Tomorrow is the day that Aditya L1, an ISRO mission to study the Sun, will be put into final orbit

The first mission from India to study the Sun, Aditya L1, is getting closer to its goal and will be launched into its final orbit on January 6 evening.

Launched on September 2, the spacecraft would enter a “halo orbit” around Lagrange Point 1 (L1), one of the five locations in the moving Sun-Earth system where the two bodies’ gravitational pulls nearly balance each other out.

A spacecraft may see the Sun from a rather stable place because to these five points, which are comparatively immobile with respect to the Earth and Sun. About 1.5 million kilometres separate the L1 point from Earth. This represents a mere 1% of the entire distance that separates Earth and Sun.

“On January 6, the manoeuvre will place Aditya L1, which has already reached the L1 point, in the intended orbit. The spacecraft will go towards the Sun without entering the orbit, according to an ISRO official.

It is challenging to maintain the spacecraft securely locked at the L1, despite the fact that it is a relatively stable position relative to the other Lagrange points. Entering a “halo orbit,” which revolves around this point, is far preferable. Entering this three-dimensional orbit allows the spacecraft to observe the Sun from various perspectives.

“Aditya L1 will reach the L1 point and enter a halo orbit. There will be movement in the L1 point as the Earth revolves around the Sun. The Indian Express was informed by Annapurni Subramaniam, head of the Indian Institute of Astrophysics in Bengaluru, that “so does the halo orbit.”

It’s a difficult manoeuvre to get into this orbit, and this is the first time ISRO has tried it.

This move is really important. In order to alter the spacecraft’s speed and course, thrusters must be fired. Multiple further corrections and thruster firings would be necessary if the intended orbit is missed on the first try, according to Dibyendu Nandi, a solar physicist and the chair of the Space Weather and Monitoring Committee for the Aditya L1 project.

Aditya had successfully spent 124 days in space as of Wednesday. Just sixteen days into its mission, on September 18, Aditya began gathering scientific data and taking pictures of the Sun. Thus far, scientists have managed to acquire photos of the entire solar disc, high-energy X-rays from solar flares, and other rare glimpses inside the solar system.

The Visible Emission Line Coronograph (VELC), Solar Ultraviolet Imaging Telescope (SUIT), Solar Low Energy X-ray Spectrometer (SoLEXS), and High-Energy L1 Orbiting X-ray Spectrometer (HEL1OS) are four of Aditya’s seven scientific payloads that are specifically made to track the Sun. Other in-situ (on-site) measuring devices include the Advanced Tri-axial High Resolution Digital Magnetometers, Plasma Analyser Package for Aditya (PAPA), and the Aditya Solar Wind Particle Experiment (ASPEX).

During the spacecraft’s cruising phase, four instruments were turned on, including PAPA and one ASPEX component called the Solar Wind Ion Spectrometer. All of the instruments are said to be operating properly. Aditya is scheduled to be launched into a halo orbit around L1, providing the spacecraft with unrestricted access to solar storms, radiation, and other solar emissions before they reach Earth or are affected by Earth’s magnetic field. When the spacecraft reaches L1, SUIT, which is seated on the top deck of the Aditya-L1, will be among the first to become operational.

The mission’s seven payloads provide an extensive study of solar phenomena, drawing attention from all over the world. The devices can observe the sun in a variety of wavelengths. They are able to see these occurrences from various angles and analyse the radiation, particles, and magnetic fields that the Sun emits.

Additionally, the spacecraft is equipped with a coronagraph, which will enable researchers to peer much closer at the Sun’s surface and supplement data from the Solar and Heliospheric Observatory (SOHO) mission, which is the only other satellite in L1 position at the moment. This mission is being carried out by NASA and the European Space Agency.

“We need to artificially block the bright light from the photosphere or the Sun’s surface in order to study the faint light coming from the corona.” The approach’s issue, since the occulting disc is typically larger than the photosphere, we might not be able to block just the photosphere. Assuming a photosphere of one unit in size, the occulting disc for prior missions has been two units in size. Prof. R Ramesh of the Indian Institute of Astrophysics recently told The Indian Express, “With the Aditya L1 mission, we are trying to see as close to the beginning of the corona as possible with a smaller occulting disc that is just 1.05 times the photosphere.” The occulting disc of the lost SOHO coronagraph measured 1.1 times the radius of the Sun’s surface.