Spanish scientists are investigating the possibility of hitting an asteroid with a spacecraft to knock it off its collision course with the Earth.
They say the mission would help experts work out how hard to hit an asteroid if it was heading for Earth.
Researchers at Deimos-Space are carrying out a feasibility study into the Don Quixote Mission.
The BBC reports the company wants to launch two spacecraft, called Hidalgoand Sancho, at a far-off asteroid.
The idea is to use Hidalgoto hit the asteroid in the right place and at the right speed and change its orbit by a few fractions of a millimetre. Sanchowill measure the effect of the impact and plot the new course.
The feasibility study is being funded by the European Space Agency. Deimos-Space hopes to secure full backing for a test on a real asteroid.
Mr Jose Antonio Gonzalez said the outcome of this mission would be "good science", because it would help scientists prepare for a real asteroid alert.
He said: "The results would either validate our proposed strategy or might mean we have to think of other solutions, such as placing a huge solar sail on the asteroid's surface to use the solar wind to change its trajectory."
Deimos hopes ESA will fund a full-scale mission at the end of the feasibility study in 2003.