PROBA-3 is a mission dedicated to the in-orbit demonstration (IOD) of precise formation flying techniques and technologies for future ESA missions. It is a part of the overall ESA IOD strategy and it is implemented by the Directorate of Technical and Quality management (D/TEC) under a dedicated element of the General Support Technology Programme (GSTP). The mission consists of two small spacecraft launched together into a highly elliptical orbit around the Earth before separating. The two satellites are intended to maintain formation to millimetre and arc second precision. In effect the pair can fly as a virtual giant satellite and achieves this autonomously, without relying on guidance from the ground. The paired satellites together form a 150-m long solar coronagraph to study the Sun’s faint corona very close to the solar limb with very low straylight.

Two scientific instruments are part of the mission: the coronagraph ASPIICS (Association of Spacecraft for Polarimetric and Imaging Investigation of the Corona of the Sun) to image both the quiescent and eruptive corona, and DARA (Digital Absolute RAdiometer), designed to measure the Total Solar Irradiance (TSI).

The nominal mission duration is 2 years, including 4 months of commissioning.