'Ready to tackle Armageddon'

By Ivan Noble BBC News Online science staff

A space mission to knock a potential rogue asteroid off course is undergoing feasibility studies with money from the European Space Agency (Esa).

We believe that the outcome of this mission would be good science

Jose-Antonio Gonzalez
Deimos-Space

A Spanish company, Deimos-Space, is designing the mission and hopes its plans will convince Esa to give the go-ahead for a full scale test on a real asteroid.

The company has come up with a plan, which it calls the Don Quixote mission, to launch a pair of probe spacecraft called Hidalgo and Sancho at a far off asteroid.

One would hit the asteroid at extremely high speed, deflecting it slightly from its orbit.

The other would observe the asteroid and make highly accurate measurements of what happened to it after the impact.

Asteroid billiards

The idea is that the mission would tell scientists how hard they would have to hit a real rogue asteroid heading for Earth in order to deflect it safely.

Deimos plans to finish its study early in 2003 and hopes Esa will then come up with the cash for the actual mission.

The company is optimistic.

"We believe that the outcome of this mission would be good science," Deimos-Space's Jose-Antonio Gonzalez told BBC News Online.

"And we are trying to demonstrate the feasibility of the mission, not only in terms of astrodynamic calculations or technology requirements but also financially," he said.

The company expects plenty of public and scientific interest in the project.

High-speed impact

"That's why we expect this mission to go on with the next phases, or at least with even more detailed studies on the key aspects of the mission," he said.

If it does, a suitable asteroid will be selected and then Hidalgo will slam into it at extremely high speed, probably around 10 kilometres (six and a half miles) per second.

Sancho will be orbiting the asteroid at a safe distance to see what happens.

If all goes to plan, the asteroid's orbit will be disturbed in the beginning by a few fractions of a millimetre.

The idea is that Sancho will measure this tiny shift and feed the data back to Earth.

Tiny changes in orbit can become much larger over time and Deimos wants to use the experiment to calculate how to knock a real rogue asteroid off course.

Early warning

Whether such an approach to dealing with an asteroid threat would work would depend largely on how much warning there is.

Hidalgo and Sancho would take many months to reach their target.

Any Hidalgo-like satellite used to deflect an incoming hazard would have to hit it in just the right place and at just the right speed.

Getting it right would involve great precision, but, as Mr Gonzalez points out, would not require the nuclear super-rockets of science fiction.

If the project does get the go-ahead, the Don Quixote mission would provide valuable information about the composition of the target asteroid.

"This mission would provide, for the first time, a look inside the asteroids," said Mr Gonzalez.

"The results of the experiment 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."