Post by Chicago Astronomer - Astro Joe on Nov 9, 2005 23:07:00 GMT -6
Gravity-Powered Asteroid Tractor Proposed to Thwart Impact
two NASA astronauts have presented a plan for an “asteroid tractor”—an unmanned, 20-ton spacecraft that uses the invisible bond of gravity to gently pull an asteroid into a new, non-threatening orbit.
“You can think of it like a big elastic band between the two pulling them together,” said Edward Lu, who presents the concept for the spacecraft with fellow astronaut Stanley Love in the Nov. 10 issue of the journal Nature.
The tractor would hover above the surface of the asteroid, without touching it, and use gravity as a towline. If the spacecraft maintains a consistent distance between it and the asteroid, and always tows in the same direction, this method won’t disturb the asteroid’s rotation or composition.
Despite the urge to give the asteroid a hardy tug, the key to moving an asteroid with gravity is to be gentle. An asteroid is likely to be loosely packed material, so tugging on it too hard could break it into unmanageable pieces. Or, the force from the spacecraft’s thrusters could break up the asteroid or stir up unwanted dust if fired too vigorously.
To make sure the thrusters couldn’t break up the asteroid—or hinder the net towing force by pushing the asteroid away—Lu and Love angled the thrusters slightly away from the body of the spacecraft.
“The jets fire off to the side, not quite as efficient as firing straight down. It’s like rowing forward by pushing off to the sides—it keeps you moving forward, but very slowly,” Lu told SPACE.com. “It takes less than a pound of force—about what you need to hold up a cup of coffee.”
Full story here: www.space.com/businesstechnology/051109_asteroid_tractor.html
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I wonder if overweight astronauts would add to the gravitational force...
