Why Chandrayaan 2's Mission To Moon's South Pole Is ISRO's Ultimate Challenge

An Indian lunar mission that will boldly go where no country has ever gone before—the moon’s south polar region. That’s how the Indian Space Research ­Organisation (ISRO) website touts the country’s second moon mission, Chandrayaan-2. On July 15, the ­orbiter-lander-rover combo will lift off from Sriharikota and stick to the circuitous route that the mavens at ISRO are familiar with to our closest galactic neighbour. Two months later, in early September, the lander will separate from the spacecraft and start its descent to the moon’s surface—a countdown to ISRO’s real test.

More than a decade after the Chan­drayaan-1 moon mission, its sequel presents the space agency with its most complex challenge so far, according to ISRO chief K. Sivan, who announced the launch date last week. The D-Day, as he put it, will be around September 6. By then, the lander will be about 30 km away from the moon and ISRO will have to execute a 15-minute braking manoeuvre to soft-land on the lunar surface.

“Those 15 minutes are going to be the most terrifying for us,” said Sivan at a press conference in Bangalore. “Every second of the flight from the start of the landing process till touchdown is crucial. It’s a new thing for ISRO.” In 2008, the organisation had experimented with a moon impact probe which was meant to crash-land on the lunar surface.

Chandrayaan-2 is headed to the moon’s south pole, a region that is relatively less explored. Part of the reason why the south pole was chosen is convenience—it is relatively flat, does not have too many craters, offers visibility and solar light to power the systems. It’s also attractive from a scientific point of view—data from ISRO’s first lunar mission had provided evidence of the presence of sub-surface ice in craters near the moon’s north pole. The south pole, which is more under shadow than the north, is expected to provide opportunities to study signs of water, ice and minerals. “We are going to a place where nobody else has gone, so we are expecting a huge amount of new science,” said Sivan.

Incidentally, the fiftieth anniversary of the 1969 Apollo 11 spaceflight is also in July. Now, half a century since Neil Armstrong and Buzz Aldrin landed on the moon, there’s renewed interest in earth’s natural satellite—a new race to the moon, as the headlines go. This January, China’s Chang’e 4 mission landed on the far side of the moon, the first spacecraft to do so. The moon’s far side poses a communication challenge because radio contact is cut off and a lander or rover can’t directly relay signals to the earth.

Meanwhile, NASA is charting out a mission named Artemis to return astronauts to the moon by 2024. “First, we are focused on speed to land the next man, and first woman, on the moon by 2024,” announced NASA administrator Jim Bridenstine in April. “Second, we will establish sustainable missions by 2028.” As NASA puts it, Artemis is the first step to begin the next era of exploration and send humans to Mars.

“There are two primary motivations driving interest in the moon, explains S. Chandrashekar of the National Institute for Advanced Studies in Bangalore. “A scientific understanding of the moon will shed light on some fundamental questions associated with the origins of the solar system. The other reason is that if you want to initiate missions to explore the outer planets, such as Mars, the obvious place to have a base is on the moon and use it to go to Mars or further explore the solar system.”

As for Chandrayaan-2, once the lander touches down on the moon, a six-whe­eled rover will inch its way out of the craft onto the lunar surface, travelling at the speed of one centimetre a second. Both the lander and the rover will have a lifespan of 14 earth days during which they will collect data and carry out ­experiments—all in a lunar day’s work, as that’s the time the moon takes to complete one rotation on its axis.

By Ajay Sukumaran in Bangalore