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In theory you could do it without completely matching orbits to save a lot of fuel. Just getting a close slow encounter, grabbing it and letting your orbit just

by rtkwe 6y ago

In theory you could do it without completely matching orbits to save a lot of fuel. Just getting a close slow encounter, grabbing it and letting your orbit just be whatever the new average of your velocities is. It'd require a stronger capture system perhaps depending on the mass of your capture vehicle, but it would save a lot of fuel. Recycling what's up there might eventually be viable but for the start we'll be shipping up raw stocks. Recycling is probably about as difficult as refining from metal rich asteroids once you consider all the coatings and paints that are added to things and having to sort all the different metals, plastics, and what have you out.

KiwiJohnno 6y ago
Sorry, not practical. Intercepting debris requires FAR more delta-v than you may expect. Changing the plane of your orbit is so expensive you just don't do it. Its cheaper to just launch a new satellite in a different plane. For example, to intercept hubble from the ISS (or vice-versa) you are looking at a velocity change of a bit over 3000m/sec. Compare that to delta-v of just over 9000 m/sec to reach the ISS from the surface of earth. Lets say you are in a really, really close orbit to your target and you only need to spend delta-v of 100m/sec to intercept . If you only use 90% of the fuel you'd need to perfectly match orbits then you are still going to impact your target at 10m/sec. Thats 36 km/h, which is a very violent collision. You aren't going to just grab your target on the way past.
- rtkwe 6y ago
  I know plane changes are a real problem but you can get nearly velocity intercepts without matching orbits. The timing is brief but to objects on dissimilar orbits can come to a relative standstill for brief periods when their orbits are setup properly. Also 36 km/h isn't /that/ fast you could have a capture mechanism that absorbs that impact or where it doesn't matter like a net.
  - KiwiJohnno 6y ago
    Sorry, I have no idea what you are talking about. I can't see how two objects on dissimilar orbits could possibly be at a standstill relative to each other. I mean, if they are at a standstill relative to each other then their orbits would be identical??

by rtkwe 6y ago

KiwiJohnno 6y ago

Sorry, not practical. Intercepting debris requires FAR more delta-v than you may expect. Changing the plane of your orbit is so expensive you just don't do it. Its cheaper to just launch a new satellite in a different plane. For example, to intercept hubble from the ISS (or vice-versa) you are looking at a velocity change of a bit over 3000m/sec. Compare that to delta-v of just over 9000 m/sec to reach the ISS from the surface of earth. Lets say you are in a really, really close orbit to your target and you only need to spend delta-v of 100m/sec to intercept . If you only use 90% of the fuel you'd need to perfectly match orbits then you are still going to impact your target at 10m/sec. Thats 36 km/h, which is a very violent collision. You aren't going to just grab your target on the way past.

rtkwe 6y ago
I know plane changes are a real problem but you can get nearly velocity intercepts without matching orbits. The timing is brief but to objects on dissimilar orbits can come to a relative standstill for brief periods when their orbits are setup properly. Also 36 km/h isn't /that/ fast you could have a capture mechanism that absorbs that impact or where it doesn't matter like a net.
- KiwiJohnno 6y ago
  Sorry, I have no idea what you are talking about. I can't see how two objects on dissimilar orbits could possibly be at a standstill relative to each other. I mean, if they are at a standstill relative to each other then their orbits would be identical??