Aditya L1, India’s mission to study the Sun, is scheduled to bid adieu to the Earth on September 19 as it slingshots towards the L1 point in space, 1.5 million kilometres away. Scientists at the Indian Space Research Organisation (ISRO) will undertake the Trans-Lagrangian Point 1 Insertion (TL1I) at 2 am on Tuesday. The space agency carried out the fourth and last manoeuvre around the Earth early on Friday morning. The spacecraft is now in a heavily elliptical orbit of 256 km x 1,21,973 km. “ISRO's ground stations at Mauritius, Bengaluru, SDSC-SHAR and Port Blair tracked the satellite during this operation, while a transportable terminal currently stationed in the Fiji islands for Aditya-L1 will support post-burn operations,” the space agency said on X, formerly Twitter. The first orbit-raising manoeuvre was carried out just the day after the successful launch. The Chandrayaan-3 mission, which had soft-landed on the Moon just days before, was still operating and collecting data at the time. The lander and rover have been put to sleep for now, awaiting the next lunar sunrise expected at the point on September 22. After travelling for nearly four months to the L1 point, covering a distance that has not been covered by any other Indian spacecraft, the Solar observatory will park itself in a halo orbit around the L1 point and study the Sun with seven complex instruments. Nigar Shaji, the project director of Aditya L1, told The Indian Express that usually satellites launched by ISRO are placed either in an orbit around the Earth or other celestial bodies like the Moon and Mars. In the case of Aditya L1, the spacecraft will move around a point in space and not around any celestial object, she said. “The gravitational pull at the L1 point is completely balanced, it actually acts like a virtual planet around which we will insert the spacecraft. This halo orbit insertion at L1 is something that ISRO has not done so far,” Shaji told The Indian Express. It is this property of the L1 point – and five other Lagrange points between any two celestial objects – that provides an ideal parking spot in space. This is because spacecraft do not need to expend a lot of fuel to remain in such orbit. In fact, an ISRO scientist said that because of the chosen L1 point to study the Sun, the mission that is planned for five years might last as long as 25 years just like the Solar and Heliospheric Observatory mission (SOHO) that had a planned life of two years but has been gathering data for nearly 28 years since its launch in 1995. According to the US-based National Aeronautics and Space Administration (Nasa), SOHO is its joint mission with the European Space Agency (ESA).
