ISRO successfully launches Aditya-L1: Significance behind name, objectives of India's first solar mission

India’s first solar mission Aditya-L1 was successfully launched by Indian Space Research Organsiation (ISRO) today, September 2, from Srihatikota in Andhra Pradesh. The spacecraft will be placed in a halo orbit about 1.5 million kilometres from the Earth around the Lagrange point 1 (L1). 

It is the first mission by ISRO after the historic success of the landing of Chandrayaan-3 spacecraft on the surface of Moon. 

“India's maiden solar mission, Aditya-L1 successfully launched from Satish Dhawan Space Centre, SHAR, Sriharikota,” tweeted PIB

__India's maiden solar mission, Aditya-L1 successfully launched from Satish Dhawan Space Centre, SHAR, Sriharikota#AdityaL1 #AdityaL1Launch @isro pic.twitter.com/3zE0Bzz4Mo

— PIB India (@PIB_India) September 2, 2023

The objectives of the Aditya-L1 mission are to study the Sun and solar activities to figure out their real-time effect on space weather.

Here’s a detailed look about the Aditya-L1 mission, its objectives and why it has been named so.

Aditya-L1 launch: Significance of the name of India’s maiden solar mission

Aditya is another name for the Sun and L1 signifies the point at which the spacecraft will be in orbit.  The Lagrange point L1 is one of the five Lagrange points in the Earth-Sun system. Lagrange points denote a spot where the gravitational forces of the two celestial bodies produce enhanced regions with attraction and repulsion. This balances the centrifugal force felt by a smaller object and allows them to “hover” in a stable force.

The Lagrange point L1 will give the spacecraft the advantage of getting a continuous view of the Sun without any eclipses or occultation. There are four other points- L2, L3, L4 and L5.

The Aditya-L1 will be placed in a low Earth orbit initially. Later, the orbit will be made more elliptical and the orbit will be launched towards Lagrange point L1 and will subsequently leave the Earth’s gravitational Sphere of Influence (SOI). The object will go into a cruise phase and be injected into a large halo orbit around Lagrange point L1.

Aditya-L1: What is the payload of the spacecraft?

The spacecraft was launched on a Polar Satellite Launch Vehicle (PSLV) rocket. The launch vehicle has been used for most of ISRO’s missions. Aditya-L1 will be the 25th mission of the PSLV-XL configuration. The PSLV-XL has been used for the Mangalyaan and the Chandrayaan-1.

The spacecraft carries four remote-sensing payloads and three in-situ payloads. The Solar Low Energy X-ray Spectrometer (SoLEXS) and the High Energy L1 Orbiting X-ray Spectrometer (HEL1OS) are of particular importance as they have the responsibility of the Sun as a star observation. The instruments at the Aditya-L1 have been fine tuned to observe the solar atmosphere and the local environment at Lagrange point L1.

The Aditya-L1 spacecraft will study the solar upper atmospheric (chromosphere and corona) dynamics, the physics of solar corona and their heating mechanism, what drives space weather and the sequence of processes at multiple layers, which eventually lead to solar eruptive events.