TIRUPATI: The Indian Space Research Organisation (Isro) on Saturday guided the Aditya-L1 solar mission into its space home, a halo orbit around what is called the Sun-Earth Lagrange Point 1 (L1), 1.5 million km from Earth.
The complex manoeuvre, conducted by the space scientists and engineers at the Isro Telemetry Tracking and Command Network (Istrac) in Bengaluru, marked the culmination of a journey that began with the spacecraft's launch on September 2, 2023.
The final phase involved firing control engines for a short duration to precisely position Aditya-L1 in the halo orbit. In this orbit, the spacecraft will leverage the balanced gravity forces from the Sun and Earth to remain relatively stationary, providing a continuous vantage point for solar observations.
Prime Minister Narendra Modi on X (formerly Twitter) announced the success, stating, "India creates yet another landmark… It is a testament to the relentless dedication of our scientists in realizing among the most complex and intricate space missions."
The Aditya-L1, launched by PSLV-C57 from the Satish Dhawan Space Centre in Sriharikota, was first placed in an orbit around the Earth. After four Earth-centric menoeuvres and five liquid engine burns, Aditya L1 was launched into the trans-L1 injection (TL1I).
To ensure the spacecraft's compliance with halo orbit insertion (HOI) parameters, the spacecraft’s rockets were fired twice, on October 5 and December 14. The spacecraft then cruised for 110 days before achieving HOI on Saturday. The performance of the payload, tested during its long cruise, was confirmed to be satisfactory.
ISRO chief S. Somanath expressed his satisfaction, saying, "It is very satisfying for us because it is the end of a long journey. 126 days from lift-off to now, it has reached the final point. Reaching the final point is always an anxious moment, but we were very sure about it. So, it happened as predicted. We are very happy."
According to Isro, has an orbital period of about 177.86 Earth days. This specific orbit was chosen to ensure a mission lifetime of five years, minimising the need for station-keeping manouvres to keep the spacecraft in its orbit, reduced fuel consumption, and providing an uninterrupted view of the Sun.
The Aditya-L1 mission aims to observe and understand the chromospheric and coronal dynamics of the Sun.
Aditya-L1's seven payloads will observe the Sun's photosphere, chromosphere and corona. Four instruments will directly image the Sun from the L1 vantage point, while three others will detect particles and fields in situ.
In its irregular orbit around L1, perpendicular to the Sun-Earth line, Aditya-L1 is expected to provide crucial data to understand coronal heating, eruptions, solar storms, and particle propagation - key factors in space weather.
The long journey
Key events in Aditya-L1 trip to the Lagrangian point L1:
2023
Sept. 2: PSLV launches Aditya-L1 spacecraft from SDSC-Sriharikota, placing it into an elliptical orbit around the Earth.
Sept. 3-15: Isro Telemetry Tracking and Command Network (Istrac) in Bengaluru executes four manoeuvres to place Aditya L1 in an orbit which took it 1,21,973 km from Earth.
Sept. 19: Aditya-L1 spacecraft sent on its way to Lagrangian Point 1, on a 110-day
Oct. 5, Dec. 14: Corrective rocket motor firings done.
What Aditya-L1 carries
Visible Emission Line Coronagraph (VELC): To study the solar corona and dynamics of coronal mass ejections (CMEs).
Solar Ultraviolet Imaging Telescope (SUIT): Images the solar photosphere and chromosphere in near ultraviolet (UV) range.
Aditya Solar wind Particle EXperiment (ASPEX), Plasma Analyser Package for Aditya (PAPA): To study solar wind and energetic ions, along with their energy distribution.
Solar Low Energy X-ray Spectrometer (SoLEXS), High Energy L1 Orbiting X-ray Spectrometer (HEL1OS): To study X-ray flares from the Sun over a wide energy range.
Advanced Tri-axial High-Resolution Digital Magnetometer: To measures interplanetary magnetic fields at the L1 point.
L1 point:
The L1 point lies on the Sun-Earth line about 1.5 million km from Earth — approximately 1 per cent of the Sun-Earth distance. A satellite in a halo orbit around L1 has the key benefit of continuously viewing the Sun. This enables continuous observation of solar activity, which is a major advantage of the Aditya-L1 mission.
