Aditya-L1 Completes First Halo Orbit around Sun-Earth Lagrange Point 1, ISRO Executes 3 Manoeuvres to Keep It from Veering Off Course – News18

India’s first-ever solar observatory Aditya-L1 has successfully completed its first orbit around the Lagrange Point (L1) of the Sun-Earth system almost 1.5 million kilometres away from Earth. The Indian Space Research Organisation (ISRO) announced that it has precisely executed the third manoeuvre to prevent it from deviating from its intended path.

The spacecraft launched last year on September 2 is the country’s first-ever space mission to study the Sun. After gliding through the space for nearly four months, it reached its target halo orbit on January 6. Normally it will take 178 days for Aditya-L1 to complete one revolution around the L1 point.

However, during its travel, the spacecraft will encounter various disturbances that may cause it to deviate from its targeted orbit. Aditya-L1 is placed in a halo orbit which is periodic, and three-dimensional, and it will require several maneuvers from time to time to ensure it remains in the intended orbit.

WHY WAS THIS IMPORTANT?

The ISRO team has already performed two station-keeping manoeuvres on February 22 and June 7 to ensure that it continued on its path as planned. The third manoeuvre was performed on Tuesday by firing the thrusters to keep it in the second halo orbit path. With this, the team has successfully validated its flight dynamics software which was also developed in-house at the UR Rao Satellite Centre (URSC), Bengaluru.

“This journey of Aditya-L1 around Sun-Earth L1 involves modelling of complex dynamics. It requires understanding of various perturbing forces which are acting on the spacecraft which can help to determine the trajectory accurately and plan precise orbit manoeuvres,” said the national space agency on Tuesday.

If the firing of thrusters had not gone as planned, it would have led Aditya-L1 to deviate from its path and affect the mission’s future. Even though the Sun is still roughly 150 million kilometres away from the L1 point, it will provide the spacecraft with an unhindered view of the Sun for the next five years. The L1 point is such that the gravitational force of the Sun and the Earth, and the centrifugal force of the orbit balance each other out and keep the spacecraft circling the point without expending much fuel and energy.

SEVEN PAYLOADS: MISSION STUDYING THE SUN

Aditya-L1 has seven scientific payloads on board, including the Visible Emission Line Coronagraph (VELC) developed by the Indian Institute of Astrophysics, Bengaluru. The mission will study different solar regions to seek answers to questions that have intrigued scientists for years – the birth of solar storms/flares, the impact on space weather, the vast temperature difference between the solar surface and its outer layer, and several more.

On June 10, two of the remote-sensing payloads of Aditya-L1 also captured the recent event around May 8-15 when solar flares erupted and led to Coronal Mass Ejections (CMEs). These were associated with the major geomagnetic storms on Earth on May 11.