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Chandrayaan-2 mission very close to 100% success, says Isro chief K Sivan

PM Modi leads the nation in rallying behind Isro after failed moon landing

T E Narasimhan  |  Chennai 

Narendra Modi, K Sivan
Prime Minister Narendra Modi consoles Isro Chairman K Sivan after contact with Chandrayaan-2’s lander was abruptly lost seconds before its touchdown | PTI

The Indian Space Research Organisation (Isro) on Saturday tried to put on a brave face hours after it lost contact with Chandrayaan-2’s landing module near the moon’s surface, leading to nationwide disappointment. Scientists of the space agency, however, indicated that it was a setback, not a failure.

India was trying to become just the fourth nation to pull off a soft landing on the moon — following the former Soviet Union, the US and China — and the only country to probe the unexplored lunar south pole.

“The mission is very close to 100 per cent success,” Chairman told Business Standard on the phone. “Regarding technology demonstration, we could go up to 2 km from 30 km, and only the final phase could not be demonstrated properly because we lost communication (with the lander). We have done 90-95 per cent technology demonstration,” he said. The chief said the orbiter’s designated lifetime was only one year, but it would now be around 7.5 years with extra fuel available.

Sivan said the Chandrayaan project would not affect any ongoing activity.

ALSO READ: Almost 95% of Chandrayaan-2 mission objectives have been accomplished: ISRO

“We will have the Cartosat-3 mission in the end of October. Subsequently, within a week, the RISAT 2BR 1 mission will be launched. We are seriously working on the flagship programme Gangayaan, and we expect the first unmanned flight to be launched by the end of 2020,” he said.

Former director D Sasikumar said: “We have to find out from the communication data whether it was a soft landing or crash landing. In my opinion, it was not a crash landing because the communication channel was on between the lander and the orbiter. It should be intact. So, let us hope after the analysis is done, we may be able to get the final figure.”

The moon lander’s descent was going as planned and normal performance was observed up to an altitude of 2.1 km. “Subsequently, communication from the lander (Vikram) to the ground stations was lost,” Sivan had announced last night, his voice choking. The communication was stopped about 11 minutes into descent for a soft landing near the lunar south pole during the fine braking phase.

The final moments

1.38 am: Lander Vikram begins its descent from an altitude of 30 km above the moon at a velocity of 1,680 metres per second
Rough braking operations begin to reduce the lander’s velocity lower
1.50 am: The rough braking phase gets over
Scientists clap and cheer as the fine braking phase starts at an altitude of about 5 km
Mood changes as the lander slightly deviates from its plotted path
2 am: Nervous silence fills the mission control centre
2.07 am: Isro Chairman walks up to Prime Minister Narendra Modi and speaks to him
2.10 am: Sivan says the performance of the lander was in accordance with the plan till the altitude of 2.1 km, after which communication links got snapped

Soft landing on the moon, especially in the uncharted south polar region, is an incredibly complex and hard task due thin exosphere density and low gravity of the moon, coupled with harsh radiation, scientists say.

The lander had completed the first rough braking part of its descent, in which four of the module’s propulsion engines were fired at the same time to lower its speed significantly. Vikram could have lost its control when its thrusters were switched off during its descent and crash-landed, snapping the communication links.

According to scientists, the orbiter, which is still in good health, will be listening to any communication from the lander. It is possible that Vikram may still have landed but could be damaged or in a tilted position. The extent of damage will decide the next course of action if scientists re-establish communication with the lander either through the orbiter or directly by mission control.

“The mission has not failed, as the orbiter is functional in the designated orbit above the lunar surface. It will be using its scientific payloads to continue studying and sending images and data mandated for its life span or as long as the fuel lasts – which could be more than a year as well,” said Ratan Shrivastava, an independent aerospace and defence consultant.

ALSO READ: Chandrayaan 2: Partial success, ISRO should be proud of what it's achieved

K Vijay Raghavan, principal scientific adviser to the Government of India, said the precise launch and mission management had ensured a long life of almost seven years, instead of the planned one year, for the orbiter, which has been placed in the intended orbit around the moon. “The orbiter shall enrich our understanding of the moon’s evolution, map minerals, water molecules in the polar regions, using its eight state-of-the-art scientific instruments. As far as the lander is concerned, its systems and sensors functioned excellently until the communication was discontinued,” he said. “Success criteria were defined for each and every phase of the mission and so far 90 to 95 per cent of the mission objectives have been accomplished and will continue to contribute to lunar science.”

Sivan, who broke into tears after the communication from the lander was snapped on Saturday early morning, had earlier mentioned the soft landing as "15 minutes of terror" with challenges including keeping the lander in its position, reducing the velocity from 1.6 km per second to zero, and avoiding dust engulfing the lander while landing on the surface. ISRO said it had learned from the mistakes of others and had conducted enough tests simulating the moon's surface.

Meanwhile, across the social media, millions of people rallied behind Isro through #ProudofIsro campaign on Twitter. “India is proud of our scientists! They’ve given their best and have always made India proud. These are moments to be courageous, and courageous we will be! Chairman @isro gave updates on We remain hopeful and will continue working hard on our space programme," Prime Minister Narendra Modi tweeted. He also addressed Isro scientists on Saturday morning and when Sivan welled up in tears, Prime Minister warmly hugged and consoled him.

Before leaving to Delhi, he addressed the scientists again and said “our determination to touch the moon has become even stronger. We came very close, but we need to cover more ground. Learnings from today will make us stronger and better," he said, adding, "The best is yet to come in our space programme. India is with you.”

First Published: Sun, September 08 2019. 00:11 IST