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Capsules like Soyuz can't land without an atmosphere. They use aerobraking and parachutes. You need a big rocket to slow down and land. At which point it's a v

Capsules like Soyuz can't land without an atmosphere. They use aerobraking and parachutes. You need a big rocket to slow down and land. At which point it's a very different machine.

ceejayoz 10y ago
I'd imagine the grandparent is thinking more SpaceX than Soyuz.
- dogma1138 10y ago
  SpaceX Dragon capsule can't land without atmosphere either it needs it to aerobreak it doesn't carry nearly enough fuel to come to a rest from orbital reentry speeds using propulsion alone.
  - ceejayoz 10y ago
    https://www.quora.com/Can-the-Dragon-V2-land-on-the-moon https://www.quora.com/Can-the-Dragon-V2-land-on-the-moon > The Dragon-2 has enough power and fuel to land and ascend back to lunar orbit. The Dragon's SuperDraco has higher performance than the Apollo Lunar Module. Apollo LM descent engines has 10,000 lbf thrust, and 3,500 lbf thrust for ascent (the lander part is left behind). The Dragon's SuperDraco has 16,000 lbf thrust. The Dragon also uses computers to control throttle and land (much more fuel efficient). Hence, the Dragon-2 has enough power and fuel to land and ascend back to lunar orbit even if it carries all it's parts during ascent. However, it may need to cut crew from 7 to 3 to loose more weight for fuel. (Plus, I said "more SpaceX" as in "capsules with powered descent", not "SpaceX's exact current models as already implemented"...)
    - dogma1138 10y ago
      Lunar orbit isn't earth reentry tho, even the SuperDraco doesn't seem to carry enough fuel nor have the specific impulse for an earth landing when you remove the aerobreaking.
      - ceejayoz 10y ago
        OK? I'm not sure what point you're trying to make, then, as there's not a no-atmosphere, Earth-sized body in the solar system for your argument to apply to.
    - mapt 10y ago
      That is not accurate. Estimates are that the Dragon v2 has about 400m/s dV. This is around what it would need for controlled landing or abort. It takes around 1720m/s just to get to the stationary Lunar surface from Lunar orbit; If a Falcon upper stage detaches during the leg of the mission between Earth and Luna, the necessary delta V for the rest of the mission will be around 5080m/s. This is a lot. You would have to build another fairly large vehicle to accomplish this mission - Dragon v2 would be an afterthought.
    - taneq 10y ago
      I don't understand how they can conclude that "the Dragon-2 has enough power and fuel to land and ascend back to lunar orbit" based only on a comparison of maximum thrust and a statement that the Dragon has an automated landing system. At the very least, they'd need to consider the dry weight and fuel load to make a fair comparison - maybe they did so offscreen but it's not mentioned anywhere in the post.
      - kobeya 10y ago
        Because it was a design requirement of the Dragon. It was designed to do that.
        zardo 10y ago
        It definitely was not designed to de-orbit and land on the moon. It has nowhere near enough dV to do that. Maybe it has been designed to work as a technology platform for deriving a lunar lander. But the Dragon 2 design is just not capable of doing it, not even close.
maxander 10y ago
SpaceX's Dragon capsules come with engines, which (in some configurations) are sufficient for powered landings. And it's still called a "capsule."
- hughes 10y ago
  Powered landings after an intense atmospheric deceleration.
  - kobeya 10y ago
    No, powered landings all the way down. At least on the Moon and Mars (from orbit). With more fuel you could do the same from Earth, but why bother?
    - deleted 10y ago
      [deleted]
    - robotresearcher 10y ago
      That's cool, I didn't know that. So Dragon 2 is a Soyuz-like passive capsule when landing in atmosphere and a powered spaceship like the Apollo LEM when landing in vacuum. Very cool that they could cram those roles into one vehicle. Looking forward to seeing it work.
      - Diederich 10y ago
        https://youtu.be/1_FXVjf46T8 https://youtu.be/1_FXVjf46T8 Work in progress..Well along in progress.
        robotresearcher 10y ago
        Oh that was cool. I have a stupid grin on my stupid face now.
        10y ago

Capsules like Soyuz can't land without an atmosphere. They use aerobraking and parachutes. You need a big rocket to slow down and land. At which point it's a very different machine.

ceejayoz 10y ago

I'd imagine the grandparent is thinking more SpaceX than Soyuz.

dogma1138 10y ago
SpaceX Dragon capsule can't land without atmosphere either it needs it to aerobreak it doesn't carry nearly enough fuel to come to a rest from orbital reentry speeds using propulsion alone.
- ceejayoz 10y ago
  https://www.quora.com/Can-the-Dragon-V2-land-on-the-moon https://www.quora.com/Can-the-Dragon-V2-land-on-the-moon > The Dragon-2 has enough power and fuel to land and ascend back to lunar orbit. The Dragon's SuperDraco has higher performance than the Apollo Lunar Module. Apollo LM descent engines has 10,000 lbf thrust, and 3,500 lbf thrust for ascent (the lander part is left behind). The Dragon's SuperDraco has 16,000 lbf thrust. The Dragon also uses computers to control throttle and land (much more fuel efficient). Hence, the Dragon-2 has enough power and fuel to land and ascend back to lunar orbit even if it carries all it's parts during ascent. However, it may need to cut crew from 7 to 3 to loose more weight for fuel. (Plus, I said "more SpaceX" as in "capsules with powered descent", not "SpaceX's exact current models as already implemented"...)
  - dogma1138 10y ago
    Lunar orbit isn't earth reentry tho, even the SuperDraco doesn't seem to carry enough fuel nor have the specific impulse for an earth landing when you remove the aerobreaking.
    - ceejayoz 10y ago
      OK? I'm not sure what point you're trying to make, then, as there's not a no-atmosphere, Earth-sized body in the solar system for your argument to apply to.
  - mapt 10y ago
    That is not accurate. Estimates are that the Dragon v2 has about 400m/s dV. This is around what it would need for controlled landing or abort. It takes around 1720m/s just to get to the stationary Lunar surface from Lunar orbit; If a Falcon upper stage detaches during the leg of the mission between Earth and Luna, the necessary delta V for the rest of the mission will be around 5080m/s. This is a lot. You would have to build another fairly large vehicle to accomplish this mission - Dragon v2 would be an afterthought.
  - taneq 10y ago
    I don't understand how they can conclude that "the Dragon-2 has enough power and fuel to land and ascend back to lunar orbit" based only on a comparison of maximum thrust and a statement that the Dragon has an automated landing system. At the very least, they'd need to consider the dry weight and fuel load to make a fair comparison - maybe they did so offscreen but it's not mentioned anywhere in the post.
    - kobeya 10y ago
      Because it was a design requirement of the Dragon. It was designed to do that.
      - zardo 10y ago
        It definitely was not designed to de-orbit and land on the moon. It has nowhere near enough dV to do that. Maybe it has been designed to work as a technology platform for deriving a lunar lander. But the Dragon 2 design is just not capable of doing it, not even close.

maxander 10y ago

SpaceX's Dragon capsules come with engines, which (in some configurations) are sufficient for powered landings. And it's still called a "capsule."

hughes 10y ago
Powered landings after an intense atmospheric deceleration.
- kobeya 10y ago
  No, powered landings all the way down. At least on the Moon and Mars (from orbit). With more fuel you could do the same from Earth, but why bother?
  - deleted 10y ago
    [deleted]
  - robotresearcher 10y ago
    That's cool, I didn't know that. So Dragon 2 is a Soyuz-like passive capsule when landing in atmosphere and a powered spaceship like the Apollo LEM when landing in vacuum. Very cool that they could cram those roles into one vehicle. Looking forward to seeing it work.
    - Diederich 10y ago
      https://youtu.be/1_FXVjf46T8 https://youtu.be/1_FXVjf46T8 Work in progress..Well along in progress.
      - robotresearcher 10y ago
        Oh that was cool. I have a stupid grin on my stupid face now.
        10y ago