'Off To Sun-Earth L1 Point': Aditya-L1 Exits Earth's Gravitational Sphere Of Influence, To Reach Destination After 110 Days

Aditya-L1 performed its fifth and final Earth-bound manoeuvre on September 19, at 2:00 am IST. After the burn, Aditya-L1 is on a trajectory that will take it to the Sun-Earth Lagrange Point 1 (L1).

Aditya-L1 has exited Earth's gravitational sphere of influence (SOI). India's first space-based solar observatory to study the Sun will reach its final destination after about 110 days. ( Image Source :X/@ISRO )

Aditya-L1 has successfully performed the Trans-Lagrangean Point 1 Insertion (TL1I) manoeuvre, the spacecraft's fifth and final Earth-bound manoeuvre. The perigee burn was performed on September 19, 2023, at 2:00 am IST. After the manoeuvre, Aditya-L1 is on a trajectory that will take it to the Sun-Earth Lagrange Point 1 (L1). Also, the spacecraft has exited Earth's gravitational sphere of influence (SOI). 

India's first space-based solar observatory to study the Sun will reach its destination, which is a halo orbit around L1, after about 110 days, through a manoeuvre. Aditya-L1 is set to begin the cruise phase of its voyage. After Aditya-L1 successfully performed the fifth Earth-bound manoeuvre, the Indian Space Research Organisation (ISRO) wrote on X (formerly Twitter): "Off to Sun-Earth L1 point!"

The TL1I manoeuvre marks the fifth consecutive time ISRO has successfully transferred a spacecraft on a trajectory towards another celestial object or location in space. 

Aditya-L1 begins scientific experiments 

Aditya-L1 has also commenced its scientific experiments. ISRO said in a mission update on September 18 that an instrument onboard Aditya-L1 has measured the properties of high-energy particles and electrons at a distance of 50,000 kilometres from the Earth. Analysing these particles will help scientists understand the behaviour of particles around Earth. 

The sensors of a remote sensing payload, called Supra Thermal & Energetic Particle Spectrometer (STEPS), have started collecting scientific data. The instrument measured suprathermal ions, or very energetic particles, and electrons at distances greater than 50,000 kilometres from the Earth. The measurements were made within Earth's magnetosphere.

STEPS has six sensors, each of which observes and measures suprathermal and energetic ions in different directions. The energies of the energetic ions range from 20 kiloelectron volts per nucleon to five megaelectronvolts per nucleon. A nucleon refers to a proton or a neutron. Meanwhile, the energies of electrons are greater than one megaelectronvolt.

ISRO aims to place Aditya-L1 in a strategic location around L1 because the halo orbit around this special point will not only allow the spacecraft to save fuel, but will also offer an uninterrupted view of the Sun, for the entirety of its mission duration, which is five years.