With Moon In Sight, ISRO Now Aims For The Sun

With the Moon well within its sight, the Indian Space Research Organization (ISRO) is now aiming for the Sun. ISRO has released first images of its satellite to study the Sun, this will be India's maiden outing towards the Sun.

ISRO has released the first images of the satellite it intends to send to study the Sun, it is appropriately named Aditya-L1. It says "our Sun is the nearest star and the largest object in the solar system."

ISRO estimates the age of the Sun to be 4.5 billion years. It is a hot glowing ball of hydrogen and helium gases. The distance to the sun from the earth is about 150 million kilometers, and is the source of energy for our solar system. Without the solar energy the life on earth, as we know, cannot exist. The gravity of the sun holds all the objects of the solar system together. At the central region of the sun, known as 'core', the temperature can reach as high as 15 million degree Celsius. At this temperature, a process called nuclear fusion takes place in the core which powers the sun. The visible surface of the sun known as photosphere is relatively cool and has temperature of about 5,500 degrees Celsius.

India's Chandrayaan-3 is racing for its rendezvous with the South Pole of the moon on August 23, 2023. Within weeks of that, the Indian space agency seeks to launch its nearly 1500 kilogram scientific robotic satellite to keep a continuous eye on the Sun.

This will be India's first dedicated mission to monitor the Sun, especially to understand what happens when the Sun gets angry. A solar observatory made at a cost of Rs 400 crores.

"India's Aditya L1 satellite is a space based protector of sorts, keeping an eye on solar flares and ensuing solar storms' explained S Somanath, Chairman, ISRO, adding that "Aditya L1" will look at Sun continuously hence it can thus forewarn us of imminent solar electro-magnetic effects on Earth and thus protect our satellites, and other power electrical and communications networks from getting disrupted and help continuing normal operations by operating them in 'safe modes, till the solar storm passes by'".

All life on earth is dependent on the Sun, both for solar radiation that helps plants capture the carbon and glucose through photosynthesis, the Earth really falls within the so called 'Goldilocks Zone' neither too near the Sun nor too far just the right distance so that life could evolve on the planet.

In addition "India has assets worth over Rs 50,000 crores in space with over fifty operational satellites and they need to be protected against the anger of the Sun' explains Mr Somanath.

When a large solar flare comes out of the Sun it can literally fry the electronics of the satellites. To protect them, space engineers shutdown the electronics and keen them in safe shut down state till highly charged storm passes over.

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 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 scientific instruments of Aditya L1 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.

The Indian space agency in its statement said the major science objectives of Aditya-L1 mission are: The 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. 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 the origin, composition and dynamics of solar wind.

ISRO said the Aditya-L1 mission, will study the photons and the solar wind ions and electrons emitted by the Sun, and the associated interplanetary magnetic field, from a halo orbit around the first Sun-Earth Lagrange point (L1).

In a way, even as ISRO attempts to soft landing on the moon, it is getting ready to do a celestial 'surya namaskar' through the Aditya satellite.

(Pallava Bagla is co-author of the books 'Destination Moon', and 'Reaching for the Stars: India's Journey to Mars and Beyond'. He can be reached on pallava.bagla@gmail.com)