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Why would you return the materials in Dragon? You can build a simple glider from space-side materials. The return trip is way easier than getting out of the gra

Why would you return the materials in Dragon? You can build a simple glider from space-side materials. The return trip is way easier than getting out of the gravity well. You don’t even need crew.

Teever 2y ago
Bonus points if you design the glider in such a way that it is covered in some sort of ablative material that helps mitigate climate change after it burns off keeping the mined material from doing so to maximize material return.
- theptip 2y ago
  This is an interesting idea. I initially assumed you’d just structure your payload (eg titanium) to ablate during reentry. But maybe you can do something better with carbonaceous asteroids, or simply with regolith, to produce a cheap ablative shield. I suppose the problem would be with the changes to aerodynamic profile during reentry - but perhaps regolith tiles could be manufactured to ablate in a consistent-enough pattern?
Ekaros 2y ago
Return trip is double the complexity as first you need to get there. And then you need to slowdown to get back here as into orbit. Getting off the Earth is somewhat solved. But getting there and back at scale is not really done.
IshKebab 2y ago
You can't glide back to the surface. Kind of feels like you should be able to but it doesn't work out like that. If it did then that's how all spacecraft would descend. Scott Manley did a good video about it. https://youtu.be/5kl2mm96Jkk?si=Uf9ntP6R39SJrVBm https://youtu.be/5kl2mm96Jkk?si=Uf9ntP6R39SJrVBm Skip to 3:45 for your exact "well meaning suggestion from people who aren't rocket scientists".
- theptip 2y ago
  Scott is debunking ideas to dump deltaV before hitting the atmosphere, to avoid having to go through the rigors of reentry. This isn’t relevant to the discussion; he’s not disproving the possibility of landing from orbit in a glider. The existence proof here is the shuttle, which did indeed manage to glide from orbit. The challenge is that you need some strategy to dissipate the kinetic energy on reentry. The approach that both the shuttle and these hypothetical gliders use is ablative heat shielding. A glider manufactured in space and autonomously piloted would have a lot more design space to explore, since you don’t have the constraint that it has to be launchable on a rocket, and you can potentially spend years on successive aerobrake approaches if that is optimal.
  - IshKebab 2y ago
    Uhm yes he is. You didn't listen to the whole video did you?
    - derdi 2y ago
      I listened to the whole video, and the parent understands this better than you do. The video doesn't say that gliders are impossible, period. It says that slowly gliding down, without a heat shield, is impossible. As the parent noted, the Space Shuttle proved that quickly gliding down with a heat shield is possible and very realistic. The video doesn't claim anything to the contrary, of course. It's a good and important point that the term "glider" needs to be qualified. But you failed to make this point.
  - lupire 2y ago
    When the vehicle disintegrates on reentry like a shuttle sometimes does, who gets the platinum?
  - theptip 2y ago
    As I’ve continued to read I realize the shuttle didn’t have ablative tiles, rather reusable heat dissipation tiles. Better aerodynamics, so maybe our glider should use this approach; the Si and C required are present in asteroids, but manufacturing is space could be challenging.

Why would you return the materials in Dragon? You can build a simple glider from space-side materials. The return trip is way easier than getting out of the gravity well. You don’t even need crew.

Teever 2y ago

Bonus points if you design the glider in such a way that it is covered in some sort of ablative material that helps mitigate climate change after it burns off keeping the mined material from doing so to maximize material return.

theptip 2y ago
This is an interesting idea. I initially assumed you’d just structure your payload (eg titanium) to ablate during reentry. But maybe you can do something better with carbonaceous asteroids, or simply with regolith, to produce a cheap ablative shield. I suppose the problem would be with the changes to aerodynamic profile during reentry - but perhaps regolith tiles could be manufactured to ablate in a consistent-enough pattern?

Ekaros 2y ago

Return trip is double the complexity as first you need to get there. And then you need to slowdown to get back here as into orbit. Getting off the Earth is somewhat solved. But getting there and back at scale is not really done.

IshKebab 2y ago

You can't glide back to the surface. Kind of feels like you should be able to but it doesn't work out like that. If it did then that's how all spacecraft would descend. Scott Manley did a good video about it. https://youtu.be/5kl2mm96Jkk?si=Uf9ntP6R39SJrVBm https://youtu.be/5kl2mm96Jkk?si=Uf9ntP6R39SJrVBm Skip to 3:45 for your exact "well meaning suggestion from people who aren't rocket scientists".

theptip 2y ago
Scott is debunking ideas to dump deltaV before hitting the atmosphere, to avoid having to go through the rigors of reentry. This isn’t relevant to the discussion; he’s not disproving the possibility of landing from orbit in a glider. The existence proof here is the shuttle, which did indeed manage to glide from orbit. The challenge is that you need some strategy to dissipate the kinetic energy on reentry. The approach that both the shuttle and these hypothetical gliders use is ablative heat shielding. A glider manufactured in space and autonomously piloted would have a lot more design space to explore, since you don’t have the constraint that it has to be launchable on a rocket, and you can potentially spend years on successive aerobrake approaches if that is optimal.
- IshKebab 2y ago
  Uhm yes he is. You didn't listen to the whole video did you?
  - derdi 2y ago
    I listened to the whole video, and the parent understands this better than you do. The video doesn't say that gliders are impossible, period. It says that slowly gliding down, without a heat shield, is impossible. As the parent noted, the Space Shuttle proved that quickly gliding down with a heat shield is possible and very realistic. The video doesn't claim anything to the contrary, of course. It's a good and important point that the term "glider" needs to be qualified. But you failed to make this point.
- lupire 2y ago
  When the vehicle disintegrates on reentry like a shuttle sometimes does, who gets the platinum?
- theptip 2y ago
  As I’ve continued to read I realize the shuttle didn’t have ablative tiles, rather reusable heat dissipation tiles. Better aerodynamics, so maybe our glider should use this approach; the Si and C required are present in asteroids, but manufacturing is space could be challenging.