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There has already been other propositions such as orbiting a small spacecraft around a large asteroid to deflect its orbit in a much more effective way over

by fintler 13y ago

There has already been other propositions such as orbiting a small spacecraft around a large asteroid to deflect its orbit in a much more effective way over time. Any citations on why this is more effective? I don't think they're guessing on how to mitagate. The US has spent some effort to simulate exactly how to get rid of asteroids. For example: https://www.youtube.com/watch?v=hOcNbAV6SiI https://www.youtube.com/watch?v=hOcNbAV6SiI

ekianjo 13y ago
> Any citations on why this is more effective? From what I remember, it's because you change the center of gravity of the whole system, not just once at impact, but constantly since it continues orbiting around it.
- blueblob 13y ago
  But how much further out do you have to detect it to do this?
  - ekianjo 13y ago
    I'll need to look into that. Obviously not just before impact, this is something you would have to do several months of maybe years before it is expected to hit, I guess. I'll come back when I find it again.
  - ekianjo 13y ago
    Here's a piece of a paper on this : Deflecting a larger asteroid would require a heavier spacecraft, more time spent hovering, or more lead time. However, in the special case in which an asteroid has a close Earth approach, followed by a later return and impact, the change in velocity needed to prevent the impact can be many orders of magnitude smaller if applied before the close approach5. For example, the asteroid 99942 Apophis (2004 MN4), a 320-m asteroid that will swing by the Earth at a distance of about 30,000 km in 2029, has a small probability (10-4) of returning to strike the Earth in 2035 or 2036 (ref. 6). If it is indeed on a return impact trajectory, a deflection of only about 10-6 m s-1 a few years before the close approach in 2029 would prevent a later impact (A. Carusi, personal communication). In this case, a 1-tonne gravitational tractor with conventional chemical thrusters could accomplish this deflection mission as only 0.1 newtons of thrust would be required for a duration of about a month. Should such a deflection mission prove necessary, a gravitational tractor offers a viable method of controllably steering asteroid 99942 Apophis away from an Earth impact. Coming from this article : http://www.nature.com/nature/journal/v438/n7065/full/438177a.html http://www.nature.com/nature/journal/v438/n7065/full/438177a...

by fintler 13y ago

ekianjo 13y ago

> Any citations on why this is more effective? From what I remember, it's because you change the center of gravity of the whole system, not just once at impact, but constantly since it continues orbiting around it.

blueblob 13y ago
But how much further out do you have to detect it to do this?
- ekianjo 13y ago
  I'll need to look into that. Obviously not just before impact, this is something you would have to do several months of maybe years before it is expected to hit, I guess. I'll come back when I find it again.
- ekianjo 13y ago
  Here's a piece of a paper on this : Deflecting a larger asteroid would require a heavier spacecraft, more time spent hovering, or more lead time. However, in the special case in which an asteroid has a close Earth approach, followed by a later return and impact, the change in velocity needed to prevent the impact can be many orders of magnitude smaller if applied before the close approach5. For example, the asteroid 99942 Apophis (2004 MN4), a 320-m asteroid that will swing by the Earth at a distance of about 30,000 km in 2029, has a small probability (10-4) of returning to strike the Earth in 2035 or 2036 (ref. 6). If it is indeed on a return impact trajectory, a deflection of only about 10-6 m s-1 a few years before the close approach in 2029 would prevent a later impact (A. Carusi, personal communication). In this case, a 1-tonne gravitational tractor with conventional chemical thrusters could accomplish this deflection mission as only 0.1 newtons of thrust would be required for a duration of about a month. Should such a deflection mission prove necessary, a gravitational tractor offers a viable method of controllably steering asteroid 99942 Apophis away from an Earth impact. Coming from this article : http://www.nature.com/nature/journal/v438/n7065/full/438177a.html http://www.nature.com/nature/journal/v438/n7065/full/438177a...