OrbitalHub

Credits: ESA

Formation flying has been a field of study since the beginning of the manned space flight. The final lunar spacecraft of the Apollo program had to be assembled in orbit. Also, docking maneuvers were required during the Skylab missions from 1973 to 1979.

The current focus of spacecraft formation flying is on maintaining a formation of various spacecraft. Maintaining the relative position of a cluster of satellites in orbit is much more challenging than having two or more spacecraft docking, as the first is more sensitive to modeling errors.

ESA’s Proba-3 will be the demonstrator for the technologies required for formation flying of multiple spacecraft.

The two independent, three-axis stabilized spacecraft comprising the Proba-3 mission will form an external coronagraph. An external coronagraph is a much more effective instrument than a terrestrial coronagraph, as the complete absence of atmosphere eliminates the glare that affects the observations from the ground.

By maintaining an accurate relative position, one of the spacecraft will block the direct light from the Sun so that the solar corona can be observed by the instruments mounted on the other. It is expected that the two spacecraft will be capable of positioning relative to each other with a sub-millimeter accuracy over a separation range of 25 to 250 meters. This positioning will be made possible by using S-band radio metrology and optical laser techniques.

You can find out more about the Proba-3 mission on ESA’s website.