Hopes to retrieve the Vikram lander, with rover Pragyan housed inside it, are fading as the 14-day window for the Indian Space Research Organisation (Isro) to restore its link with the lander ended on Saturday (September 21). The lander and the rover have a mission life of 14 earth days. Lander Vikram, with rover Pragyan housed inside it, lost communication with ground-station on September 7 seven during its final descent, just 2.1 km above the lunar surface, minutes before the planned touch-down on the Moon. The space agency’s efforts to re-establish the lost link with the Vikram lander had been going on since then. However, the deadline to reestablish contact with the Vikram lander ended on Saturday since it has been 14 days since the Isro lost its contact with the lander. A day later losing contact with the lander, the space agency said the lander was spotted on the lunar surface by camera on-board of the Chandrayaan-2 orbiter. Vikram lander had a hard-landing, Isro had said. An Isro official associated with the Chandrayaan-2 mission later claimed that the lander lies on the lunar surface as a single piece, unbroken and it is in a tilted position. “The lander is there [on the lunar surface] as a single piece, not broken into pieces. It’s in a tilted position,” he said.
“Progressively, you can imagine that it becomes that much more difficult, with each passing hour, the available power on the battery gets drained out, and there won’t be anything left for it to power and operate,” an Isro official had said. “With every passing minute, the situation becomes worse only…less and less probable (to establish contact with Vikram,” he said, adding, “the chance to reestablish the link looks more and more remote only” since its system functionality was a prerequisite to achieve that.
On 12 November 2007, an agreement was signed between Russian Federal Space Agency(Roscosmos) and ISRO to work together for Chandrayaan-2 project. It was discussed that ISRO have responsibilities for orbiter and rover, while Roscosmos will provide the lander. So, on September 18, 2008 GOI approved the mission chaired under PM Manmohan Singh. By August 2009, the design of spacecraft was complete jointly by the scientists of both the countries. ISRO prepared the payload for the mission on time but Russia failed to prepare lander on time. So the mission was postponed to January 2013 and later rescheduled to 2016 after which Russia took a step back from the mission because of the failure of the Fobos-Grunt mission to Mars, since the technical aspects connected with the Fobos-Grunt mission were also used in the lunar projects, which needed to be reviewed. When Russian exclaimed its inability to provide the lander even by 2015, India decided to go ahead with the mission all alone.
The spacecraft’s launch was first schedule for March 2018 which got extended to April and then to October to conduct further tests. On 19 June 2018, after the program’s fourth Comprehensive Technical Review meeting terminated with a number of changes, launching was pushed to first half of 2019. Two of the lander’s legs got damaged during one of the damage tests in February 2019. Chandrayaan-2 launch was initially scheduled for 14 July 2019, 21:21 UTC (15 July 2019 at 02:51 IST local time), with the landing expected on 6 September 2019. However, the launch was aborted due to a technical glitch and was rescheduled. The launch occurred on 22 July 2019 at 09:13 UTC (14:43 IST) on the first operational flight of a GSLV MK III M1.
The mission was launched on a Geosynchronous Satellite Launch Vehicle Mark III which is nothing but a three stage medium lift launch vehicle developed by ISRO especially designed for launching. It has an approximate lift-off mass of 3,850 kg (8,490 lb) and was launched from Satish Dhawan Space Centre on Sriharikota Island.
As of June 2019, the mission has an allocated cost of ₹978 crore (approximately US$141 million) which includes ₹603 crore for space segment and ₹375 crore as launch costs on GSLV Mk III. Chandrayaan-2 stack was initially put in an Earth parking orbit of 170 km perigee and 40,400 km apogee by the launch vehicle.
Till September 2019, the orbiter was orbiting moon at an altitude of 100km. It carries eight scientific instruments among which two are modified versions of those in Chandrayaan-1. The Orbiter High Resolution Camera (OHRC) is aimed to have high-resolution observations of the landing site prior to separation of the lander from the orbiter. The orbiter’s structure was manufactured by Hindustan Aeronautics Limited filed a tender to manufacture orbiter’s structure which was delivered to ISRO Satellite Centre on 22 June 2015
Specifications of Orbiter
-Dimensions: 3.2 × 5.8 × 2.2 m
-Gross lift-off mass: 2,379 kg (5,245 lb)
-Propellant mass: 1,697 kg (3,741 lb)
-Dry mass: 682 kg (1,504 lb)
-Power generation capacity: 1000 W
-Mission duration: approximately 7.5 years, extended from the planned 1 year owing to the precise launch and mission management, in lunar orbit.
The word Pragyan is taken from Sanskrit literature meaning Wisdom. Pragyan was the name of the rover designed by ISRO . It weighed around 27 kilograms and was operated on solar power. This six wheeled rover aimed to traverse 500 metres at a speed of 1cm per second in order to perform on-site analysis and hence forwarding data to Vikram lander which would have relayed that data to earth station. For uninterrupted navigation, rover was equipped with:
- Stereoscopic camera-based 3D vision: two 1 megapixel, monochromatic NAVCAMs in front of the rover to provide the ground control team a 3D view of the surrounding terrain, and help in path-planning by generating a digital elevation model of the terrain. IIT Kanpur contributed to the development of the subsystems for light-based map generation and motion planning for the rover.
- Control and motor dynamics: the rover design has a rocker-bogie suspension system and six wheels, each driven by independent brushless DC electric motors. Steering is accomplished by differential speed of the wheels or skid steering.
The expected operating time of rover was one lunar day or fourteen earth days because its system was not designed in a way to get a hold if chilling lunar night. Its power system had a solar-powered sleep/wake-up cycle implemented, which could have resulted in longer service time than planned. The Pragyan rover was carried by Vikram Lander.
Dimensions: 0.9 × 0.75 × 0.85 m
Power: 50 W
Travel speed: 1 cm/sec.
Mission duration: ≤14 days (one lunar day)
Planned Landing Sites
Two landing sites namely the prime landing site (PLS54) at 70.90267 S 22.78110 E (~350 km north of the South Pole-Aitken Basin rim), and the site ALS01 at 67.874064 S 18.46947 W were selected after proper inspection.
The prime site was on a high plain between the craters Manzinus C and Simpelius N, on the near side of the Moon. The criteria used to select the landing zones were: south polar region, on the near side, slope less than 15 degrees, boulders less than 50 cm (20 in), crater and boulder distribution, sunlit for at least 14 days, nearby ridges do not shadow the site for long durations.
The planned landing site and its alternate site, are located within the polar LQ30 quadrangle. The surface likely consists of impact melt, possibly mantled by ejecta from the massive South Pole–Aitken basin and mixing by subsequent nearby impacts. The nature of the melt is mostly mafic, meaning it is rich in silicate mineral, magnesium and iron. The region could also offer scientifically valuable rocks from the lunar mantle if the basin impactor excavated all the way through the crust.
ISRO choose eight scientific instruments for orbiter, four for lander and two for rover. It was initially reported that NASA and ESA would participate in the mission by providing some scientific instruments for the orbiter, ISRO in 2010 had clarified that due to weight restrictions it will not be carrying foreign payloads on this mission. However, in an update just a month before launch, an agreement between NASA and ISRO was signed to include a small laser retroreflector from NASA to the lander’s payload to measure the distance between the satellites above and the microreflector on the lunar surface. Payloads are basically the items which were boarded on the lander. The eight payloads on orbiter were:
1. Chandrayaan-2 Large Area Soft X-ray Spectrometer (CLASS) from ISRO Satellite Centre (ISAC), makes use of X-ray fluorescence spectra to determine the elemental composition of the lunar surface.
2. Solar X-ray monitor (XSM) from Physical Research Laboratory (PRL), Ahmedabad for mapping major elements present on the lunar surface.
3. Dual Frequency L and S band Synthetic Aperture Radar (DFSAR) from Space Applications Centre (SAC) for probing the first few meters of the lunar surface for the presence of different constituents, including water ice. DFSAR is expected to provide further evidence confirming the presence of water ice, and its distribution below the shadowed regions of the Moon. It has lunar surface penetration depth of 5 meters (L-band).
4. Imaging IR Spectrometer (IIRS) from Space Applications Centre (SAC) for mapping of lunar surface over a wide wavelength range for the study of minerals, water molecules and hydroxyl present. It works up to 5 microns, an improvement over previous lunar missions whose payloads worked up to 3 microns.
5. Chandrayaan-2 Atmospheric Compositional Explorer 2 (ChACE-2) Quadrupole Mass Analyzer from Space Physics Laboratory (SPL) to carry out a detailed study of the lunar exosphere.
6. Terrain Mapping Camera-2 (TMC-2) from Space Applications Centre (SAC) for preparing a three-dimensional map essential for studying the lunar mineralogy and geology.
7. Radio Anatomy of Moon Bound Hypersensitive Ionosphere and Atmosphere — Dual Frequency Radio Science experiment (RAMBHA-DFRS) by SPL for the studying electron density in the Lunar ionosphere.
8. Orbiter High Resolution Camera (OHRC) by SAC for scouting a hazard-free spot prior to landing. It will later help prepare high-resolution topographic maps and digital elevation models of the lunar surface. OHRC has spatial resolution of 0.3 m from 100 km polar orbit.
Pragyan rover carries two instruments to determine the abundance of elements near the landing site:
-Laser induced Breakdown Spectroscope (LIBS) from Laboratory for Electro Optic Systems (LEOS), Bangalore.
-Alpha Particle Induced X-ray Spectroscope (APXS) from PRL, Ahmedabad.
Pragyan rover was carried by Vikram lander and so the losing communication with the lander created nightmares for ISRO after adrenaline rush. So what was this Vikram lander and lets know more about it.
The Lander of Chandrayaan 2 is named Vikram after Dr Vikram A Sarabhai, the Father of the Indian Space Programme. It is designed to function for one lunar day, which is equivalent to about 14 Earth days. Vikram has the capability to communicate with IDSN at Byalalu near Bangalore, as well as with the Orbiter and Rover. The Lander is designed to execute a soft landing on the lunar surface. Pragyan can only communicate with the Lander. So losing connection with lander signifies the lost in connection with pragyan as well. The lander weighed 1471 kg and operates at a power of 650 W.
At the time of launch, the Chandrayaan 2 Orbiter will be capable of communicating with Indian Deep Space Network (IDSN) at Byalalu as well as the Vikram Lander. The mission life of the Orbiter is one year and it will be placed in a 100X100 km lunar polar orbit. It weighed 2379 kg and required an electric power generation of 1000W.