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Gravity Tractor Could Deflect Asteroids
Hugh Pickens writes "A new study at the Jet Propulsion Labs shows that weak gravitational pull of a "gravity tractor" could deflect an Earth-threatening asteroid if it was deployed when the asteroid was at least one orbit away from potential impact with Earth. First a spacecraft would be crashed directly into the asteroid, similar to the Deep Impact mission that impacted a comet in 2005. This would provide a big change of direction, but in a less controllable fashion that could push the path of the asteroid into a dangerous keyhole. But then a second spacecraft, the gravity tractor, would come into play, hovering about 150 meters away from the asteroid, to exert a gentle gravitational force, changing the asteroid's velocity by only 0.22 microns per second each day. Over a long enough time, that could steer it away from the keyhole. In the simulation, a simple control system kept the spacecraft in position, and a transponder on the asteroid helped monitor its position and thus determine its trajectory more precisely than would be possible otherwise. 'The gravity tractor is a wimp, but it's a precise wimp,' said astronaut Jack Schweickart. 'It can make very small, precise changes in orbit, and that's what you need to avoid a keyhole.'"
Or 1/3rd US population ?
Considering how hard it is to steer it out of the 'keyhole', how hard is it to steer it into the 'keyhole'.
Armageddon 2:
Bruce Willis has a 'training' montage that is him eating lots of food to improve the amount of gravity he has, then hovering near the asteroid while the skinny under-fed terrorist fights to keep it on target.
Moral of the story: eat more or the terrorists win. brought to you by the ag-business and heart doctors.
Geeks will point out that they could just add metal to the ship to add weight for the extra gravity.
only 0.22 microns per second each day
It helps to read all the words.
This would equate to 1.9cm a day, which is a lot, when you factor in that the earliest adjustments result in the widest changes. It is also worthy to note that by delaying or hastening the asteroid a mere 5 minutes would take a global killer to a near miss.
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