The European Space Agency has published the first image taken by the Proba-3 mission. It demonstrates an artificial solar eclipse in near-Earth orbit.
How to see the solar corona
The Proba-3 mission was launched in December 2024. Its purpose is to study the solar corona — the outer, most rarefied, and hottest layer of the star’s atmosphere, whose temperature reaches millions of degrees. It is the source of solar wind and mass ejections. When the latter reach Earth, they cause geomagnetic storms and auroras.
The corona becomes visible during total eclipses, when the Moon completely covers the solar disk. The Proba-3 mission uses this principle. It consists of two spacecraft located in an elongated near-Earth orbit. The Occulter satellite acts as an artificial moon, covering the Sun for the Coronagraph instrument, which can then observe its corona.
To make this work, Occulter and Coronagraph have to be 150 meters apart and stay in position with millimeter precision. This task is assigned to the laser system. It constantly measures the distance between the vehicles, allowing them to maintain formation. To change their position, satellites are equipped with a set of high-precision engines capable of performing micro-course corrections with thrust comparable to the force of a falling feather. In addition, a shadow position sensor is installed on the Coronagraph. An onboard algorithm based on light intensity measurements ensures that it remains in the shadow cast by Occulter.
Artificial eclipse in orbit
In March 2025, a pair of spacecraft lined up in perfect formation for the first time and maintained it for several hours without any control from Earth. Occulter blocked the Sun, casting a shadow with a diameter of 8 cm onto the Coronagraph optical instrument.
This made it possible to obtain the first test images of the solar corona. They turned out to be quite comparable in quality and detail to photos taken during eclipses on Earth. The difference is that satellites can cause eclipses every 19.6 hours, lasting six hours, while total solar eclipses occur no more than a couple of times a year and last only a few minutes.
According to experts, the first images of the corona demonstrate all the advantages of group flight technology. They also provide a clear insight into the potential of the data that will be collected by the mission during its work. Proba-3 will be able to see much more detail and detect fainter structures than traditional coronagraphs, thanks to a sharp reduction in the amount of “scattered” light reaching the detector.
According to ESA
