ISRO’s Aditya-L1 Mission: Why Lagrange Point 1 Is Crucial To Study Sun?

The Aditya-L1 mission is set to be launched by ISRO's PSLV XL rocket from Satish Dhawan Space Centre in Bengaluru's Sriharikota.

New Delhi: ISRO on Saturday launched the country’s ambitious Solar mission, Aditya L1 eyeing history again after its successful lunar expedition, Chandrayan 3 a few days ago. According to ISRO, Aditya-L1 is the first space-based observatory to study the Sun. The spacecraft, after traveling about 1.5 million km from the Earth over 125 days, is expected to be placed in a Halo orbit around the Lagrangian point L1 which is considered closest to the Sun.

What Is Langrage Point 1

The Lagrange Point 1 or L1 lies between the Sun-Earth line, about 1.5 million kilometers (about 930,000 miles) away from Earth, in the direction of the Sun. For a two-body gravitational system, the Lagrange Points are the positions in space where a small object tends to stay if put there. These points in space for a two-body systems such as Sun and Earth can be used by spacecraft to remain at these positions with reduced fuel consumption. Technically at Lagrange point, the gravitational pull of the two large bodies equals the necessary centripetal force required for a small object to move with them. For two-body gravitational systems, there are a total five Lagrange points denoted as L1, L2, L3, L4, and L5.

The Significance Of L1 In Studying The Sun

The Aditya-L1 mission will be launched by ISRO’s PSLV XL rocket from Satish Dhawan Space Centre SHAR (SDSC-SHAR) in Sriharikota. Initially, the spacecraft will be placed in a Low Earth Orbit. Subsequently, the orbit will be made more elliptical and later the spacecraft will be launched towards the L1 by using onboard propulsion. As the spacecraft travels towards L1, it will exit the Earths’ gravitational Sphere of Influence (SOI). After exit from SOI, the cruise phase will start and subsequently the spacecraft will be injected into a large halo orbit around L1. The total travel time from launch to L1 would take about four months for Aditya-L1.

Any object placed in L1 relatively remains stable with respect to the Earth-Sun system. A satellite placed in the halo orbit around the L1 point has the major advantage of continuously viewing the Sun without any occultation or eclipses. “This will provide a greater advantage of observing the solar activities and its effect on space weather in real-time,” the ISRO said.