5 ms·

Sounds like we need to bring back Star Wars and laser them out of the air! Kidding/Not Kidding.

hughes 10y ago
Actually an interesting idea. If the Starshot project [1] (which uses ground-based laser propulsion) gets off the ground, perhaps the system could be equally useful for de-orbiting space junk. Firing at orbital objects as they approach from low on the horizon could produce an ablative thrust that could accelerate the natural de-orbiting process. [1] https://en.wikipedia.org/wiki/Breakthrough_Initiatives#Breakthrough_Starshot https://en.wikipedia.org/wiki/Breakthrough_Initiatives#Break...
- deleted 10y ago
  [deleted]
anarazel 10y ago
Wouldn't one-sided heating, from earth, quite frequently lead to them being moved into a higher orbit (one side gasses off, conservation of momentum leads to movement)? That sounds quite hard to predict exactly and thus might end up being pretty dangerous for objects on other orbits.
- azernik 10y ago
  Thrust in the radial direction (straight out) unintuitively does not raise an orbit; it increases eccentricity, so the highest point is higher and the lowest point is lower, but since the impulse is orthogonal to the direction of motion it does not add any energy to the object. In any case, heating from the Sun vastly outweighs anything coming from the Earth, and so would tend to push the object inwards on average. You can get orbit raising/lowering from outgassing and radiation pressure with a rotating object [https://en.wikipedia.org/wiki/Yarkovsky_effect https://en.wikipedia.org/wiki/Yarkovsky_effect], but that depends entirely on rate and direction of rotation.
  - anarazel 10y ago
    > Thrust in the radial direction (straight out) unintuitively does not raise an orbit; it increases eccentricity, so the highest point is higher and the lowest point is lower, but since the impulse is orthogonal to the direction of motion it does not add any energy to the object. That doesn't really address the point that that'd make it dangerous due to hard to predict flight paths - and the outgassing wouldn't just happen directly outwards for all broken up parts. > In any case, heating from the Sun vastly outweighs anything coming from the Earth, and so would tend to push the object inwards on average. In the case of trying to destroy orbiting garbage via laser from earth (the OPs proposal, not my idea!)? You'd pretty fundamentally need higher energy than the sun delivers, albeit for obviously a very limited amount of time.
psyc 10y ago
Low-tech solution: cowcatchers.
- dreamcompiler 10y ago
  If the cow is traveling 10 miles per second relative to the catcher, both simply explode and create more cows.

Actually an interesting idea. If the Starshot project [1] (which uses ground-based laser propulsion) gets off the ground, perhaps the system could be equally useful for de-orbiting space junk. Firing at orbital objects as they approach from low on the horizon could produce an ablative thrust that could accelerate the natural de-orbiting process. [1] https://en.wikipedia.org/wiki/Breakthrough_Initiatives#Breakthrough_Starshot https://en.wikipedia.org/wiki/Breakthrough_Initiatives#Break...

deleted 10y ago
[deleted]

anarazel 10y ago

Wouldn't one-sided heating, from earth, quite frequently lead to them being moved into a higher orbit (one side gasses off, conservation of momentum leads to movement)? That sounds quite hard to predict exactly and thus might end up being pretty dangerous for objects on other orbits.

azernik 10y ago
Thrust in the radial direction (straight out) unintuitively does not raise an orbit; it increases eccentricity, so the highest point is higher and the lowest point is lower, but since the impulse is orthogonal to the direction of motion it does not add any energy to the object. In any case, heating from the Sun vastly outweighs anything coming from the Earth, and so would tend to push the object inwards on average. You can get orbit raising/lowering from outgassing and radiation pressure with a rotating object [https://en.wikipedia.org/wiki/Yarkovsky_effect https://en.wikipedia.org/wiki/Yarkovsky_effect], but that depends entirely on rate and direction of rotation.
- anarazel 10y ago
  > Thrust in the radial direction (straight out) unintuitively does not raise an orbit; it increases eccentricity, so the highest point is higher and the lowest point is lower, but since the impulse is orthogonal to the direction of motion it does not add any energy to the object. That doesn't really address the point that that'd make it dangerous due to hard to predict flight paths - and the outgassing wouldn't just happen directly outwards for all broken up parts. > In any case, heating from the Sun vastly outweighs anything coming from the Earth, and so would tend to push the object inwards on average. In the case of trying to destroy orbiting garbage via laser from earth (the OPs proposal, not my idea!)? You'd pretty fundamentally need higher energy than the sun delivers, albeit for obviously a very limited amount of time.

psyc 10y ago

Low-tech solution: cowcatchers.

dreamcompiler 10y ago
If the cow is traveling 10 miles per second relative to the catcher, both simply explode and create more cows.