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.
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.
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.
The SLS isn’t owned by the people ether, not really anyways, all the infrastructure and production lines are owned by Boeing which is just as bad as any of the new companies.
Personally I think NASA should just have an internal booster production team/facility like they do with rovers and probes through JPL.
It’s ludicrous to me that the consensus coming out of the space shuttle program and SLS that nasa’s designs were blamed for cost when the cost mainly came from choices made by private interests and contractors.
But still… you’re burning hydrocarbons so you end up producing a lot of CO2 which is going straight into the atmosphere. That’s not what I’d call super green.
If it’s capture from a landfill, it’d likely be released as methane directly into the atmosphere.
If it’s made from things like chaff, it often gets simply burnt and released immediately back as CO2 into the atmosphere. No difference but significant usable energy.
The methane just breaks down into an equivalent amount of CO2 when vented anyways and until then is a much more potent greenhouse gas. That’s why it’s usually flared off apart from safety.
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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.
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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.
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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.
The SLS isn’t owned by the people ether, not really anyways, all the infrastructure and production lines are owned by Boeing which is just as bad as any of the new companies.
Personally I think NASA should just have an internal booster production team/facility like they do with rovers and probes through JPL.
It’s ludicrous to me that the consensus coming out of the space shuttle program and SLS that nasa’s designs were blamed for cost when the cost mainly came from choices made by private interests and contractors.
I hadn’t heard that take before… very interesting to learn of the influence Boeing has on NASA.
I’d recommend looking in to the cost plus contracting system that nasa used for years and that can likely be blamed for the cost over runs and delays.
Let’s just ignore the partially burned polymers and aluminum and stuff billowing out of the boosters, huh?
Elon is a shithead, but that does not make SLS a good rocket.
Natural gas can be green too. You can extract it from landfills or from bioreactors of organic waste.
But still… you’re burning hydrocarbons so you end up producing a lot of CO2 which is going straight into the atmosphere. That’s not what I’d call super green.
It’s carbon that’s already part of the carbon cycle. Like burning wood or consuming food.
The carbon to worry about is the stuff we’re extracting from underground.
And where are the bioreactors located? What would happen to that carbon if it weren’t collected by the reactors?
I agree its better than mined gas, it falls under the 3Rs, but it’s still taking carbon from the ground and releasing it into the atmosphere.
In the grand scheme of things the deus ex machina of fusion is the only long term solution.
If it’s capture from a landfill, it’d likely be released as methane directly into the atmosphere.
If it’s made from things like chaff, it often gets simply burnt and released immediately back as CO2 into the atmosphere. No difference but significant usable energy.
I was absolutely arguing the wrong side of that, sorry. I didn’t realize landfill emissions don’t stay in the ground.
https://www.epa.gov/lmop/basic-information-about-landfill-gas
The methane just breaks down into an equivalent amount of CO2 when vented anyways and until then is a much more potent greenhouse gas. That’s why it’s usually flared off apart from safety.