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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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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.