Sunshine moment: ISRO puts Aditya-L1 in halo orbit to study sun dynamics

Shubhadeep Choudhury

New Delhi, January 6

India’s solar probe Aditya-L1 was on Saturday successfully placed in its intended orbit by the Indian Space Research Organisation (ISRO), making India the fourth country in the world to have a space-based observatory to study the sun, including corona, flares and sun storm.

Prime Minister Narendra Modi described ISRO’s success in placing the spacecraft in an orbit 1.5 million km away from the earth as an “extraordinary feat”.

• 5 years Mission life
• 177.86 earth days Orbital period

Satellite equipped with scientific gear

• The objective of the mission is “observing and understanding the chromospheric and coronal dynamics of the sun”
• Satellite equipped with seven indigenously developed gadgets to help achieve objectives
• The three-dimensional orbit at L1 has been selected to ensure a mission lifetime of five years

Lagrange point

• Lagrange Point 1 (L1) of the sun-earth system is about 1 per cent of the total distance between the earth and the sun
• A satellite in a halo orbit around Lagrange Point has the major advantage of continuously viewing the sun without any occultations/eclipses

“It is a testament to the relentless dedication of our scientists in realising one of 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,” Modi wrote on X.

President Droupadi Murmu highlighted the presence of a large number of women engineers and scientists in Team ISRO. “Significant participation of women scientists in ISRO missions takes women empowerment too onto a higher orbit,” Murmu wrote on X.

1.5 million km journey

Sept 2, 2023: ISRO launches Aditya-L1 aboard PSLV-C57

Sept 3: First manoeuvre puts it in 245 km x 22,459 km orbit

Sept 5: Elevated to 282 km x 40,225 km orbit in 2nd manoeuvre

Sept 10: Attains 296 km x 71,767 km orbit in third manoeuvre

Sept 15: Moved to 256 km x 1,21,973 km orbit in 4th manoeuvre

Sept 30: Escapes sphere of earth’s influence, heads to Lagrange Point 1

Dec 10: Payload captures full-disk images of sun in near UV wavelengths

Jan 6, 2024: Aditya-L1 reaches destination, 1.5 mn km from earth

The Project Director of the Aditya L1 mission, Nigar Shaji, is also a woman.

According to ISRO, a critical phase of the spacecraft’s voyage was its insertion into the halo orbit near Lagrange Point. The manoeuvre demanded precise navigation and control. ISRO scientists and engineers from the Bengaluru-based ISTRAC handled the difficulties by constantly monitoring the spacecraft and adjusting its speed and position by using on-board thrusters. The success of the insertion not only demonstrated ISRO’s capabilities in such complex orbital manoeuvres, but also enhanced the space agency’s confidence with regard to managing future interplanetary missions.

The specific orbit of Aditya-L1 is located on the continuously moving sun-earth line with an orbital period of about 177.86 earth days. The three-dimensional orbit at L1 (Lagrange Point 1) has been selected to ensure a mission lifetime of five years, minimising station-keeping manoeuvres and thus reducing fuel consumption and ensuring a continuous, unobstructed view of the sun.

Extraordinary feat, among most complex missions realised

A testament to the relentless dedication of our scientists in realising one of the most complex space missions. —Narendra Modi, pm, on x

ISRO chairman S Somanath said, “It was a complex mission, I won’t say challenging mission. Challenges are something which we love, complexities are something which we have to overcome. Today, we have overcome the complexity, and we were able to achieve that precisely. Payloads are working very well, but now many more things are to be done on payloads to make sure that the data is reliable and usable, so that will start from now.”

“He (PM Modi) messaged us through his social media platform and appreciated the work we did. We are very happy about it. We are waiting, maybe he will interact with us at an appropriate time,” Somanath said acknowledging Modi’s interest in the hi-tech mission.