Aditya-L1 enters final orbit: Why studying the Sun is essential

It was yet another big moment for India in space. Aditya L1, the country’s first sun mission, reached its final destination on Saturday. This comes more than four months after the Indian Space Research Organisation (ISRO) successfully launched the mission on 2 September 2023. On Saturday, Aditya L-1 was successfully inserted into Lagrange Point 1, which is one of the five locations in the Earth-Sun system where the gravitational effects of the two roughly cancel each other. It is from here that spacecraft will observations on the Sun for five years.

𝐈𝐧𝐝𝐢𝐚, 𝐈 𝐝𝐢𝐝 𝐢𝐭. 𝐈 𝐡𝐚𝐯𝐞 𝐫𝐞𝐚𝐜𝐡𝐞𝐝 𝐭𝐨 𝐦𝐲 𝐝𝐞𝐬𝐭𝐢𝐧𝐚𝐭𝐢𝐨𝐧!

Aditya-L1 has successfully entered the Halo orbit around the L1 point.#ISRO #AdityaL1Mission #AdityaL1 pic.twitter.com/6gwgz7XZQx

— ISRO InSight (@ISROSight) January 6, 2024

Prime Minister Narendra Modi was among the first to hail Aditya L1’s final manoeuvre. Calling it a landmark achievement wrote on X, “India’s first solar observatory Aditya-L1 reaches its destination. It is a testament to the relentless dedication of our scientists in realising among the most complex and intricate space missions. I join the nation in applauding this extraordinary feat. We will continue to pursue new frontiers of science for the benefit of humanity.” So what does India’s sun mission entail? And why studying the sun matters? We explain. What is the Aditya-L1 mission? The Aditya-L1 is an ‘observatory’ or spacecraft that will monitor the Sun 24x7. This is the first time that India has put a spacecraft on a Lagrange point – a position in space where, as per NASA, “the gravitational forces of a two-body system like the Sun and Earth produce enhanced regions of attraction and repulsion”. There are five Lagrange points in the Sun-Earth system; India’s solar mission is now placed in a halo orbit around Lagrange point 1, or L1, which is about 1.5 million km from the Earth. The gravitational forces at L1 lead to the creation of a stable environment, rendering it an optimal location for scientific observations and space missions. This strategic positioning ensures relative stability for a spacecraft to be parked and observe the Sun. L1, Aditya’s parking spot, has been housing Solar and Heliospheric Observatory, a project by America’s NASA and the European Space Agency (ESA) since 1996, reported Space.com. What are the objectives of the mission? The Aditya-L1 mission carries seven payloads, out of which four will directly observe the Sun. These seven payloads or scientific instruments include Visible Emission Line Coronagraph(VELC), Solar Ultraviolet Imaging Telescope (SUIT), Solar Low Energy X-ray Spectrometer (SoLEXS), High Energy L1 Orbiting X-ray Spectrometer (HEL1OS), Aditya Solar wind Particle Experiment (ASPEX), Plasma Analyser Package For Aditya (PAPA) and Advanced Tri-axial High Resolution Digital Magnetometers. These instruments will study the photosphere or the Sun’s visible surface; the layer above the photosphere known as the chromosphere; and the corona – the outermost part of the Sun’s atmosphere. As per ISRO, the spacecraft will examine the dynamics of the chromosphere and corona; in-situ particle and plasma environment; the heating mechanism of the corona; magnetic field topology and magnetic field measurements in corona; temperature, velocity and density of coronal and coronal loops plasma; and development, dynamics and origin of coronal mass ejections (CMEs). It will also study chromospheric and coronal heating, space weather, the physics of the partially ionized plasma, what leads to solar eruptive events, and how CMEs and solar flares start. “Since Aditya-L1 will look at Sun continuously, it can warn us of imminent solar electro-magnetic effects on Earth and protect our satellites, and other power electrical and communications networks from getting disrupted. This will help continue normal operations by operating them in safe modes, till the solar storm passes by,” ISRO chairman S Somanat had told NDTV. What happens now that Aditya L1 has reached its destination? On Saturday, all seven scientific instruments aboard Aditya L1 were switched off before ISRO fired the satellite thrusters to inject it into orbit. The challenge was to manoeuvre at once to use the least amount of fuel. ISRO will wait for a few more days to switch on all the payloads to ensure a stable orbit with an unobstructed view of the Sun. The Visible Emission Line Coronagraph (VELC), the main payload on board the spacecraft, will be switched on for the first time since the mission took off. “We will wait till January-end to switch on VELC, so we can safely capture the faint light of the Sun’s outer layer — Corona — by blocking the light from the main disk. That is the main goal. We have not opened its aperture because we did not want the mirrors to get affected by the molecular dust or disturbance when thrusters are fired during orbital insertion,” Professor R Ramesh from the Indian Institute of Astrophysics, Bengaluru, which built the payload told News18. All seven instruments will study different regions of the Sun and will be activated by the end of January. Why is studying the Sun important? Before that, here are some facts about the centre of our solar system. The Sun, which sustains most life on Earth, is a 4.5 billion-year-old star. Located 150 million kilometres away from the Earth , the Sun’s gravity holds the solar system together. Unlike Earth, the Sun’s surface is not solid but made of “super-hot, electrically charged gas called plasma”, noted NASA. According to the US space agency, “The Sun’s activity, from its powerful eruptions to the steady stream of charged particles it sends out, influences the nature of space throughout the solar system.” The solar activity constitutes solar flares, CMEs or huge plasma clouds, high-speed solar wind, and solar energetic particles. [caption id=“attachment_13036872” align=“alignnone” width=“640”] The Sun is a 4.5 billion-year-old star, vital for most life on Earth. Wikimedia Commons/NASA File Photo[/caption] A solar flare is a severe burst of radiation capable of affecting radio communications and harming astronauts in space. The activity on the Sun’s surface creates a type of weather called space weather which can impact the Earth and the rest of the solar system. Thus, understanding solar events becomes more important for better knowledge of space weather, as per Indian Express. Moreover, ultraviolet rays from the Sun affect as well as are impacted by global climate change, according to the Smithsonian Environmental Research Center. As BussinessLine noted “changes in UV radiation can influence cloud formation, water vapor content and temperature patterns in the Earth’s lower atmosphere. It is important, therefore, to study the behaviour of the Sun to see its impact on the Earth’s climate.” While the Sun has been analysed by scientists for a long time, there are still many unanswered questions. As per a Space.com report, researchers are yet to unravel why the corona, at 1 million degrees Celsius, gets hotter than the photosphere – 5,500 degrees Celsius. Sun’s hottest part is its core where temperature is as high as 15 million degrees Celsius. It is also not known what goes on before the Sun ejects solar flares and CMEs in space and sometimes towards the Earth and “how CMEs accelerate to tremendous speeds close to the sun’s disk,” the report added. With Aditya L-1, scientists are hoping to unearth some of the Sun’s secrets. With inputs from agencies