Nearly six months after it arrived at Lagrange Point 1, a unique location about 15,00,000 kilometres away from Earth, India’s Aditya L1 has completed its first halo orbit.
The first Indian spacecraft to be tasked with studying the Sun, the lone star which powers life on the planet, Aditya L1 has been hard at work since it arrived at its new home in the first week of January 2024. The spacecraft took 178 days to complete one revolution in its halo orbit.
During its six-month stay at L1, the spacecraft crucially observed the Sun during a record solar storm that bruised Earth in the first week of May. Aditya L1 observed the dynamic activities on the surface of the Sun as it kept a close watch on the events that followed.
However, it was not a cakewalk.
ADITYA L1’s DANCE WITH NEWTON
The Indian space agency has revealed that during the first six months at L1, the spacecraft experienced several perturbing forces that caused it to depart from the targeted orbit. The most powerful among them was gravitational drag, which is experienced in the orbit.
While gravitational drag is not a standard term in physics, it refers to concepts related to the effects of gravity on objects moving through a medium. The drag force causes satellites to lose energy, resulting in a gradual decrease in altitude.
Officials at Isro told IndiaToday.in that like every other satellite, Aditya L1 also experienced forces that led to its orbital decay, and it began losing its trajectory. This is where Isaac Newton comes into play with his first law of motion.
Newton’s first law of motion states that an object at rest will stay at rest, and an object in motion will continue in motion with the same speed and in the same direction unless acted upon by an unbalanced external force.
STATION-KEEPING BEGINS
In order to counter the drag and other perturbing forces that would have forced Aditya L1 to lose its trajectory at L1, Isro conducted three station-keeping manoeuvres. Had Isro not intervened and put an external force on the spacecraft, it would have continued to lose its orbit.
Station-keeping manoeuvres with Aditya L1 involved firing the thrusters, mini motor engines on the spacecraft, to put an external force and counteract the perturbing forces at the L1. Two station-keeping manoeuvres were performed on February 22 and June 7, and the third on July 2 to ensure the spacecraft remained in the designated orbit.
Isro released a graphic which showed how the orbit would have changed had it not fired the thrusters and performed the manoeuvres on the spacecraft. “If an accurate firing were not done, the spacecraft would have moved away in a trajectory,” Isro said.
With the spacecraft beginning its second orbit at L1, it is poised to unravel the secrets of the Sun that has remained enigmatic for ages. But, more such crucial manoeuvres will have to be performed to ensure the spacecraft remains where it is suppose to be.
Source Agencies
