Aditya-L1 Achieves Successful Halo-Orbit Insertion, Marking A Milestone In ISRO's Solar Observatory Mission

On January 6, 2024, at approximately 16:00 Hrs (IST), the Indian Space Research Organisation (ISRO) successfully achieved the Halo-Orbit Insertion (HOI) of its solar observatory spacecraft, Aditya-L1. This critical maneuver involved the firing of control engines during the final phase to place Aditya-L1 into a periodic Halo orbit, located approximately 1.5 million km from Earth along the Sun-Earth line. The orbit boasts an orbital period of about 177.86 Earth days, ensuring a continuous, unobstructed view of the sun.

The specific Halo orbit selected for Aditya-L1, with semi-axes Ax: 209200 km, Ay: 663200 km, and Az: 120000 km, is integral for the mission's objectives. Placing the spacecraft in a Halo orbit at Lagrangian point L1 offers several advantages over a Low Earth Orbit (LEO). It provides a smooth Sun-spacecraft velocity change suitable for helioseismology, places the spacecraft outside Earth's magnetosphere for solar wind sampling, and allows continuous observation of the sun along with uninterrupted communication with ground stations.

The Halo orbit insertion process began as Aditya-L1 crossed the XZ plane in the Sun-Earth-L1 rotating system, requiring precise navigation and control. The insertion maneuver nullified the X and Z velocity components, achieving the necessary Y-velocity for the Halo orbit. This successful insertion not only showcases ISRO's prowess in complex orbital maneuvers but instills confidence for future interplanetary missions.

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Aditya-L1, designed and realized at the UR Rao Satellite Centre (URSC), embarked on its journey on September 2, 2023, with a launch by PSLV-C57 from SDSC SHAR. The spacecraft underwent five liquid engine burns during the Earth orbit phase, progressively increasing its orbital size. The trans-L1 injection maneuver on October 5, 2023, and another adjustment burn on December 14, 2023, ensured compliance with Halo orbit insertion conditions.

The meticulously planned trajectory, involving a cruise phase of approximately 110 days, led to the successful Halo orbit insertion on January 6, 2024. This achievement not only validates ISRO's technical capabilities but also sets the stage for Aditya-L1's mission to observe and understand the chromospheric and coronal dynamics of the sun continuously, offering valuable insights into solar phenomena.