The European Space Agency’s (ESA) Proba-3 mission will consist of two satellites flying together, proving precision formation flying technology.

They’ll also be conducting a large-scale experiment, where the two will “form a 150-m long solar coronagraph to study the Sun’s faint corona closer to the solar rim than has ever before been achieved,” according to the mission’s description.

Below you can watch a summary of Proba-3’s formation flying mission.

A radio link between the two will be maintained via a radio antenna, and it’s currently undergoing tests at the ESA’s Compact Antenna Test Range (CATR), located in the ESTEC technical center in Noordwijk, the Netherlands, as it gears up for the 2021 launch date.

There, the team was able to analyze the antenna’s emitted signal patterns. The antenna can be seen in the photo below.

Proba-3 is the third mission in the ESA’s Proba series, where low-cost satellites validate new technologies for spacecraft while also carrying scientific instruments.