The Paris Air Show on June 16, 2025 unveiled a groundbreaking achievement in space and engineering by creating the first ever artificial solar eclipse in the orbit, thousands of kilometers above the Earth. The Proba-3 mission led by the European Space Agency (ESA) is an approximately $210 million scientific endeavour allowing the scientists to study the Sun’s corona— its outer atmosphere while addressing key mysteries about solar phenomenon with unprecedented detail and duration.
What is the Proba-3 mission? It is the world’s first mission flying over 250 meters while achieving millimeter precision, paving way for future applications like distributed telescopes or planetary exploration. It will generate over 1000 hours of coronal observations through nearly 200 eclipses planned. The project operates on global collaboration with contributions from 29 companies across 14 countries fostering global research and participation.
How does Proba-3 stimulates a solar eclipse? It consists of two cube-shaped satellites (each less than 5 feet) named the Occulter and the Coronagraph. These were launched on 5th December 2024 from Satish Dhawan Space Centre in India, operating in highly elliptical orbit ranging from 600-60,000 kilometers above Earth. The Occulter carries a 1.4m wide carbon fibre and plastic disk to block sun’s bright disk aligning precisely with the Sun’s center playing the role of the Moon in a natural eclipse, together with, casting a shadow on the Coronagraph satellite located 150m behind the Occulter. It houses the Association of Spacecraft for Polarimetric and Imaging Investigation of the Corona of the Sun (ASPIICS), a sensitive optical instrument capturing high-resolution images of inner corona, particularly closest to the Sun’s edge. The satellites maintain their relative positions with millimeter-level accuracy, forming a “giant coronagraph” in space. This separation is critical because it minimizes light scattering, enabling ASPIICS to observe the corona down to 1.08 solar radii (almost to the Sun’s surface).
The satellites perform their tasks farthest from the elliptical orbit, functioning in minimal gravity, magnetic field and atmospheric drag, thereby, reducing fuel consumption and allowing autonomous flying for up to 6 hours. The mission plans to generate approximately 2 eclipses per week over its 2-year lifespan.
Is operating the mission as simple as it looks? No. The mission’s success depends on precise formation flying, an intricate and autonomous ‘celestial dance’ which requires extraordinary accuracy. The satellites must maintain a 150m separation with a precision of one millimeter while orbiting at speeds of thousands of kilometers per hour. They must overcome diffraction of light and the dynamic environment in the space comprising of solar radiations, thermal fluctuation, etc. This is enabled by advance navigation systems (GPS, star tracker, lasers, etc.), onboard autonomy algorithms, shadow precision and propulsion and control.
The Sun’s corona refers to its outer atmosphere but what makes it a subject of profound scientific interest? The corona has extreme conditions and a strong influence on the space weather. Studying it is challenging because it is 10 million times fainter than the Sun’s photosphere, visible only during natural total solar eclipses. The Proba-3 enables the scientists and researchers to understand coronal heating which defies expectations, as its temperature is 1-3 million degrees Celsius, vastly hotter that Sun’s surface at 5500 degrees Celsius though it is away from the source of heat. The mission provides observations related to acceleration of solar wind and its interaction with Earth’s magnetosphere along with information about Coronal Mass Ejections’ origins and trajectories, enhancing space weather forecasting.
The Proba-3 offers up to 6 hours of eclipse, much longer than a 2–7-minute natural eclipse while enabling continuous and high-resolution observations. It carries the Digital Absolute Radiometer (DARA) to measure total solar irradiance and the 3D Energetic Electron Spectrometer (3DEES) to study electrons in Earth’s radiation belts. The mission’s images reveal fine coronal structures improving our understanding of solar phenomena and their terrestrial impacts. Proba-3’s first images mark the dawn of a new era in solar research, with far-reaching implications for science and society.
Riya Goyal is a trainee journalist at Cult Current. The views expressed in the article are
her ownand do not necessarily reflect the official stance of Cult Current