ISRO’s Aditya L1 successfully placed in a halo orbit around L1 point

The Indian Space Research Organisation (ISRO) has placed the Aditya L1 spacecraft in a halo orbit around the Lagrangian point (L1). India’s maiden solar mission Aditya L1 reached the L1 point on January 6, 127 days after it was launched on September 2, 2023 . Also read: What are the Lagrange points and why is Aditya L1 headed to one? | Explained After a 1.5 million km long journey the spacecraft was placed in a halo orbit around L1 following a firing manoeuvre which was carried out by ISRO Scientists and Engineers at the ISRO Telemetry Tracking and Command Network (ISTRAC) in Bengaluru.

Prime Minister Narendra Modi announced that the Aditya L1 has reached its destination. “India creates yet another landmark. India’s first solar observatory Aditya L1 reaches it’s destination. It is a testament to the relentless dedication of our scientists in realising among the most complex and intricate space missions.

I join the nation in applauding this extraordinary feat. We will continue to pursue new frontiers of science for the benefit of humanity,” Mr Modi tweeted from his X (formerly Twitter) account. Aditya L1 the first Indian space based observatory to study the Sun was launched on September 2, 2023 from the Satish Dhawan Space Centre in Sriharikota.

Subsequently, ISTRAC carried out four earth bound manoeuvres between September 3 and September 15. Aditya L1 on September 19 underwent the Trans Lagrangian 1 insertion manoeuvre, marking the beginning of its 110 day trajectory to the destination around the L1 point. L1 is roughly about 1.5 million km from the Earth and the distance of L1 from Earth is approximately 1% of the Earth Sun distance.

With the Aditya L1 satellite placed in the halo orbit around the L1 point it will be continuously viewing the Sun without any occultation/eclipse. This will provide a greater advantage of observing the solar activities continuously. Aditya L1 carries seven payloads to observe the photosphere, chromosphere, and the outermost layers of the Sun (the corona) using electromagnetic and particle detectors.

Using the special vantage point of L1, four payloads will directly view the Sun and the remaining three payloads will carry out in situ studies of particles and fields at the L1. According to ISRO the satellite will spend its whole mission life orbiting around L1 in an irregularly shaped orbit in a plane roughly perpendicular to the line joining the Earth and the Sun.

Aditya L1 has a mission life of five years during which its payloads are expected to provide the most crucial information to understand the problem of coronal heating; coronal mass ejection; pre flare and flare activities and their characteristics; dynamics of space weather; and propagation of particles and fields.

Editorial | Onward, sunward: On India’s mission to study the sun What are Lagrange points? According to ISRO, for a two body gravitational system, the Lagrange Points are the positions in space where a small object tends to stay, if put there. These points in space for a two body system such as Sun and Earth can be used by the spacecraft to remain at these positions with reduced fuel consumption.

For two body gravitational systems, there are total five Lagrange points, denoted as L1, L2, L3, L4, and L5. What is the L1 point? The L1 lies between the Sun Earth line which is about 1.5 million km from the Earth. The distance of L1 from Earth is approximately 1% of the Earth Sun distance. A satellite placed in the halo orbit around the L1 point has the major advantage of continuously viewing the Sun without any occultation/eclipse.

This will provide a greater advantage of observing the solar activities continuously. There are currently four operational spacecraft at L1 which are WIND, Solar and Heliospheric Observatory (SOHO), Advanced Composition Explorer (ACE) and Deep Space Climate Observatory (DSCOVER). Time line : Aditya L1’s journey to Lagrangian point (L1).

The Aditya L1 spacecraft launched by the PSLV from Sriharikota was placed into an elliptical orbit of 235x19500 km around the Earth. Subsequently, ISTRC in Bengaluru carried out four earth bound manoeuvres between September 3 and September 15. First manoeuvre placed the spacecraft in the 245 km x 22459 km orbit.

Second manoeuvre placed the spacecraft in the 282 km x 40225 km orbit. Third manoeuvre placed the spacecraft in the 296 km x 71767 km orbit. Fourth manoeuvre placed the spacecraft in the 256 km x 121973 km orbit. Aditya L1 underwent the Trans Lagrangian1 insertion manoeuvre, marking the beginning of its 110 day trajectory to the destination around the L1 point.

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