EOS-8 seen onboard third and final developmental flight SSLV-D3-EOS-08 at  at Sriharikota, Andhra Pradesh
| Photo Credit: PTI

The Indian Space Research Organisation on Friday (August 16, 2024) successfully launched an earth observation satellite, onboard the third and final development flight of Small Satellite Launch Vehicle-03 from the the first launch pad at Satish Dhawan Space Centre in Sriharikota

The SSLV-D3-EOS-08 mission follows the second successful launch of the second test flight of the Small Satellite Launch Vehicle (SSLV-D2-EOS-07) in February 2023.

Today’s mission is the third for the Bengaluru-headquartered space agency in 2024, after the successful PSLV-C58/XpoSat in January and GSLV-F14/INSAT-3DS missions in February.

The smallest SSLV rocket, which measures about 34 metre in height, was planned to be launched on August 15 at 9.17 am and was later rescheduled to August 16, at 9.19 am from the first launch pad at Satish Dhawan Space Centre here.

The primary objectives of the SSLV-D3-EOS-08 mission include designing and developing a microsatellite, creating payload instruments compatible with the microsatellite bus, and incorporating new technologies required for future operational satellites, ISRO said.

With today’s (August 16, 2024) mission, ISRO completes the developmental flight of the smallest rocket which can carry satellites weighing up to 500 kg and can place them into Low Earth Orbit (of up to 500 km above Earth).

The mission would also give a boost to NewSpace India Ltd, the commercial arm of ISRO to take up commercial launches using such Small Satellite Launch Vehicles with the industry.

Built on the Microsat/IMS-1 bus, the Earth Observation Satellite carries three payloads: Electro Optical Infrared Payload (EOIR), Global Navigation Satellite System-Reflectometry payload (GNSS-R), and SiC UV Dosimeter.

The spacecraft has a mission life of one year. It has a mass of approximately 175.5 kg and generates power of around 420 W. The satellite interfaces with the SSLV-D3/IBL-358 launch vehicle, ISRO said.

The first payload EOIR is designed to capture images in the Mid-Wave IR (MIR) and Long-Wave IR (LWIR) bands, both during the day and night, for applications such as satellite-based surveillance, disaster monitoring, environmental monitoring, fire detection, volcanic activity observation, and industrial and power plant disaster monitoring.

The second GNSS-R payload demonstrates the capability of using GNSS-R-based remote sensing for applications such as ocean surface wind analysis, soil moisture assessment, cryosphere studies over the Himalayan region, flood detection, and inland waterbody detection.

The third payload — SiC UV Dosimeter monitors UV irradiance at the viewport of the Crew Module in the Gaganyaan Mission and serves as a high-dose alarm sensor for gamma radiation.

(With PTI input)

Agnikul Cosmos successfully test launches the Agnibaan rocket powered by the world’s first single-piece 3D printed semi-cryogenic engine from the Satish Dhawan Space Centre (SDSC) SHAR, in Sriharikota.
| Photo Credit: ANI

After the successful test-flight of Agnibaan SOrTeD, Chennai-based space start-up Agnikul Cosmos is hoping to start launching satellites early next year.

In an interview with PTI, Agnikul co-founder and Chief Executive Officer Srinath Ravichandran said the 3D-printed semi-cryogenic engines and the rocket will offer quick turnaround for customers who will be able to have customised launch vehicles for their satellites.

“Nine to 12 months I would say. Probably by the end of this financial year or the early part of the next financial year is what we are targeting,” Mr. Ravichandran said when asked about the commercial orbital launch of the Agnibaan rocket.

The first test flight of Agnibaan SOrTeD (suborbital technology demonstrator) on May 30, which lasted for 66 seconds, came after four unsuccessful attempts.

“It was a big sense of relief. I think we got a lot of learning in differentiating between building a vehicle and launching a vehicle,” said Mr. Ravichandran, whose idea to use 3D printing technology to build engines and rockets led to Agnikul Cosmos, a space sector start-up incubated at the IIT Madras Research Park in 2017.

The other co-founders were Moin SPM, an operations specialist and Satyanarayanan Chakravarthy, a professor at IIT Madras and Head of the National Centre for Combustion Research and Development.

Women engineers Saraniya Periaswamy, the Vehicle Director for Agnibaan SOrTeD and Umamaheswari. K, the Project Director of the first Mission played a key role in the test flight.

Agnibaan SOrTeD was a vertical ascent flight unlike sounding rockets that are launched using guiding rails placed at a particular angle.

“Seven seconds after lift-off we checked the health of the vehicle and that is when the auto-pilot kicked in. Little bit into the flight, it started moving over the ocean and performed the pitch-over manoeuvre and then continued on its planned trajectory,” Ravichandran said, sharing details of Agnibaan SOrTeD’s maiden flight.

“Once it reached about 60 seconds or so, we entered the wind biasing manoeuvre, where we solve the wind speed and actually fly into the wind so there is not much wind load on the vehicle,” he said.

After the wind-biasing manoeuvre, the rocket continued to fly till burnout and dropped back into the ocean.

“There was continuous radar tracking of the vehicle. All the devices and instruments enabling that also worked really well,” Mr. Ravichandran said.

The next steps for Agnikul is to master the technology of firing multiple engines together and carry out tests for stage separation.

“We will have to figure out two things. Our orbital rocket has multiple engines fired together. So, that will have to be tested out on the ground. And the stage separation. SOrTeD was a single stage vehicle. The orbital vehicle will have two stages. So stage separation has to be tested,” Mr. Ravichandran said.

“We are already in the middle of building rigs at our facility. We will take six-seven months to get that and from there we will be able to target the orbital mission in the next three months,” he said.

According to Mr. Ravichandran, the demand for small satellites was high with as many as 30-35 tonnes of payloads put in low earth orbits every year.

He said small satellites have a low life-span and the same need to be replenished for continued earth-imaging or communications applications.

The Agnibaan launch vehicle is designed to be compatible with the mobile launchpad called Dhanush and can be configured to accommodate payloads ranging from 30 kg to 300 kg, ensuring versatility across a wide range of mission requirements.

Agnikul Cosmos successfully test launches the Agnibaan rocket powered by the world’s first single-piece 3D printed semi-cryogenic engine from the Satish Dhawan Space Centre (SDSC) SHAR, in Sriharikota.
| Photo Credit: ANI

After the successful test-flight of Agnibaan SOrTeD, Chennai-based space start-up Agnikul Cosmos is hoping to start launching satellites early next year.

In an interview with PTI, Agnikul co-founder and Chief Executive Officer Srinath Ravichandran said the 3D-printed semi-cryogenic engines and the rocket will offer quick turnaround for customers who will be able to have customised launch vehicles for their satellites.

“Nine to 12 months I would say. Probably by the end of this financial year or the early part of the next financial year is what we are targeting,” Mr. Ravichandran said when asked about the commercial orbital launch of the Agnibaan rocket.

The first test flight of Agnibaan SOrTeD (suborbital technology demonstrator) on May 30, which lasted for 66 seconds, came after four unsuccessful attempts.

“It was a big sense of relief. I think we got a lot of learning in differentiating between building a vehicle and launching a vehicle,” said Mr. Ravichandran, whose idea to use 3D printing technology to build engines and rockets led to Agnikul Cosmos, a space sector start-up incubated at the IIT Madras Research Park in 2017.

The other co-founders were Moin SPM, an operations specialist and Satyanarayanan Chakravarthy, a professor at IIT Madras and Head of the National Centre for Combustion Research and Development.

Women engineers Saraniya Periaswamy, the Vehicle Director for Agnibaan SOrTeD and Umamaheswari. K, the Project Director of the first Mission played a key role in the test flight.

Agnibaan SOrTeD was a vertical ascent flight unlike sounding rockets that are launched using guiding rails placed at a particular angle.

“Seven seconds after lift-off we checked the health of the vehicle and that is when the auto-pilot kicked in. Little bit into the flight, it started moving over the ocean and performed the pitch-over manoeuvre and then continued on its planned trajectory,” Ravichandran said, sharing details of Agnibaan SOrTeD’s maiden flight.

“Once it reached about 60 seconds or so, we entered the wind biasing manoeuvre, where we solve the wind speed and actually fly into the wind so there is not much wind load on the vehicle,” he said.

After the wind-biasing manoeuvre, the rocket continued to fly till burnout and dropped back into the ocean.

“There was continuous radar tracking of the vehicle. All the devices and instruments enabling that also worked really well,” Mr. Ravichandran said.

The next steps for Agnikul is to master the technology of firing multiple engines together and carry out tests for stage separation.

“We will have to figure out two things. Our orbital rocket has multiple engines fired together. So, that will have to be tested out on the ground. And the stage separation. SOrTeD was a single stage vehicle. The orbital vehicle will have two stages. So stage separation has to be tested,” Mr. Ravichandran said.

“We are already in the middle of building rigs at our facility. We will take six-seven months to get that and from there we will be able to target the orbital mission in the next three months,” he said.

According to Mr. Ravichandran, the demand for small satellites was high with as many as 30-35 tonnes of payloads put in low earth orbits every year.

He said small satellites have a low life-span and the same need to be replenished for continued earth-imaging or communications applications.

The Agnibaan launch vehicle is designed to be compatible with the mobile launchpad called Dhanush and can be configured to accommodate payloads ranging from 30 kg to 300 kg, ensuring versatility across a wide range of mission requirements.

S. Somanath, Chairman, Indian Space Research Organisation (ISRO).
| Photo Credit: K. Murali Kumar K

ISRO will conduct three more test vehicle missions under the ambitious Gaganyaan programme after the maiden TV-D1 test flight, which is scheduled on October 21, the space agency’s chairman S. Somanath said on October 14.

The Gaganyaan project envisages a demonstration of the human spaceflight capability by launching a human crew to an orbit of 400 km and bringing them safely back to earth by landing in Indian sea waters.

The test vehicle development flight (TV-D1) will be conducted at the Satish Dhawan Space Centre in Sriharikota in Andhra Pradesh to test the crew module that is scheduled to house Indian astronauts during the human spaceflight late next year.

“The first test vehicle flight (of the Gaganyaan mission) will be conducted on October 21. After that we have planned for three more test missions, D2, D3, D4. We will hold thorough tests during the test flight sequence,” Mr. Somanath, who is also the secretary, Department of Space, told reporters in Madurai. He was here to participate in a couple of events in Rameswaram.

Also read | ISRO to conduct first test flight of Gaganyaan mission on October 21

TV-D1 involves launching the crew module to outer space, bringing it back to earth and recovering it after touchdown in the Bay of Bengal.

Recently, the Union Science and Technology Minister Jitendra Singh said the Bengaluru-headquartered space agency would carry out the first of several test flights ahead of the Gaganyaan maiden mission on October 21 at Sriharikota.

To a query about the Aditya-L1 programme, the maiden solar mission undertaken by ISRO, Mr. Somanath expressed hope that the spacecraft will reach the Lagrange point (L1) in the middle of January 2024.

“We will insert it in the L1 point and undertake various scientific experiments from that point,” he said.

Last week, ISRO scientists performed a trajectory correction manoeuvre on the Aditya L1 spacecraft. The spacecraft was launched by a PSLV-C57 rocket on September 2.

On the setting up of another launch pad in Kulasekarapattinam in Tuticorin district, he said ISRO would be able to avail several benefits from that launch pad as it would be useful for launching smaller rockets and to serve private players.

“…right now bigger rockets like PSLV need to take a turn towards the southward direction above Sri Lanka since the launch pad is in the east (in Sriharikota). Whereas in Kulasekarapattinam, we don’t need to make rockets to make that turn as they will be already facing southward,” he said.

“Smaller Satellite Launch Vehicles and private players will be able to use that launch pad (in Kulasekarapattinam). Right now, the land is in the acquisition stage. It will take two years for completion,” Mr. Somanath said.

Preparations are on for the Gaganyaan Mission’s Flight Test Vehicle Abort Mission-1 (TV-D1), which is likely to be launched by the end of October 2023.
| Photo Credit: Special arrangement

The Indian Space Research Organisation (ISRO), which is planning to commence uncrewed flight tests for the Gaganyaan mission, has started to make preparations for the Flight Test Vehicle Abort Mission-1 (TV-D1).

“Mission Gaganyaan: ISRO to commence unmanned flight tests for the Gaganyaan mission. Preparations for the Flight Test Vehicle Abort Mission-1 (TV-D1), which demonstrates the performance of the Crew Escape System, are under way,” the space agency posted on X (formerly Twitter).

Though the space agency has not announced the date for the TV-D1, it is expected to take place by the end of October 2023 from the Satish Dhawan Space Centre in Sriharikota (SDSC-SHAR).

According to ISRO, the Crew Module (CM) is where the astronauts are contained in a pressurised earthlike atmospheric condition during the Gaganyaan mission.

“The CM for the Gaganyaan mission is in different stages of development. For the TV-D1, the CM is an unpressurised version that has completed its integration and testing and is ready to be shipped to the launch complex. This unpressurised CM version has to have an overall size and mass of actual Gaganyaan CM. It houses all the systems for the deceleration and recovery. With its complete set of parachutes, recovery aids, actuation systems and pyros. The avionics systems in CM are in a dual redundant mode configuration for navigation, sequencing, telemetry, instrumentation and power. The CM in this mission is extensively instrumented to capture the flight data for evaluation of the performance of various systems. The CM will be recovered after touchdown in the Bay of Bengal, using a dedicated vessel and diving team from the Indian Navy,” ISRO said. It added that the TV-D1 is in the final stages of preparation.

“The Test Vehicle is a single-stage liquid rocket developed for this abort mission. The payloads consist of the CM and Crew Escape Systems (CES) with their fast-acting solid motors, along with CM fairing (CMF) and Interface Adapters. This flight will simulate the abort condition during the ascent trajectory corresponding to a Mach number of 1.2 encountered in the Gaganyaan mission. CES with CM will be separated from the Test Vehicle at an altitude of about 17 km. Subsequently, the abort sequence will be executed autonomously commencing with the separation of CES and deployment of the series of parachutes, finally culminating in the safe touchdown of CM in the sea, about 10 km from the coast of Sriharikota,” it added.

The CM after integration underwent various electrical testing, at ISRO’s facility in Bengaluru, including an acoustic test and was dispatched to SDSC-SHAR on August 13. At SDSC, it will undergo vibration tests and pre-integration with the CES, before final integration to the Test Vehicle at the Launch Pad. This Test Vehicle mission with this CM is a significant milestone for the overall Gaganyaan programmes a near-complete system is integrated for a flight test. The success of this test flight will set the stage for the remaining qualification tests and unmanned missions, leading to the first Gaganyaan mission with Indian Astronauts.

The Gaganyaan mission aims to demonstrate the capability to launch human beings (three crew members) to low earth orbit and bring them back safely to earth by landing them in either the Bay of Bengal or the Arabian Sea.

For the Gaganyaan mission, four astronauts who have been selected are undergoing crew training and Gaganyaan Mission-specific training at the Astronaut Training Facility in Bengaluru.

Group Director of ISRO at Satish Dhawan Space Centre G. Appanna and Raghu Group of Educational Institution chairman K. Raghu releasing a poster for World Space Week programme, in Visakhapatnam on Wednesday.
| Photo Credit: K.R. DEEPAK

With the success of the Chandrayaan-3 mission, the scientists at the Indian Space Research Organisation (ISRO) are geared up for its next programmes such as Gaganyaan and Shukrayaan, said Group Director of ISRO at Satish Dhawan Space Centre, G. Appanna.

Addressing the media, along with Raghu Group of Institutions chairman K. Raghu, here on October 4 (Wednesday), he announced the launch of the four-day World Space Week at Raghu Engineering College, Dakamarri. The four-day celebration will begin on October 5 (Thursday) and end on October 8 (Sunday).

The celebration coincides with the launch of Sputnik on October 4, 1957, and the signing of the treaty on October 10, 1967, between nations to use outer space for peaceful exploration, he said.

IT Minister Gudivada Amarnath will inaugurate the programme while Y. Sreenivasa Rao, Director General, Naval System and Materials, DRDO, will deliver the valedictory address.

Around 20 scientists from ISRO will take part in the celebrations. They will deliver lectures, conduct symposiums and organise paintings, poster making and quiz competitions for school and college students.

“About 3,000 students are expected to visit the REC campus daily. We are setting up a huge exhibition corner, showcasing rocket and satellite prototypes, right from the first one to the latest,” said Mr. Appanna.

Such shows are being conducted in four centres in Andhra Pradesh, apart from Visakhapatnam. Such programmes are being held in various colleges in Kurnool, Rajamahendravaram and Sriharikota.

Mr. Raghu said that food would be provided to all students visiting the college on all the four days.

Speaking about the success of Chandrayaan-3, Mr. Appana said that the mission was highly critical and every step had to be monitored. “The mission has been accomplished. We conducted a hopping test and this has given us the idea that we have to manufacture a module that can land and lift off, once the mission is accomplished. The spectrometer has found many minerals on the surface of the moon. Primarily, there is abundant sulphur, which can be used as refuelling material for the modules that land on the moon,” Mr. Appanna said.

He said that the Gaganyaan mission is progressing well and India will soon have a flight to carry astronauts. “We will be testing the recovery vehicle shortly,” he said.

He also said that the World Space Week programme is being organised to encourage young minds to undertake space study and become entrepreneurs in this field. Startups are welcome to chip in with their ideas and products, said Mr. Appanna.

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.

For launching its Aditya-L1 mission on September 2, the Indian Space Research Organisation (ISRO) will be using a variant of the Polar Satellite Launch Vehicle (PSLV) which also launched India’s first missions to the moon and Mars.

With the PSLV-C57/Aditya-L1 mission, India’s first solar mission, the PSLV-XL variant will mark its 25th flight.

Read more here

Preparations in the final phase for the launch of PSLV-C57/Aditya-L1 Mission.
| Photo Credit: PTI

The countdown for the launch of India’s first solar observatory mission, Aditya-L1 has commenced at the Satish Dhawan Space Centre in Sriharikota.

“The countdown leading to the launch at 11:50 Hrs. IST on September 2, 2023 has commended,” ISRO posted on X (formerly Twitter).

The Aditya-L1 spacecraft is scheduled to be launched by the Polar Satellite Launch Vehicle (PSLV) on September 2, 2023, at 11:50 a.m. from Sriharikota.

This is the 59th flight of the PSLV and the 25th mission using the PSLV-XL configuration.

The PSLV will launch Aditya-L1 spacecraft in a highly eccentric Earth bound orbit.

According to ISRO 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 propagatory effect of solar dynamics in the interplanetary medium,” states the Aditya L1 mission profile.

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 etc.

The seven payloads onboard the satellite is Visible Emission Line Coronagraph(VELC), Solar Ultraviolet Imaging Telescope (SUIT), Solar Low Energy X-ray Spectrometer (SoLEXS), High Energy L1 Orbiting X-ray Spectrometer(HEL1OS), Aditya Solar wind Particle Experiment(ASPEX), Plasma Analyser Package For Aditya (PAPA) and Advanced Tri-axial High Resolution Digital Magnetometers.

The launch of Aditya-L1 comes days after the space agency created history making India only the fourth country to successfully land on the moon and first to land near the lunar south pole.

Aditya L1 onboard the PSLV-C57 the Satish Dhawan Space Centre in Sriharikota on September 1, 2023 on the eve of its launch. Photo: X/@ISRO via PTI

India’s first solar observatory mission, named Aditya-L1, will be launched onboard the Polar Satellite Launch Vehicle (PSLV) from the Satish Dhawan Space Centre in Sriharikota at 11.50 am on Saturday.

On Friday, the Indian Space Research Organisation (ISRO) commenced the 23-hour 40-minute countdown for the launch of the Aditya-L1 mission.

Approximately sixty-three minutes after liftoff, the satellite separation is expected to take place as the PSLV will launch the Aditya-L1 spacecraft into a highly eccentric earth-bound orbit at around 12.53 pm.

This PSLV-C57/Aditya-L1 mission can be counted as one of the longest missions involving ISRO’s workhorse launch vehicle. However, the longest of the PSLV missions is still the 2016 PSLV-C35 mission which was completed two hours, 15 minutes and 33 seconds after lift-off.

Long journey

Following the launch, Aditya-L1 will stay in earth-bound orbits for 16 days, during which it will undergo five manoeuvres to gain the necessary velocity for its journey.

“Subsequently, 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,” ISRO said.

Aditya-L1 will stay approximately 1.5 million km away from the earth, directed towards the sun; this is about 1% of the distance between the earth and the sun.

Studying the solar corona

The Aditya L-1 payloads are expected to provide 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 etc.

The seven payloads onboard the satellite are: Visible Emission Line Coronagraph (VELC), Solar Ultraviolet Imaging Telescope (SUIT), Solar Low Energy X-ray Spectrometer (SoLEXS), High Energy L1 Orbiting x-ray Spectrometer (HEL1OS), Aditya Solar wind Particle Experiment (ASPEX), Plasma Analyser Package for Aditya (PAPA), and Advanced Tri-axial High Resolution Digital Magnetometers.

The primary payload is VELC, which was developed by the Indian Institute of Astrophysics (IIA), Bengaluru and is designed to study the solar corona and the dynamics of coronal mass ejections.

The Aditya-L1 satellite placed in the halo orbit around the L1 point has a major advantage of continuously viewing the sun without any occultation or eclipse. It is expected to provide a greater advantage in observing the solar activities continuously.

Tracking solar quakes

“There are certain activities which take place around the sun which we call solar quakes. In the aftermath of these solar quakes, a lot of energetic material from the sun is thrown out. Some of them can be directed towards the earth and they can travel at a maximum speed of 3,000 km per hour and reach the near-earth space within 15 hours,” Ramesh R., the principal investigator of the VELC payload, told The Hindu.

Prof. Ramesh added that once the energetic material reaches the earth, it may not cause any physical damage, but it does have the capability to cripple life on earth.

“Our present-day life scenario depends very much on the stationary satellites which are parked in space be it for our internet connectivity, cell phone or TV connectivity. These charged particle clouds can engulf the satellites and damage all the electronics on board the satellites. Hence, we do not know when the solar quakes will happen, it can happen any time of the day so it is very essential to observe the sun on a 24-hour basis and carry out observations,” Prof. Ramesh added.