Aditya-L1

Lore & Background

The mission was conceptualised in January 2008 by the Advisory Committee for Space Sciences (ADCOS). Initially envisaged as a small 400 kg satellite in low Earth orbit with a coronagraph, the scope expanded to a comprehensive solar observatory at L1, leading to the name Aditya-L1. The spacecraft was launched aboard the PSLV-C57 at 11:50 IST on 2 September 2023 from the Second Launch Pad of the Satish Dhawan Space Centre in Sriharikota. It successfully achieved its intended orbit nearly an hour later and separated from its fourth stage at 12:57 IST. After a series of Earth-bound orbit-raising maneuvers and a Trans-Lagrangian 1 Injection on 19 September 2023, it was inserted at the L1 point on 6 January 2024 at 4:17 pm IST. Aditya-L1 completed its first halo orbit around L1 on 2 July 2024, taking approximately 178 days per orbit.

Reader's Guide

Aditya-L1 represents a significant step for Indian space science as the nation's first dedicated solar observatory. Positioned at the Lagrange point 1, it provides uninterrupted views of the Sun and studies the solar atmosphere, including the chromosphere and corona, as well as solar magnetic storms and their impact on Earth's environment. The mission addresses fundamental questions in solar physics, such as coronal heating—why the upper atmosphere is millions of degrees hotter than the surface—and how solar radiation affects Earth's atmosphere. Its seven payloads, including the Visible Emission Line Coronagraph (VELC) and the Solar Ultraviolet Imaging Telescope (SUIT), enable simultaneous remote sensing and in-situ observations. By observing near-UV solar radiation and coronal mass ejections, Aditya-L1 contributes to understanding space weather and the dynamics of solar wind, with implications for satellite operations and terrestrial climate. The mission's success demonstrates India's growing capability in space-based solar research and international collaboration, supported by the European Space Operations Centre.

Did You Know?

• The SUIT instrument captured its first near-UV observations of a solar flare in February 2024, marking a milestone in solar studies.
• The spacecraft's orbit around L1 takes approximately 178 days to complete.

From Concept to Comprehensive Observatory

The Aditya-L1 mission traces its intellectual roots to January 2008, when the Advisory Committee for Space Sciences first sketched out a modest solar-observation satellite. That original vision called for a roughly 400-kilogram spacecraft carrying a single coronagraph, parked in a low Earth orbit at about 800 kilometres altitude. An experimental budget of three crore rupees was set aside for the 2016–2017 financial year to explore the idea. Over the following years, however, the scope grew dramatically. Engineers and scientists recognised that the mission's scientific payloads would be compromised by interference from Earth's magnetic field if kept in low orbit, so the architecture was rethought entirely. The satellite was repositioned to the Sun–Earth Lagrange point 1, and the project was renamed Aditya-L1 to reflect its new halo-orbit home. By mid-2019 the allocated cost had climbed to 378 crore rupees, excluding launch expenses, as the spacecraft evolved into a full solar and space-environment observatory. Under the leadership of project director Nigar Shaji, the programme ultimately became India's first dedicated solar-observation mission, a milestone long absent from the country's space portfolio.

The Long Road to Lagrange Point 1

On the morning of 2 September 2023, a 44-metre-tall Polar Satellite Launch Vehicle stood ready on the Second Launch Pad at the Satish Dhawan Space Centre in Sriharikota. The PSLV-XL, designated C57, combined four alternating solid- and liquid-fuelled stages with six small solid boosters, totalling roughly 321 tonnes of propellant and structure. At 11:50 IST the rocket ignited, and after a 63-minute, 20-second flight, Aditya-L1 was injected into a highly elliptical Earth orbit with a perigee of 235 kilometres and an apogee of 19,500 kilometres, inclined 19.2 degrees. The spacecraft separated from the fourth stage at 12:57 IST. Over the next two weeks, four successive orbit-raising burns—on 3, 5, 10, and 15 September—progressively stretched the apogee from 22,459 km to 121,973 km. On 19 September the spacecraft executed its Trans-Lagrangian 1 Injection, breaking free of Earth's gravity well. A trajectory correction manoeuvre followed on 6 October. By 30 September the craft had already escaped Earth's sphere of influence. After a four-month cruise of 1.5 million kilometres, Aditya-L1 was finally inserted into its halo orbit around L1 on 6 January 2024 at 4:17 pm IST, 126 days after liftoff.

Cracking the Coronal Heating Puzzle

One of the most stubborn unsolved problems in solar physics is why the Sun's outer atmosphere is so extraordinarily hot. The lower solar atmosphere sits at roughly 6,000 kelvin, yet the corona above it reaches a staggering 2,000,000 kelvin. Aditya-L1 was designed in large part to illuminate exactly how energy is channelled and transferred between these layers. Its suite of instruments will capture near-simultaneous images of the photosphere, chromosphere, and corona, allowing scientists to trace the sequence of processes that build up to solar eruptions. The mission will examine the physics of partially ionised plasma, the origins and dynamics of coronal mass ejections, and the structure of the coronal magnetic field. It will also measure the in-situ particle and plasma environment around the spacecraft, study the origin, composition, and dynamics of the solar wind, and analyse magnetic-field topology in the corona. By observing factors such as temperature, velocity, and density in coronal loops, the observatory aims to provide a comprehensive picture of the Sun's dynamical processes and address outstanding questions in both solar physics and heliophysics that have resisted explanation for decades.

Pioneering Firsts in Indian Solar Science

Aditya-L1 carries a remarkable set of firsts for India's space programme. It is the nation's first mission devoted entirely to observing the Sun, a gap that had persisted despite India's long history of Earth-observation and planetary missions. During its cruise to L1, the spacecraft's SUIT instrument captured an X-class solar flare and an accompanying coronal mass ejection on 31 December 2023, just one week before orbital insertion. That event marked the first time a solar flare was observed using near-ultraviolet light from an Indian instrument, a capability previously unavailable to the country's solar-observation efforts. The mission also demonstrated the full operational chain of a deep-space insertion: four precise orbit-raising manoeuvres, a trans-Lagrangian injection, a trajectory correction, and a final halo-orbit insertion—executed by a team led by project director Nigar Shaji. The launch itself was publicly applauded by Union Science and Technology Minister Dr Jitendra Singh Rana, underscoring the political and scientific significance of the event. Together, these milestones position India as a growing player in heliophysics and space-weather science.