What is India's Aditya-L1 sun mission.

Aditya L1 shall be the first space based Indian mission to study the Sun. The spacecraft shall be 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 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 effect of solar dynamics in the interplanetary medium

The suits of Aditya L1 payloads are expected to provide most crucial information 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.

Why is studying the Sun important?

Every planet, including Earth and the exoplanets beyond the Solar System, evolves and this evolution is governed by its parent star.
The solar weather and environment, which is determined by the processes taking place inside and around the sun, affects the weather of the entire system.
Variations in this weather can change the orbits of satellites or shorten their lives, interfere with or damage onboard electronics, and cause power blackouts and other disturbances on Earth. Knowledge of solar events is key to understanding space weather.
To learn about and track Earth-directed storms, and to predict their impact, continuous solar observations are needed.
Every storm that emerges from the Sun and heads towards Earth passes through L1, and a satellite placed in the halo orbit around L1 of the Sun-Earth system has the major advantage of continuously viewing the Sun without any occultation/eclipses.
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 A Halo orbit around the Lagrangian point 1 (L1) of the Sun-Earth system:
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1. Lagrange Points, named after Italian-French mathematician Josephy-Louis Lagrange, are positions in space where the gravitational forces of a two-body system (like the Sun and the Earth) produce enhanced regions of attraction and repulsion.
2. The L1 point is about 1.5 million km from Earth, or about 1/100th of the way to the Sun.
3. L1 refers to Lagrangian/Lagrange Point 1, one of 5 points in the orbital plane of the Earth-Sun system.
4. These can be used by spacecraft to reduce fuel consumption needed to remain in position.
5. A Satellite placed in the halo orbit around the Lagrangian point 1 (L1) has the major advantage of continuously viewing the Sun without any eclipses.
6. The L1 point is home to the Solar and Heliospheric Observatory Satellite (SOHO), an international collaboration project of National Aeronautics and Space Administration (NASA) and the European Space Agency (ESA).
The satellite will be launched during 2019 – 2020 timeframe by PSLV-XL from Sriharikota:
1. Aditya-1 was meant to observe only the solar corona. The outer layers of the Sun, extending to thousands of km above the disc (photosphere) is termed as the corona.
2. It has a temperature of more than a million degree Kelvin which is much higher than the solar disc temperature of around 6000K.
3. In addition, particle payloads will study the particle flux emanating from the Sun and reaching the L1 orbit, and the magnetometer payload will measure the variation in magnetic field strength at the halo orbit around L1.
4. These payloads have to be placed outside the interference from the Earth’s magnetic field and could not have been useful in the low earth orbit.
Studying lower corona:
1. The Aditya-L1 Support Centre (ASC) will provide training through regular workshops for the guest users.
2. Apart from this, it will provide ready-to-use Python and Java apps for the satellite data and demos and handouts to facilitate the guest users.
3. An ARIES team has recently developed an algorithm to study the accelerating solar eruptions in the lower corona called CMEs Identification in Inner Solar Corona (in short, CIISCO), where CME stands for coronal mass ejection.
4. The group has also developed several advanced image processing algorithms to detect fine-scale structures in the solar atmosphere.
5. Such techniques are important to capture dynamics at different spatial and temporal scals.