The Vikram lander was supposed to release a briefcase-size rover from its belly.
ISRO
By Sanjay Kumar
India’s attempt to land near the south pole of the moon, part of the Chandrayaan-2 mission, ended when mission managers lost contact with the lander, seconds before touchdown, just 2 kilometers from the moon’s surface. The lander, which would have made India the fourth nation to land on the moon after the United States, the Soviet Union and China, is presumed to be lost, although officials at the Indian Space Research Organization (ISRO) have not confirmed whether the spacecraft crashed or not.
When contact was lost, at 1:52 am Indian time, the mood in the ISRO mission control center in Bangalore, was transformed. Cheerful smiles became sullen expressions on the faces of crestfallen scientists and engineers. A running mission commentary, part of a nationwide broadcast to millions of Indians, was stopped suddenly. Prime Minister Narendra Modi, who was observing from just outside the control center, was briefed and left soon thereafter. A press conference, set for the next morning, was cancelled.
“Failure is part of the game, and India was attempting something it had never attempted before, had no experience in,” says Ajey Lele, a senior fellow with India’s Institute of Defence Studies and Analysis, a government-funded think tank in New Delhi.
ISRO scientists believe that a malfunction occurred during the “15 minutes of terror”: the duration of the lander’s descent from lunar orbit to the surface. In this critical phase, the lander was functioning autonomously, based on in-built intelligence, with no direct commands from ground stations. There are indications that the lander deviated from its pre-programmed trajectory and could not control its speed with its four side thrusters and one middle engine. ISRO says it is analysing data to pinpoint what went wrong.
The 1477 kilogram lander was called Vikram, after Vikram Sarabhai, one of the founders of India’s space program. If it had landed successfully, a 26 kilogram rover the size of a briefcase, called Pragyaan, was to have rolled down a ramp from the belly of the lander. Plans called for the solar-powered rover to traverse half a kilometer and collect data for 14 Earth days or 1 lunar day.
ISRO officials were conscious of the low success rate of moon missions. ISRO chairman Kailasavadivoo Sivan never tired of explaining that this was an extraordinarily complex mission, the kind of which ISRO had never attempted before – and at a difficult site, the south pole of the moon, where landing is not easy, and where nobody had gone before.
In April, an Israeli robotic spacecraft called Beresheet crash landed on the moon after communications were lost near the surface. However, on January 3rd, China successfully launched and landed their ongoing robotic lander and rover mission Chang’e 4 at South Pole-Aitkin Basin, a site on the far side of the moon further from the south pole than Chandrayaan-2’s landing site.
Over the past few years, the Chandrayaan-2 mission suffered numerous hiccups and delays and was postponed more than half a dozen times. A major delay came in 2013, when Russia, which was supposed to supply the lander and the rover, backed out of the joint mission, forcing India to develop these technologies from scratch.
And this year, on 15 July, barely an hour before a scheduled launch, the mission was aborted. The reason, ISRO soon discovered, was a leak in a pressure-supplying system. ISRO plugged the leak just in time to launch the mission on July 22.
Some experts believe that India needs to improve its space technology. Fifty years ago, it took NASA’s Apollo missions just 3 days to reach the moon because of the power of its rockets. It took Chandrayaan-2 48 days to reach the moon, using its GSLV Mk III-M1 rocket, in its first operational flight. Lele says the low capacity of the rockets is a problem because it limits mission payloads. “That’s where India is lacking and needs to augment its capabilities,” Lele says.
G. Madhavan Nair, a former ISRO chairman who was a key steward of the Chandrayaan-1 mission, says even with a failure of the lander, the mission can still do science with its Chandrayaan-2 Orbiter. The orbiter, which released Vikram, has 8 instruments that will map the moon for at least one year – and possibly identify the fate of the lander near its intended landing site. “I will say 90% of the mission is successful,” he says.
Hours after the landing broadcast ended, Modi returned to the mission control center to offer support to ISRO scientists, and hugged Sivan. “We came close but need to cover more ground. The effort was worth it and so was the journey,” Modi told ISRO scientists.
C. BICKEL/SCIENCE
Source: Science Mag