India’s first space-based observatory to study the Sun, Aditya-L1, is headed to the Lagrangian 1 (L1) point as ISRO carried out the Trans-Lagrangian 1 Insertion (TL1I) manoeuvre in the early hours of September 19.
The TL1I manoeuvre marks the beginning of Aditya-L1’s 110-day journey towards the L1 point which lies between the Sun-Earth line. L1 is about 1.5 million km from the Earth and the distance of L1 from Earth is approximately 1% of the Earth-Sun distance.
“Off to Sun-Earth L1 point! The Trans-Lagrangean Point 1 Insertion (TL1I) maneuvre is performed successfully. The spacecraft is now on a trajectory that will take it to the Sun-Earth L1 point. It will be injected into an orbit around L1 through a maneuver after about 110 days. This is the fifth consecutive time ISRO has successfully transferred an object on a trajectory toward another celestial body or location in space,” ISRO posted on X.
Aditya-L1 was launched on September 2 by the Polar Satellite Launch Vehicle (PSLV) from the Satish Dhawan Space Centre in Sriharikota.
Following the launch, Aditya-L1 carried out four earth-bound manoeuvres between September 3 and September 15.
Aditya-L1, which is dedicated to the comprehensive study of the Sun, has seven payloads. Five payloads were developed by ISRO and two by Indian academic institutes in collaboration with the space agency.
Upon arrival at the L1 point in January 2024, another manoeuvre will be performed which will bind Aditya-L1 to an orbit around L1. The satellite will spend its 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.
Scientific data collection has started: ISRO
ISRO on September 18 announced that the Supra Thermal and Energetic Particle Spectrometer (STEPS) instrument, a part of the Aditya Solar Wind Particle EXperiment (ASPEX) payload, has begun the collection of scientific data.
STEPS comprises six sensors, each observing in different directions and measuring supra-thermal and energetic ions ranging from 20 keV/nucleon to 5 MeV/nucleon, in addition to electrons exceeding 1 MeV. These measurements are conducted using low and high-energy particle spectrometers. The data collected during Earth’s orbits helps scientists to analyse the behaviour of particles surrounding the Earth, especially in the presence of the magnetic field of Earth.
“STEPS was activated on September 10, 2023, at a distance greater than 50,000 km from Earth. This distance is equivalent to more than 8 times the Earth’s radius, placing it well beyond Earth’s radiation belt region. After completing the necessary instrument health checks, data collection continued until the spacecraft had moved farther than 50,000 km from Earth,” the space agency said.
It added that each unit of STEPS is operating within normal parameters.
“A figure displays measurements depicting variations in the energetic particle environment within Earth’s magnetosphere, collected by one of the units. These STEPS measurements will persist during the cruise phase of the Aditya-L1 mission as it progresses toward the Sun-Earth L1 point. They will continue once the spacecraft is positioned in its intended orbit. Data collected around L1 would provide insights into the origin, acceleration, and anisotropy of solar wind and space weather phenomena,” ISRO said.
STEPS was developed by the Physical Research Laboratory (PRL) with support from the Space Application Centre (SAC) in Ahmedabad.