Sancho observes Hidalgo's impact with an asteroid

Sancho is monitoring the effect of Hidalgo’s impact with an asteroid.
Don Quijote is an asteroid-deflecting mission currently under study by ESA’s Advanced Concepts Team (ACT). Its aim is the development of a means to tackle asteroid impacts.
To this purpose ESA has selected two target asteroids (2002 AT4 and 1989 ML).
The current scenario envisages two spacecraft in separate interplanetary trajectories. One spacecraft (Hidalgo) will impact an asteroid; the other (Sancho) will arrive earlier at the target asteroid, rendezvous and orbit the asteroid for several months, observing it before and after the impact to detect any changes in its orbit.