Chandrayaan Orbiter Could Last 6 Years Longer Than Planned: K Sivan

On the flip side, Sivan – as well as an official update from ISRO – confirmed Chandrayaan 2's surface mission has ended for now.

Bengaluru: K. Sivan, chairman of the Indian Space Research Organisation (ISRO), said in an interview that the schedule of Gaganyaan – the organisation’s maiden human spaceflight programme set to be operationalised in 2022 – won’t be affected by the loss of the Chandrayaan 2 mission’s surface payloads on September 7. In fact, he said the events wouldn’t affect any of its other missions.

Shortly before 2.30 am, the mission’s Vikram lander had reached up to 2.1 km above the Moon’s surface with all its engines and sensors performing nominally. However, ISRO scientists on Earth lost contact with the lander shortly after and it was considered lost. The lander was carrying the rover Pragyan, and the two were together carrying five scientific instruments to study the neighbourhood of the Moon’s south polar landing region in greater detail.

Sivan also said in the interview, given to DD News and broadcast at 8 pm on September 7, that the “Chandrayaan 2 mission was very close to being a 100% success”. He added that more than the loss of scientific instruments onboard Vikram and Pragyan, the organisation was more concerned at least for now about the lost opportunity to validate certain technologies that the duo employed.

Also today, ISRO posted the following update (edited only for clarity) on its website. Though it doesn’t explicitly say as much, the text implies the Vikram lander and the Pragyan rover are to be considered lost, and that the Chandrayaan 2 mission will continue with just the orbiter component. However, Sivan has separately said that the organisation is also pursuing efforts to reestablish contact with the lander.

Chandrayaan 2 was a highly complex mission, which represented a significant technological leap compared to the previous missions of ISRO, which brought together an orbiter, lander and rover to explore the unexplored south pole of the Moon. Since the launch on July 22, 2019, not only India but the whole world watched its progress from one phase to the next with great expectations and excitement.

This was a unique mission which aimed at studying not just one area of the Moon but all the areas combining the exosphere, the surface as well as the sub-surface of the moon in a single mission. The orbiter has already been placed in its intended orbit around the Moon and shall enrich our understanding of the Moon’s evolution and mapping of the minerals and water molecules in the polar regions, using its eight state-of-the-art scientific instruments.

The orbiter camera is the highest resolution camera (0.3m) in any lunar mission so far and shall provide high resolution images which will be immensely useful to the global scientific community. The precise launch and mission management has ensured a long life of almost seven years instead of the planned one year.

The Vikram Lander followed the planned descent trajectory from its orbit of 35 km to just below 2 km above the surface. All the systems and sensors of the lander functioned excellently until this point and proved many new technologies such as variable thrust propulsion technology used in the lander. The success criteria was defined for each and every phase of the mission and till date 90-95% of the mission objectives have been accomplished and will continue to contribute to lunar science, notwithstanding the loss of communication with the lander.

Prime Minister Narendra Modi apparently told Sivan after the landing attempt that they shouldn’t look to science for results but simply conduct experiments, and that the experiments would produce results.

K. VijayRaghavan, the principal scientific adviser to the Government of India, was present at the mission control centre during the Vikram lander’s ill-fated autonomous descent attempt and tweeted in the afternoon that ISRO had begun review meetings even before sunrise. In response to a question, VijayRaghavan also mentioned that Ritu Karidhal, the mission director for Chandrayaan 2, was “leading the mission review team presentation which began at 4 am today”.

Though official statements have been few and far between, ISRO is expected to announce another mission to the Moon and possibly with the same mission profile as Chandrayaan 2. While its human spaceflight programme is in its nascent stage, robotic exploration of space is high on the organisation’s agenda and experts believe continuing down this path will allow ISRO – and India with it – to keep up in the 21st century race to Moon and Mars.

Indeed, prior to Chandrayaan 2’s launch on July 22, ISRO appeared to be in talks with scientists from JAXA, the Japanese space agency, to explore the Moon together on ISRO’s prospective Chandrayaan 2 mission in the next decade. Setting aside the implications of Vikram’s presumed loss, such a future mission was also expected to be more complicated, including carrying a larger volume and mass of payloads.

This is further implied by ISRO’s plan to upgrade the GSLV Mk III launcher – by substituting its liquid-fuel-powered second stage with a semi-cryogenic engine fed by kerosene and liquid oxygen. Such a change is expected to increase the Mk III’s payload capacity by 1,000 kg, allowing the rocket to lift more into space per launch. The Mk III’s next major outing will be the uncrewed Gaganyaan test flights slated for late 2020, according to Sivan.

For now, as the ISRO statement above attests, the Chandrayaan 2 mission’s lifetime appears to be extendable to until 2026 because the “precise launch and mission management” resulted in an over-performance of the GSLV rocket that launched it at a greater altitude. This in turn left the orbiter with a shorter distance to travel on its own fuel, leaving it with enough in its tanks for a mission duration of more than the planned one year.

The orbiter carries a suite of eight instruments that will together study the Moon’s surface characteristics, terrain and the composition of its upper atmosphere. Sivan singled out one in particular for especial praise during the interview: the dual-band synthetic-aperture radar (SAR). All lunar orbiters thus far have used single-band radars, he said, but SAR’s L- and S-band radar – by virtue of employing two bands – could penetrate the Moon’s surface to a distance of up to 10 metres and look for water in the lunar soil. “Such data will be available for the first time to scientists globally” as a result.