The longest corridor in ESA's largest establishment was turned into a test site for one of the Agency's most ambitious future missions, Proba-3. The two satellites making up this mission will line up so that one casts a shadow onto the other, revealing inner regions of the Sun's ghostly atmosphere. But such precision formation flying will only be possible through a vision-based sensor system allowing one satellite to lock onto the other.
source https://phys.org/news/2021-03-corridor-proba-formation-sensors.html
