Total Solar Eclipse today: ISRO's Aditya-L1 to track Sun during the celestial event

Chennai: In a significant achievement, India's first sun mission Aditya-L1 spacecraft will track the Sun during Total Solar Eclipse on Monday.

This will provide important scientific studies of the propagatory effect of solar dynamics in the interplanetary medium.

The Total Solar Eclipse will occur on April 8 as the Sun, Moon and Earth align in a straight line leading to a brief period of darkness during the daytime.

The Adiya L1 mission has six instruments as it observes the Sun from Lagrange Point 1, nearly 15 kms from Earth. Of the six, two instruments could be primed to observe the Sun during the eclipse.

These are the Visible Emission Line Coronagraph (VELC) and the Solar Ultraviolet Imaging Telescope (SUIT).

Reports received here said the coronagraph studies the Sun's outer layer, the corona.

During the eclipse, the Sun's corona is visible as the Moon blocks the solar disk and India's maiden solar probe, Aditya L1, will track the Sun as it gets cloaked by the moon, creating a brief period of darkness in several parts of North America, during the Total Solar Eclipse.

The Total Solar Eclipse will occur on April 8 as the Sun, Moon and Earth align in a straight line leading to darkness during the daytime. The cloaking will create a period of totality expected to last over four minutes, illuminating the enigmatic outer layer of the Sun that is not visible from Earth, the reports said.

Aditya L1 was be the first space based Indian mission to study the Sun. The spacecraft was placed in a halo orbit around the Lagrange point 1 (L1) of the Sun-Earth system, which is about 1.5 million km from the Earth.

A satellite placed in the halo orbit around the L1 point has the major advantage of continuously viewing the Sun without any occultation/eclipses.

This will provide a greater advantage of observing the solar activities and its effect on space weather in real time. The spacecraft carries seven payloads to observe the photosphere, chromosphere and the outermost layers of the Sun (the corona) using electromagnetic and particle and magnetic field detectors.

Using the special vantage point L1, four payloads directly view the Sun and the remaining three payloads carry out in-situ studies of particles and fields at the Lagrange point L1, thus providing important scientific studies of the propagatory effect of solar dynamics in the interplanetary medium.

The suits of Aditya L1 payloads are expected to provide most crucial informations to understand the problem of coronal heating, coronal mass ejection, pre-flare and flare activities and their characteristics, dynamics of space weather, propagation of particle and fields etc.

The major science objectives of Aditya-L1 mission included Study of Solar upper atmospheric (chromosphere and corona) dynamics; Study of chromospheric and coronal heating, physics of the partially ionized plasma, initiation of the coronal mass ejections, and flares; Observe the in-situ particle and plasma environment providing data for the study of particle dynamics from the Sun; Physics of solar corona and its heating mechanism; Diagnostics of the coronal and coronal loops plasma; Temperature, velocity and density; .Development, dynamics and origin of CMEs and Identify the sequence of processes that occur at multiple layers (chromosphere, base and extended corona) which eventually leads to solar eruptive events.

Magnetic field topology and magnetic field measurements in the solar corona Drivers for space weather (origin, composition and dynamics of solar wind are also part of its objectives, ISRO said.

The instruments of Aditya-L1 are tuned to observe the solar atmosphere mainly the chromosphere and corona. In-situ instruments will observe the local environment at L1. There are total seven payloads on-board with four of them carrying out remote sensing of the Sun and three of them carrying in-situ observation.

The ISRO had on January six this year successfully inserted Aditya-L1 spacecraft in the L1 Orbit.

ISRO said that Halo-Orbit Insertion (HOI) of its solar observatory spacecraft, Aditya-L1 was accomplished at 1600 hrs (approx) on January 6, 2024 (IST).

The orbit of Aditya-L1 spacecraft is a periodic Halo orbit which is located roughly 1.5 million km from earth on the continuously moving Sun – Earth line with an orbital period of about 177.86 earth days.

This Halo orbit is a periodic, three-dimensional orbit at L1 involving Sun, Earth and a spacecraft.

This specific halo orbit is selected to ensure a mission lifetime of 5 years, minimising station-keeping manoeuvres and thus fuel consumption and ensuring a continuous, unobstructed view of sun.

The Aditya-L1 mission is an Indian solar observatory at Lagrangian point L1 for “Observing and understanding the chromospheric and coronal dynamics of the Sun” in a continuous manner.

Placing the Aditya-L1 in a halo orbit around L1 point has advantages as compared to placing in a Low Earth Orbit (LEO). It provides a smooth Sun-spacecraft velocity change throughout the orbit, appropriate for helio seismology. It is outside of the magnetosphere of Earth, thus suitable for the "in situ" sampling of the solar wind and particles. It allows unobstructed, continuous observation of the Sun, and view of earth for enabling continuous communication to ground stations.

The Aditya-L1 spacecraft was launched by PSLV-C57 on September 2, 2023 from SDSC SHAR, into an elliptical parking orbit (EPO) of 235.6 km by 19502.7 km. From here, Aditya-L1 embarked on an extraordinary journey towards the Sun-Earth-L1 Lagrange point, with the help of the onboard propulsion system, increased its orbital size progressively and moved toward L1 point. Five liquid engine burns (LEB) were executed during Earth orbit phase; gradually raised the apogee of the EPO in order to attain the desired trajectory with the fifth burn, known as the trans-L1 injection (TL1I) maneuver.