ISRO chief S. Somnath on April 21 said that the Aditya L1 solar mission of the premier space research agency is continuously sending data about the Sun.
| Photo Credit: ANI

ISRO chief S. Somnath on April 21 said that the Aditya L1 solar mission of the premier space research agency is continuously sending data about the Sun.

Mr. Somnath, who was speaking to reporters here after being conferred a special award by jewellery major P.C. Chandra Group, said several instruments of the spacecraft are working continuously to feed data on many aspects.

“We are looking into the sun in a continuous manner – UV magnetic charges observation, corona graph observation, X-ray observation and other things,” he said.

India’s first solar mission craft, Aditya-L1 spacecraft was launched on September 2, 2023.

“As we are keeping this satellite for five years, the observation will be analysed as a long-term measure. It is not like your instant news that something has been reported about the sun today, something else will happen tomorrow, things will happen every day,” he explained.

All observations will happen now but the results will be known later, he said.

“Eclipse happens as the sun is blocked by the moon. It is not like that anything happens within the sun during an eclipse. But obviously, our mission is also collecting data about the sun before, during and after an eclipse, Mr. Somnath said, while answering a question on whether the mission will throw light on the solar eclipse.

Speaking about collaborations with other space agencies, he said ISRO is building a joint satellite NISAR (NASA-ISRO Synthetic Aperture Radar).

New Delhi:

India’s first space-based solar observatory, Aditya L1, is continuously studying the Sun but will miss the total solar eclipse today that will be visible over vast swaths of North America. The total solar eclipse is a rare event that people across the USA and several events, from skydiving to special flights, are being organized to witness the celestial phenomenon.

For the first time in almost a century, the western and northern parts of New York State will experience a total eclipse. The path of totality – a narrow stretch where the Moon obscures the Sun entirely – tracks across cities and has set the USA into a tizzy.

In its statement about the event, NASA says, “On April 8, 2024, a total solar eclipse will cross North America, passing over Mexico, the United States, and Canada. A total solar eclipse happens when the Moon passes between the Sun and Earth, completely blocking the face of the Sun. The sky will darken as if it were dawn or dusk.”

NASA is also flying special research planes to chase the shadow among many other experiments. Though the entire event will last for several hours, the main spectacle – when day turns to night – is expected to last only about four minutes when there will be total darkness.

But India’s Aditya L1 satellite will not be able to witness the event. This is not because the Indian Space Research Organization (ISRO) has erred, but because the satellite is placed appropriately at a location that provides an uninterrupted 24×7, 365-day view of the Sun. The Indian scientists chose a spot to ensure that the satellite’s view is never blocked due to an eclipse.

“Aditya L1 spacecraft will not see the solar eclipse as the moon is behind the spacecraft, at the Lagrange Point 1 (L1 point), the eclipse that is visible on Earth doesn’t have much significance at that location,” ISRO chairman S. Somanath told NDTV.

The Indian Aditya L1 spacecraft is placed in a halo orbit around the Lagrange point 1 (L1) of the Sun-Earth system, which is about 1.5 million km from Earth. A satellite placed in the halo orbit around the L1 point has the major advantage of continuously viewing the Sun without any occultation or eclipses. This provides a greater advantage of observing solar activity and its effect on space weather in real-time.

Aditya L1 weighs nearly 1,500 kilograms and is a scientific robotic satellite to keep a continuous eye on the Sun. This is India’s first dedicated mission to monitor the Sun, especially to understand what happens when the Sun becomes active. The solar observatory has been made at a cost of Rs 400 crore.

In fact, the Aditya L1 satellite creates its own artificial solar eclipse to effectively study the Sun with its special instrument, the Visible Emission Line Coronagraph (VELC). Mr. Somanath says, “A solar eclipse is created in the coronagraph by eliminating the light from the disc of the Sun.”

Dr. Dipankar Banerjee, a solar physicist with the Indian Institute of Astrophysics (IIAP), Bengaluru, says the spacecraft offers scientists the opportunity to see and study the corona of the Sun as seen from space and as viewed from the ground during a total solar eclipse.

Dr. Banerjee will be conducting some experiments on the ground in Dallas, Texas, USA, during today’s eclipse, and that data will be compared with Aditya L1 data for the same viewing period.

Nigar Shaji, the Project Director for the Aditya L1 satellite from ISRO, says that nothing will change in the Sun due to the eclipse.

“Due to the eclipse, nothing special happens to the Sun. The VELC spectroscopic channels will be operated in raster scan and sit and stare mode of operation [special observation modes] to observe the coronal structures in emission lines. This will be a joint campaign to corroborate with ground-based observations,” Ms. Shaji tells NDTV.

Aditya L1 carries seven payloads to observe the photosphere, chromosphere, and the outermost layers of the Sun (the corona) using electromagnetic, 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.

Cautionary Note:

NASA says, “Except during the brief total phase of a total solar eclipse, when the Moon completely blocks the Sun’s bright face, it is not safe to look directly at the Sun without specialized eye protection for solar viewing. Viewing any part of the bright Sun through a camera lens, binoculars, or a telescope without a special-purpose solar filter secured over the front of the optics will instantly cause severe eye injury.”

In this Sept. 2, 2023 file photo, ISRO’s PSLV-C57 carrying Aditya-L1, India’s maiden solar mission spacecraft, lifts off from the launch pad at Satish Dhawan Space Centre, in Sriharikota.
| Photo Credit: PTI

Advanced sensors of a payload on board India’s maiden solar mission Aditya-L1 have successfully detected the impact of coronal mass ejections (CMEs), according to ISRO.

The payload— Plasma Analyser Package for Aditya (PAPA)— is an energy and mass analyser designed for in-situ measurements of solar wind electrons and ions in the low energy range, the space agency noted.

It has two sensors: the Solar Wind Electron Energy Probe (SWEEP, measuring electrons in the energy range of 10 eV to 3 keV) and the Solar Wind Ion Composition Analyser (SWICAR, measuring ions in the energy range of 10 eV to 25 keV and mass range of 1-60 amu).

The sensors are also equipped to measure the direction of arrival of solar wind particles.

The data collected by PAPA, developed by the Space Physics Laboratory and Avionics Entity of the Vikram Sarabhai Space Centre, revealed the occurrence of CME events, notably on December 15, 2023, and during February 10-11, 2024.

“The CME on December 15, 2023, was a single event. PAPA observations during this period showed an abrupt increase in total electron and ion counts and the time variations align with the solar wind parameters and magnetic field measurements obtained from the Deep Space Climate Observatory and Advanced Composition Explorer satellites at the L1 point,”, an ISRO statement said.

In contrast, the observed variations in electron and ion counts during February 10-11, 2024, are the result of multiple minor events, with differences in the time variations of electrons and ions, it was noted.

The SWEEP and SWICAR sensors on PAPA-Aditya-L1, ISRO said, are currently making continuous observations of solar wind electrons and ions in the default mode, demonstrating that they are performing as per the design in all modes of operations.

The observations made by PAPA emphasise its effectiveness in monitoring space weather conditions and its capability to detect and analyse solar phenomena, it said.

The launch of Aditya-L1 by PSLV-C57 rocket was successfully accomplished by ISRO on September 2.

Aditya-L1 spacecraft carried seven payloads to study the Sun— four to observe the light from the Sun and the remaining three to measure in situ parameters of the plasma and magnetic fields.

Aditya-L1 was placed in a halo orbit around the Lagrangian Point 1 (L1), which is 1.5 million km from the Earth in the direction of the Sun. It revolves around the Sun with the same relative position and hence can see the Sun continuously, ISRO officials said.

Aditya-L1 Mission: The fourth Earth-bound maneuvre (EBN#4) is performed successfully. ISRO’s ground stations at Mauritius, Bengaluru, SDSC-SHAR and Port Blair tracked the satellite during this operation, while a transportable terminal currently stationed in the Fiji islands for Aditya-L1 will support post-burn operations.
| Photo Credit: ANI

ISRO said on Saturday the Aditya-L1 spacecraft has travelled beyond a distance of 9.2 lakh km from Earth, successfully escaping the sphere of Earth’s influence.

It is now navigating its path towards the Sun-Earth Lagrange Point 1 (L1), the Bengaluru-headquartered national space agency said in a statement on X, formerly Twitter.

“This is the second time in succession that ISRO could send a spacecraft outside the sphere of influence of the Earth, the first time being the Mars Orbiter Mission,” it said.

The ISRO said earlier this month the Aditya-L1 solar mission spacecraft has commenced collecting data which will help scientists analyse the behaviour of particles surrounding Earth.

Data collected around L1 would provide insights into the origin, acceleration, and anisotropy of solar wind and space weather phenomena, it said.

The launch of Aditya-L1 by PSLV-C57 rocket was successfully accomplished by ISRO on September 2.

Aditya-L1 spacecraft carries a total seven different payloads to study the Sun, four of which will observe the light from the Sun and the remaining three will measure in-situ parameters of the plasma and magnetic fields.

Aditya-L1 will be placed in a halo orbit around the Lagrangian Point 1 (L1), which is 1.5 million km from the Earth in the direction of the Sun. It will revolve around the Sun with the same relative position and hence can see the Sun continuously.

Some of the most amazing phenomena in nature, from electromagnetic radiation and infrared vision to subatomic particles and cosmic rays, are invisible, and we get to know them only through their various applications. This is true of Lagrange points as well – points in space between celestial bodies where a spacecraft stays more or less stationary, as if held in place by some cosmic magic.

The ‘magic’, of course, owes itself to the unseen forces of gravity exerted by these bodies. Lagrange points are found along the plane of two objects in orbit around their common centre of gravity, where their gravitational forces cancel each other, so that a third body of negligible mass will remain at rest between them.

For example, the combined gravitational force between the sun and the earth equals the centrifugal force required by a satellite or an asteroid to orbit the sun-earth centre of gravity. At this Lagrange point, a satellite will keep its position constant relative to both the sun and the earth.

Maths instead of law

Planetary scientists are fascinated by Lagrange points because they offer the best ‘parking spots’ in space for satellites. That is, seen from the earth, Lagrange points appear to stay motionless, and this makes them ideal for controllers on the ground to communicate with spacecraft stationed there. No wonder these locations are home to several astronomical observatories that utilise their vantage position to have ringside views of the earth and the backyard of the Solar System, which would not be possible nearer to the planet.

Lagrange points exist throughout the Solar System due to this gravitational interaction between the sun and its retinue of planets and their moons.

The points were named after the Italian-French mathematician Joseph-Louis Lagrange, who was born January 25, 1736, in Turin, Italy. His parents wanted him to study law and enrolled him at the University of Turin. But as it happened, a 17-year-old Lagrange chanced upon an algebra paper by the English astronomer Edmond Halley and was so intrigued that he decided to become a mathematician instead.

He went on to excel in all fields of analytic number theory and celestial mechanics, and became one of the youngest and brightest mathematics professors of his time. He subsequently moved to Berlin, where his work on astronomy, mechanics and calculus resulted in several groundbreaking papers, including one on the moon’s orbital dynamics and another on perturbations of the orbits of comets.

The three-body problem

But Lagrange’s most important contributions were related to the so-called ‘three body problem’, which investigated the motion of three bodies (with mass) relative to each other in space – such as the sun, the earth, and the moon. The problem question itself is: if you know the starting positions of the sun, the earth, and the moon, can you predict their exact locations at a later date as they move under the influence of each other’s gravity?

Lagrange found that the problem could be solved if he assumed the third body was much smaller than the other two larger masses. This eventually led him to describe the famous five Lagrange points that we know today as L1, L2, L3, L4, and L5.

In any three-body system, three of these Lagrange points – L1, L2, and L3 – are unstable positions that lie along an imaginary straight line connecting the two larger bodies. The other two – L4 and L5 – are stable locations that form the apexes of two imaginary equilateral triangles with the two large celestial bodies at the vertices of each triangle.

Points of accumulation

Objects stay undisturbed at L4 or L5 because of a ‘restoring force’ – a force acting against any displacement – that prevents them from being nudged away from the stable point. Because of their stability, however, L4 and L5 also tend to accumulate a lot of interstellar dust and asteroids called Trojans that zip around the points. Scientists have detected nearly 10,000 Trojans in the L4 and L5 points of the sun-Jupiter system alone, where gravitational and centrifugal forces prompt the space rocks to follow the giant planet’s revolution around the sun.

Astronomers have also found four Trojans at Lagrange points around Mars and eight Trojans in the L4 and the L5 points around Neptune. One of Saturn’s larger moons, Tethys, even has two moonlets at its Lagrange points.

On the other hand, an object positioned at one of the three unstable Lagrange points  L1, L2, and L3 – can be easily de-orbited by even weak forces, and they will then drift off into space. That is to say: a spacecraft at, say, L3 needs only the slightest disruption to slip and fall from its orbit towards the sun or the earth, unless it frequently burns fuel via its thrusters, at the various moments of displacement, to adjust its orbital movement frequently.

Importance for space exploration

Without Lagrange points, space exploration would have been so restricted, with scientists struggling to find the best orbits and velocities for satellites, and reckoning with the challenges of orbital perturbations. To think that space efforts like the Aditya-L1 solar mission of the Indian Space Research Organisation (ISRO) would never have materialised had an Italian boy pursued a career in law, instead of being distracted by mathematics, in the 18th century!

Aditya-L1 is a space-based observatory that ISRO launched on September 2. It is now en route to its designated parking slot at L1 in the sun-earth system. Once it reaches L1 – at a distance of 1.5 million km away from the earth – the probe will settle into a ‘halo’ orbit around L1 to acquire an unobstructed view of the Sun.

L1 is already home to four other robotic explorers: NASA’s Solar and Heliospheric Observatory Satellite, Deep Space Climate Observatory, Advanced Composition Explorer, and the Global Geospace Science Wind satellite. The point will get even more crowded when three U.S. probes – Interstellar Mapping and Acceleration Probe, Near Earth Object Surveyor, Space Weather Follow On-Lagrange 1 – and the European Vigil mission begin their Lagrangian journeys in the next few years.

Sites of space colonies

Space scientists are also exploring the potential of the L4 and the L5 points to host space colonies in the future because these points are relatively close to the earth. At these locations, where gravitational forces cancel each other out, spacecraft will need very little fuel to remain in orbit or to launch to another planet, unlike launches from the earth that take up most of the fuel rockets carry. This, in theory, allows space engineers to build habitable space stations at L4 and L5 using resources mined from the moon or an asteroid.

A big space station built this way could be spun on its axis using rocket thrusters so that the artificial gravity thus created would help a large number of people to live and work on board the orbiting post permanently.

Prakash Chandra is a freelance science writer.

Bengaluru:

Aditya L1 spacecraft, India’s first space-based mission to study the Sun, got a “send-off” from the Earth after orbiting it since its September 2 launch as it underwent a key manoeuvre in the early hours of Tuesday, ISRO said.

The Trans-Lagrangian Point 1 Insertion manoeuvre marks the beginning of the spacecraft’s about 110-day trajectory to the destination around the L1 Lagrange point, a balanced gravitational location between the Earth and the Sun.

“Off to Sun-Earth L1 point! The Trans-Lagrangian Point 1 Insertion (TL1I) manoeuvre is performed successfully. The spacecraft is now on a trajectory that will take it to the Sun-Earth L1 point. It will be injected into an orbit around L1 through a maneuver after about 110 days,” ISRO said in a post on X (formerly Twitter).

This is the fifth consecutive time the Indian Space Research Organisation (ISRO) has successfully transferred an object on a trajectory toward another celestial body or location in space, the country’s space agency said.

Aditya-L1 is the first Indian space-based observatory to study the Sun from a halo orbit around first Sun-Earth Lagrangian point (L1), located roughly 1.5 million km from earth, which is about one per cent of the Earth-Sun distance.

The Sun is a giant sphere of gas, and Aditya-L1 would study the outer atmosphere of the Sun. It will neither land on the Sun nor approach the Sun any closer.

Since its launch, Aditya-L1, during its journey around the Earth, underwent four Earth-bound manoeuvres on September 3, 5 ,10 and 15 respectively, during which it gained the necessary velocity for its further journey to L1.

Upon arrival at the L1 point, another manoeuvre binds Aditya-L1 to an orbit around L1.

The satellite spends its whole mission life orbiting around L1 in an irregularly shaped orbit in a plane roughly perpendicular to the line joining the Earth and the Sun.

Aditya-L1 is expected to arrive at the intended orbit at the L1 point after about 127 days, ISRO had said soon after the launch.

ISRO’s Polar Satellite Launch Vehicle (PSLV-C57) on September 2 successfully launched the Aditya-L1 spacecraft, from the Second Launch Pad of Satish Dhawan Space Centre (SDSC), Sriharikota.

After a flight duration of 63 minutes and 20 seconds that day, Aditya-L1 spacecraft was successfully injected into an elliptical orbit of 235×19500 km around the earth.

According to ISRO, a spacecraft 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.

Aditya-L1 carries seven scientific payloads indigenously developed by ISRO and national research laboratories including Indian Institute of Astrophysics (IIA), Bengaluru, and Inter University Centre for Astronomy and Astrophysics (IUCAA), Pune.

The payloads are 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 suits of Aditya L1 payloads are expected to provide the 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 particles and fields.

According to scientists, there are five Lagrangian points (or parking areas) between the Earth and the Sun where a small object tends to stay if put there. The Lagrange Points are named after Italian-French mathematician Joseph-Louis Lagrange for his prize-winning paper — “Essai sur le Problème des Trois Corps, 1772.” These points in space can be used by spacecraft to remain there with reduced At a Lagrange point, the gravitational pull of the two large bodies (the sun and the earth) equals the necessary centripetal force required for a small object to move with them.

(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)

Bengaluru:

India’s Aditya-L1 solar mission spacecraft has commenced collecting data that will help scientists analyse the behaviour of particles surrounding Earth, ISRO said on Monday.

The sensors of an instrument on board India’s first solar observatory have begun measuring supra-thermal and energetic ions and electrons at distances greater than 50,000 km from Earth, it said.

“This data helps scientists analyse the behaviour of particles surrounding Earth,” the Bengaluru-headquartered national space agency said in a post on social media platform X.

Aditya-L1 Mission:
Aditya-L1 has commenced collecting scientific data.

The sensors of the STEPS instrument have begun measuring supra-thermal and energetic ions and electrons at distances greater than 50,000 km from Earth.

This data helps scientists analyze the behaviour of… pic.twitter.com/kkLXFoy3Ri

— ISRO (@isro) September 18, 2023

The Supra Thermal & Energetic Particle Spectrometer (STEPS) instrument is a part of the Aditya Solar Wind Particle Eeperiment (ASPEX) payload.

“These STEPS measurements will persist during the cruise phase of the Aditya-L1 mission as it progresses toward the Sun-Earth L1 point. They will continue once the spacecraft is positioned in its intended orbit”, ISRO said.

Data collected around L1 would provide insights into the origin, acceleration, and anisotropy of solar wind and space weather phenomena, it said.

STEPS was developed by the Physical Research Laboratory with support from the Space Application Centre in Ahmedabad.

ISRO had launched Aditya-L1 on September 2 using a PSLV-C57 rocket.

The Aditya-L1 spacecraft carries a total of seven different payloads to study the Sun, four of which will observe the light from the Sun and the remaining three will measure in situ parameters of the plasma and magnetic fields.

Aditya-L1 will be placed in a halo orbit around the Lagrangian Point 1 (L1), which is 1.5 million km from the Earth in the direction of the Sun. It will revolve around the Sun with the same relative position and hence can see the Sun continuously.

STEPS comprises six sensors, each observing in different directions and measuring supra-thermal and energetic ions ranging from 20 keV/nucleon to 5 MeV/nucleon, in addition to electrons exceeding 1 MeV.

These measurements are conducted using low and high-energy particle spectrometers.

The data collected during Earth’s orbits helps scientists to analyse the behaviour of particles surrounding Earth, especially in the presence of the magnetic field of Earth.

STEPS was activated on September 10 at a distance greater than 50,000 km from Earth. This distance is equivalent to more than eight times the Earth’s radius, placing it well beyond Earth’s radiation belt region, ISRO added.

(This story has not been edited by NDTV staff and is auto-generated from a syndicated feed.)

he fourth Earth-bound manoeuvre of the Aditya-L1 mission has been performed successfully in the early hours of September 15.
| Photo Credit: Twitter/@isro

The fourth Earth-bound manoeuvre of the Aditya-L1 mission has been performed successfully in the early hours of September 15.

“Aditya-L1 Mission:

The fourth Earth-bound manoeuvre (EBN#4) is performed successfully.

ISRO’s ground stations at Mauritius, Bengaluru, SDSC-SHAR and Port Blair tracked the satellite during this operation, while a transportable terminal currently stationed in the Fiji islands for Aditya-L1  will support post-burn operations.The new orbit attained is 256 km x 121973  km,” ISRO posted on X (formerly Twitter). 

The next manoeuvre Trans-Lagragean Point 1 Insertion (TL1I)— a send-off from the Earth— is scheduled for September 19, 2023, around 02:00 Hrs. IST

Aditya-L1 mission pursues the enigma of space weather

After the final manoeuvre on September 19, Aditya-L1 undergoes a Trans-Lagrangian1 insertion manoeuvre, marking the beginning of its 110-day trajectory to the destination around the L1 Lagrange point. Upon arrival at the L1 point, another manoeuvre binds Aditya-L1 to an orbit around L1, a balanced gravitational location between the Earth and the Sun. The satellite spends its whole mission life orbiting around L1 in an irregularly shaped orbit in a plane roughly perpendicular to the line joining the Earth and the Sun.

The Aditya-L1, India’s first solar observatory mission was been successfully launched by the Indian Space Research Organisation (ISRO) on September 2 from the Satish Dhawan Space Centre in Sriharikota.

Bengaluru:

Aditya L1 spacecraft, India’s first space-based mission to study the Sun, during the early hours on Friday, underwent the fourth earth-bound manoeuvre successfully, ISRO said.

“The fourth Earth-bound manoeuvre (EBN#4) is performed successfully. ISRO’s ground stations at Mauritius, Bengaluru, SDSC-SHAR and Port Blair tracked the satellite during this operation, while a transportable terminal currently stationed in the Fiji islands for Aditya-L1 will support post-burn operations,” the space agency said in a post on X, a platform formerly known as Twitter.

The new orbit attained is 256 km x 121973 km, it said: “The next manoeuvre Trans-Lagragean Point 1 Insertion (TL1I) — a send-off from the Earth — is scheduled for September 19, around 02:00 Hrs. IST.” Aditya-L1 is the first Indian space-based observatory to study the Sun from a halo orbit around the first Sun-Earth Lagrangian point (L1), which is located roughly 1.5 million km from the Earth.

The first, second and third earth-bound manoeuvre was successfully performed on September 3, 5 and 10 respectively.

The manoeuvres are being performed during the spacecraft’s 16-day journey around the Earth during which the spacecraft will gain the necessary velocity for its further journey to L1.

With the completion of four earth-bound orbital manoeuvres, Aditya-L1 will next undergo a Trans-Lagrangian1 insertion manoeuvre, marking the beginning of its nearly 110-day trajectory to the destination around the L1 Lagrange point.

Upon arrival at the L1 point, another manoeuvre binds Aditya L1 to an orbit around L1, a balanced gravitational location between the Earth and the Sun.

The satellite spends its whole mission life orbiting around L1 in an irregularly shaped orbit in a plane roughly perpendicular to the line joining the Earth and the Sun.

ISRO’s Polar Satellite Launch Vehicle (PSLV-C57) on September 2 successfully launched the Aditya-L1 spacecraft from the Second Launch Pad of Satish Dhawan Space Centre (SDSC), Sriharikota.

After a flight duration of 63 minutes and 20 seconds that day, the Aditya-L1 spacecraft was successfully injected into an elliptical orbit of 235×19500 km around the Earth.

Aditya-L1 Mission:
The fourth Earth-bound maneuvre (EBN#4) is performed successfully.

ISRO’s ground stations at Mauritius, Bengaluru, SDSC-SHAR and Port Blair tracked the satellite during this operation, while a transportable terminal currently stationed in the Fiji islands for… pic.twitter.com/cPfsF5GIk5

— ISRO (@isro) September 14, 2023

According to ISRO, a spacecraft 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.

Aditya-L1 carries seven scientific payloads indigenously developed by ISRO and national research laboratories, including the Indian Institute of Astrophysics (IIA) in Bengaluru and the Inter-University Centre for Astronomy and Astrophysics (IUCAA) in Pune.

The payloads are to observe the photosphere, chromosphere and the outermost layers of the Sun (the corona) using electromagnetic 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 suits of Aditya L1 payloads are expected to provide the 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, and propagation of particles and fields.

According to scientists, there are five Lagrangian points (or parking areas) between the Earth and the Sun where a small object tends to stay if put there. The Lagrange Points are named after Italian-French mathematician Joseph-Louis Lagrange for his prize-winning paper — “Essai sur le Probleme des Trois Corps, 1772.” These points in space can be used by spacecraft to remain there with reduced fuel consumption.

At a Lagrange point, the gravitational pull of the two large bodies (the Sun and the Earth) equals the necessary centripetal force required for a small object to move with them.

(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)

On a cold winter night on March 13, 1989, the power grid in Quebec, Canada, went down without a warning, plunging the province into darkness. The underground metro railway in the city of Montreal came to a grinding halt and airport operations were disrupted. Down south in the neighbouring United States, nights lit up in beautiful bright aurorae as far south as Texas, which is not used to seeing such spectacles. Several sensors on the space shuttle Discovery started misbehaving. The broadcast of Radio Free Europe over Russia fell silent, giving rise to fears of jammed communications.

More than three decades later, in the first week of February 2022, almost an entire batch of newly launched SpaceX Starlink communication satellites fell out of their orbit unexpectedly, as if sunk by a storm.

Despite the variety of events across continents, all of them have a common cause: bad space weather.

Sun, meet Aditya

On September 2 this year, the Indian Space Research Organisation (ISRO) launched the Aditya-L1 satellite, its first space mission to explore the activities of the sun. After swinging by the earth a few times in increasingly distant orbits, the spacecraft will be boosted towards Lagrange point L1 – a strategic location in space about 1.5 million km from the earth. From here, a spacecraft can continuously observe the sun and monitor the changing local environment, or space weather, just before the earth experiences it – giving us critical tens of minutes of advance warning.

The sun is a massive ball of fiery plasma. Energy is generated by nuclear fusion at its core, where temperatures are as high as 15 million degrees Celsius and the density more than 20-times that of iron. From the centre to the surface of the sun, the temperature drops and energy flows outwards. Inside the sun, the temperature is high enough that atoms are broken up into negatively charged electrons and positively charged ions – the state of matter called plasma. Below the sun’s surface lies the convection zone, where heated plasma rises and radiates its energy as sunlight upon reaching the surface. The light from the sun that reaches us sustains life and drives atmospheric processes that govern the earth’s climate.

After the solar plasma radiates its energy away from the surface, it cools and sinks back down, much like cyclonic convection in the earth’s atmosphere. This twisting, churning motion of plasma within the sun creates vast electric currents and, as a by-product, powerful magnetic fields. This process, known as the solar dynamo, generates dark, earth-sized blotches on the sun’s surface known as sunspots, and magnetic loops that rise up like giant arches threading the star’s outer atmosphere, the corona.

A storm in space

While the sun’s visible surface, or photosphere, is only about 6,000 degrees Celsius hot, the temperature in the sun’s corona rises to a million degrees. How does it get so hot – in apparent contradiction to the laws of thermodynamics, which state that heat energy can only flow from a region of higher to lower temperature?

We know that other novel processes, such as waves rippling along those giant coronal magnetic loops, superhot plasma jets rising from the surface to coronal layers, and a process known as magnetic reconnection, are at the heart of coronal heating. The hot magnetic corona of the sun is also responsible for the supersonic outflow of plasma wind that bathes all planets in the solar system and forms the background space weather. Sometimes that environment can be violently disturbed.

The legs of the magnetic loops in the solar corona are being constantly jostled around by turbulent plasma flows beneath the surface, where they are rooted. These loops, energised by the serpentine motion of the plasma, sustain huge electric currents, and sometimes, in the course of their frenzied dance, they cross each other’s path. When the conditions are right, this results in a magnetic reconnection event that destroys the loops. The magnetic energy they shed is harnessed to create the most violent events we witness in our star: a solar flare, with an energy yield that can surpass a 100 billion nuclear bombs.

The energy released in such a solar storm heats the solar atmosphere even further, generating intense X-ray radiation and accelerating charged particles to a nontrivial fraction of the speed of light. The most energetic events can hurl magnetised coronal plasma material into outer space at speeds exceeding a few million kilometres an hour, giving rise to a coronal mass ejection – a space storm that, when directed at the earth, severely perturbs our own space environment.

A new infrastructure dependence

Severe space weather can give rise to geomagnetic storms that create beautiful aurorae on the one hand and cause power-grid failures in high-latitude regions, disrupt communications and GPS navigational networks, affect air-traffic over polar routes, and jam radar signals on the other. They can fry sensitive electronics of satellites and sometimes precipitate catastrophic orbital decays, as in the loss of the Starlink satellites in 2022.

With our increasing dependence on space-based infrastructure, a catastrophic solar storm could result in a trillion-dollar adverse economic impact. Yet we don’t yet have the means to accurately forecast severe space weather.

ISRO’s Aditya-L1 mission will explore how magnetic fields result in variations in the sun’s ultraviolet radiation, which plays a critical role in governing the earth’s atmosphere and climate dynamics. It will observe the flow of energy in the sun’s outer atmosphere to test competing theories for the heating of the sun’s corona. By analysing X-ray radiation, it will seek to understand how violent solar storms are born. Aditya-L1 will also track the early motion of magnetic storms near the sun and monitor the local space environment in its vicinity at Lagrange point L1, the environment that eventually affects the earth.

A national collaboration

Aditya-L1 was originally envisaged as a mission of purely fundamental scientific enquiry. In 2020, ISRO constituted a committee to explore how mission data could be used to extract relevant information for space-weather monitoring and predictions. I chaired that committee; it drafted a set of specific recommendations on onboard intelligence for space weather alerts and supporting data analytics and computational modelling initiatives to create value-added space weather knowledge.

More than 60 scientists from about 20 academic organisations participated in that exercise, and many more scientists, engineers, and students contributed to the mission – exemplifying the national collaborative effort that produced Aditya-L1.

If the mission succeeds, it will be a resounding vindication of India’s investment in space science research, which can on the one hand spur fundamental enquiry of our cosmos and on the other generate knowledge of strong societal relevance. Today, we wake up to the weather forecast. The day is not far when we will wake up to space weather forecasts. Not since our first sounding rocket screamed over a remote beach in Thumba have the people of India been so excited about space.

Dr. Dibyendu Nandi is professor of physics and head of the Centre of Excellence in Space Sciences India at IISER Kolkata. He specialises in understanding and predicting space weather.