India’s star rises

Prime Minister Narendra Modi hailed the achievement as “landmark” as he congratulated the scientists for their “relentless dedication”

At 4pm on Saturday, India made history by parking its observatory — Aditya-L1 — in an orbit around Lagrange Point 1, about 1.5 million kilometres from us, setting the stage for at least five years of observations.

Aditya-L1

Scientists at the Indian Space Research Organisation (Isro) performed a series of manoeuvres to place the craft in its intended halo orbit on Saturday, 126 days after the mission was launched on September 2 last year.

“Halo-Orbit Insertion (HOI) of its solar observatory spacecraft, Aditya-L1 was accomplished at 4pm on January 6,” the space agency said after the insertion.

Prime Minister Narendra Modi hailed the achievement as “landmark” as he congratulated the scientists for their “relentless dedication”.

“India creates yet another landmark. India’s first solar observatory Aditya-L1 reaches its destination. It is a testament to the relentless dedication of our scientists in realising among the most complex and intricate space missions. I join the nation in applauding this extraordinary feat. We will continue to pursue new frontiers of science for the benefit of humanity,” PM Modi said on X, formerly Twitter.

The insertion of Aditya-L1 into the Halo Orbit presents a critical phase for the mission, which demanded precise navigation and control, the space agency said in a statement.

The L1 point mentioned in the statement refers to Lagrange Point 1, a region where gravitational forces of celestial objects work in such a way that the spacecraft can be parked in what is known as a halo orbit — an oval that shifts on three axes.

Following its launch, the spacecraft was placed in a low-Earth orbit. Subsequently, the orbit was made more elliptical, and the craft was catapulted towards its final destination using onboard propulsion. Once it left Earth’s gravitational Sphere of Influence (SOI), the cruise phase started.

On Saturday, the final manoeuvres were performed, which involved “firing of control engines for a short duration” to control the speed of the craft, and orient it towards the orbit by maintaining a minimum fuel consumption condition, Isro said.

Explaining the process, an official said that the craft was moving from the Earth towards L1 in the direction of the Sun.

“A final firing was done at this point, making the spacecraft align with the Halo Orbit. If the HOI (Halo Orbit insertion) manoeuvre was not conducted as done today, the spacecraft would have moved in the direction marked (towards the Sun),” the Isro statement added.

“A successful insertion further involved constant monitoring along with the adjustment of the spacecraft’s speed and position by using onboard thrusters. The success of this insertion not only signifies Isro’s capabilities in such complex orbital manoeuvres, but it gives confidence to handle future interplanetary missions,” the statement read.

The orbit of Aditya-L1 is periodic, located roughly 1.5 million km from Earth on the continuously moving Sun-Earth line with an orbital period of about 177.86 Earth days.

“This specific Halo orbit is selected to ensure a mission lifetime of 5 years, minimising station-keeping manoeuvres and thus, fuel consumption and ensuring a continuous, unobstructed view of sun,” Isro said.

Highlighting the scientific importance of the mission, Isro chief S Somanath said, “The solar mission, Aditya-L1 is for the whole of the world, not for India alone, for all of us to understand and make use of its scientific importance.”

While the space agency had the option of performing multiple attempts at adjusting the orbit of the spacecraft, it was preferred that the manoeuvre be completed in a single attempt to avoid utilisation of excess fuel.

An excess fuel bank ensures the space agency has the window to perform additional experiments with the same craft. This was also the case with the propulsion module of Chandrayaan-3 when it was brought back to the Earth’s orbit to test for future return missions. This was possible only because the propulsion module of Chandrayaan-3 had excess fuel.

The spacecraft is equipped with seven payloads to study the Sun’s corona, chromosphere, photosphere and solar wind. From L1, the spacecraft will be able to see how particles and radiation from heightened solar activity has an effect, while also studying the outer surface of the star in close detail — something that is normally not possible from the Earth, or even its orbit.