Preparations in the final phase for India's maiden solar mission, Aditya L1 onboard the PSLV-C57, ahead of its launch on Sept. 2, 2023. (PTI Photo)
TIRUPATI: While still studying the Moon and making exciting new discoveries, India will aim for the Sun on Saturday with the launch of Aditya-L1, its maiden solar expedition. To be sure, this mission also has a few firsts,
The 23-hour-10-minute countdown commenced on Friday for the blast-off scheduled at 11.50 am on Saturday from the Satish Dhawan Space Centre, Sriharikota. ISRO will use its PSLV-XL rocket to launch the spacecraft on its 125-day voyage to the Sun. If all goes well, Aditya-L1 will reach the Lagrange point L1, its space home 1.5 million km away from the Earth, in January next year.
Indian Space Research Organisation (Isro) chairman S. Somanath said the Sun mission is designed for providing remote observations of the solar corona (the Sun’s outermost layer) and conduct observations of the solar wind at L1 (Sun-Earth Lagrangian point), the spot in space that Aditya-L1 will orbit.
"This will provide a greater advantage of observing the solar activities continuously," Isro said.
Initially, Aditya-L1 would be placed in a low earth orbit. It would be made more elliptical, which will give it speed, and then launched towards the Sun-Earth Lagrange point L1 by using on-board propulsion systems.
The Lagrange points are positions in space where the gravitational forces of two large bodies, in this case, the Sun and Earth, is balanced. A smaller object can remain relatively stationary at these points. Aditya-L1's placement at L1 will give it an uninterrupted view of the sun and enable to study the impact of solar activity in real-time. This strategic location will allow the observatory to continuously monitor the Sun without any interruptions.
Aditya-L1 is equipped with seven scientific payloads designed to study various aspects of the Sun. These payloads are expected to provide the most crucial information to understand the problems of coronal heating, solar wind acceleration, coronal mass ejection (CME), pre-flare, and flare activities, and their characteristics, dynamics, and space weather, comprehending the coupling and dynamics of the solar atmosphere, and examining solar wind distribution and temperature anisotropy.
Of the total 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. These payloads employ electromagnetic and particle detectors, as well as magnetic field detectors, to gather critical data.
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 in 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 approximately 1,440 images for 24 hours, we will be receiving at the ground station," said Dr Muthu Priyal, Aditya L1 project scientist and VELC operation manager.
As regards the propulsion systems, which will take it all the way to L1 and keep it there, Thiruvananthapuram-based Liquid Propulsion System Centre (LPSC) provided the required components.
The Liquid Apogee Motor (LAM) developed has worked flawlessly on the three Chandrayaan expeditions and the 2013 Mars Orbiter Mission (MOM). "The Aditya spacecraft. which has a very interesting, very versatile thruster called LAM, which is delivering a thrust of 440 newtons," Dr A.K. Asraff, deputy director of LPSC, said.
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 geomagnetic fields of the Earth.