India’s Aditya L1 Mission is set to conduct a complex insertion into Halo Orbit around the Lagrange Point L1, which is a point of gravitational equilibrium between Earth and the Sun.
The spacecraft is in the final leg of the journey which has stretched over 15 lakh kilometers in the cold vacuum of space. ISRO launched the spacecraft (PSLV-C57 Rocket) on September 2, 2023, from Sriharikota, the primary launchpad of the Indian Space Research Organisation (ISRO). The journey is expected to culminate on January 6, 2024.
Importance of the L1 Point
The L1 or Lagrange Point L1 is a strategic location in space where the gravitational forces between the Earth and the Sun balance out one another allowing a spacecraft to maintain a stable position relative to both bodies. There are several other such points akin to the L1 such as L2, L3, L4, and L5. They can be called as car-parks in space informally.
The insertion into the L1 is a critical phase of the mission requiring precise navigation and control. Aditya L1 underwent a series of four-orbital maneuvers before being injected into a transfer orbit towards L1. This meticulous process involves careful planning to ensure that the spacecraft maintains its trajectory and velocity to successfully enter the Halo Orbit. The significance of the L1 cannot be overstated. It offers an uninterrupted view of the Sun allowing the Aditya L1 to study solar atmosphere, solar magnetic storms, and their impact on the Earth’s environment.
Objectives of the Mission
The spacecraft will measure various events such as Coronal Mass Ejections (CMEs) and the interplanetary magnetic fields providing data not only for India but for the global scientific community. To ensure a successful insertion, ISRO ‘s team must take several precautions. The position of the Spacecraft and speed must be constantly monitored and adjusted using onboard thrusters to counteract any deviations from the planned path.
Additionally, the spacecraft instruments, including the Visible Emission Line Coronagraph (VELC) and the Solar Ultraviolet Imaging Telescope (SUIT) must be protected from intense radiations and particles emitted from the surface of the Sun. The CME and related phenomena have far-reaching implications and they can affect satellite operations and communications on Earth.
The Aditya-L1 mission was conceptualized back in January 2008 by the Advisory Committee for Space Sciences (ADCOS). Initially envisioned as a modest 400 kg satellite orbiting at 800 km above Earth, the mission’s scope expanded to become a comprehensive study of the Sun’s corona from a vantage point 1.5 million km away from our planet.
The stability of the L1 an unstable Lagrange Point has immense advantages, but at the same time poses certain challenges. Station-keeping maneuvers will be required to maintain Aditya L1’s halo orbit, with adjustments of 0.2–4 m/s per year. These maneuvers are crucial to counteract the gravitational influences of other celestial bodies and the pressure exerted by solar radiation.