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> Conversely, if SpaceX and Blue Origin can’t make cryogenic refueling work, then NASA has no plan B for landing on the moon. If SpaceX and Blue Origin can't.

> Conversely, if SpaceX and Blue Origin can’t make cryogenic refueling work, then NASA has no plan B for landing on the moon. If SpaceX and Blue Origin can't. Then Nasa will find someone who can. Cryogenic refueling is the projects real engineering target. Landing on the moon in the twenty twenties just isn't that impressive anymore. The Artemis program is nominally about going to the moon, but it really isn't. It's about building and living in habitats beyond low orbit, in orbit refueling, building habitats on the surface of another planetary body, and obviously in the future in situ resource extraction and surface refueling. If the mission was to land on the moon, a carbon copy of the Apollo program would do. But the mission is to prove they can do what it takes to go to and return from Mars.

geertj 2y ago
Why is cryogenic propellant transfer any more difficult than other difficult things SpaceX have already done (eg landing a rocket, and building a full flow staged combustion engine)? They do this on earth every time they fuel the rocket. I understand it will be more difficult in space, but I don’t see why specifically this problem is the real engineering target over say, reuse.
- preisschild 2y ago
  Landing/reusing a rocket isn't new and has been done before.
- K0balt 2y ago
  I wouldn’t go so far as to say it is the “real” engineering target, but it is a foundational capability that underpins the ability for humans to explore beyond the earth-moon system, and it is fraught with difficulty and uncertainty. Fuel transfer and storage in orbit is problematic in many respects.
  - geertj 2y ago
    Very hard and foundational capability need not be correlated though. I think the more likely explanation that orbital refueling hasn't been done yet is not that's it's exceptionally hard, but that there hasn't been a need for it. Orbital refueling needs rapid reuse, and that has only been possible recently (with Falcon 9, and soon Starship).
    - K0balt 2y ago
      Good point?
- GuB-42 2y ago
  From the article: > Like a lot of space technology, orbital refueling sounds simple, has never been attempted, and can’t be adequately simulated on Earth.[18] The crux of the problem is that liquid and gas phases in microgravity jumble up into a three-dimensional mess, so that even measuring the quantity of propellant in a tank becomes difficult. And for cryogenic propellents specifically: > Getting this plan to work requires solving a second engineering problem, how to keep cryogenic propellants cold in space. Low earth orbit is a toasty place, and without special measures, the cryogenic propellants Starship uses will quickly vent off into space.
- objclxt 2y ago
  > They do this on earth every time they fuel the rocket. I understand it will be more difficult in space, but I don’t see why specifically this problem is the real engineering target over say, reuse. The article goes into this in some detail. In particular: * You have to get the propellant into space. This is going to take a large number of flights (~15) at a pace that has not been done before for a vehicle of that size (a launch every six days) * You need to launch at pace because otherwise the propellant will boil off, which is another issue - you need to shade or insulate the propellant for a much longer period of time in much harsher conditions * There is no gravity: whereas on earth the propellant separates relatively cleanly into liquid and gas this isn't the case in space
  - exe34 2y ago
    > There is no gravity: whereas on earth the propellant separates relatively cleanly into liquid and gas this isn't the case in space can you use a plunger, instead of a pump? more like a syringe?
    - imglorp 2y ago
      Yeah, a 9 meter diameter one, which adds mass and volume and complexity and detracts from the payload. Instead what they do is use thrust to accelerate the whole vehicle a little, which presses all the liquid into one end of its tank where it can be pumped out. Instead of carrying special settling thrusters, they originally planned to use ullage gas for this but it's not clear that can work. deeper discussion with math: https://forum.nasaspaceflight.com/index.php?topic=60124.60 https://forum.nasaspaceflight.com/index.php?topic=60124.60
      - exe34 2y ago
        plastic balloon?
        pantalaimon 2y ago
        What plastic is elastic at those temperatures? (-182 °C)
- foreverobama 2y ago
  [dead]
moffkalast 2y ago
> Then Nasa will find someone who can. Who's even left? Northrop? Lockmart? Adds an extra 10 years to the timeline at the most optimistic.
- spiritbear14 2y ago
  I think they should give it to Boeing
  - moffkalast 2y ago
    Ha I was just thinking how after the recent QA whistleblower fiasco and MCAS, one can't really look at Starliner's ongoing list of problems without a sensible chuckle. It truly is the 737 Max of space capsules.
usrbinbash 2y ago
> It's about building and living in habitats beyond low orbit And what for if I may ask? And please don't say "technological development" or "colonizing space". ad Development): Most of the tech that needs to be developed for this, is what is commonly called space plumbing: Figuring out ways to make human bodily functions not immediately fail in space. Next to none of these technologies benefit humanity at large in any way. Also: We keep coming up with amazing new tech all the time, without the extra cost of strapping it to a human and shooting that package into orbit. ad Colonization): There is nothing in our solar system to colonize. Period. Everything other than Earth is less hospitable than Earth would be after a thermonuclear war, by a huge margin. Terraforming another planet is practically impossible fora species that still has to count the kilos for every launch. And as for the one goal that makes sense, which is exploration: We have a perfectly reliable form of space exploration: Robots. And they are much better at it than we are, for one simple reason: They don't require space plumbing. There is exactly ONE reason why Apollo was manned by people instead of robots: Because computers, electronics and robotics in the 60s were not up to the task. If todays tech existed back then, I would bet the Apollo rocket would have had exactly one passenger, and that would have been the Lunar Roving vehicle.
- lupusreal 2y ago
  > There is exactly ONE reason why Apollo was manned by people instead of robots: Because computers, electronics and robotics in the 60s were not up to the task. If todays tech existed back then, I would bet the Apollo rocket would have had exactly one passenger, and that would have been the Lunar Roving vehicle. The Soviet Union did send a rover. Anyway, the science wasn't worth it and the project was driven by romantics who thought that it was the duty of mankind to explore. Putting men on the Moon was the real point of it.
- jwells89 2y ago
  Long-term habitation of surfaces of bodies other than that of Earth is a stepping stone to being able to live in space long term in very large, permanently spaceborne crafts. It’s easier to develop these things on the moon, mars, etc because of immediate access to materials that’d need to be launched into orbit otherwise. In the long term, it may make sense to build shipyards on the moon, on Mars, or somewhere in the asteroid belt where large ships can be built and launched without having to fight Earth’s strong gravity well. As for why to do that, I like to think of Earth as a very cozy cave that humanity’s caveman would serve itself well to venture beyond, if only to increase the number of possibilities for the species. In a universe where there are large human civilizations not just throughout the solar system but also scattered amongst other star systems, there are numerous paths that each branch will take that Earth’s branch in its lonesome may never have trodden. It also just seems a bit cruel to be able to see the vastness of the universe and never be able to touch any of it in person. At the risk of being dramatic, only sending rovers and probes while we remain on earth feels a bit like being stuck in a gilded cage piloting around drones and RC cars to explore what lies beyond.
wffurr 2y ago
The advanced technologies you're describing are part of Artemis. The other part is a huge pork barrel jobs project for the SLS workforce across the country, in as many states as possible.
- hehdhdjehehegwv 2y ago
  Nobody in congress will vote to kill jobs in their district. The military industrial complex figured that out a while ago, which is why at least one screw for some weapon or aircraft is produced in every state. If NASA is going to use the same playbook to be benefit space exploration, I’m not remotely upset.
  - wffurr 2y ago
    Is it benefiting space exploration though? Or is it wasting huge sums of money that could be going towards real science.
- mcswell 2y ago
  It's not called the Senate Launch System (SL) for nothing!
api 2y ago
Hmm... so it's really a half-mission to Mars with the Moon as stand-in? That makes a lot more sense. It's still sub-optimal but not as bad as it looks at first glance.
deleted 2y ago
[deleted]
xondono 2y ago
> The Artemis program is nominally about going to the moon, but it really isn't. It's about building and living in habitats beyond low orbit, in orbit refueling, building habitats on the surface of another planetary body, and obviously in the future in situ resource extraction and surface refueling. Side-goals, fake goals and scope creep are one of the biggest red flags for “projects to avoid”.
kristianp 2y ago
One thing that boggles the mind is that Blue Origin decided to use liquid Hydrogen fuel in their design. I don't see their lander working early enough to matter to Artemis with that challenge to overcome, given how slowly Blue Origin works.

geertj 2y ago

Why is cryogenic propellant transfer any more difficult than other difficult things SpaceX have already done (eg landing a rocket, and building a full flow staged combustion engine)? They do this on earth every time they fuel the rocket. I understand it will be more difficult in space, but I don’t see why specifically this problem is the real engineering target over say, reuse.

preisschild 2y ago
Landing/reusing a rocket isn't new and has been done before.
K0balt 2y ago
I wouldn’t go so far as to say it is the “real” engineering target, but it is a foundational capability that underpins the ability for humans to explore beyond the earth-moon system, and it is fraught with difficulty and uncertainty. Fuel transfer and storage in orbit is problematic in many respects.
- geertj 2y ago
  Very hard and foundational capability need not be correlated though. I think the more likely explanation that orbital refueling hasn't been done yet is not that's it's exceptionally hard, but that there hasn't been a need for it. Orbital refueling needs rapid reuse, and that has only been possible recently (with Falcon 9, and soon Starship).
  - K0balt 2y ago
    Good point?
GuB-42 2y ago
From the article: > Like a lot of space technology, orbital refueling sounds simple, has never been attempted, and can’t be adequately simulated on Earth.[18] The crux of the problem is that liquid and gas phases in microgravity jumble up into a three-dimensional mess, so that even measuring the quantity of propellant in a tank becomes difficult. And for cryogenic propellents specifically: > Getting this plan to work requires solving a second engineering problem, how to keep cryogenic propellants cold in space. Low earth orbit is a toasty place, and without special measures, the cryogenic propellants Starship uses will quickly vent off into space.
objclxt 2y ago
> They do this on earth every time they fuel the rocket. I understand it will be more difficult in space, but I don’t see why specifically this problem is the real engineering target over say, reuse. The article goes into this in some detail. In particular: * You have to get the propellant into space. This is going to take a large number of flights (~15) at a pace that has not been done before for a vehicle of that size (a launch every six days) * You need to launch at pace because otherwise the propellant will boil off, which is another issue - you need to shade or insulate the propellant for a much longer period of time in much harsher conditions * There is no gravity: whereas on earth the propellant separates relatively cleanly into liquid and gas this isn't the case in space
- exe34 2y ago
  > There is no gravity: whereas on earth the propellant separates relatively cleanly into liquid and gas this isn't the case in space can you use a plunger, instead of a pump? more like a syringe?
  - imglorp 2y ago
    Yeah, a 9 meter diameter one, which adds mass and volume and complexity and detracts from the payload. Instead what they do is use thrust to accelerate the whole vehicle a little, which presses all the liquid into one end of its tank where it can be pumped out. Instead of carrying special settling thrusters, they originally planned to use ullage gas for this but it's not clear that can work. deeper discussion with math: https://forum.nasaspaceflight.com/index.php?topic=60124.60 https://forum.nasaspaceflight.com/index.php?topic=60124.60
    - exe34 2y ago
      plastic balloon?
      - pantalaimon 2y ago
        What plastic is elastic at those temperatures? (-182 °C)
foreverobama 2y ago
[dead]

moffkalast 2y ago

> Then Nasa will find someone who can. Who's even left? Northrop? Lockmart? Adds an extra 10 years to the timeline at the most optimistic.

spiritbear14 2y ago
I think they should give it to Boeing
- moffkalast 2y ago
  Ha I was just thinking how after the recent QA whistleblower fiasco and MCAS, one can't really look at Starliner's ongoing list of problems without a sensible chuckle. It truly is the 737 Max of space capsules.

usrbinbash 2y ago

> It's about building and living in habitats beyond low orbit And what for if I may ask? And please don't say "technological development" or "colonizing space". ad Development): Most of the tech that needs to be developed for this, is what is commonly called space plumbing: Figuring out ways to make human bodily functions not immediately fail in space. Next to none of these technologies benefit humanity at large in any way. Also: We keep coming up with amazing new tech all the time, without the extra cost of strapping it to a human and shooting that package into orbit. ad Colonization): There is nothing in our solar system to colonize. Period. Everything other than Earth is less hospitable than Earth would be after a thermonuclear war, by a huge margin. Terraforming another planet is practically impossible fora species that still has to count the kilos for every launch. And as for the one goal that makes sense, which is exploration: We have a perfectly reliable form of space exploration: Robots. And they are much better at it than we are, for one simple reason: They don't require space plumbing. There is exactly ONE reason why Apollo was manned by people instead of robots: Because computers, electronics and robotics in the 60s were not up to the task. If todays tech existed back then, I would bet the Apollo rocket would have had exactly one passenger, and that would have been the Lunar Roving vehicle.

lupusreal 2y ago
> There is exactly ONE reason why Apollo was manned by people instead of robots: Because computers, electronics and robotics in the 60s were not up to the task. If todays tech existed back then, I would bet the Apollo rocket would have had exactly one passenger, and that would have been the Lunar Roving vehicle. The Soviet Union did send a rover. Anyway, the science wasn't worth it and the project was driven by romantics who thought that it was the duty of mankind to explore. Putting men on the Moon was the real point of it.
jwells89 2y ago
Long-term habitation of surfaces of bodies other than that of Earth is a stepping stone to being able to live in space long term in very large, permanently spaceborne crafts. It’s easier to develop these things on the moon, mars, etc because of immediate access to materials that’d need to be launched into orbit otherwise. In the long term, it may make sense to build shipyards on the moon, on Mars, or somewhere in the asteroid belt where large ships can be built and launched without having to fight Earth’s strong gravity well. As for why to do that, I like to think of Earth as a very cozy cave that humanity’s caveman would serve itself well to venture beyond, if only to increase the number of possibilities for the species. In a universe where there are large human civilizations not just throughout the solar system but also scattered amongst other star systems, there are numerous paths that each branch will take that Earth’s branch in its lonesome may never have trodden. It also just seems a bit cruel to be able to see the vastness of the universe and never be able to touch any of it in person. At the risk of being dramatic, only sending rovers and probes while we remain on earth feels a bit like being stuck in a gilded cage piloting around drones and RC cars to explore what lies beyond.

wffurr 2y ago

The advanced technologies you're describing are part of Artemis. The other part is a huge pork barrel jobs project for the SLS workforce across the country, in as many states as possible.

hehdhdjehehegwv 2y ago
Nobody in congress will vote to kill jobs in their district. The military industrial complex figured that out a while ago, which is why at least one screw for some weapon or aircraft is produced in every state. If NASA is going to use the same playbook to be benefit space exploration, I’m not remotely upset.
- wffurr 2y ago
  Is it benefiting space exploration though? Or is it wasting huge sums of money that could be going towards real science.
mcswell 2y ago
It's not called the Senate Launch System (SL) for nothing!

api 2y ago

Hmm... so it's really a half-mission to Mars with the Moon as stand-in? That makes a lot more sense. It's still sub-optimal but not as bad as it looks at first glance.

deleted 2y ago

[deleted]

xondono 2y ago

> The Artemis program is nominally about going to the moon, but it really isn't. It's about building and living in habitats beyond low orbit, in orbit refueling, building habitats on the surface of another planetary body, and obviously in the future in situ resource extraction and surface refueling. Side-goals, fake goals and scope creep are one of the biggest red flags for “projects to avoid”.

kristianp 2y ago

One thing that boggles the mind is that Blue Origin decided to use liquid Hydrogen fuel in their design. I don't see their lander working early enough to matter to Artemis with that challenge to overcome, given how slowly Blue Origin works.