Sun mission: First orbit raising maneuvre of Aditya-L1 success

Chennai: The first orbit rasing maneuvre of Aditya-L1 spacecraft, the first Indian Mission to study the Sun, was performed successfully on Sunday and the satellite is healthy and operating nominally. ISRO in an update said the first Earth-bound maneuvre (EBN#1) is performed successfully from ISTRAC, Bengaluru. The new orbit attained is 245 km x 22459 km. The next maneuvre (EBN#2) is scheduled for September 5, 2023, around 0300 hrs, ISRO said. The Aditya-L1 was launched yesterday from Sriharikota by PSLV-C57 and it was injected into the precise orbit which was raised in the first firing of motors onboard the spacecraft. India’s first solar observatory has begun its journey to the destination of Sun-Earth L1 point, ISRO said after the launch. Aditya L1 is the first space based Indian mission to study the Sun.

The spacecraft will be placed in a halo orbit around the Lagrange point-1(L1) of the Sun-Earth system, which is about 1.5 million km from the Earth. Aditya-L1 is a satellite dedicated to the comprehensive study of the Sun. It has 7 distinct payloads developed, all developed indigenously. Five of the payloads were developed by ISRO and two by Indian academic institutes in collaboration with ISRO. Aditya in Sanskrit means the Sun. L1 here refers to Lagrange Point 1 of the Sun-Earth system. For common understanding, L1 is a location in space where the gravitational forces of two celestial bodies, such as the Sun and Earth, are in equilibrium. This allows an object placed there to remain relatively stable with respect to both celestial bodies, ISRO said. Following the launch, Aditya-L1 stays Earth-bound orbits for 16 days, during which it undergoes 5 maneuvres to gain the necessary velocity for its journey.

Subsequently, Aditya-L1 undergoes a Trans-Lagrangian1 insertion maneuvre, marking the beginning of its 110-day trajectory to the destination around the L1 Lagrange point. Upon arrival at the L1 point, another maneuvre binds Aditya-L1 to an orbit around L1, a balanced gravitational location between the Earth and the Sun. The satellite spends its whole mission life orbiting around L1 in an irregularly shaped orbit in a plane roughly perpendicular to the line joining the Earth and the Sun, the Space Agency said, in a mission update. The strategic placement at the L1 Lagrange point ensures that Aditya-L1 can maintain a constant, uninterrupted view of the Sun. This location also allows the satellite to access solar radiation and magnetic storms before they are influenced by Earth’s magnetic field and atmosphere. Additionally, the L1 point’s gravitational stability minimizes the need for frequent orbital maintenance efforts, optimizing the satellite’s operational efficiency.

Aditya-L1 will stay approximately 1.5 million km away from Earth, directed towards the Sun, which is about 1% of the Earth-Sun distance. The Sun is a giant sphere of gas and Aditya-L1 would study the outer atmosphere of the Sun. Aditya-L1 will neither land on the Sun nor approach the Sun any closer. 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 Aditya-L1 spacecraft–realised at the U R Rao Satellite Centre (URSC), Bengaluru–shall be placed in a halo orbit around the Lagrange point 1 (L1) of the Sun-Earth system, which is about 15 lakh km from the Earth”, ISRO said. A satellite placed in the halo orbit around the L1 point has the major advantage of continuously viewing the Sun without any occultation/ eclipses.

This will provide a greater advantage of observing the solar activities and its effect on space weather in real time. The spacecraft has seven payloads to observe the photosphere, chromosphere and the outermost layers of the Sun (the corona) using electromagnetic and particle and magnetic field detectors. Using the special vantage point L1, four payloads directly view the Sun and the remaining three payloads carry out in-situ studies of particles and fields at the Lagrange point L1, thus providing important scientific studies of the propagatory effect of solar dynamics in the interplanetary medium. The suits of Aditya L1 payloads are expected to provide most crucial informations to understand the problem of coronal heating, coronal mass ejection, pre-flare and flare activities and their characteristics, dynamics of space weather, propagation of particle and fields etc. UNI

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