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> But why would you set that as a pre-requisite? Well, the argument in his video is that there are multi-day gaps in the ability to rescue astronauts off the m

> But why would you set that as a pre-requisite? Well, the argument in his video is that there are multi-day gaps in the ability to rescue astronauts off the moon. Balancing that out with a few very small relay satellites, I would pay for a couple Electron launches for the relay, and have a lifeboat capability 24/7. > The Gateway is also, as I understand it, a staging ground for testing habitation for a vehicle to Mars. I have heard that as well, but what I don't understand is how a higher orbit simulates a Mars trip much better. I mean, either way you are not inside a magnetosphere, right? I guess in low-lunar orbit you are more shaded from solar wind by the moon half the time?

JumpCrisscross 3y ago
> the argument in his video is that there are multi-day gaps in the ability to rescue astronauts off the moon Right, which is where he loses me--this is not why we have a Gateway. > Balancing that out with a few very small relay satellites, I would pay for a couple Electron launches for the relay, and have a lifeboat capability 24/7 Building a communications relay constellation isn't a simple task. It's on the roadmap for Artemis. > what I don't understand is how a higher orbit simulates a Mars trip much better The high orbit is irrelevant to this aim. You'd get the same deep-space habitation science from a low, circularised orbit. The high orbit is for creating a one-and-done communication relay.
- consumer451 3y ago
  > Right, which is where he loses me--this is not why we have a Gateway. I am just an everyday armchair astronaut, so please correct me where I'm wrong, but I figured: 1) A lunar lander does not have the delta-v for direct return to earth, from the lunar surface. (or the heat shielding) (2) Part of the Gateway's function is similar to Apollo's Command Module. A place for the lander to dock upon return, and facilitate return to earth. I can see how Gateway differs from Apollo's Command Module, in that it does not return to Earth, but stays in lunar orbit. This does test Mars-like endurance, and is cool. Orion will detach from Gateway, and return independently, right? But why the near-rectilinear halo orbit, which puts the lifeboat capability out reach sometimes? If an astronaut needs something like an appendix removed (random example,) then a few days waiting for Gateway to swing by could make a difference. edit: Oh, near-rectilinear halo orbit also makes it easier for Orion to return to Earth, right? So maybe he said that Orion lacks the delta-v, not SLS. Maybe that helps explain it.
  - JumpCrisscross 3y ago
    > lunar lander does not have the delta-v for direct return to earth, from the lunar surface. (or the heat shielding) Starship HLS is the lunar lander [1]. That said, it is not designed to survive Earth re-entry at lunar velocities. > why the near-rectilinear halo orbit, which puts the lifeboat capability out reach I guess I'm sceptical of any Gateway serving as a lifeboat in an emergency with a day-to-day sensitivity where aid can be provided on Earth but not on the Moon. > Orion lacks the delta-v, not SLS Correct. SLS is expensive, Orion underpowered. [1] https://en.wikipedia.org/wiki/Starship_HLS https://en.wikipedia.org/wiki/Starship_HLS
    - rbanffy 3y ago
      > That said, it is not designed to survive Earth re-entry at lunar velocities. Or any velocity. It doesn't have thermal tiles.

JumpCrisscross 3y ago

> the argument in his video is that there are multi-day gaps in the ability to rescue astronauts off the moon Right, which is where he loses me--this is not why we have a Gateway. > Balancing that out with a few very small relay satellites, I would pay for a couple Electron launches for the relay, and have a lifeboat capability 24/7 Building a communications relay constellation isn't a simple task. It's on the roadmap for Artemis. > what I don't understand is how a higher orbit simulates a Mars trip much better The high orbit is irrelevant to this aim. You'd get the same deep-space habitation science from a low, circularised orbit. The high orbit is for creating a one-and-done communication relay.

consumer451 3y ago
> Right, which is where he loses me--this is not why we have a Gateway. I am just an everyday armchair astronaut, so please correct me where I'm wrong, but I figured: 1) A lunar lander does not have the delta-v for direct return to earth, from the lunar surface. (or the heat shielding) (2) Part of the Gateway's function is similar to Apollo's Command Module. A place for the lander to dock upon return, and facilitate return to earth. I can see how Gateway differs from Apollo's Command Module, in that it does not return to Earth, but stays in lunar orbit. This does test Mars-like endurance, and is cool. Orion will detach from Gateway, and return independently, right? But why the near-rectilinear halo orbit, which puts the lifeboat capability out reach sometimes? If an astronaut needs something like an appendix removed (random example,) then a few days waiting for Gateway to swing by could make a difference. edit: Oh, near-rectilinear halo orbit also makes it easier for Orion to return to Earth, right? So maybe he said that Orion lacks the delta-v, not SLS. Maybe that helps explain it.
- JumpCrisscross 3y ago
  > lunar lander does not have the delta-v for direct return to earth, from the lunar surface. (or the heat shielding) Starship HLS is the lunar lander [1]. That said, it is not designed to survive Earth re-entry at lunar velocities. > why the near-rectilinear halo orbit, which puts the lifeboat capability out reach I guess I'm sceptical of any Gateway serving as a lifeboat in an emergency with a day-to-day sensitivity where aid can be provided on Earth but not on the Moon. > Orion lacks the delta-v, not SLS Correct. SLS is expensive, Orion underpowered. [1] https://en.wikipedia.org/wiki/Starship_HLS https://en.wikipedia.org/wiki/Starship_HLS
  - rbanffy 3y ago
    > That said, it is not designed to survive Earth re-entry at lunar velocities. Or any velocity. It doesn't have thermal tiles.