“Off to Sun-Earth L1 point!” said the Indian Space Research Organisation (ISRO) on Tuesday as an early morning manoeuvre by the Aditya-L1 spacecraft put it in a trajectory towards the point 1.5 million kilometres away from where it will continuously study the Sun.
The spacecraft will remain in the Trans-Lagrangean Point 1 trajectory for 110 days before being inserted into an orbit around the point where the gravitational pull of the Sun and Earth on the spacecraft will be completely balanced. “This is the fifth consecutive time ISRO has successfully transferred an object on a trajectory toward another celestial body or location in space,” the space agency said.
After travelling for nearly four months to the L1 point, covering a distance that has not been covered by any other Indian spacecraft, the Solar observatory will park itself in a halo orbit around the L1 point and study the Sun.
In fact, this is the first mission by India where the spacecraft will get into an orbit around a point and not a celestial body like Earth, Moon, or Mars. Mission director Nigar Shaji earlier told Indian Express: “This halo orbit insertion at L1 is something that ISRO has not done so far.”
The L1 point that lies at only 1% of the distance between Earth and the Sun has been selected as it allows for an unobstructed view of the Sun as no celestial body can come in between to cause an eclipse. The point also allows us to study the Sun without interference of the dust found in the Earth’s atmosphere or the atmosphere and magnetic fields itself that do not allow some of the harmful radiations like UV radiation from the Sun to enter the Earth.
There are seven scientific instruments on board the observatory class spacecraft.
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One of the instruments called the Supra Thermal and Energetic Particle Spectrometer (STEPS) has started collecting scientific data already, measuring high temperature, energetic particles in the solar wind. STEPS comprises six sensors, each observing in different directions. The instrument was switched on nine days ago after reaching a distance of more than 50,000 kilometres from the Earth. This distance of more than eight times the Earth’s radius meant that the spacecraft was out of the Earth’s radiation belt.
The observations started after the necessary instrument health checks were completed. “The data collected during Earth’s orbits helps scientists to analyse the behaviour of particles surrounding the Earth, especially in the presence of the magnetic field of Earth,” the space agency said.
The ISRO launched Aditya L-1, its first space-based mission to study the Sun, from the Satish Dhawan Space Centre in Sriharikota on September 2.
