After months of silence and speculation, the first official confirmation of the Chandrayaan 2 mission's Vikram lander having had a hard-landing on the moon came Thursday from the Department of Space Chief Jitendra Singh at an afternoon Lok Sabha session. This came after a frustrating few weeks for India's space community and space enthusiasts, being denied any closure as to the final, deciding moments of India's first attempt at a soft-landing on the Moon.
Chandrayaan 2 was an indigenously-developed spacecraft that was made by an Orbiter, a Lander (Vikram) and a Rover (Pragyan). A fitted "composite" of these three components was launched on-board the indigenous GSLV-Mk-III-M1 launch vehicle on 22 July 2019.
The GSLV MkIII lifts off from a Sriharikota launchpad. Image: ISRO
The long-awaited launch, originally scheduled for 14 July, but stopped less than an hour before liftoff to "a technical snag observed in launch vehicle system". The successful second attempt on 22 July was followed by a modified flight plan from the Earth to the moon, so the lander and rover would still be in time to start their missions in time with the beginning of a lunar day (equivalent to 14 Earth days).
The duo eventually made it time, just as planned, and 2.1 kilometres from the surface, things went (mysteriously) south. The Vikram lander, in the final leg of its descent, had a malfunction of some kind that caused it to accelerate instead of slow down, and the only direct communication link with the lander went silent.
An illustration of Chandrayaan 2's lander Vikram. Image: ISRO
Tears were shed and nervous looks exchanges in the control room at ISRO mere minutes after the radio silence with the lander. And while investigations were undoubtedly ongoing as to what went wrong in these final moments, the space agency has divulged next to no important details about what actually went wrong. It seems that wait for closure – 48 days later – is still to continue.
"As of now, the report is unlikely to be made public, but the findings will come out in Parliament. I cannot say anything else apart from what is given in writing," Vivek Singh, spokesperson for ISRO, told PTI.
That said, Singh did share details in the Lok Sabha on Thursday casting light on the Vikram lander's final minutes before touching moon dust (one way or the other). He also elaborated on other projects currently on ISRO's plate, like ongoing remote sensing satellite projects and satellite projects aimed at civil and environmental applications.
K Sivan takes a model of the Chandrayaan 2 composite for a virtual spin. Image: ISRO
Below are summations of the key topics Singh covered.
On cost of Chandrayaan 2
The cost of ISRO's Chandrayaan 2 mission, excluding the cost of the Geosynchronous Satellite Launch Vehicle (GSLV) rocket it was launched on and related launch costs, was Rs 603 crore. The GSLV-Mk-M1 cost an additional Rs 367 crore.
On reasons behind Vikram's hard-landing
On its 48-day-journey – from a launchpad in Sriharikota to the moon, a series of successful Earth- and moon-bound maneuvers, and a skillful injection into a low orbit around the moon – it was time for the lander to separate. This separation of lander and rover took place, as planned, from the orbiter on 2 September, 2019. After two maneuvers to bring the landing module closer to the surface, the aptly-named "15 minutes of terror" – the powered descent – was begun on 7 September, towards a carefully-chosen landing site on the moon's relatively unexplored South Pole.
The first phase ("rough-braking") of descent was performed "nominally", bringing the lander from an altitude of 30 kilometres to 7.4 kilometres from the surface. At the same time, the velocity of the module was also brought down from 1,683 m/s to 146 m/s.
During the second phase ("fine-braking") of descent, the velocity was reduced further. And while the reduction was intended as a more drastic one than in the first phase, Singh said that the actual velocity of the lander dropped further than planned. This deviation led to a change in the "initial conditions at the start of the second phase... beyond the designed parameters".
A glimpse of the Chandrayaan 2 command centre at ISRO's ISTRAC satellite tracking facility in Bengaluru. Image: DD National/ISRO
The landing module, as a result, hard-landed within 500 m of the chosen landing site, Singh said. And while the soft-landing itself was unsuccessful, much of the technology demonstration components in the mission – the launch of a modified GSLV-Mk III variant, critical in-orbit maneuvers, separation of the lander from the orbiter, de-boosting to reduce speed for landing, and the first leg of the descent phase – were all accomplished successfully, he added.
Singh, like the ISRO chairman K Sivan shortly after the loss of communication with the lander, was quick to point out the Orbiter's promise in carrying the mission's potential forward.
"..all the eight state-of-the-art scientific instruments of the Orbiter are performing as per the design and providing valuable scientific data," Singh said. "The data received from the Orbiter is being provided continuously to the scientific community. The same was recently reviewed in an all India user meet organized at New Delhi," he added.
Owing to "the precision" with which the launch and in-orbit maneuvers were carried out, the Orbiter's mission life is now placed at seven years, versus the one year that it was intended for.
Singh didn't elaborate on what the investigation revealed about the broken communication link or the reasons for the abrupt acceleration that was seen in the control room seconds before the communication link with the lander went offline.
ISRO Chairman Dr K Sivan (L) and Minister of State in the Department of Atomic Energy and Minister of State in the Department of Space Dr Jitendra Singh brief media on Chandrayaan 2 on 13 June 2019 in New Delhi. Image: Getty
On BRICS nations' remote sensing satellite constellation
Another Indian space project Singh touched upon was a planned "virtual constellation of remote sensing satellites" built and designed by space agencies of BRICS nations (Brazil, Russia, India, China, and South Africa).
"The BRICS nations have been negotiating a Framework Agreement to formalize the cooperation on building a virtual constellation of remote sensing satellites, made up of satellites contributed by BRICS space agencies," Singh said. "Technical aspects with respect to identifying the satellites and the ground stations for the initial virtual constellation were discussed (by the space agencies involved.
The proposed virtual constellation is planned as a co-operative initiative to gain access to a wide variety of satellite remote sensing data that can be used by individual BRICS nations for many applications including the management of natural resources and natural disasters.
"The BRICS Remote Sensing Satellite Virtual Constellation is a practical step towards high-tech cooperation between these countries that will assist in attaining the sustainable development goals and challenges pertaining to our respective economies and societies," Vaneshree Maharaj, spokesperson for said, when the South African National Space Agency (SANSA) joined the initiative in July 2017.
"There are two phases proposed for the BRICS Remote Sensing Satellite Constellation: phase one, comprising a virtual constellation of existing satellites; and phase two, a new satellite constellation," she added.
IRNSS-1 spacecraft (centre) integrated with PSLV-C31 fourth stage (base) with two halves of the heat shield in view, on either side. Image courtesy: ISRO
On the NavIC and IRNSS projects
As of April 2018, the Navigation with Indian Constellation (NavIC) is an already an established and functional provider of accurate position information across India. NavIC is an autonomous regional satellite navigation system that can provide users with accurate real-time positioning and timing information. For now, NavIC's range covers all of India and a region that stretches some 1,500 kilometres outwards. There are plans to further extend the range in the future.
All commercial vehicles are now required to have a NavIC-based vehicle tracker system fitted to them. Over 75 companies are now manufacturing NavIC-based vehicle trackers across the country, with several thousand vehicles now plying on India's roads equipped with NavIC-powered technology, Singh said. NavIC's services are also available to the general public, via a recently-updated version of a mobile app for GPS-tracking services within the satellite's (nationwide) range.
Interestingly, Qualcomm has collaborated with ISRO to develop and test chipset platforms across its portfolio to support NavIC's technology usage. This NavIC technology will (per an ISRO press release from Oct 2019) be available on Qualcomm's OEM platforms starting November 2019, and in commercial devices with NavIC support are expected to be available during the first half of 2020.
Apart from civilian and transportation, NavIC's technology has also been useful in applications like drones, surveillance, balloon weather-research instruments, forestry, agriculture, among others.
Satellite data for pollution monitoring
The INSAT-3D and -3DR satellites are oddballs. They are useful in meteorology, data relaying and search and rescue operations. They were developed by ISRO and launched in July 2013 and August 2016. The Imager payloads on both these satellites are useful in monitoring Aerosol Optical Depth (AOD) – an indicator of particles and smoke from biomass-burning, which can affect particulate matter (both PM2.5 and PM10) concentrations in the atmosphere.
INSAT-3D and 3DR can generate 3-D maps of atmosphere. land and ocean for various observations. Image: ISRO
These measures come in extremely useful to monitor air pollution in the North of India, which is plagued with poor air quality – enough to make it a major public health emergency every winter in recent years. Singh also drew attention to spatial maps made available on web portals (IIRS Air Quality, MOSDAC) to visualise aerosol levels, courtesy data from the INSAT 3D & 3DR.
A big contributor to winter air quality during winters in several states of Northern India is stubble burning, which isn't very well understood. Data from the Indian Remote Sensing (IRS) satellite can help generate maps to track down areas with a lot of stubble burning activity during the Kharif season (winter, harvest), during which stubble burning becomes a grave concern. ISRO has been monitoring stubble burning since 2015, Singh said, and the resulting product is "comparable to NASA's products".
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