CHANDRAYAAN 2: THRILL AND TERROR
Even though Dr K. Sivan, chairman, Indian Space Research Organisation (ISRO), has been involved in over 50 launches, he confesses he is still tense during every new launch. As he puts it, “My stomach churns, my heart beats faster and I feel breathless.” On June 22, as the countdown began for the launch of Chandrayaan-2, India’s second moon mission, from the space port in Sriharikota in Andhra, he was even more so. A week earlier, the first attempt to launch the spacecraft had to be aborted because of a plumbing leak in the upper-stage engine of the 15-storey tall, brand new GSLV Mark-III launcher. Though disappointed, Sivan decided to postpone the launch as he was acutely aware that there was so much of ISRO and India’s prestige riding on it.
The Chandrayaan-2 mission is a quantum leap over its successful forerunner launched in 2008 and is crammed with new technologies. The foremost is the launch vehicle itself. In a gutsy decision, ISRO decided to use its heavy-lifting GSLV Mark-III, though it had undergone only two development tests—the Chandrayaan-2 launch would be its first operational flight. Apart from the new launcher and an upgraded orbiter, space scientists had built for the first time a lunar lander assisted by a rover that could roam the moon surface for a radius of half a kilometre and perform critical experiments. These were cutting edge technologies and, if India succeeded, it would be only the fourth nation after the US, Russia and China to have operated a robotic lander on the moon. Another worry for Sivan was that if the glitch was serious and they were unable to attempt another launch by endJuly they would have to wait till next year to get the perfect earth-moon alignment required for the Chandrayaan-2 mission.
After it was announced that the first launch was on hold, Sivan rapidly reassessed the situation. He told his team members, “ISRO scientists have always been ready for challenges, they have always risen to the occasion. Why not now?” Spurred on by the appeal, the team of scientists from the Vikram Sarabhai Space Centre (VSSC) who had built the rocket, headed by director S. Somanath, worked non-stop for over 36 hours to identify and fix the problem. The snag had occurred in the critical cryogenic stage that uses super-cooled hydrogen and oxygen as fuel. The malfunctioning joint had caused a noticeable pressure drop in the helium bottles that control the opening and closing of fuel valves in the engine. As Sivan told india today, “The problem was simple, but if we had decided to go ahead with the launch without correcting it, the impact would have been catastrophic.”
After fixing the leaking joint, scientists then conducted a series of tests at the launch pad itself to ensure the problem
wouldn’t recur. The scientists from VSSC—where ISRO’s rocketry is developed—had in the past year made major modifications to GSLV Mark-III to meet the increased payload weight of 4 tonnes that Chandrayaan-2 required. It was the first time the enhanced launcher was being put to test, but the VSSC team assured Sivan they were confident that there would be no further glitches. The ISRO chairman was conscious that space is an unforgiving zone and even a small malfunction could result in the Rs 1,000 crore Chandrayaan-2 mission ending up in the bottom of the Bay of Bengal. But he took the brave decision to go ahead with the launch before the July window closed.
On launch day, Sivan says he felt the familiar tension building up in his gut as the countdown neared zero. It didn’t diminish even after the first stage consisting of two giant booster rockets ignited and hurled the vehicle towards its predetermined flight path. It was only 16 minutes later, after the upper stage cryogenic engine completed its firing and injected the Chandrayaan-2 into a trans-lunar orbit that his anxiety gave way to “exhilaration”. He shook hands with the top scientists seated near him and hugged some of them. The monitor had shown that the cryogenic engine had “over-performed”, putting Chandrayaan-2 at an orbit of 45,000 km at its apogee instead of the planned 39,000 km. The gain of 6,000 km, which the lunar module would have otherwise had to achieve by firing its onboard engines, would save it considerable amount of fuel. Sivan termed it a “bonus” and a jubilant Somanath said, “The GSLV Mark-III has declared its operational capability with an even bigger bang.”
While lauding the rocket scientists for their work, Sivan knew there were many more challenges ahead. As he told them, “This is just the beginning of a historic journey.” Chandrayaan-2 was on track in its 400,000-kilometre trip. It would rendezvous with the moon’s orbit only by mid-August. Days after the launch, after the first firing of the module’s onboard engines to push it into a higher orbit performed “beautifully”, Sivan said he was confident that the module would reach the moon on schedule. Only after it stabilised its orbit around the moon would the lander carrying the rover separate itself from the orbiter and perform an intricate manoeuvre to land on the surface on September 7. Sivan describes the entire operation “as 15 minutes of sheer terror for us” till the lander touches down. There would be more concern as the rover rolls out and, along with the lander, begins the dozen-odd experiments including searching for water molecules on the moon. Only after they do so will ISRO declare the mission successful. Sivan has a long time to go before he can relax. ■
“The lunar landing will be 15 minutes of sheer terror for us”
—K. SIVAN, Chairman, ISRO