[X] My Assistant

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Here's a Christmas present for us all...a 0.7 km NEO may make a 4200 km altitude Earth flyby on Halloween, 2041: http://neo.jpl.nasa.gov/risk/2006xg1.html

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Yeah, I'm sure that will be the case. I noticed that the NASA NEO site already had 76 observations logged between 11-22 Dec; it must be very favorably placed, so we should see it drop off the radar screen after the holidays.

Good thing, too. 1900 megatons of impact energy could be a bit unpleasant. With that in mind, does anybody think that we should get serious about devising a way to deflect these things, if it's ever needed? I like the idea of "docking" a DS1-style propulsion system to a threatening rock & steering it clear...or, ideally, steering it slowly into an exploitable orbit for future mining!

And on a somewhat related topic, is there anything at all we could do about an imminent long-period comet impact? I can't think of a single countermeasure. (Okay, I confess...I rented the classic When Worlds Collide two days ago, and it's been bugging me ever since... )

[Bob Shaw]

1900 megatons of impact energy could be a bit unpleasant. With that in mind, does anybody think that we should get serious about devising a way to deflect these things, if it's ever needed? I like the idea of "docking" a DS1-style propulsion system to a threatening rock & steering it clear...or, ideally, steering it slowly into an exploitable orbit for future mining!

And on a somewhat related topic, is there anything at all we could do about an imminent long-period comet impact? I can't think of a single countermeasure. (Okay, I confess...I rented the classic When Worlds Collide two days ago, and it's been bugging me ever since... )

The most attractive proposal I've seen is for a 'gravitational tractor' where a vehicle with an ion-engine is held aloft 'above' the target rock/dustpile/snowdrift and gradually applies a small force (equivalent to it's local weight, so merely ounces in the case of a test vehicle) for years at a time. In the case of a more urgent removal mission, you could send more spacecraft rather than being stuck with a Saturn V/Icarus scenario. By remaining perched above the sweet spot you could have the best possible trajectory adjustment, constant sunlight, and the ability to move loose structures.

Bob Shaw