being green.
This is an ad hominem. Please, be nice here...and thank you for apologizing to @TWeaK@lemm.ee.
I mean, we’re talking about hydrogen for rockets here which is an absolutely tiny portion of global fuel consumption, wether or not we should be using it for anything else and the costs and scale of doing so is neither here nor there. ( Personally I think hydrogen powered cars are dumb)
In the context of rocket science hydrogen is just a better fuel in absolute terms. It is ~25% more efficient than methane. It’s less dense and thus needs larger tanks, but due to the square cube law that matters less and less the larger the rocket is, so on particularly large rockets like those going to the moon, hydrogen is just flat out better and leads to smaller less costly rockets if done properly.
The problem is that Boeing has been holding nasa hostage and extracting ransom, I don’t think nasa should be reliant on private companies for it’s rockets, they should have a internal department that develops and builds boosters in a similar way to how JPL works with probes and rovers. It would be costly upfront for sure, but would save money in the long run since it would prevent private companies from exploiting public interests in the future.