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I agree with most people that it would be nearly impossible without a Manhattan Project style commitment from the Government and I don't see that happening. Th

I agree with most people that it would be nearly impossible without a Manhattan Project style commitment from the Government and I don't see that happening. That said, an interesting thought experiment would be to put a Falcon 9 second stage to 'sleep' on an up coming mission for a couple of weeks and then have it wake up and relight. If that works push it to a month. With a system like that you could Falcon Heavy to launch a return stage into a Lunar transfer orbit and have it go into orbit at the moon. Then launch one into LEO. Finally launch a service module and landing craft rendezvous with the stage in orbit, burn to the moon. Land, take off, rendezvous with the lunar return stage, and fly back. This uses all "known" technology from SpaceX with a new lunar lander but we know that SpaceX has the propulsive landing chops to pull that off. It avoids the currently "unknown" technology of refueling a cryogenic rocket in space. It does require a reasonable launch cadence on SpaceX's part which is why the experiment of can you leave a cryogenic stage around and relight it.

NikolaeVarius 7y ago
They've done extended, multiple relight tests of the second stage as part of their Air Force mission rating tests. I don't think it is anywhere near designed to stay usable after multiple days of staying cold, that is a completely different mission profile from what the second stage was designed to do, aka earth orbit missions. I would expect the stored cryogenics would not take well to it.
- m4rtink 7y ago
  Exactly, the main issue is the liquid oxygen on board - withou either active cooling or very clever isolation, there will not be any left after a while, as it will evaporate. The soviets did experiments with a blok d upper stage that was also kerosene/LOX and were able to push it to a couple days, maybe up to a single week. So really multiple weeks are not doable due to LOX alone withou turning your already mass limitted upper stage to an advanced orbital propelant depot. Also longer term you will start hitting also other issues, such as battery power (might need to add solar panels), stuff getting too cold/hot, long term exposure of electronics to cosmic radiation, lack of ulage fuel, etc.
  - ChuckMcM 7y ago
    This was the ULA paper I read about 5 years ago : https://www.ulalaunch.com/docs/default-source/extended-duration/micro-gravity-cryogenic-experiment-opportunity.pdf https://www.ulalaunch.com/docs/default-source/extended-durat... There are a number of papers on the ULA site describing fairly innovative ways to keep the LOX from boiling away. As this stage would not have a "payload" in the traditional sense it could have a refrigerator attached :-)
harryh 7y ago
a Manhattan Project style commitment The Manhattan Project spent about 2 billion over a 5 year period. That's around 23 billion in today's dollars. The 5 year budget for NASA exceeds 100 billion dollars.
- ChuckMcM 7y ago
  Interestingly enough, Ars Technica is reporting today that NASA pegged the cost of meeting this timeline at $35B (https://arstechnica.com/science/2020/02/nasa-puts-a-price-on-a-2024-moon-landing-35-billion/ https://arstechnica.com/science/2020/02/nasa-puts-a-price-on...) so your estimate of the cost of a Manhattan Project and my suggestion that it was that order of magnitude seem to both be correct!

NikolaeVarius 7y ago

They've done extended, multiple relight tests of the second stage as part of their Air Force mission rating tests. I don't think it is anywhere near designed to stay usable after multiple days of staying cold, that is a completely different mission profile from what the second stage was designed to do, aka earth orbit missions. I would expect the stored cryogenics would not take well to it.

m4rtink 7y ago
Exactly, the main issue is the liquid oxygen on board - withou either active cooling or very clever isolation, there will not be any left after a while, as it will evaporate. The soviets did experiments with a blok d upper stage that was also kerosene/LOX and were able to push it to a couple days, maybe up to a single week. So really multiple weeks are not doable due to LOX alone withou turning your already mass limitted upper stage to an advanced orbital propelant depot. Also longer term you will start hitting also other issues, such as battery power (might need to add solar panels), stuff getting too cold/hot, long term exposure of electronics to cosmic radiation, lack of ulage fuel, etc.
- ChuckMcM 7y ago
  This was the ULA paper I read about 5 years ago : https://www.ulalaunch.com/docs/default-source/extended-duration/micro-gravity-cryogenic-experiment-opportunity.pdf https://www.ulalaunch.com/docs/default-source/extended-durat... There are a number of papers on the ULA site describing fairly innovative ways to keep the LOX from boiling away. As this stage would not have a "payload" in the traditional sense it could have a refrigerator attached :-)

harryh 7y ago

a Manhattan Project style commitment The Manhattan Project spent about 2 billion over a 5 year period. That's around 23 billion in today's dollars. The 5 year budget for NASA exceeds 100 billion dollars.

ChuckMcM 7y ago
Interestingly enough, Ars Technica is reporting today that NASA pegged the cost of meeting this timeline at $35B (https://arstechnica.com/science/2020/02/nasa-puts-a-price-on-a-2024-moon-landing-35-billion/ https://arstechnica.com/science/2020/02/nasa-puts-a-price-on...) so your estimate of the cost of a Manhattan Project and my suggestion that it was that order of magnitude seem to both be correct!