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.

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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.

A memorable black-and-white photograph from the early days of the Indian space programme shows the nose cone of a small rocket being taken to the launchpad on the carrier rack of a bicycle. It’s an incongruous sight. All around the bicycle is the dusty, palm-bedecked rural India of the 1960s. Cut to 2023, and the image of a jubilant S. Somanath, Chairman, Indian Space Research Organisation (ISRO), declaring, “We have achieved soft-landing on the moon. India is on the moon.”

In the slow yet eventful decades separating the two images, the space programme evolved from what many perceived as the frivolous aspirations of an upstart, poverty-stricken third-world country to a sparkling example of scientific excellence that Indians can look up to. Truth is, the ISRO had made it to the elite space club much before the Chandrayaan-3 mission’s ‘Vikram’ lander touched down on the lunar south pole on August 23. The space agency has proved its capabilities time and again by placing satellites in precise orbits on modest budgets and embarking upon highly publicised missions to the moon (in 2008 and 2019) and Mars (in 2014).

In 2017, the ISRO turned up the heat on the space race by launching 104 satellites in one go on the 39th flight of its trusted Polar Satellite Launch Vehicle (PSLV). But beyond such immediately visible, high-profile achievements are the countless ways in which the ISRO and its home-grown technologies have touched the lives of the common people; be it weather forecasts, telemedicine, navigation or tele-education. It is this connect with the grassroots that has made ISRO a household name.

Second to none

Vikram Sarabhai, the driving spirit behind India’s space ambitions, was keen for India to be “second to none in the application of advanced technologies to the real problems of man and society which we find in our country.” To him, the application of sophisticated technologies and methods of analysis “to our problems is not to be confused with embarking on grandiose schemes whose primary impact is for show rather than for progress measured in hard economic and social terms.” This is perhaps why it did not surprise anyone when the Vikram Sarabhai Space Centre (VSSC), ISRO’s lead facility responsible for launch vehicles, including the hefty LVM3 which put Chandrayaan-3 in orbit last July, turned its skills to developing mechanical ventilators in the bleak days of the COVID-19 pandemic. But then, the beginnings of ISRO too were modest; on land relinquished by the fishing community and a local church in a little-known coastal village in Kerala’s Thiruvananthapuram.

“A historic landmark in the entire process of land acquisition was the singular act of grace on the part of the Christian community at Thumba and the bishop of Thiruvananthapuram Rt Rev. Dr. Peter Bernard Pereira, in 1962. The venerated place of worship (the St. Mary Magdalene Church, now a popular space museum) was graciously laid at the altar of science,’’ the book A Brief History of Rocketry in ISRO, by P. V. Manoranjan Rao and P. Radhakrishnan, veterans of the space agency, notes. On November 21 this year, it will be 60 years since the first sounding rocket, an American-made Nike-Apache, lifted off from Thumba. Five years after that event, Prime Minister Indira Gandhi, in 1968, dedicated the Thumba Equatorial Rocket Launching Station (TERLS) to the UN.

Over the years, the space agency has had its ups and downs. The occasional mission setbacks aside, the ISRO was rocked by the spy scandal in the early 1990s and the Antrix-Devas case later on. Nevertheless, the agency has always displayed an ability to bounce back stronger. Today, the ISRO, with its many facilities spread over the country, has a pride of place among India’s government establishments. In the midst of institutions bogged down by laidback attitudes to work and bureaucratic lethargy, it is seen as one of the rare ones that can ‘’deliver.’’

By indigenously developing technologies like the cryogenic rocket engine and the Indian Regional Navigation Satellite System (IRNSS – NavIC), often in the face of sanctions, it has demonstrated to the country’s larger scientific community that such things are not the exclusive, impregnable domains of the West alone.

Perhaps, this is ISRO’s greatest contribution to the country’s scientific community; a ‘work culture’, epitomised by an unwavering commitment to excellence and teamwork that can be traced back to the days of Sarabhai, Satish Dhawan and A.P.J. Abdul Kalam.

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