Aditya-L1 blasts off from Sriharikota in India’s quest to unravel Sun’s secrets

Aditya-L1, the first space-based observatory to study the sun was launched by the ISRO’s reliable Polar Satellite Launch Vehicle (PSLV)’s C57 variant.

“The launch of Aditya-L1 by PSLV-C57 is accomplished successfully. The vehicle has placed the satellite precisely into its intended orbit. India’s first solar observatory has begun its journey to the destination of Sun-Earth L1 point,” ISRO said after the launch.

Aditya-L1 started generating the power.
The solar panels are deployed.

The first EarthBound firing to raise the orbit is scheduled for September 3, 2023, around 11:45 Hrs. IST pic.twitter.com/AObqoCUE8I

— ISRO (@isro) September 2, 2023

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125-day journey

The spacecraft, after travelling for more than 125 days covering 1.5 million km from Earth, is expected to be placed in a halo orbit around the Lagrangian point one (L1) which is considered closest to the sun.

Lagrange Points. (ISRO)

Aditya-L1 is designed for providing remote observations of the solar corona and conducting in situ observations of the solar wind at L1.

According to ISRO, there are five Lagrangian points between the sun and Earth, and L1 in the Halo orbit would provide a greater advantage of continuously viewing the sun without any occurrence of an eclipse.

“This will provide a greater advantage of observing the solar activities continuously,” ISRO said.

On embarking on such a complex mission, the Bengaluru-headquartered space agency said the Sun is the nearest star and therefore can be studied in much more detail as compared to others.

By studying the sun, much more could be learnt about stars in the Milky Way as well as in various other galaxies, the organisation said.

The Sun shows several eruptive phenomena and releases immense amounts of energy in the solar system. If such explosive solar phenomena are directed towards the Earth, it could cause various types of disturbances in the near-Earth space environment.

Spacecraft and communication systems are prone to such disturbances. Therefore, an early warning of such events is important for taking corrective measures beforehand, the ISRO added.

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The launch vehicle

The ISRO scientists have used “C57”, the more powerful variant of the polar satellite launch vehicle (PSLV) to carry the spacecraft along with the seven payloads. Earlier, PSLV-XL variants were used in the Chandrayaan-1 mission in 2008 and the Mars Orbiter Mission (MOM) in 2013.

The spacecraft, after travelling for more than 125 days covering 1.5 million km from the Earth, is expected to be placed in a Halo orbit around. (Supplied)

Of the total seven payloads, four onboard the spacecraft would directly view the Sun while the remaining three would undertake in situ studies of particles and fields at the L1 point.

Initially, the Aditya-L1 spacecraft would be placed in a low-Earth orbit. It would be made more elliptical and later the spacecraft will be launched towards L1 by using on-board propulsion systems.

As the spacecraft travels towards L1, it will exit the Earth’s gravitational Sphere of Influence. After the exit, the cruise phase will start and subsequently, the spacecraft will be injected into a large halo orbit around L1. It would take nearly four months to reach the intended L1 point.

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The payloads

The Aditya-L1 payloads are expected to provide the most crucial information to understand the problems of coronal heating, coronal mass ejection (CME), pre-flare, and flare activities, and their characteristics, dynamics, and space weather.

The primary payload of Aditya-L1 the Visible Emission Line Coronagraph would be sending 1,440 images per day to the ground station for analysis on reaching the intended orbit.

VELC, “the largest and technically most challenging” payload on Aditya-L1, was integrated, tested, and calibrated at the Indian Institute of Astrophysics CREST (Centre for Research and Education in Science Technology), campus at Hoskote near Bengaluru with substantial collaboration with ISRO.

“From the continuum channel, which is the imaging channel, an image will come — one image per minute. So, the ground station will be receiving approximately 1,440 images for 24 hours,” Aditya-L1 Project Scientist and Operation Manager for VELC Dr Muthu Priyal said.

Thiruvananthapuram-based Liquid Propulsion System Centre (LPSC) provided the required components for the propulsion systems.

The Liquid Apogee Motor (LAM) developed by the LPSC has been crucial in satellite/spacecraft propulsion in India’s major space achievements, be it the three Chandrayaan expeditions or the 2013 MOM.

“Now we also play a large role in the Aditya-L1 mission. The Aditya spacecraft. which has a very interesting, very versatile thruster called LAM, delivers a thrust of 440 newtons,” Dr AK Asraff, deputy director of the LPSC, said.

The objectives of the mission include understanding the solar atmosphere, solar wind distribution, and temperature anisotropy, among others.

According to Indian Institute of Astrophysics (IIA) professor and in-charge scientist Dr R Ramesh, the monitoring of the Sun on a 24-hour basis is a must to study solar quakes which can alter the  Earth’s geomagnetic fields.

Explaining the need to study the Sun, he said that just as there are earthquakes on Earth, there are something called solar quakes — called Coronal Mass Ejections (CME) — on the solar surface.

In this process, millions and millions of tonnes of solar materials are thrown into the interplanetary space, and these CMEs can also be directed towards the Earth, he said.

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(The story has been updated)