First images of solar corona captured using artificial eclipse

This marked a world-first in both scientific and engineering terms, as well as a major step forward for high-precision formation flying – a technology expected to underpin the next generation of space missions.

Led by Spain and developed by Sener as prime contractor, Proba-3 is also a major industrial success for the country’s space sector. The mission’s core team includes Spanish firms Airbus Defence and Space, GMV, Airbus Crisa, Thales España, and Deimos, along with Belgium’s Redwire and Spacebel. In total, the mission brought together more than 29 companies from 17 countries, supported by the Centre for the Development of Industrial Technology (CDTI) and the Spanish Space Agency.

Proba-3 demonstrated a radically innovative method for observing the outermost layer of the Sun, the corona – typically only visible during a total solar eclipse. The mission deployed two satellites, the Coronagraph and the Occulter, which autonomously flew in perfect synchrony to recreate this rare optical alignment from orbit.

The Coronagraph satellite carried the scientific payload: a coronagraph designed to image the solar atmosphere. Positioned 150 metres away, the Occulter satellite featured a 140cm disc to block the Sun’s intense light. Achieving the precise alignment needed to cast a millimetre-accurate shadow onto the Coronagraph’s optics involved a combination of camera systems, laser rangefinding, cold gas propulsion, and advanced navigation software.

This observation mode occurred during the apogee of the satellites’ elliptical orbit, at a distance of more than 60,000km from Earth. Each orbit required the two spacecraft to independently detect, align, and maintain their relative positions for up to six hours with a stability of less than one millimetre – all without human intervention.

ESA highlighted the mission as a critical milestone for formation flying, a technique that allows multiple spacecraft to operate as a single, distributed satellite system. This approach could reduce costs and improve performance for large-scale future missions in science, Earth observation, and communications.

The scientific benefit of Proba-3 is equally significant. By providing stable and extended eclipse conditions, researchers are now able to study the solar corona in greater detail and over longer periods than ever before. This region of the Sun is believed to be the source of the solar wind and various magnetic phenomena – such as flares and coronal mass ejections – which can interfere with satellites, power grids, and radio communications on Earth.

ESA stated that these observations offer a new opportunity to better understand the dynamics of solar activity and its impact on human technology and infrastructure.

Proba-3 forms part of ESA’s General Support Technology Programme and represents a flagship example of how international collaboration and technological innovation can converge to unlock new scientific frontiers.