ISRO : aditya l1 mission upsc

 

After successful launch of Chandrayan-3, ISRO is planning to launch the Aditya-L1 mission, first Indian space mission to observe the Sun by AUGUST 2023 to observe the Sun and the solar corona.

Earlier, the Visible Line Emission Coronagraph (VLEC), the primary payload on board Aditya-L1, was handed over to  Indian Space Research Organisation (ISRO) by the Indian Institute of Astrophysics (IIA). 

§  Aditya L1 will be ISRO’s 2^nd space-based astronomy mission after AstroSat, which was launched in 2015.

§  Aditya 1 was renamed as Aditya-L1. The Aditya 1 was meant to observe only the solar corona.

AstroSat

• AstroSat, was launched in September, 2015, by PSLV-C30 from Sriharikota (Andhra Pradesh).
• It is the first dedicated Indian astronomy mission aimed at studying celestial sources in X-ray, optical and UV spectral bands simultaneously.

 

 

About Aditya-L1 Mission?

§  Launch Vehicle:

o    Aditya L1 will be launched using the Polar Satellite Launch Vehicle (PSLV) with 7 payloads (instruments) on board.

o    The 7 payloads include:

Aditya L1 Payloads: The 1,500 kg satellite carries seven science payloads with diverse objectives.

• Visible Emission Line Coronagraph (VELC): To study the diagnostic parameters of solar corona and dynamics and origin of Coronal Mass Ejections, magnetic field measurement of solar corona.
• Solar Ultraviolet Imaging Telescope (SUIT): To image the spatially resolved Solar Photosphere and Chromosphere in near Ultraviolet (200-400 nm) and measure solar irradiance variations.
• Aditya Solar wind Particle Experiment (ASPEX): To study the variation of solar wind properties as well as its distribution and spectral characteristics.
• Plasma Analyser Package for Aditya (PAPA): To understand the composition of solar wind and its energy distribution
• Solar Low Energy X-ray Spectrometer (SoLEXS): To monitor the X-ray flares for studying the heating mechanism of the solar corona .
• High Energy L1 Orbiting X-ray Spectrometer (HEL1OS): To observe the dynamic events in the solar corona and provide an estimate of the energy used to accelerate the particles during the eruptive events.
• Magnetometer: To measure the magnitude and nature of the Interplanetary Magnetic Field.

What are the Features and Significance of VELC Payload?

§  Features:

o    VELC will be the main payload among seven designed to study various aspects of the sun and is one of the most precise instruments made in India.

o    It was conceptualised and designed in 15 years which will help in solving mysteries related to solar astrophysics.

§  Significance:

o    It will help in studying the temperature, velocity and density of the corona, understand the processes that result in heating of the corona and acceleration of the solar wind, aid studies on drivers of space weather, measure the magnetic field of corona and study the development and origin of coronal mass ejection.

 

§  Objective:

o    Aditya L1 will study -

1.Sun’s corona :The Sun’s corona is the outermost part of the Sun’s atmosphere. The corona is usually hidden by the bright light of the Sun's surface. That makes it difficult to see without using special instruments. However, the corona can be viewed during a total solar eclipse.

Why is the corona so dim?

The corona reaches extremely high temperatures. However, the corona is very dim. Why? The corona is about 10 million times less dense than the Sun’s surface. This low density makes the corona much less bright than the surface of the Sun.

 

2.Sun's photosphere : 

The surface of the Sun is called the photosphere, a term which means “sphere of light.” The glowing ball of light that you see in the sky is the photosphere. The surface of the Sun is the only part that we can see from Earth on a typical day, without use of specialized equipment.

Its temperature is about 5,500 °C (9,900 °F), which is much cooler than the Sun's core. Most of the light energy produced in the Sun’s core escapes from the photosphere. Because the plasma is cooler and less dense at the surface, there are fewer collisions to trap the energy carrying photons within the Sun. Instead, energy radiates away through space, some of it reaching Earth.

3.Chromosphere :

Chromosphere is a reddish and glowing layer of gas above a star’s (or Sun's) photosphere. It is actually the transition between corona and the photosphere. Out of the three layers of the Sun’s atmosphere, chromosphere is the second one (with photosphere being the first layer and corona as the third).
                  As the name suggests, chromosphere literally translates into ‘sphere of light’. It is about 2,000 to 3,000 kilometres deep, which is located immediately above the photosphere and just below the corona.

4.Solar emissions: 

The solar emission is the range of electromagnetic radiation emitted by the sun, extending from the ultraviolet to the infrared region. It is composed of photons with various wavelengths, which define the spectrum’s shape and intensity. It can be defined in terms of solar radiation or solar irradiance. Solar radiation is the direct emission of energy from the sun while solar irradiance is the amount of energy that reaches the Earth’s surface.

The solar spectrum can be divided into three main regions: the ultraviolet (UV), visible, and infrared (IR).

.

5.Solar winds and flares :

A solar flare is an intense burst of radiation coming from the release of magnetic energy associated with sunspots. Flares are our solar system’s largest explosive events. They are seen as bright areas on the sun and they can last from minutes to hours.

6.Coronal Mass Ejections (CMEs) : 

The outer solar atmosphere, the corona, is structured by strong magnetic fields. Where these fields are closed, often above sunspot groups, the confined solar atmosphere can suddenly and violently release bubbles of gas and magnetic fields called coronal mass ejections. A large CME can contain a billion tons of matter that can be accelerated to several million miles per hour in a spectacular explosion

7.Will carry out round-the-clock imaging of the Sun.

·         The mission will be launched by ISRO to the L1 orbit which is about 1.5 million km from the Earth. The orbit allows Aditya-L1 to look at the Sun continuously.

L1 refers to Lagrangian/Lagrange Point 1, one of 5 points in the orbital plane of the Earth-Sun system.

o    Lagrange Points are positions in space where the gravitational forces of a two-body system like the Sun and Earth produce enhanced regions of attraction and repulsion.

§  These can be used by spacecraft to reduce fuel consumption needed to remain in position.

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

§  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).

 

o    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.

o    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 of the mission

§  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.

 

 

Some Other Missions to the Sun?

§  NASA’s Parker Solar Probe: Aims to trace how energy and heat move through the Sun’s corona and to study the source of the solar wind’s acceleration.

o    It is part of NASA’s ‘Living With a Star’ programme that explores different aspects of the Sun-Earth system.

§  Helios 2 Solar Probe: 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.

§  Solar Orbiter: A joint mission between the ESA and NASA to collect data that will help answer a central question of heliophysics like how the Sun creates and controls the constantly changing space environment throughout the solar system.

§  Other Active Spacecraft Monitoring the Sun: Advanced Composition Explorer (ACE), Interface Region Imaging Spectrograph (IRIS), WIND, Hinode, the Solar Dynamics Observatory, and Solar Terrestrial Relations Observatory (STEREO).