India's solar mission: Countdown begins today

The Indian Space Research Organisation, hot on the heels of its lunar landing success, is set to blast a probe even deeper into space to study the sun. Slated for launch on 2 September, the Aditya-L1 (Aditya is a name for the sun in the Hindi language) is the first Indian space mission to study the sun.

On Thursday, ISRO chairman S Somanath said the space agency was getting ready for the launch and that the countdown for its launch will start on Friday.

India's first solar mission is scheduled to be launched on 2 September at 11.50am from the Sriharikota spaceport in Andhra Pradesh.

Aditya-L1 mission purpose

Aditya-L1 spacecraft is designed to provide remote observations of the solar corona and in situ observations of the solar wind at L1 (Sun-Earth Lagrangian point), which is about 1.5 million kilometres from the Earth. Notably, Aditya-L1 is a fully indigenous effort with the participation of national institutions.

It will be the first dedicated Indian space mission for observations of the Sun to be launched by the Bengaluru-headquartered space agency.

"We are just getting ready for the launch. The rocket and satellite are ready. We completed the rehearsal for the launch. So tomorrow, we have to start the countdown for the day after tomorrow's launch," Somanath told reporters.

Aditya-L1's parking

Aditya-L1 will be placed in an orbit around the L1 of the Sun-Earth system, where the gravitational effects of both bodies cancel each other out. That "parking lot" in space allows objects to stay put because of balancing gravitational forces, reducing fuel consumption by the spacecraft.

Cost of Aditya-L1 mission

In 2019, the Centre sanctioned the equivalent of about $46 million for the Aditya-L1 mission. The ISRO has not given an official update on costs.

Why is the Aditya-L1 mission significant for India?

For the ISRO, success would be another major feat after India became the first country to land a spacecraft close to the lunar south pole in August.

If all goes according to plan, Aditya-L1 will enter into a halo orbit around one of five Lagrange points. From there, Aditya-L1 should enjoy an uninterrupted view of the sun and study in real-time its effect on environmental conditions in the vicinity of Earth and other planets.

The ISRO's spacecraft can also help scientists dig out the hidden history of the Earth's climate as solar activities have an impact on the planet's atmosphere.

Solar missions by other countries

India will be one of a small group of countries which are studying the sun.

China has two such spacecraft orbiting Earth, including the Advanced Space-based Solar Observatory launched last year to investigate solar flares and coronal mass ejections.

Hinode, backed by space agencies from Japan, the UK, the US and Europe, is orbiting Earth and measures the magnetic fields of the sun.

The Solar & Heliospheric Observatory mission (SOHO), a joint project of NASA and the European Space Agency, is near the same Lagrange point as the one ISRO is targeting for Aditya-L1. Another joint US-European mission, Solar Orbiter, can travel as close as about 42 million km from the sun.

The US has other solar missions, including the Parker Solar Probe, which in 2021 became the first spacecraft to pass through the sun's corona, or upper atmosphere.

What are Lagrangian points?

Lagrangian points are where gravitational forces, acting between two objects, balance each other in such a way that the spacecraft can 'hover' for a longer period of time.

The L1 point is considered the most significant of the Lagrangian points, for solar observations, which mathematician Joseph Louis Lagrange discovered.