Proba-3, a collaboration among 14 ESA Member States and Canada, was launched to facilitate autonomous space operations and precision maneuvering. The mission focuses on the solar corona, aiming to fill critical observational gaps and advance the capability for precision formation flying in space.
Two spacecraft launched on December 5 from India, marking a breakthrough in space mission technology. ESA’s twin Proba-3 satellites will fly in precise formation, maintaining accuracy within a single millimeter — functioning as if they were one giant spacecraft. This advanced coordination will allow them to create artificial solar eclipses in space, enabling extended observations of the Sun’s faint outer atmosphere, the corona.
Proba-3 Mission Launch
Fourteen ESA Member States including Canada collaborated on the Proba-3 mission to showcase cutting-edge European technology. The mission aims to advance autonomous space operations and precision satellite maneuvering while unlocking unprecedented scientific discoveries.
Proba-3 launched aboard a four-stage PSLV-XL rocket from the Satish Dhawan Space Centre in Sriharikota, India, on December 5 at 11:34 CET (10:34 GMT, 16:04 local time). Approximately 18 minutes after liftoff, the mission’s two satellites separated from the rocket’s upper stage.
The satellites will remain connected during the initial commissioning phase, which will be managed by mission control at the European Space Security and Education Centre (ESEC) in Redu, Belgium.
Dietmar Pilz, ESA Director of Technology, Engineering and Quality notes, “Proba-3 has been many years in the making, supported through ESA’s General Support Technology Programme fostering novel technologies for space. It is an exciting feeling to see this challenging enterprise enter orbit.”
Partnerships and Technological Challenges
Proba-3 mission manager Damien Galano adds, “Today’s liftoff has been something all of us in ESA’s Proba-3 team and our industrial and scientific partners have been looking forward to for a long time. I’m grateful to ISRO for this picture-perfect ascent to orbit. Now the hard work really begins, because to achieve Proba-3’s mission goals, the two satellites need to achieve positioning accuracy down to the thickness of the average fingernail while positioned one and a half football pitches apart.”
“We are honored that ESA entrusted NewSpace India Limited, NSIL, with its Proba-3 mission, and we are extremely satisfied to have delivered the satellites precisely into their designated orbit,” remarked Radhakrishnan Durairaj, Chairman and Managing Director of NSIL. “This is an extremely ambitious mission, with an ambitious orbit to go with it: the satellites have been placed into a highly elliptical orbit which extends more than 60 500 km from the surface of Earth. Reaching this orbit required the most powerful PSLV-XL variant of our launcher, equipped with additional propellant in its six solid rocket boosters.”
Advanced Solar Observations and Scientific Goals
Up around the top of their orbits the Proba-3 Occulter spacecraft will cast a precisely controlled shadow onto the Coronagraph spacecraft around 150 m away, to produce solar eclipses on demand for six hours at a time.
“There was simply no other way of reaching the optical performance Proba-3 requires than by having its occulting disc fly on a separate, carefully controlled spacecraft,” explains ESA’s Proba-3 mission scientist Joe Zender. “Any closer and unwanted stray light would spill over the edges of the disc, limiting our close-up views of the Sun’s surrounding corona.”
“Despite its faintness, the solar corona is an important element of our Solar System, larger in expanse than the Sun itself, and the source of space weather and the solar wind,” explains Andrei Zhukov of the Royal Observatory of Belgium, Principal Investigator for Proba-3’s ASPIICS (Association of Spacecraft for Polarimetry and Imaging Investigation of the Corona of the Sun) coronagraph.
“At the moment we can image the Sun in extreme ultraviolet to image the solar disc and the low corona, while using Earth- and space-based coronagraphs to monitor the high corona. That leaves a significant observing gap, from about three solar radii down to 1.1 solar radii, that Proba-3 will be able to fill. This will make it possible, for example, to follow the evolution of the colossal solar explosions called Coronal Mass Ejections as they rise from the solar surface and the outward acceleration of the solar wind.”
Impact and Future Potential of the Mission
ESA Director General Josef Aschbacher commented, “Proba-3’s coronal observations will take place as part of a larger in-orbit demonstration of precise formation flying. The best way to prove this new European technology works as intended is to produce novel science data that nobody has ever seen before.
“It is not practical today to fly a single 150-m long spacecraft in orbit, but if Proba-3 can indeed achieve an equivalent performance using two small spacecraft, the mission will open up new ways of working in space for the future. Imagine multiple small platforms working together as one to form far-seeing virtual telescopes or arrays.”
If Proba-3’s initial commissioning phase goes to plan then the spacecraft pair will be separated early in the new year to begin their individual check-outs. The operational phase of the mission, including the first observations of the corona through active formation flying, should begin in about four months.
The Proba-3 mission was led by Sener in Spain on behalf of ESA, coordinating contributions from 14 ESA Member States and Canada. Airbus Defence and Space in Spain built the spacecraft, while Redwire Space in Belgium handled the spacecraft’s avionics, assembly, and operations. CSL in Belgium developed Proba-3’s ASPIICS coronagraph, and Spacebel, also based in Belgium, created the onboard and ground segment software. GMV was responsible for the formation flying system and flight dynamics.
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