Science

PROBA-3 CSC

Formation-Flying Solar Coronagraph (Coronagraph Spacecraft) · ESA

The Coronagraph Spacecraft half of ESA's most audacious formation-flying experiment ever attempted. PROBA-3's two satellites — this one carrying the telescope, its partner the Occulter carrying a 1.4-meter disk — fly in a precisely choreographed dance 150 meters apart for six hours out of every 19.6-hour orbit, blocking the Sun's blinding disk to reveal the faint solar corona in a way no single spacecraft ever could. Together they form what is effectively one 150-meter-long virtual telescope, holding formation to millimeter precision and arcsecond pointing accuracy entirely autonomously, without any commands from the ground. Launched December 5, 2024, PROBA-3 has already produced over 50 artificial solar eclipses and up to 250 hours of unprecedented corona observation — a technique first attempted crudely during the 1975 Apollo-Soyuz mission and now perfected fifty years later.