ISRO reschedules Proba-3 launch after detecting 'anomaly'

The ISRO has rescheduled the launch of PSLV-C59 to Thursday due to an "anomaly" detected in the PROBA-3 spacecraft, the agency announced on Wednesday, minutes before the scheduled launch.

The Bengaluru-headquartered space agency had originally planned the launch at 4.08 pm on Wednesday from the spaceport here.

"Due to an anomaly detected in PROBA-3 spacecraft PSLV-C59/PROBA-3 launch rescheduled to tomorrow at 16:12 hours," the space agency said in an update minutes ahead of the lift-off.

Dubbed as world's first initiative of its kind, the Proba-3 (Project for Onboard Anatomy) consists of two satellites -- Coronagraph (310kgs) and Occulter (240kgs) -- in which two spacecraft would fly together as one, maintaining precise formation down to a single millimetre to study the Corona, the Sun's outer atmosphere.

The European Space Agency (ESA) said the Corona is much hotter than the Sun itself and it is where space weather originates. It is also a topic of widespread scientific and practical interest.

For ISRO, this launch would provide key insights on taking up scientific experiments on the Sun after its maiden mission--Aditya-L1 which was successfully launched in September 2023.

Proba-3 is a technology demonstration mission funded via the General Support Technology Programme. The instruments onboard the satellites would travel closer to the solar rim for up to six hours at a time and each spacecraft would take up approximately a 19-hour orbit around the Earth.

NewSpace India Ltd, the commercial arm of ISRO has bagged the order from the ESA.

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.

The 25-hour countdown was progressing smoothly since it commenced on Tuesday at 3.08 pm and scientists at the spaceport here have been working on preliminary works for the launch.

'Probas' is a Latin word, meaning 'Let's try'.

The mission objective is to demonstrate precise formation flying and the two spacecraft inside the satellites would be launched together in a stacked configuration after the desired orbit level is reached.

PSLV-C59 is a 44.5 metre tall rocket and is on its 61st flight and the 26th with the PSLV-XL variant which is normally used to place heavy satellites.

The two satellites (Coronagraph and Occulter) would undertake an 18-minute journey to reach the desired orbit.

After reaching the preparatory conditions, the two spacecraft would fly 150 metres apart (as one large satellite structure) in tandem so that the 'Occulter' spacecraft would block out the solar disk of the sun enabling 'Coronagraph' to study the corona of the Sun or the surrounding atmosphere, for scientific observation.