In a significant achievement, the Indian Space Research Organisation (ISRO) has successfully placed the Aditya-L1 spacecraft in a halo orbit around the Lagrangian point (L1). This was accomplished after a journey of 1.5 million km and a carefully executed firing manoeuvre by the dedicated team at ISRO’s Telemetry Tracking and Command Network (ISTRAC) in Bengaluru.
ISRO Chairman S Somnath shared with the media that the process of inserting the spacecraft into the halo orbit went as planned. He explained that while the spacecraft was already moving towards the halo orbit, some adjustments were necessary to ensure it reached the right place. He emphasized that without these corrections, the spacecraft could have potentially escaped from the L1 point, although contingencies were in place to prevent this.
Prime Minister Narendra Modi proudly announced the successful placement of Aditya-L1, India’s first solar observatory, in its intended orbit. He praised the relentless dedication of the scientists who made this complex mission possible and promised to continue pushing the boundaries of science for the benefit of humanity.
ISRO confirmed that the final phase of the manoeuvre, which involved a short burst from the control engines, was completed at 4 p.m. The spacecraft is now in a periodic halo orbit, approximately 1.5 million km from Earth, on the continuously moving Sun-Earth line. This specific orbit was chosen to ensure a mission lifetime of 5 years, minimize fuel consumption, and provide a continuous, unobstructed view of the Sun.
The successful insertion of Aditya-L1 into this halo orbit is a testament to ISRO’s capabilities in executing complex orbital manoeuvres and boosts confidence for future interplanetary missions.
Launched on September 2, 2023, from the Satish Dhawan Space Centre in Sriharikota, Aditya-L1 is India’s first space-based observatory to study the sun. After the launch, ISTRAC carried out four earth-bound manoeuvres between September 3 and September 15. On September 19, the spacecraft began its 110-day journey to the L1 point following the Trans-Lagrangian 1 insertion manoeuvre. The L1 point is approximately 1% of the Earth-Sun distance away from Earth.
In a fun twist, the Aditya-L1 camera even managed to snap a selfie along with images of Earth and the Moon!
The Aditya-L1 satellite, launched by ISRO, is on a special mission to continuously observe the sun without any interruptions. It’s equipped with seven payloads that will study different layers of the sun - the photosphere, chromosphere, and the corona - using electromagnetic and particle detectors.
Four of these payloads will have a direct view of the sun, while the remaining three will conduct in-situ studies of particles and fields at the L1 point. The satellite will spend its entire mission life, which is five years, orbiting around L1 in an orbit that’s irregularly shaped and roughly perpendicular to the line joining the earth and the sun.
During its mission life, Aditya-L1 is expected to provide crucial information to help us understand various solar phenomena like coronal heating, coronal mass ejection, pre-flare and flare activities, dynamics of space weather, and propagation of particles and fields.
Now, you might be wondering what Lagrange points are. In a two-body gravitational system, like the sun and the earth, Lagrange Points are specific positions in space where a small object tends to stay put. These points can be used by spacecraft to remain in position with reduced fuel consumption. There are five such points, known as L1, L2, L3, L4, and L5.
The L1 point, where Aditya-L1 is placed, lies along the line joining the sun and the earth, about 1.5 million km from the earth. This is approximately 1% of the earth-sun distance. A satellite in a halo orbit around the L1 point has the major advantage of being able to continuously view the sun without any interruptions. This makes it ideal for observing solar activities.
Currently, there are four operational spacecraft at L1 - WIND, Solar and Heliospheric Observatory (SOHO), Advanced Composition Explorer (ACE), and Deep Space Climate Observatory (DSCOVER).