India’s sun-watching observatory, Aditya L-1, tucked into its spot 

Aditya L-1, India’s space observatory meant to watch the sun — and warn humans against any mischief of the sun — is now in place, at its designated spot, the Lagrange-1 point, some 1.5 million km from the earth. 

Aditya L-1 took off onboard a PSLV rocket (PSLV C-57) on September 2, 2023, was taken to L-1 point, through a fuel-saving, multiple-loop trajectory and was finally manoeuvered into the designated “Halo orbit” at around 4 pm today (January 6, 2023).  

“This is a very important moment in the journey of Aditya L-1,” Annapurni Subramaniam, Director, Indian Institute of Astrophysics, told the Press Trust of India today. The “journey” actually began in 2006, when UR Rao, a former Chairman of India’s space agency ISRO, suggested placement of a sun-observing spacecraft at the L-1 point, between the earth and the sun.  

This moment marks the end of the spacecraft’s “cruise phase” and the beginning of the “orbit phase”, from where it will be looking at the sun every moment, travelling along with the earth as earth moves in an elliptical path around the sun. It will be orbiting an invisible point at L-1, due to an interplay of cosmic forces. 

The next step is the “door opening” of the onboard instruments, which will be done once the spacecraft settles down in its halo orbits. Making the spacecraft get into the exact halo orbit is extremely complex, which demanded precise navigation and control, and was akin to remote-controlling a toy from 1.5 million km away. 

Early warning system

Aditya L-1 houses seven scientific instruments to read the sun — three of which get data by ‘looking at’ the sun, and the rest by analysing the particles from the sun that stream into the instruments. The data generated by these instruments shall contribute to mankind’s understanding of the sun. But more than that, they can provide an early warning against solar storms that can damage our satellites and electrical grids. 

Solar storms can take many forms, such as coronal mass ejections (or billions of tons of matter flung out of the sun, which can shoot off anywhere including towards the Earth) and solar flares, which are sudden bursts of energy, often in the form of tongues of fire thousands of kilometres long that can spew X-rays, electromagnetic waves, or high-energy particles all across space and can disrupt radio communications and harm astronauts in space). Aditya L-1 is a sort of an early warning system.   

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