PROBA-3 satellites in orbit. Computer illustration of the European Space Agency's PROBA-3 (PRoject for OnBoard Autonomy-3) in Earth orbit. Proba-3's pair of satellites will be in a highly elliptical orbit around Earth, performing formation flying manoeuvres as well as scientific studies of the solar corona as one satellite creates an artificial solar eclipse for the other. The occulter satellite (outer orbit, centre), which obscures the Sun, will have solar panels on its Sun-facing side. Proba-3 is part of the European Space Agency's series of PROBA low-cost satellites that are being used to test new spacecraft technologies, whilst also carrying scientific instruments. The Proba-3 mission is scheduled to launch in late 2020.