A pair of spacecraft Proba-3 were launched together from India on a four-stage PSLV-XL rocket from Satish Dhawan Space Centre in Sriharikota, India, on Thursday, 5 December. Stacked together, the two satellites separated from their upper stage about 18 minutes after launch. with the potential to change the nature of future space missions.

ESA’s twin Proba-3 platforms will perform precise formation flying down to a single millimetre, as if they were one single giant spacecraft. To demonstrate their degree of control, the pair will produce artificial solar eclipses in orbit, giving prolonged views of the Sun’s surrounding corona.

“We are honoured that ESA entrusted NewSpace India Limited, NSIL, with its Proba-3 mission, and we are extremely satisfied to have delivered the satellites precisely into their designated orbit,” remarked Radhakrishnan Durairaj, Chairman and Managing Director of NSIL. “This is an extremely ambitious mission, with an ambitious orbit to go with it: the satellites have been placed into a highly elliptical orbit which extends more than 60 500 km from the surface of Earth. Reaching this orbit required the most powerful PSLV-XL variant of our launcher, equipped with additional propellant in its six solid rocket boosters.”

ESA Director General Josef Aschbacher commented, “Proba-3’s coronal observations will take place as part of a larger in-orbit demonstration of precise formation flying. The best way to prove this new European technology works as intended is to produce novel science data that nobody has ever seen before.
Up around the top of their orbits the Proba-3 Occulter spacecraft will cast a precisely controlled shadow onto the Coronagraph spacecraft around 150 m away, to produce solar eclipses on demand for six hours at a time.

“It is not practical today to fly a single 150-m long spacecraft in orbit, but if Proba-3 can indeed achieve an equivalent performance using two small spacecraft, the mission will open up new ways of working in space for the future. Imagine multiple small platforms working together as one to form far-seeing virtual telescopes or arrays.” https://www.esa.int/Newsroom/Press_Releases/Eclipse-making_double_satellite_Proba-3_enters_orbit