ISRO's ESA Proba-3 launch postponed: Here's what we know so far

The mission aims to capture continuous, detailed images of the Sun’s corona to improve our understanding of solar activity and space weather, while also demonstrating advanced precision formation flying (Image: ISRO)

ISRO announced that the PSLV-C59 mission has been rescheduled to Thursday due to an "anomaly" found in the PROBA-3 spacecraft, just minutes before the scheduled launch.

The mission, initially scheduled for 4:08 pm IST on December 4, was delayed to 4:12 pm on December 5 due to an anomaly in the PROBA-3 spacecraft.

Due to an anomaly detected in PROBA-3 spacecraft PSLV-C59/PROBA-3 launch rescheduled to tomorrow at 16:12 hours.
ISRO (@isro) December 4, 2024

Facilitated by NewSpace India Limited (NSIL), ISRO is set to launch the European Space Agency's (ESA) PROBA-3 mission satellites from Sriharikota using its PSLV-C59 rocket to study Sun's outermost layer, Corona, in unprecedented details.

According to an ISRO official, scientists at the ESA identified the 'anomaly' in one of the satellites of PSLV-C59-mission, ahead of the lift-off, following which they requested their counterpart to reschedule it to December 5.

"Based on their request, the launch has been rescheduled (for Thursday at 4.12 pm)," an official told PTI.

#Proba3 launch update: As part of standard operations in the preparation of launch, a technical issue was detected in the Proba-3 spacecraft. Liftoff is now scheduled no earlier than 5 December 10:42 GMT/11:42 CET. Join us live tomorrow https://t.co/cPbPMCWZ39 https://t.co/2QOzzP2pY8 European Space Agency (@esa) December 4, 2024

ESA Director General Josef Aschbacher reported that an anomaly occurred in the redundant propulsion system of the Coronagraph spacecraft, which was part of the PSLV-C59 mission. Scientists are currently working to identify the cause of the issue.

"During Proba3's pre-launch preparations at the Satish Dhawan Space Centre in India, an anomaly in the redundant propulsion system of the Coronagraph Spacecraft occurred. This propulsion system is part of the attitude and orbit control subsystem of the satellite and used to maintain orientation and pointing in space." Aschbacher said in a social media post.

He added, "The anomaly is being thoroughly investigated. The mission control team at ESA’s ESEC centre in Redu, Belgium, is assessing the use of a software solution to enable the launch scheduled for Thursday, 5 December, at 11:34 CET (10:34 GMT, 16:04 local time)."

During Proba3s pre-launch preparations at the Satish Dhawan Space Centre in India, an anomaly in the redundant propulsion system of the Coronagraph Spacecraft occurred. This propulsion system is part of the attitude and orbit control subsystem of the satellite and used to https://t.co/x5JPgMZ5GB
Josef Aschbacher (@AschbacherJosef) December 4, 2024

PROBA-3 is world’s first precision formation-flying mission, where two satellites, the Coronagraph Spacecraft (CSC) and the Occulter Spacecraft (OSC), will fly 150 meters apart, maintaining a fixed configuration like a single large rigid structure in space, to prove innovative formation flying and rendezvous technologies.

The Occulter Spacecraft (OSC), has a 1.4-meter occulting disk that will cast a shadow, about 8 cm wide, on the second satellite, the Coronagraph Spacecraft (CSC). The CSC, equipped with a 5 cm telescope, must stay within this shadow with millimeter precision.

The satellites will maintain this precise formation flying at apogee, about 60,000 km, where less propellant is needed. This will allow continuous corona observation for six hours during each 19-hour, 36-minute orbit, significantly improving study time.

The mission seeks to capture unparalleled details of the Sun’s faint corona, offering insights into solar dynamics, the corona's high temperature, and the acceleration of solar wind. It also aims to deepen our understanding of solar storms and coronal mass ejections, which impact Earth's communication systems, satellites, and power grids.

Proba-3 will serve as a space-based laboratory to test strategies, guidance, navigation, and control systems, along with algorithms like relative GPS navigation that were previously tested in ground simulators. These techniques and simulators developed for Proba-3 will be made available for broader use, playing a key role in preparing for future missions, according to ESA.

The launch will also highlight ISRO's growing space technology capabilities, with the PSLV-XL rocket being used for the 61st flight of the PSLV and the 26th use of its PSLV-XL configuration.

The mission aims to capture continuous, detailed images of the Sun’s corona to improve our understanding of solar activity and space weather, while also demonstrating advanced precision formation flying, with the satellites maintaining a precise 150-meter separation as a unified system.

*With Agency Inputs