When you start reading this piece, Chandrayaan-2 will be performing manoeuvres to change its orbit around the earth until it leaves earth orbit and begins the 7-day journey to the lunar orbit on August 13. The spacecraft has to undergo 15 such manoeuvres before the final, and the most important of all, on September 7: the landing of Vikram and Pragyan on the lunar surface at the south pole of the moon. The Indian Space Research Organisation (ISRO) says the descent will be “fifteen minutes of terror” as the lander has to see the landing site correctly, reduce its velocity and land with minimal impact.
India’s second mission to the moon is the first quest to land a spacecraft on it; Chandrayaan-1 only had an orbiter that circled the earth’s only natural satellite. The mission is also the first ever to land on the south pole; all the previous 28 landings by US, Russia and China, including the human landings, have been in the equatorial region.
Another first on this mission is the use of a new rocket, the GSLV-MkIII, which became operational in November last year. The rocket is the launch vehicle that carries a spacecraft into space. Prior to GSLV, ISRO has made three classes of rocket or launch vehicles – SLV, ASLV and PSLV. GSLV’s success also means that India space agency, which worked hard for 20 years, has finally mastered the cryogenic technology. This rocket is slated to be used for the human spaceflight programme, with some tweaks, in 2022.
India’s most powerful rocket, GSLV MK-III, lifted off with 3,850-kg Chandrayaan-2 on July 22 afternoon from the Sriharikota launch range at its appointed time of 2.43pm, and in less than 17 minutes placed it in the earth’s orbit after burning its successive stages. But the first round of applause happened 132 seconds after the lift-off when the indigenous cryogenic engine (CE-20) ignited.
The July 22 launch was better-than-textbook launch: the rocket took the lunarcraft to an orbit that is 6,000km higher than the planned, saving on fuel and thus increasing the life span. This is commendable because ISRO had to abort the mission on July 15, the original date for lift-off, due to a technical snag. The rocket was on the launchpad since then and ISRO team swung into action to remove the glitch.
ISRO chairman K Sivan said after the launch: “We have bounced back with flying “colours. A success on the back of a failure is doubly sweet.” Prime Minister Narendra Modi, who watched the launch on television, said the event will be etched in the annals of history. “The launch of zChandrayaan-2 illustrates the prowess of our scientists and the determination of 130 crore zIndians to scale new frontiers of science,” he said.
NASA congratulated ISRO said it was looking forward to learn from the mission about the unexplored lunar south pole. Taking to Twitter, NASA said, “Congrats to ISRO on the launch of Chandrayaan 2, a mission to study the Moon. We’re proud to support your mission using our Deep Space Network and look forward to what you learn about the lunar south pole where we will send astronauts on our Artemis mission in a few years.”
Chandrayaan-2 is a 62-day mission – 48 days during the journey of about 400,000km, and 14 days after the rover touchdown.
From July 22 to August 13, Chandrayaan-2 will be in the orbit, which, at its nearest, is 170 km from earth, and, at its furthest, 39,120 km. The lunarcraft will leave earth’s orbit on August 13 and enter moon’s orbit on August 20. Vikram and Pragyan will separate from the orbiter on September 2, lower themselves in an orbit closer to the moon and continue to go around it before the descent on the 48th day.
Chandrayaan-2 is to land on the south pole of the moon. The regions near the poles are full of craters whose diameter ranges between 2km and 15km. American space agency, NASA, says moon has around 600 million tones of water ice and most of it lies in the shadows of craters. Scientists have planned to land Vikram on a high plain between two craters, named Manzinus C and Simpelius N.
The search for water is one of the main objectives of Chandrayaan-2. Chandrayaan-1 detected signature of water when it landed an impact probe wrapped in Indian tricolor.
When Vikram will separate from the orbiter after the three have been in moon’s orbit for 13 days, it will take four days to land, and four hours after that, Pragyan, the rover, will crawl out of it. For next 14 days, which is one lunar day, it will move on the lunar surface at an extremely slow pace of 1 cm per second. In 14 days, Pragyan is likely to cover a maximum distance of 500 metres.
Vikram, scientists said, is like a research station. The mission is carrying 14 payloads, the jargon for instruments. Some of these will be in the orbiter, some in the lander and some in the rover. This, of course, is apart from the onboard computers.
The lunarcraft will do a detailed study of the topography, seismography, mineral identification and distribution, surface chemical composition, thermophysical characteristics of top soil and composition of the lunar atmosphere for the new understanding of origin and evolution of the moon. The south pole is supposed to have rocks and craters that will offer knowledge about fossil records of earlier solar system.
Chandrayaan 2 has been one of the most awaited missions of ISRO. After the success of Chandrayaan 1 in 2008, it was expected that the second mission would get moon-bound shortly. In fact, ISRO did plan the second mission for 2014. For this, Russia was to provide the lander and rover system, but they failed to do so owing to the crisis within their space programme. The delay caused India’s moon agenda to lag behind significantly – by this time, we should have progressed towards undertaking its third moon mission – but the delay has been a blessing in disguise. Russia’s non-participation made ISRO design and develop the entire lander-rover system indigenously. In the long run, this would make ISRO more self-sufficient.
According to Ajay Lele, a research fellow at Institute for Defence Studies and Analysis (IDSA), New Delhi, andauthor of ‘Mission Mars: India’s Quest for the Red Planet, during the last five decades, the world has witnessed an around 50 per cent success rate for missions to land on the moon. “Very recently, Israel’s attempt for soft landing on the moon had resulted in failure,” he wrote in The Indian Express.
“In the backdrop of all this, ISRO has planned its mission. It has taken on the challenge upfront. Let us all wish India’s lander (Vikram) and rover (Pragyan) happy-landings on September 6, and godspeed,” he wrote.