ISRO Aditya – L1 First Indian mission to Explore the Sun

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The project is approved and the satellite will be launched during 2019 – 2020 timeframe by PSLV-XL from Sriharikota.

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.  It has a temperature of more than a million degree Kelvin which is much higher than the solar disc temperature of around 6000K. How the corona gets heated to such high temperatures is still an unanswered question in solar physics. 

Aditya-L1 with additional experiments can now provide observations of Sun’s Corona (soft and hard X-ray, Emission lines in the visible and NIR), Chromosphere (UV) and photosphere (broadband filters).  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.   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.

Deployed view

The main payload continues to be the coronagraph with improved capabilities.  The main optics for this experiment remains the same.  The complete list of payloads, their science objective and lead institute for developing the payload is provided below:

  • Visible Emission Line Coronagraph (VELC): To study the diagnostic parameters of solar corona and dynamics and origin of Coronal Mass Ejections (3 visible and 1 Infra-Red channels); magnetic field measurement of solar corona down to tens of Gauss – Indian Institute of Astrophysics (IIA)
  • 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 – Inter-University Centre for Astronomy & Astrophysics (IUCAA)  
  • Aditya Solar wind Particle Experiment (ASPEX) : To study the variation of solar wind properties as well as its distribution and spectral characteristics – Physical Research Laboratory (PRL)        
  • Plasma Analyser Package for Aditya (PAPA) : To understand the composition of solar wind and its energy distribution – Space Physics Laboratory (SPL), VSSC        
  • Solar Low Energy X-ray Spectrometer (SoLEXS) : To monitor the X-ray flares for studying the heating mechanism of the solar corona – ISRO Satellite Centre (ISAC)
  • 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 – ISRO Satellite Centre (ISAC)and Udaipur Solar Observatory (USO), PRL
  • Magnetometer: To measure the magnitude and nature of the Interplanetary Magnetic Field – Laboratory for Electro-optic Systems (LEOS) and ISAC.

With the inclusion of multiple payloads, this project also provides an opportunity to solar scientists from multiple institutions within the country to participate in space based instrumentation and observations.  Thus the enhanced Aditya-L1 project will enable a comprehensive understanding of the dynamical processes of the sun and address some of the outstanding problems in solar physics. 

CESSI is playing a pivotal role within the Aditya-L1 undertaking as affiliated researchers here are running with scientists and engineers at ISRO and other institutions inside the united states to layout and develop a number of the onboard devices and provide computational simulation aid for the assignment.

While the Aditya project is a breakthrough within the making, considering handiest NASA, the Japanese Aerospace Exploration Agency (JAXA) and the European Space Agency (ESA) have had solar probes in the past, why must India start to apprehend the dynamics of the Sun? What can Aditya tell us about other stars and the Universe? What kind of scientific progress can statistics from Aditya enable? Here are the answers.

Why observe the Sun?

Humanity’s hobby in watching the Sun is as old as history. In approximately 800 BC, the Chinese appear to have made the first reviews of sunspots. In the early 1600s, four astronomers in Europe, which includes Galileo Galilei, made impartial observations of sunspots with telescopes. Observations of the Sun and investigations of what is going on in it have driven many advances over the years, like the discovery of helium, better know-how of nuclear physics and even the invention of neutrino oscillations. In the 20 th century, as scientists observed the outlines of how stars work, know-how the Sun higher assumed even extra importance. As the closest star to us, observations and investigations of the Sun can provide an unparalleled perception into the inner workings of stars.

“The Sun, which controls the ecosystem of all planets inside the Solar System, suggests many versions in its radiations because of the activities in it,” explains Prof Nandi. Hence, expertise those variations can provide clues at the beginning of existence, the environment of exoplanets and insights into plasma—the nation of rely abundant within the Universe.

A long-studied issue of the Sun’s pastime is the sunspots—darkish spots on the surface of the Sun that have excessive magnetic flux. So far, we realize that those sunspots have an 11-yr cycle, for the duration of which they first growth in number, and then decrease. During the first half of of this period, sunspots frequently appear on the mid-latitudes in both the northern and southern hemispheres, after which move in the direction of the equator, before reducing for the duration of the second one 1/2.


“In the early 1900s, astronomers observed that these sunspots are especially magnetised, and the magnetic discipline in these regions is about ten thousand times stronger than the Earth’s,” says Prof Nandi.

The high magnetic subject additionally outcomes in sun storms and solar flares, when excessive electricity photons are emitted by using the Sun. Sometimes, the plasma inside the corona additionally receives spewed into space because of the excessive energy, and this is called ‘coronal mass ejection‘. These sun occasions ought to interfere with the workings of our satellite verbal exchange structures, like GPS (Global Positioning System) and climate monitoring, resulting in chaos.

Hence, it’s miles vital to recognize whilst such sun flares occur, and at what magnitude, so we may be better prepared. “Hence, it’s miles vital to recognize how activities inside the solar surroundings impact the space climate in our Solar System. By doing so, we are able to predict, and have catastrophe control systems in vicinity for sensitive applications,” explains Prof Nandi. With Aditya, all those may be completed indigenously, making India self-reliant in dealing with the vagaries of space weather.

Lastly, the assignment hopes to answer a long-unsolved query in solar physics—the coronal heating. The Sun’s corona, that’s the outermost layer of the solar surroundings, is abnormally hot with temperatures within the variety of thousands and thousands of degrees. On the contrary, the Sun’s surface is ready 5,600o C. The laws of thermodynamics do now not explain this abnormally warm corona, and scientists agree with that this is not the result of thermal heating, however magnetic heating. “When magnetic fields of opposite polarity come collectively, they lose their discipline lines due to a process known as magnetic reconnection. It is believed that this loss of magnetic strength is transformed into localised heating within the corona,” explains Prof Nandi.

As the corona will become extraordinarily hot, it throws out plasma from the Sun and creates solar storms and winds. An know-how of this tremendous magnetic pastime and the way it restructures the form of the corona and causes solar storms is fundamental to know-how plasma physics. Sun provides a unique laboratory to observe these activities, that is not possible with other remote stars. The models that we construct about how plasma flows, can help solution more tremendous questions about the structure of different objects inside the Universe like active galactic nuclei— vibrant and dense regions on the centres of galaxies.

Instruments onboard Aditya L1

The contraptions at the venture are aimed at studying the magnetic interest on the Sun’s corona, and understanding the way it affects space climate. The Visible Emission Line Coronagraph (VELC), built at the Indian Institute of Astrophysics, Bengaluru, is designed to understand coronal mass ejections and the way they propagate in space. This sensitive tool measures the density and electricity of the magnetic discipline in the corona, which can then help us discern out the coronal temperature.

“Right now, no solar assignment can degree the magnetic subject of the Sun’s corona as it’s far simplest observable at some stage in the eclipse. With Aditya, we will now acquire this records in real-time,” says Dr Nandi.

The Solar Ultraviolet Imaging Telescope (SUIT), being designed by way of the Inter-University Centre for Astronomy & Astrophysics (IUCAA), Pune, measures the Ultraviolet radiation emitted from the Sun, which is a primary determinant of life of Earth.

“One of the primary questions we are looking to deal with is how does the Sun manipulate to supply ultraviolet radiation from the upper floor of the atmosphere. We want to have a look at the radiation at extraordinary layers of the ecosystem and discern out how it’s miles produced and why it varies,” says Dr Durgesh Tripathi from IUCAA, who is the Principal Investigator of SUIT. The facts amassed from this tool would also be used as inputs to weather models that correctly are expecting the Earth’s weather.

Onboard Aditya-L1 are X-ray spectrometers that study the X-rays radiated for the duration of solar flares. The Solar Low Energy X-ray Spectrometer (SoLEXS) analyses low-energy X-rays, while the High Energy L1 Orbiting X-ray Spectrometer (HEL1OS) estimates the strength used to accelerate particles all through eruptive events like sun flares. These spectrometers are being built at the U R Rao Satellite Centre (URSC) – ISRO.

Two in-situ gadgets measure the local space weather around the satellite. The Aditya Solar wind Particle Experiment (ASPEX), designed via the Physical Research Laboratory (PRL) at Ahmedabad, appears at the variations within the houses of the solar wind, and its distribution and spectral characteristics. The Plasma Analyser Package for Aditya (PAPA) facilitates to recognize the composition of the sun wind and is being designed by way of ISRO’s Vikram Sarabhai Space Centre. An onboard magnetometer, referred to as MAG and built with the aid of ISRO’s Laboratory for Electro-Optics Systems (LEOS), measures the enhancement inside the magnetic subject when a solar hurricane is passing.


  • 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.

Enabling better research in sun physics

With a suite of effective contraptions, Aditya is popping to be a darling for India’s solar astrophysicists, who have massive audacious studies goals. “The facts from Aditya will permit each essential and applied research,” hopes Prof Nandi. The undertaking’s records might help in deciphering the Sun’s coronal magnetic subject and information how they drive solar storms and energy plasma heating in the sun corona. The understanding of the space weather is also going to feature to India’s may of indigenous generation in shielding its satellites and communique structures.

A higher perception into the Sun’s sports that enhance the Ultraviolet emissions has implications at the planetary environment in the Solar System. With gadgets like SUIT, we can get an picture of numerous layers of the Sun’s ecosystem. “The facts shall help us screen the solar activity and their connections inside the atmosphere. It might also be used to reveal the solar UV spectral irradiance, that is vital to the chemistry of Ozone and Oxygen in the stratosphere of the Earth,” explains Dr Tripathi.

The coming together of numerous institutes of the us of a in supplying the clinical prowess to Aditya is also remarkable. “It is probably one of the few instances where we’ve taken a bottom-up method in designing the units based on what technological know-how we want to allow eventually,” opines Dr Nandi. The project has seen multiple discussions among educational researchers in these institutes who may be the eventual users of the records that Aditya provides, and the engineers at ISRO who are crucial in launching the assignment.

The studies community is making ready to use records from Aditya as soon as possible—within six months of the launch. For instance, Prof Nandi’s studies group is already constructing a framework of tools which can use information approximately the Sun’s coronal commentary and apprehend the magnetic fields within the corona. “We can use maps of the Sun’s surface to perform information-driven computational fashions of the corona and constrain those fashions with observations,” he says, explaining how his institution intends to develop our understanding of the Sun. There have additionally been efforts to as it should be calibrate the onboard units such that the statistics, while they come in, are usable and accurate.

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