We often talk about the need to find and track Earth-crossing objects, but what do we do if we find one that’s likely to hit us? We’re far from demonstrating our ability to deflect an incoming asteroid, making a precursor mission of some kind a necessity. The European Space Agency has been carrying out design studies with three industrial consortia — led by Alcatel Alenia Space, EADS Astrium and QinetiQ — for a precursor mission called Don Quijote that would involve two separate spacecraft.

The Hidalgo impactor closes in

What the ESA has in mind is to drive an impactor into an asteroid to assess the resulting deflection. The impactor vehicle, called Hidalgo, would hit the target asteroid at a relative speed in the area of ten kilometers per second. The orbiter, called Sancho, would measure the deflection with a high degree of precision and act as a data relay for the approaching impactor. It would also deploy instruments in the form of what ESA calls an ‘autonomous surface package’ to to study the asteroid’s composition and other properties.

Image: The moments before impact… The Impactor spacecraft (Hidalgo) heads towards the target asteroid. Credit: ESA – AOES Medialab.

The late word out of ESA is that a Sancho mission study has been completed that builds on the larger Don Quijote industrial study. As the idea evolves, the agency is talking about first flying a Sancho mission without accompanying impactor to demonstrate key technologies for rendezvous and close operations around the asteroid. At this early stage, both electric and chemical propulsion options are still in the mix, with a launch assumed somewhere between 2013 and 2015. The duration of the preliminary Sancho mission would be four years.

You can read more about Sancho and Hidalgo, the primary components of the Don Quijote mission, here. Based on conventional technologies (although the SMART-1 electrical thruster, if chosen, would need some tweaking for the required seven-year mission lifetime), Don Quijote would tell us a great deal about what is and isn’t possible with some classes of near-Earth objects. Let’s hope that’s knowledge we never have to use in a collision scenario, but the cratered face of the Moon is a nightly reminder that the Solar System is an active, frequently hostile place.