The first space-based Indian solar observatory, Aditya L1, entered a halo orbit around Lagrange Point 1 (L1) on January 6, 2024, at around 10:30 UTC. The orbit insertion maneuver ended with the firing of control engines for a short duration. This specific halo orbit is selected to ensure a mission lifetime of 5 years.
Now that #AdityaL1 has arrived at the L1 point, it will take another 3 months for all its scientific payloads to become fully operational. 🛰— ISRO Spaceflight (@ISROSpaceflight) January 9, 2024
While some payloads (eg. SUIT) were turned on by #ISRO during the cruise to L1, over the next 3 months the rest of the instruments will… pic.twitter.com/npxvMQsDm6
Lagrange Point 1, a privileged Sun observation spot
Lagrange points are the equilibrium points for small-mass objects influenced gravitationally by two massive orbiting bodies. In the Sun-Earth system, Lagrange Point 1 (L1) is the equilibrium point positioned along the leader line at 1.5 million kilometers from the Earth.
Any object positioned at that point, or just orbiting it, will never be shadowed by the Earth or other bodies and will always view the sunlit face of the Earth. It will benefit from the gravitational equilibrium to stay at L1 using a very minimum quantity of fuel. For these reasons, L1 is the perfect spot for solar space observatories and telescopes.
The International Sun-Earth Explorer-3 (ISEE-3) was the first mission to leverage this panoramic viewpoint in November 1978. The objective of its first mission was to collect data on solar wind and other interactions with cosmic rays. The spacecraft then moved on to another orbit to fulfill its second mission.
Unveiling the whims of the sun
The main scientific mission objectives include the study of coronal heating, solar wind acceleration, Coronal Mass Ejections (CME), and dynamics of solar atmosphere and temperature anisotropy. The spacecraft payload carries seven payloads developed in collaboration with various ISRO centers (see our article Aditya-L1: India’s First Solar Mission Successfully Launched for more details).
Some of the scientific instruments were calibrated during the voyage, and they started the initial observation of the Sun. The spacecraft will continue commissioning in the next three months and then move to the formal operational status.