
CHENNAI: The European Space Agency’s (ESA) Proba-3 mission, initially slated for launch on Wednesday, has been rescheduled for December 5, due to a technical issue that emerged during final pre-launch preparations.
The mission, which is set to be launched aboard ISRO’s PSLV-XL rocket from the Satish Dhawan Space Centre in Sriharikota, will now lift off at 4:04 pm on Thursday.
According to Josef Aschbacher, Director General, ESA, the delay was triggered by an anomaly detected in the redundant propulsion system of the Coronagraph Spacecraft. This system is part of the satellite's altitude and orbit control subsystem, which ensures that the spacecraft maintains its correct orientation and precise pointing in space. The issue was identified during routine pre-launch checks at the Satish Dhawan Space Centre. The propulsion system is critical to the spacecraft’s ability to maintain the correct position relative to its companion spacecraft during the mission, as they will fly in formation with millimeter-level accuracy.
He confirmed that the anomaly is under detailed investigation, with engineers working to understand the cause and determine the best course of action. In the meantime, the mission’s control team at ESA’s European Space Operations Centre (ESOC) in Redu, Belgium, is evaluating the feasibility of a software solution to overcome the propulsion system issue. Should this software fix prove effective, the launch will proceed as planned on December 5.
Proba-3 is a unique mission consisting of two spacecraft designed to fly in precise formation to within millimetres. This cutting-edge capability will enable the mission’s primary scientific objective of creating artificial solar eclipses in space to study the Sun’s faint corona, the outermost layer of its atmosphere. By blocking the Sun’s fiery disk, Proba-3’s “Occulter” spacecraft will cast a shadow onto its companion “Coronagraph” spacecraft, allowing uninterrupted observation of the corona—an environment that is a million times fainter than the Sun itself.
The twin satellites will be separated by 150 metres in orbit, and their precise alignment will allow continuous solar observation for up to six hours during each 19-hour orbit. The system’s accuracy—down to a single millimetre—is unparalleled and represents a breakthrough in satellite formation flying.
Meanwhile, ISRO’s ground teams are on high vigil as any further delay would mean they have to drain the propellant from the tanks. Sources said they can keep the propellant for a maximum of 48 hours.