Largest payload onboard mission to study the Sun will be handed over to ISRO on R-Day

The Indian Institute of Astrophysics has built the Visible Emission Line Coronagraph (VELC), the largest payload that would fly on Aditya-L1.

ByPTI

Published Jan 25, 2023 | 9:50 PMUpdatedJan 25, 2023 | 9:50 PM

Aditya-L1 in launch configuration and Lagrange points in the Sun–Earth system. (Wikimedia Commons)

In a milestone for Indian space astronomy, the Indian Institute of Astrophysics (IIA) has built the Visible Emission Line Coronagraph (VELC), the largest payload that would fly on Aditya-L1, the country’s first dedicated scientific mission to study the Sun.

It is expected to be launched by the Indian Space Research Organisation (ISRO) by mid-2023.

The VELC payload would be formally handed over to ISRO Chairman S Somanath at IIA’s CREST campus on Thursday. “It’s a milestone in the development of space astronomy in India,” said an IIA official.

About the mission

Aditya-L1 is the first space-based Indian mission to study the Sun from a halo orbit around the Lagrange point 1 (L1) of the Sun-Earth system.

This mission, with seven payloads on board, to observe the photosphere, chromosphere, and the outermost layers of the Sun (the corona) will provide greater advantage of observing solar activities and their effect on space weather, stated ISRO officials.

Aditya-L1 in deployed configuration. (Wikimedia Commons)

Aditya-L1 in deployed configuration. (Wikimedia Commons)

VELC, which the IIA has built at its CREST (Centre for Research and Education in Science and Technology) campus at Hosakote near Bengaluru, is the largest and one of the most technically challenging of the seven payloads/telescopes that will fly on Aditya-L1.

The space solar mission was initially conceived as Aditya-1 with a 400-kg-class satellite carrying one payload (VELC) and it was to be launched in a 800 km low-Earth orbit.

Since a satellite placed in a halo orbit around the L1 of the Sun-Earth system has a major advantage of continuously viewing the Sun without any occultation/eclipses, the mission was revised to Aditya-L1.

It is now to be inserted into a halo orbit around the L1, which is 1.5 million km from Earth towards the Sun.

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The other six payloads are Solar Ultraviolet Imaging Telescope, Aditya Solar Wind Particle Experiment, Plasma Analyser Package for Aditya, Solar Low Energy X-ray Spectrometer, High Energy L1 Orbiting X-ray Spectrometer, and Magnetometer.

VELC system configuration. (VELC website)

VELC system configuration. (VELC website)

Purpose of the mission

“The scientific studies by the satellite will enhance our current understanding of the solar corona and also provide vital data for space weather studies,” stated ISRO officials.

The VELC payload is an internally occulted solar coronagraph with simultaneous imaging, spectroscopy, and spectro-polarimetry channels close to the solar limb.

“Both imaging and spectroscopic observations obtained by the VELC payload are key to study the diagnostic parameters of the solar corona and dynamics — as well as origin — of the coronal mass ejections and magnetic field experiments of the solar corona,” the IIA officials said.

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