Sriharikota, India: Final preparations are underway for the European Space Agency’s (£166m) Proba-3 mission, which will use satellites in close formation to create artificial solar eclipses.
The mission, ESA’s first venture into precise formation flying, involves two spacecraft orbiting Earth with millimetre-level accuracy, equivalent to the thickness of a human fingernail.
Scheduled to launch from India’s Satish Dhawan Space Centre at 4:08 PM IST (10:38 AM UK time) on 4th of December, the spacecraft will travel for four months to reach a highly elliptical orbit ranging from 370 miles to 37,000 miles from Earth.
If the satellites function as planned, they will align precisely with the sun, enabling the lead spacecraft to cast a controlled shadow onto its companion, allowing the latter’s instruments to study the sun’s corona, the outermost layer of its atmosphere.
Historically, scientists have examined the sun’s ring-like corona during solar eclipses, when the moon obscures the sun’s glare enough to reveal the corona from Earth. This process often involves traveling worldwide to observe eclipses, typically allowing only a few minutes of study—or none at all if clouds obstruct the view.
The €200m (£166m) Proba-3 mission promises to transform scientists’ understanding of the corona by producing 50 artificial solar eclipses a year, each lasting six hours.
The lead spacecraft carries a 1.4-metre-wide occulter disc to block the sun as seen from the second spacecraft, turning the pair into a 150-metre-long instrument called a coronagraph.
Unlike traditional solar eclipse observations, which are limited by geography and weather, Proba-3 will offer extended and consistent study opportunities.
This innovative approach will help solve the mystery of why the sun’s corona is significantly hotter than its surface and improve predictions of solar weather, including coronal mass ejections and solar storms that can disrupt technology on Earth. The sun’s surface is about 5,500C, but the corona can exceed 1mC.
The two spacecraft will maintain formation for six hours of every 19.7-hour orbit using optical sensors, LEDs, and precision lasers. The first images are expected in March 2025, marking a major milestone in solar research.
The Proba-3 mission marks a significant leap in solar research and space innovation, paving the way for deeper understanding of the sun’s mysteries and improved resilience against solar weather impacts on Earth.