The first phase will see a spacecraft rendezvous with an asteroid and go into orbit around it. It would monitor the asteroid for several months, precisely determining its position, shape, mass and gravity field.
In the second phase, another spacecraft would slam into the asteroid at a speed of around 10 km/s, with the first spacecraft watching the collision, looking for any changes in the asteroid's trajectory.
In this way, a mission involving two spacecraft would attempt to be the first to actually move an asteroid.
Under the present scheme of things, the first spacecraft, Sancho, could reach any one of 5 or 6 small, nearby asteroids. Each one is no larger than a few hundred metres in diameter. Presently, mission planners have chosen to concentrate on Apophis, a small asteroid that can swing dangerously close to Earth on the outwards stretch of its orbit around the Sun.
Ian Carnelli, Technical Officer for the Don Quijote mission at ESA, said, the mission could launch sometime early in the next decade.
Sancho would take some 25 months to reach its target. Once there, it would begin its groundbreaking study - both literally and metaphorically.
"The idea is to get the technology ready before you really need it," said Carnelli.