3 NASA, 1 NASA-ESA spacecraft at final destination of Aditya L1, Isro conducts situational awareness | Indian News – Times of India

BENGALURU: Like Aditya-L1India’s first solar mission heads to final destination, Isro has done a location, L1 point situational awareness analysis.
There are currently four spacecraft in L1 halo orbit: NASA has WIND, the Advanced Composition Explorer (ACE), and Deep Space Climate Observatory (DSCOVER), while the fourth, the Solar and Heliospheric Observatory (SOHO), is a joint mission between NASA and the European Space Agency (ESA).
Lagrange points, also known as libration points, are unique locations in space where the gravitational force of two massive bodies (such as Sun and Earth) is exactly equal to the centripetal force required to propel a small object (like a spacecraft) with them, Isro said.
This makes Lagrange points an excellent location for spacecraft, he added, because the orbital corrections and thus the fuel required to maintain the desired orbit are minimized.

For any combination of two orbital bodies (such as the Sun-Earth and Earth-Moon systems), there are five Lagrange points (L1 through L5), all of which lie in the orbital plane of the two large bodies. The three points L1, L2 and L3 are dynamically unstable and lie on a line passing through the centers of the two large bodies, while the remaining two points L4 and L5 are stable points and both act as the third apex of an equilateral triangle formed by the centers of the two large bodies, Isro said .
L1 is particularly important because it lies between the two primaries (the Sun and the Earth), making it an ideal location for spacecraft as they allow continuous observation of the primary bodies, continuous communication with Earth, and an unobstructed view of the celestial bodies.
These orbits are well suited for scientific missions like Aditya, which acts as a solar observatory around L1 and communicates with Earth.
Despite the extremely sparse population of L1 points and their high resolution, a close evaluation by a spacecraft operating in Lagrange Point Orbit (LPO) is desirable because of the high positional uncertainty and sensitivity to other perturbing forces, Isro said.
LPO orbit determination (OD) requires collecting tracking data over a longer period of time, typically a few days, he said. Typical OD accuracy is on the order of a few kilometers.
In the case of Isro’s Aditya-L1, we plan to conduct such analysis periodically with support from NASA-JPL to ensure safety and avoid any chance of approaching other spacecraft in the vicinity, Isro added.
Aditya-L1 will operate in a halo orbit around the Sun-Earth point L1, which is about 1.5 million km from Earth.
Halo orbits are periodic three-dimensional orbits around a Lagrange point (L1, L2 or L3) and involve an out-of-plane component of motion relative to the primary bodies. The orbit is large enough to be continuously viewed from Earth and appears to form a halo around the Lagrange points (here L1 for Aditya L1), Isro said.
Isro said the L1 point has been used in various previous missions, including International Sun-Earth Explorer (ISEE-3), Genesis mission, ESA’s LISA Pathfinder, China’s lunar orbiter Change 5 and NASA’s Gravity Recovery and Interior Recovery (GRAIL) mission. all of which have contributed to the understanding of space and the ability to monitor space weather.
And the operational spacecraft currently stationed there also provide critical early warnings of adverse space weather events that help protect orbiting space assets and ground infrastructure.
Look ISRO’s solar mission Aditya L1 is taking significant steps towards the Earth-Sun L1 point