If ISRO is able to put the satellite around the L1 point, it would guarantee a major advantage of continuously viewing the Sun without any eclipse for the entire duration of the mission of at least five years

Nearly a decade after India successfully got its spacecraft to fly millions of kilometers away to the Martian orbit in its first-ever inter-planetary mission, it is now aiming straight for the Sun. The country’s first solar mission – Aditya L1 has been a long time in coming.

Though initially set to take-off this year, the mission has suffered multiple delays, only to be pushed further back by the pandemic. But with ISRO now on track to speed up its series of pending missions including taking a second shot at moon landing with Chandrayaan-2 this year, country’s first solar mission has also gathered pace and is now edging towards completion, say scientists.

What’s The Plan?

The Sun has eluded scientists for long — the closest star that carries the secret to the ultimate source of energy that drives life on Earth. The US-led National Aeronautics and Space Administration (NASA) and other international space agencies already have a fleet of spacecraft which have been studying everything from its atmosphere to its surface. Launched in 2018, NASA’s Parker Solar Probe in fact became the first space craft to have had the closest encounter with the Sun in 2021.

But for Indian Space Research Organisation (ISRO), it will be a first such mission to study the Sun. The idea is to place the spacecraft in a halo orbit around the first Lagrange point — L1 of the Sun-Earth system. L1 is a vantage point in space where the gravitation forces of the Earth and the Sun are roughly equal – such that a satellite can orbit steadily around both the Earth and the Sun, and monitor it 24/7.

If ISRO is able to put the satellite around the L1 point, it would guarantee a major advantage of continuously viewing the Sun without any eclipse for the entire duration of the mission of at least five years.

Seven Payloads Aboard A PSLV

According to the plan, Aditya-L1 would carry as many as seven payloads which would observe the three layers of the Sun — photosphere, chromosphere, and the outermost layers — the corona using electromagnetic and particle detectors. Four of the payloads would directly view the Sun from the unique vantage point of L1, while the remaining three would carry out in-situ studies of particles and fields at L1.

Scientists expect that they would be able to study coronal heating, and delve more into the particle dynamics of the Sun. Till date, Sun remains a burning mystery, and researchers have been trying to understand the physics of its heating mechanism where surface temperatures shoot up to 5700 ℃. They want to decode the sequences that occur at its multiple layers, which drive its processes, and the magnetic field around it.

The payloads will also look at gaining new information into drivers for space weather, and what forms solar winds.

A Science Working Group with physicists from several institutes of India including the Bengaluru-based Indian Institute of Astrophysics (IIA) which are engaged in solar science research has already been working to finalise the mission design.

With Dr Sankarasubramanian K at the helm, Space Astronomy Group (SAG) of UR Rao Satellite Centre (URSC), Bengaluru, is now leading the work on readying all the scientific payloads for Aditya-L1. The mission is crucial, and it will help the global scientific community better understand the all-powerful Sun, but ISRO has a hard task to navigate a challenging orbit millions of kilometres away to reach the point.

With Chandrayaan-2 and Gaganyaan already scheduled, it remains to be seen, when the agency finally decides to head out for its next big destination — the Sun.