Aditya L1 Mission - India's First Solar Mission

Aditya L1 is the first space-based Indian mission to study the Sun.
It will be launched by the PSLV-XL launch vehicle.
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 occultation/eclipses.
This will provide a greater advantage in observing solar activities and their 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 other objectives of Aditya L1 mission will be to understand the drivers for space weather (origin, composition and dynamics of solar wind), and identify the sequence of processes that occur at multiple layers (chromosphere, base and extended corona) which eventually leads to solar eruptive events.

Objectives of the mission

Study– Solar upper atmospheric (chromosphere and corona) dynamics.
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.
Identify– The sequence of processes that occur at multiple layers which eventually leads to solar eruptive events.
Magnetic field topology and magnetic field measurements in the solar corona.
The origin, composition and dynamics of solar wind.

Challenges:

The distance of the Sun from Earth ( approximately 15 crore kms on average, compared to the only 3.84 lakh kms to the Moon).This huge distance poses a scientific challenge. Due to the risks involved, payloads in earlier ISRO missions have largely remained stationary in space; however, Aditya L1 will have some moving components which increases the risks of collision. Other issues are the super hot temperatures and radiation in the solar
atmosphere. However, Aditya L1 will stay much farther away, and the heat is not expected to be a major concern for the instruments on board.

Importance:

Evolution of every planet, including Earth and the exoplanets beyond the Solar System, is governed by its parent star i.e the Sun in our case. The Solar weather and environment affects the weather of the entire system. Therefore, it is important to study the Sun. Effects of Variation in Solar Weather 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. Many of the instruments and their components for this mission are being manufactured for the first time in the country.

What are Lagrangian Points?

Lagrangian points, also known as Lagrange points or libration points, are specific locations in space where the gravitational forces of two large bodies, such as a planet and its moon or a planet and the Sun, produce enhanced regions of gravitational equilibrium.
In these points, the gravitational pull from the two bodies creates a stable or quasi-stable region where a third, smaller object can maintain a relatively constant position relative to the larger bodies.
There are five primary Lagrangian points, labeled L1 through L5, in a Sun-Earth system.
L1 (Lagrange Point 1):
- It was found by mathematician Joseph Louis Lagrange.
- It is located about 1.5 million kilometers inside Earth’s orbit, between the Sun and the Earth.
- The L1 point of the Earth-Sun system gives a clear view of the sun all the time, without any occultation/ eclipses.
- Once the Aditya L1 mission reaches the L1 Lagrange point, it will be injected to a halo orbit. A halo orbit is a type of orbit that allows the satellite to remain in a stable position between the Earth and the Sun.

Other Missions to the Sun

NASA’s Parker Solar Probe’s aim is to trace how energy and heat move through the Sun’s corona and to study the source of the solar wind’s acceleration. It is part of NASA’s ‘Living With a Star’ programme that explores different aspects of the Sun-Earth system.
The earlier Helios 2 solar probe, a joint venture between NASA and space agency of erstwhile West Germany, went within 43 million km of the Sun’s surface in 1976.

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