Saturday 7 September 2019

ISRO's Vikram Lander drops short by 2.1 km, but Orbiter keeps Chandrayaan2 alive

The Vikram Lander from Chandrayaan 2’s orbiter was meant to land on the lunar surface on Sept 7 but telecommunication link was lost.

Like everything Indian, there was plenty of drama and high emotion at the scheduled touchdown of Chandrayaan2's Vikram Lander on the Moon's surface on Sept 7 at 1:52 am IST.

Just 2.1 km short of landing, all connections with the Vikram Lander was lost. The Lander, which had detached from Chandrayaan 2’s Orbiter on September 2, had been manoeuvring around the Moon for nearly five days.

As ISRO Chairman Dr K Sivan said, everything was according to plan and just short of 2.1 km, communication was lost. He added that ISRO is analysing the data sent by Vikram Lander.

In an official statement released at 3 am, ISRO said, "Vikram Lander descent was as planned and normal performance was observed up to an altitude of 2.1 km. Subsequently, communication from Lander to the ground stations was lost. Data is being analyzed."
The mission is being constantly monitored by the ISRO Telemetry Tracking and Command Center (ISTRAC) at Bengaluru.

Prime Minister Narendra Modi, who was at the ISTRAC, encouraged the scientists for the hard work and said he had full faith in them. He said, "Let's not lose hope. You (ISRO scientists) have done a lot for mankind and I am with you all the way."

PM Modi also met school children, who had come to witness the historic landing. To a question posed by a student on how can they keep themselves motivated in life, PM Modi said do not carry your failures on your shoulder. Keep moving ahead.

Which is what the ISRO scientists will be doing now. All is not lost. The Orbiter, which is equipped with instruments to carry out various tests, is still on course.

The sequence of soft landing of Vikram lander on the lunar surface (Image: ISRO)
What should have happened according to plan had Vikram landed?
With two engines on at an altitude of 400 metres, the Vikram Lander should have descended in a parabolic manner. During its final stage, Vikram Lander would have created an opposite force to make sure it lands softly on the lunar surface and is also equipped with touchdown sensors at its feet.

Later, it would have started its operation of the deployment of payloads, which is touted as a critical operation. As per ISRO, the Vikram Lander was carrying CHASTE (Chandra’s Surface Thermo-physical Experiment), RAMBHA (Radio Anatomy of Moon Bound Hypersensitive ionosphere and Atmosphere) and ILSA (Instrument for Lunar Seismic Activity).

After the deployment of specific payloads, the six-wheeled Pragyan Rover would have started rolling out on the lunar surface at 5:30 am. Prior to which its solar panel would have powered its battery as it descended, and it would have used its NAV camera to scan its surrounding.

Once the scanning was completed, the data was planned to be sent to Earth via Vikram. This scan would have then processed at mission control for planning the path for Pragyan to move ahead.

In case of any obstacle, Pragyan would have used its Rocker Bogie mechanism to overcome it. It was equipped with a movement range of 50 mm upward and downward. Also, mission control would have instructed Pragyan to stop and determine elemental composition of lunar rocks soil using the APXS (Alpha Particle X-ray Spectrometer) payload.

For understanding the lunar surface, Pragyan was meant to engage its LIBS (Laser Induced Breakdown Spectrometer) payload to derive the elemental composition of the lunar surface.

However, all is not lost. Watch this space for updates on Vikram Lander's fate and the next steps by ISRO.

(Source: YS)

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