How would you change the course of an
One possibility - a massive spacecraft that uses gravity as a towline -
is illustrated in this artist's vision of a gravitational
tractor in action.
In the hypothetical
scenario worked out
in 2005 by Edward Lu and Stanley Love at NASA's
Space Center, a 20 ton
spacecraft tows a 200 meter diameter asteroid by simply hovering
near the asteroid.
thrusters are canted away from the surface.
Their slight but 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.
One advantage of using a gravitational tractor is that
it would work regardless of the asteroid's
Given sufficient warning and time,
a gravitational tractor could
deflect the path of an asteroid known to be on a collision course
enough to miss planet Earth.
Credit & Copyright:
Dan Durda (FIAAA,