5 ms·

I'm far from being an expert on such matters, but why doesn't SpaceX attempt to lasso the upper part of the rocket on landing? How about a super big soft pillow

I'm far from being an expert on such matters, but why doesn't SpaceX attempt to lasso the upper part of the rocket on landing? How about a super big soft pillow? At the very least spread out some huge arms to aid stability?

Bjartr 11y ago
They're trying to build a system that will work for a mars landing where there will be zero infrastructure on the ground.
- throwaway000002 11y ago
  Wow, that is crazy ambitious. Why aim for the problems of today when you can solve the problems of tomorrow. SpaceX, by now, should have enough people with strong applied math backgrounds to tell them, given a formal specification of the control systems on the rocket, whether what they're even trying to do is possible (within probability bounds). I'd be interested in seeing their calculations. I just hope they're not throwing more computation at a problem that's totally dependent on how fine they can a) sense their position and momentum, and b) do something to adjust it.
  - lmm 11y ago
    They are very happy with the calculations - they've given presentations to this effect already, and they've successfully landed the "grasshopper" test vehicle. The issues with their previous attempts have all been mechanical problems (running out of hydraulic fluid the first time, stuck valve the second time, a structural failure earlier in flight the third time).
    - JoeAltmaier 11y ago
      From that description, it sounds like there's barely enough rocket there to succeed. A sample size of 4, no statistics yet possible about whether its getting better or not? Anyway, its amazing how many stuck valves have derailed grand plans. The rover rocket static test had that problem (nuclear engine for Mars mission back in the 60s(?)) and killed that program.
chriswarbo 11y ago
I'm not an expert, but I believe it's to do with the Falcon 9's strength: it's strong when compressed length-ways, since it must endure the force of the rocket motors, air resistance, etc. but it is much weaker when squeezed from the side, which your lasso, robot arm, etc. would do. There's probably an analogy to a drinks can too: when full they're difficult to squeeze, but when empty they crumple easily. By the time the Falcon 9 attempts a landing, its fuel tanks are mostly empty.
- elbigbad 11y ago
  Maybe more aptly, an empty soda can is always difficult to compress vertically but easy to compress horizontally.
pricechild 11y ago
United Launch Alliance have shown a plan to catch their falling engines with a helicopter: http://www.planetary.org/blogs/jason-davis/2015/20150413-united-launch-alliance-vulcan-rocket.html http://www.planetary.org/blogs/jason-davis/2015/20150413-uni...

Bjartr 11y ago

They're trying to build a system that will work for a mars landing where there will be zero infrastructure on the ground.

throwaway000002 11y ago
Wow, that is crazy ambitious. Why aim for the problems of today when you can solve the problems of tomorrow. SpaceX, by now, should have enough people with strong applied math backgrounds to tell them, given a formal specification of the control systems on the rocket, whether what they're even trying to do is possible (within probability bounds). I'd be interested in seeing their calculations. I just hope they're not throwing more computation at a problem that's totally dependent on how fine they can a) sense their position and momentum, and b) do something to adjust it.
- lmm 11y ago
  They are very happy with the calculations - they've given presentations to this effect already, and they've successfully landed the "grasshopper" test vehicle. The issues with their previous attempts have all been mechanical problems (running out of hydraulic fluid the first time, stuck valve the second time, a structural failure earlier in flight the third time).
  - JoeAltmaier 11y ago
    From that description, it sounds like there's barely enough rocket there to succeed. A sample size of 4, no statistics yet possible about whether its getting better or not? Anyway, its amazing how many stuck valves have derailed grand plans. The rover rocket static test had that problem (nuclear engine for Mars mission back in the 60s(?)) and killed that program.

chriswarbo 11y ago

I'm not an expert, but I believe it's to do with the Falcon 9's strength: it's strong when compressed length-ways, since it must endure the force of the rocket motors, air resistance, etc. but it is much weaker when squeezed from the side, which your lasso, robot arm, etc. would do. There's probably an analogy to a drinks can too: when full they're difficult to squeeze, but when empty they crumple easily. By the time the Falcon 9 attempts a landing, its fuel tanks are mostly empty.

elbigbad 11y ago
Maybe more aptly, an empty soda can is always difficult to compress vertically but easy to compress horizontally.

pricechild 11y ago

United Launch Alliance have shown a plan to catch their falling engines with a helicopter: http://www.planetary.org/blogs/jason-davis/2015/20150413-united-launch-alliance-vulcan-rocket.html http://www.planetary.org/blogs/jason-davis/2015/20150413-uni...