Your one-stop guide to decoding ISRO's Aditya-L1 mission

India’s first space-based mission to study the Sun launched on Saturday at 11:50 am from the Satish Dhawan Space Centre in Sriharikota. With the whole country expecting the same kind of success from ISRO’s solar mission as the Chandrayaan-3 mission achieved, here is all you need to know about India’s solar mission—Aditya-L1.

• With the Aditya-L1 mission, ISRO plans to place the spacecraft on a halo orbit around L1, the first Lagrange point of the Sun-Earth system, at about 1.5 million km from the earth. L1 is one of the five points in the Sun-Earth system where the gravitational forces between these two bodies are balanced, providing stability to spacecraft that remain locked on the Sun-earth line.

• The spacecraft will take 125 days to travel to L1. This positioning will give the spacecraft the advantage of uninterrupted viewing of the Sun, without blockage, and with reduced consumption of fuel.

Credit: X/@isro

• The main science drivers of Aditya-L1 are to understand the origin, dynamics, and propagation of Coronal Mass Ejections and to help solve the Coronal Heating Problem.

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• The mission will carry seven payloads that will observe the Sun’s photosphere (its visible surface), corona (its outermost layer), and chromosphere (the atmospheric layer in between). Stated among the mission objectives are a study of the dynamics of the Sun’s upper atmosphere (chromosphere and corona), patterns in coronal heating, space weather, magnetic field measurements in the corona, and plasma and magnetic field eruptions from the corona known as Coronal Mass Ejections (CMEs).

• Visible Emission Line Coronagraph (VELC) is the mission’s key payload, developed by the Indian Institute of Astrophysics(IIA), Bengaluru. The VELC on board the Aditya-L1 mission is equipped to study CMEs and their impact on space weather, and try to understand factors that make the corona significantly hotter than the Sun’s surface.

• The extremely bright light from the photosphere (Sun’s surface) makes observation of the lower corona region – where CMEs take shape – difficult. VELC has an internal occulter that separates this bright light out and sends the remaining light, from the corona, for processing.

• According to IIA officials, the 190 kg VELC payload will send images for five years, which is the nominal life of the satellite, but it could last long depending on the fuel consumption, etc.

• Though ESA (European Space Agency) and NASA (National Aeronautics and Space Administration) have launched similar missions in the past, the Aditya-L1 mission will be unique in two main aspects. We will be able to observe the solar corona from the place where it almost starts and observe the magnetic field changes in the solar atmosphere, which are the cause for coronal mass ejections or solar quakes.

• Data from the satellite will be downloaded at ISRO's Indian Deep Space Network near Byalalu on the outskirts of Bengaluru and will be transmitted by a dedicated internet link to the Payload Operations Centre of the Indian Institute of Astrophysics.

• By studying the Sun, ISRO said, scientists can learn much more about stars in the Milky Way as well as about stars in various other galaxies. Since various thermal and magnetic phenomena on the Sun are of extreme nature, the Sun will serve as a good natural laboratory to understand those phenomena which cannot be directly studied in the lab.

(With agency and DHNS inputs)