Explanation:
How would you change the course of an
Earth-threatening
asteroid?
One idea - a massive spacecraft that uses gravity as a towline -
is illustrated in this dramatic artist's view of a gravitational
tractor in action.
In the hypothetical
scenario worked out
in 2005 by Edward Lu and Stanley Love at NASA's
Johnson
Space Center, a 20 ton
nuclear-electric
spacecraft tows a 200 meter diameter asteroid by simply hovering
near the asteroid.
The spacecraft's
ion drive
thrusters are canted away from the surface.
The steady thrust would gradually and
predictably alter the course of the tug and asteroid, coupled by their
mutual gravitational attraction.
While it sounds like the stuff of science fiction, ion drives do power
existing spacecraft
and a gravitational tractor would work
regardless of the asteroid's structure or surface properties.
