The European Space Agency’s (ESA) Proba-3 satellites will be launched by the Polar Satellite Launch Vehicle-XL (PSLV-XL) on Wednesday, December 4, at 4.08 pm IST.

ISRO said this mission “highlights the advanced space technologies made possible by the collaboration between” the NewSpace India Limited (NSIL), ISRO, and the ESA.

Proba-3 mission | In points

• The PSLV-C59 will carry the Proba-3 spacecraft into a highly elliptical orbit as a dedicated commercial mission of NewSpace India Limited (NSIL).
• The mission is an “In-Orbit Demonstration” (IOD) mission of the European Space Agency, aimed at demonstrating the precise formation flying.
• The mission has two spacecrafts — the Coronagraph Spacecraft (CSC) and the Occulter Spacecraft (OSC) — which will be launched together in a stacked form.
• In this mission, a pair of satellites will fly together, maintaining a fixed configuration as if they are a single large rigid structure in space. This is intended at proving innovative formation flying and rendezvous technologies, ISRO said.
• With a height of 44.5 m and lift off mass of 320 t, the Proba-3 missions will have four stages of propulsion, the Indian space agency said.
• The Coronagraph Spacecraft has laser and visual based targets, with hydrazine propulsion. Its payloads include Association of Spacecraft for Polarimetric and Imaging Investigation of Corona of the Sun (ASPIICS) and 3D Energetic Electron Spectrometer (3DEES). It has a mass of 310 kilograms.
• The Occulter Spacecraft, meanwhile, has laser and visual based optical heads, with cold gas propulsion. Its payloads include Digital Absolute Radiometer Science (DARA) experiment instrument. It has a mass of 240 kilograms.

How will Proba-3 function?

According to ISRO, the mission will function as an orbital lab, “demonstrating acquisition, rendezvous, proximity operations and formation flying, while validating innovative metrology sensors and control algorithms, opening up novel methods of mission control”.

The two satellites will adopt a fixed configuration in space, 150 meter apart while lined up with the Sun so that OSC blocks out the brilliant solar disk for the CSC.

The configuration movement will provide continuous views of the Sun’s faint corona — surrounding atmosphere — for scientific observation.

Notably, NSIL is India’s first commercial satellite service provider which has its own fleet of 11 state of the art communication satellites.

It is the commercial arm of ISRO, which has been mandated to provide transponder capacity on INSAT/GSAT fleet of satellite to Indian users for various SATCOM based broadcasting and telecom services, its website read. NSIL is also to provide Remote Sensing Services and Mission Support Services to the global users.