ESA and the Johns Hopkins University Applied Physics Laboratory (which runs several space missions including the Messenger probe now orbiting Mercury) are proposing a joint experiment to test impact deflection of an asteroid. A JHU-APL spacecraft would ram into an asteroid while an ESA spacecraft would monitor the impact and its effects on the object.

• Asteroid deflection mission seeks smashing ideas – ESA – Jan.15.12
• High impact factor space R&D : ¨AIDA¨ Call For Experiment Ideas – ESA
• Asteroid Impact & Deflection: Assessment (AIDA) Mission – Opportunities and Tests in a US-Europe Space Mission Cooperation – ESA – May.25.12 (pdf)

Asteroid Impact Monitor Design