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Moon liftoff is relatively gentle… the Apollo lunar module didn’t have seats… the astronauts stood during landing and ascent. It experienced like a half a G.

midoridensha 4y ago
Yes, Moon gravity is very low. If you can't handle liftoff from the Moon, you can't handle a helicopter ride either.
- samatman 4y ago
  Not only that, a Lunar space elevator to L1 can be fabricated from Kevlar. Now, you do need 50,000 km of Kevlar, and that sounds like a lot until I tell you that there are 1.2 million km of submarine cable right now. We got this one.
  - Johnny555 4y ago
    It's not so much the amount of material that seems daunting, it's getting it to lunar orbit. If my calculations are right, 50,000km of 5cm kevlar cable (which probably isn't nearly thick enough near the top) would weigh over 500,000 metric tons. Which would take around 25,000 Falcon Heavy launches to get to the moon I hope it can be manufactured on the moon or on an asteroid or something.
    - skykooler 4y ago
      Unfortunately, Kevlar is a carbon-based polymer, and carbon is in short supply on the Moon.
      - midoridensha 4y ago
        Perhaps the carbon could be flown to the Moon from Earth, and combined there with the available oxygen and hydrogen to manufacture kevlar. (Not sure about nitrogen; is that available on the Moon?)
        skykooler 4y ago
        There's a small amount that gets embedded by the solar wind, but not enough to be extracted practically.
    - nyokodo 4y ago
      > 500,000 metric tons. Which would take around 25,000 Falcon Heavy launches to get to the moon Starship can apparently take 100t to the moon which would be 5000 launches. Elon math has cost per launch eventually reaching $2m which would mean $10b to get the cables to the moon. If terminally optimistic Elon math is roughly correct that puts the project into merely unlikely territory rather than impossible.
      - Teever 4y ago
        even if Elon math is off by a factor of ten thats still $100 billion which IIRC is less than the cost of the ISS without even accounting for inflation.
      - sneak 4y ago
        Starship is planned to take 100T to LEO. I think getting to the moon (and landing softly on it) would reduce that figure substantially (or increase the cost/time due to LEO refueling prior to translunar injection).
        nyokodo 4y ago
        > Starship is planned to take 100T to LEO The SpaceX website says “100+ t” to LEO. So 100t is a lower bound? Who knows? [1] However: “Starship can land 100 tons on the lunar surface," said Aarti Matthews, Starship Human Landing System program manager for SpaceX.” [2] Aarti may mean “with refueling in LEO” so that would require additional launches without an established orbital refueling station. So to fix my math would require knowing the cost of tanker launches which I’m not going to attempt to do. 1. https://www.spacex.com/vehicles/starship/ https://www.spacex.com/vehicles/starship/ 2. https://arstechnica.com/science/2022/05/spacex-engineer-says-nasa-should-plan-for-starships-significant-capability/ https://arstechnica.com/science/2022/05/spacex-engineer-says...
doctor_eval 4y ago
It's not the liftoff you have to worry about, it's the landing. Apollo 11 had more than 6G during reentry. https://history.nasa.gov/afj/ap11fj/27day9-entry.html https://history.nasa.gov/afj/ap11fj/27day9-entry.html

midoridensha 4y ago

Yes, Moon gravity is very low. If you can't handle liftoff from the Moon, you can't handle a helicopter ride either.

samatman 4y ago
Not only that, a Lunar space elevator to L1 can be fabricated from Kevlar. Now, you do need 50,000 km of Kevlar, and that sounds like a lot until I tell you that there are 1.2 million km of submarine cable right now. We got this one.
- Johnny555 4y ago
  It's not so much the amount of material that seems daunting, it's getting it to lunar orbit. If my calculations are right, 50,000km of 5cm kevlar cable (which probably isn't nearly thick enough near the top) would weigh over 500,000 metric tons. Which would take around 25,000 Falcon Heavy launches to get to the moon I hope it can be manufactured on the moon or on an asteroid or something.
  - skykooler 4y ago
    Unfortunately, Kevlar is a carbon-based polymer, and carbon is in short supply on the Moon.
    - midoridensha 4y ago
      Perhaps the carbon could be flown to the Moon from Earth, and combined there with the available oxygen and hydrogen to manufacture kevlar. (Not sure about nitrogen; is that available on the Moon?)
      - skykooler 4y ago
        There's a small amount that gets embedded by the solar wind, but not enough to be extracted practically.
  - nyokodo 4y ago
    > 500,000 metric tons. Which would take around 25,000 Falcon Heavy launches to get to the moon Starship can apparently take 100t to the moon which would be 5000 launches. Elon math has cost per launch eventually reaching $2m which would mean $10b to get the cables to the moon. If terminally optimistic Elon math is roughly correct that puts the project into merely unlikely territory rather than impossible.
    - Teever 4y ago
      even if Elon math is off by a factor of ten thats still $100 billion which IIRC is less than the cost of the ISS without even accounting for inflation.
    - sneak 4y ago
      Starship is planned to take 100T to LEO. I think getting to the moon (and landing softly on it) would reduce that figure substantially (or increase the cost/time due to LEO refueling prior to translunar injection).
      - nyokodo 4y ago
        > Starship is planned to take 100T to LEO The SpaceX website says “100+ t” to LEO. So 100t is a lower bound? Who knows? [1] However: “Starship can land 100 tons on the lunar surface," said Aarti Matthews, Starship Human Landing System program manager for SpaceX.” [2] Aarti may mean “with refueling in LEO” so that would require additional launches without an established orbital refueling station. So to fix my math would require knowing the cost of tanker launches which I’m not going to attempt to do. 1. https://www.spacex.com/vehicles/starship/ https://www.spacex.com/vehicles/starship/ 2. https://arstechnica.com/science/2022/05/spacex-engineer-says-nasa-should-plan-for-starships-significant-capability/ https://arstechnica.com/science/2022/05/spacex-engineer-says...

doctor_eval 4y ago

It's not the liftoff you have to worry about, it's the landing. Apollo 11 had more than 6G during reentry. https://history.nasa.gov/afj/ap11fj/27day9-entry.html https://history.nasa.gov/afj/ap11fj/27day9-entry.html