Chandrayaan-3 is all about doing more with less. When a country has limited capabilities but dreams big, it has to be smart to use the love and gravity of Mother Earth to go all the way to the moon.
Chandrayaan-3 is a three-in-one satellite launched by India’s most reliable and trustworthy launcher, Launch Vehicle Mark-3 (LVM-3), a humongous but elegant rocket that weighs 642 tonnes, or the equivalent of 130 full-grown Asian elephants. At 43.5m, it is roughly half as tall as the Qutb Minar. The Chandrayaan-3 launch on July 14 was the homegrown rocket’s seventh consecutive successful flight.
LVM-3 may be a bahubali, but it still lacked the punch to send the 3,921kg Chandrayaan-3 satellite on a direct flight to the moon. ISRO engineers devised a way to overcome this big problem―use the earth’s gravity to slingshot Chandrayaan-3 to the moon. Using the spacecraft’s propulsion module, the scientists gradually kept raising its orbit and velocity. On August 1, Chandrayaan-3 attained enough ‘escape velocity’ to leave Mother Earth’s loving hold and go on its solitary journey of 3.84 lakh kilometres to the moon. The marathon was completed and the satellite entered the moon’s orbit on August 5.
“This was a very, very tricky operation requiring great precision, since the approach velocity had to be just right,” said S. Somanath, ISRO chairman. “If it were too fast, the satellite would have bounced off and become a flyby mission. If it were too slow, it could have been pulled in and crash-landed on the lunar surface. The optimal velocity ensured that Chandrayaan-3 was pulled into orbit and began its dance around the moon.”
Velocity was reduced, and the satellite gradually stabilised in orbit. On August 17, the propulsion module and the Vikram lander, which had the Pragyan rover tucked in its womb, separated.
Countdown to success: The Chandrayaan-3 mission operations team in Bengaluru monitoring landing preparations on August 23 | PTI
Vikram’s target was to land near the south pole of the moon, an area that many now call ‘Chandra Gangotri’, since it was here that Chandrayaan-1 first discovered water molecules on the moon. Till the historic discovery was made, moon was thought to have a desert-like parched surface.
Vikram landed in a 4x2.5km strip, which I call ‘Kalam Vihar’. It was former president A.P.J. Abdul Kalam who nudged ISRO to land India’s flag near the south pole using a moon impact probe, which landed in the same strip in 2008. There is already talk that the spot should be named ‘India Point’.
Prof Annapurni Subramaniam, director, Indian Institute of Astrophysics, Bengaluru, said, “There is a lunar gold rush at the moon’s south pole”, and that Russia, the US, India and China want to explore the unexplored region as it is supposed to harbour what could be life-giving water.
It took nearly four years for ISRO to build Chandrayaan-3 satellite at the U.R. Rao Satellite Centre in Bengaluru. While the satellite is designed and made in India, most of the electronics aboard it are imported, as India does not make space-grade electronic components.
The 2,145kg propulsion module has an instrument that can view earth from the lunar orbit, looking for spectroscopic signatures of life. These signatures can then be matched with similar spectroscopic signs gathered from planets outside the solar system. This is a long shot at finding extraterrestrial life, but still scientifically useful.
The 1,745kg Vikram lander is named after Vikram Sarabhai, the father of the Indian space programme. In Chandrayaan-2, the failure of the guidance algorithm had caused the Vikram lander to crash-land on the lunar surface on September 6, 2019. In the past four years, the lander was made more robust, its legs strengthened, and the algorithm perfected with hundreds of tests. “The design philosophy for the Vikram lander in Chandrayaan-3 was that even if everything fails, it should still be able to land on the lunar surface,” said Somanath.
Vikram carries three scientific instruments that will look for moonquakes and variations in plasma ion distribution, and decipher how heat dissipates on the moon surface. Inside the lander was the indigenously designed, six-wheel, 26kg Pragyan rover. (Pragyan means knowledge.) Both the lander and the rover are equipped with many cameras, and the rover will conduct two experiments to analyse the lunar soil.
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ISRO chose the lunar dawn for landing so that the solar-powered lander and rover would get full 14 days of sunlight to complete their experiments. The rover can communicate with the lander, which in turn can communicate with the Chandrayaan-2 orbiter. The lander also can communicate directly with ISRO.
The mission is so frugal that it cost India just around $75 million, which is less than the price of a Boeing 737-800 airplane. Incidentally, Air India has just ordered 470 planes, each costing more than Chandrayaan-3. Somanath said around 1,000 ISRO personnel were involved in Chandrayaan-3.
Hopefully, by the end of 2024, India will launch its biggest-ever scientific mission―Gaganyaan, an ambitious, Rs10,000-crore project to send an Indian astronaut to space. If the mission succeeds, India will become the fourth country, after USSR/Russia, the US and China to have the capability to send astronauts to space.
India is also making a futuristic heavy launch vehicle. Dubbed ‘Pushpak Vimana’, the Re-usable Launch Vehicle, or RLV, has passed scale model tests. Re-usable launchers are the top tier of rockets; they are also the most expensive.
Even as ISRO keeps the moon in its gaze, its love affair with the sun will soon begin. The Aditya L1 satellite, India’s first space-based solar observatory, will try to understand why the sun gets angry sometimes and sends intense solar storms towards earth. Last year, 40 satellites of the Starlink constellation of SpaceX were fried in a solar storm.
“With India having assets worth more than Rs50,000 crore in space, it is mandatory that we understand, be able to forecast and then mitigate the danger posed by intense solar storms,” said Somanath.
ISRO is truly reaching for the stars.
―Bagla is a science journalist who has tracked India’s space programme for decades. He is coauthor of Destination Moon: India’s Quest for the Moon, Mars and Beyond and Reaching for the Stars: India’s Journey to Mars and Beyond.