Over 125 days of travel, 15 lakh kilometres covered, and a precision orbit insertion later, the Aditya-L1 mission has been successfully parked at an optimum spot in the vastness of space from where it will have an unobstructed view of the Sun.
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| Snap - ISRO :: Aditya L1 Mission before launch |
"Another grand feat accomplished by ISRO! As part of India’s maiden solar mission, Aditya L1, the observatory has been placed in the final orbit and reached its destination at Lagrange Point 1," tweeted President Droupadi Murmu.
Congratulations to the entire Indian scientist community for the great achievement! This mission will enhance our knowledge of the Sun-Earth System and benefit the entire humanity. Significant participation of women scientists in ISRO missions takes women empowerment too onto a higher orbit.
Prime Minister Narendra Modi shared the news and said, "India creates yet another landmark. India’s first solar observatory, Aditya-L1 reaches its destination."
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| Aditya L1 mission -- go through a final firing on Jan 6, 2024 (Photo: India Today) |
The halo orbit around L1 is a three-dimensional loop
To ensure/maintain its precise position, ISRO will conduct periodic Orbit Determination
Launched on September 2, 2023, from the Satish Dhawan Space Centre, Aditya-L1 has undergone a complex journey involving four Earth-bound manoeuvres and a Trans-Lagrangian Point 1 Insertion manoeuvre.
These precise operations have been crucial in guiding the spacecraft to its current position approximately 1.5 million kilometres from Earth.
India's first dedicated solar mission, Aditya-L1, successfully entered the halo orbit around Lagrange Point 1 (L1) on Saturday, marking a significant milestone for the Indian Space Research Organisation (ISRO).
The spacecraft is now poised to begin its comprehensive study of the Sun, but before it can start relaying valuable solar observations, a series of critical steps must be completed.
The final insertion into the halo orbit was achieved through a firing manoeuvre using the spacecraft's 440N Liquid Apogee Motor (LAM), similar to the one used in ISRO's Mars Orbiter Mission. This motor, along with eight 22N thrusters and four 10N thrusters, will continue to play a vital role in maintaining the spacecraft's orientation and orbit.
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"As Aditya-L1 gracefully settles into its orbit at the L1 point, it stands as a beacon of India's scientific ambition and ingenuity. This mission represents a blend of lessons from the past, current collaborations, and aspirations for the future," said Manish Purohit, a solar energy and spacecraft solar panel expert, told 'India Today'.
THE HALO ORBIT
The halo orbit around L1 is a three-dimensional loop that allows Aditya-L1 to maintain an uninterrupted view of the Sun, free from eclipses. This unique vantage point is shared by other international missions like NASA's WIND, ACE, DSCOVR, and the ESA/NASA collaborative mission SOHO. However, the equilibrium at L1 is delicate, requiring continuous monitoring to prevent collisions and ensure mission safety.
To maintain its precise position, ISRO will conduct periodic Orbit Determination (OD) analyses, with support from NASA, to track any deviations and adjust the spacecraft's trajectory as needed. The Attitude and Orbit Control System (AOCS), comprising sensors, control electronics, and actuators such as reaction wheels and thrusters, will keep the spacecraft stable against gravitational disturbances.
ISRO in its missive on X also talks about the flight of Si-Graphite anode and says:
"ISRO successfully demonstrates the flight of Si-Graphite anode based High Energy Density Li-ion Cells on PSLV-C58's ....
With 35-40% battery mass savings, these cells are set to make future space and ground applications lighter and more efficient."
"Vikram Sarabhai Space Centre (VSSC)/ISRO has qualified 10 Ah Silicon–Graphite anode based high energy density Li-ion cells as a low weight and low cost alternative to present cells being used. The flight demonstration of the cells as a battery was successfully completed by powering a resistive load on-board the POEM-3 platform of PSLV-C58. The on-orbit voltage, current and temperature values of the battery were acquired through telemetry and found to match well with the predictions.
Compared to conventional Li-ion cells which use pure graphite as anode material, this cell uses Si-Graphite composite as anode material. This helps in accommodating more Lithium ions for a given unit mass of anode material and thus improves the energy density of the cell. In addition to the material change, this cell also employs cost effective hardware which are readily available and a crimped sealing based design which reduces the hardware cost and fabrication cost significantly.
The energy density of the Silicon High energy Li-ion cells is 190 Wh/kg with an operating voltage of 4.2 to 2.8 V, against Lithium-ion cells (157 Wh/kg). During flight the battery system worked for 21 hours in 15 orbits delivering a capacity of 8.9 Ah with final drained voltage of 0.4 V." - ISRO
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