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European mission transforms solar eclipses into controlled orbital routine and expands observation capacity of the Sun’s corona with unprecedented precision, using two synchronized satellites that operate as a single scientific instrument in space.
The European Space Agency has put into operation Proba-3, a mission that transforms two satellites into a single precision observatory capable of creating artificial solar eclipses and observing the Sun’s corona continuously, repeatedly, and with strict control over alignment and shadow.
After the launch, the initiative was declared operational, combining technological demonstration and scientific investigation to tackle an age-old challenge in heliophysics: recording the Sun’s outer atmosphere without the intense interference of light emitted by the solar disk.
How Proba-3 creates artificial eclipses in space
Unlike what happens under natural conditions, the main difficulty lies in the extreme contrast between regions, as the solar corona is much weaker than the visible surface, requiring the blocking of direct light to reveal delicate structures and plasma flows near the edge.
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In total eclipses seen from Earth, the Moon fulfills this role for a few minutes and on rare occasions; Proba-3, on the other hand, was designed to reproduce the phenomenon in orbit frequently, extending the time available for measurements and images under controlled conditions.
At the core of the project are two spacecraft with distinct but precisely synchronized functions: the Occulter, equipped with a 1.4-meter occultation disk, and the Coronagraph, responsible for carrying the ASPIICS, the central scientific instrument of the European mission.
When alignment with the Sun occurs and the separation remains close to 150 meters, the Occulter’s disk blocks direct light and projects a reduced shadow onto the optical opening of the Coronagraph, allowing the operation of a coronagraph distributed in space.
Millimeter formation flight and autonomy in space
For the system to function correctly, the two platforms need to operate as if they were a single rigid structure, even though they are physically separated, continuously and autonomously adjusting their positions to preserve the geometry required for observation.
According to ESA, each orbit lasts about 19.7 hours, allowing approximately five to six hours per cycle for precise formation flying and the creation of the artificial eclipse, during which any deviation compromises the necessary alignment.
This level of precision is not limited to solar observation, as the same operational logic can be applied in future orbital service missions, refueling, autonomous encounters, and the construction of modular observatories formed by multiple independent vehicles.
Even with advanced control, the system needs to deal with constant risks, as two spacecraft operate at a short distance without physical connection, which requires automatic safety mechanisms capable of preventing collisions or responding to unexpected failures.
What the mission observes in the solar crown
Located near the apparent edge of the Sun, the analyzed region concentrates processes related to solar wind and coronal mass ejections, phenomena that directly influence space weather and its effects on technological systems on Earth.
Designed to operate in a difficult-to-record range, the ASPIICS observes the inner corona between approximately 1.1 and 3 solar radii, filling a relevant gap between instruments that capture regions closer to the surface and those aimed at more external areas.
Within this range, scientists investigate why the corona reaches temperatures exceeding one million degrees Celsius and how plasma structures accelerate before expanding into interplanetary space, affecting the Earth’s magnetic environment.
In addition to scientific interest, there are practical implications, as solar storms and variations in solar wind can interfere with communications, satellites, navigation, and electrical grids, increasing the importance of observing the dynamics of this region with greater precision.
Initial results and scientific advancement of the mission
The transition from the testing phase to operation occurred throughout 2025, during which the ESA announced the first artificial eclipse obtained in orbit, accompanied by the first images of the corona recorded with the two spacecraft operating in precise formation.
By April 2026, the European agency reported that the mission had produced 57 artificial eclipses and accumulated over 250 hours of high-resolution observation of the solar atmosphere, a volume considered significant for this type of experiment.
Based on this data, the initial analyses indicated movements in structures of slow solar wind with speeds higher than expected, highlighting the gain provided by the continuity of observations obtained with the new orbital configuration.
Another relevant advancement is the coverage of a zone that traditionally escaped available instruments, creating a connection between different scales of solar activity and allowing for a more integrated view of the dynamics of the corona.
Beyond the crown: technology and new uses in space
Although ASPIICS has greater visibility, Proba-3 also carries the DARA radiometer, aimed at measuring total solar irradiance, and the 3DEES, an instrument dedicated to the study of energetic electrons in the radiation belts traversed by the mission.
With this set, the initiative positions itself not only as a visual experiment but as an orbital laboratory that tests onboard autonomy, relative navigation, and new ways to distribute functions among independent platforms in a space environment.
By operating two small spacecraft as parts of the same system, ESA materializes an approach previously restricted to conceptual studies, based on the construction of flexible in-flight infrastructures with adjustable geometry and shared functions.
In this scenario, Proba-3 transforms a rare phenomenon into a recurring scientific tool, consolidating a model that can influence the development of future distributed missions and expand observation possibilities in space.
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