Joint Russian–Ukrainian project involving two orbiting solar observatories to investigate the Sun's internal structure and solar flares.

Coronas-I was launched in March 1994 but failed after only a few months. Coronas-F was launched in July 2001 to study the dynamic processes of solar activity in the Sun's active regions, flares, and mass ejections. Its instruments include X-ray and gamma-ray scintillation spectrometers.