However, the lander deviated from its intended trajectory starting at 2.1 kilometres (1.3 mi) altitude, and had lost communication when touchdown confirmation was expected. Initial reports suggesting a crash have been confirmed by ISRO chairman K. Sivan, stating that the lander location had been found, and "it must have been a hard landing".
As of 8 September 2019, on-going efforts are being made by ISRO in hopes of restoring communications with Vikram. Both ISRO and NASA are in the process of trying to restore communications through their respective Deep Space Networks. Communication attempts will likely cease on 21 September 2019, fourteen days after Vikram's landing attempt. The orbiter, part of the mission with eight scientific instruments, remains operational and is expected to continue its seven-year mission to study the Moon.
On 12 November 2007, representatives of the Russian Federal Space Agency (Roscosmos) and ISRO signed an agreement for the two agencies to work together on the Chandrayaan-2 project. ISRO would have the prime responsibility for the orbiter and rover, while Roscosmos was to provide the lander. The Indian government approved the mission in a meeting of the Union Cabinet, held on 18 September 2008 and chaired by Prime MinisterManmohan Singh. The design of the spacecraft was completed in August 2009, with scientists of both countries conducting a joint review.
Although ISRO finalised the payload for Chandrayaan-2 per schedule, the mission was postponed in January 2013 and rescheduled to 2016 because Russia was unable to develop the lander on time. Roscosmos later withdrew in wake 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 Russia cited its inability to provide the lander even by 2015, India decided to develop the lunar mission independently.
The spacecraft's launch had been scheduled for March 2018, but was first delayed to April and then to October to conduct further tests on the vehicle. On 19 June 2018, after the program's fourth Comprehensive Technical Review meeting, a number of changes in configuration and landing sequence were planned for implementation, pushing the launch to the first half of 2019. Two of the lander's legs got minor damage during one of the 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.
As of September 2019, the Chandrayaan-2 orbiter was orbiting the Moon on a polar orbit at an altitude of 100 km (62 mi). It carries eight scientific instruments; two of which are improved versions of those flown on Chandrayaan-1. The approximate launch mass was 2,379 kg (5,245 lb). The Orbiter High Resolution Camera (OHRC) will conduct 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 and delivered to ISRO Satellite Centre on 22 June 2015.
The Vikram lander detached from the orbiter and descended to a low lunar orbit of 30 km × 100 km (19 mi × 62 mi) using its 800 N (180 lbf) liquid main engines. It then performed a comprehensive check of all its on-board systems before attempting a soft landing that would have deployed the rover, and perform scientific activities for approximately 14 Earth days. Vikram spacecraft apparently crash-landed. The lander's location has been spotted on the surface via thermal imaging, but its condition is unknown. The approximate combined mass of the lander and rover is 1,471 kg (3,243 lb).
The preliminary configuration study of the lander was completed in 2013 by the Space Applications Centre (SAC) in Ahmedabad. The lander's propulsion system consists of eight 50 N (11 lbf) thrusters for attitude control and five 800 N (180 lbf) liquid main engines derived from ISRO's 440 N (99 lbf) Liquid Apogee Motor. Initially, the lander design employed four main liquid engines, but a centrally mounted engine was added to handle new requirements of having to orbit the Moon before landing. The additional engine was expected to mitigate upward draft of lunar dust during the soft landing.Vikram was designed to safely land on slopes up to 12°.
Some associated technologies include a high resolution camera, Laser Altimeter (LASA), Lander Hazard Detection Avoidance Camera (LHDAC), Lander Position Detection Camera (LPDC), Lander Horizontal Velocity Camera (LHVC), an 800 N throttleable liquid main engine,attitude thrusters, Ka band radio altimeters (KaRA), Laser Inertial Reference & Accelerometer Package (LIRAP), and the software needed to run these components. Engineering models of the lander began undergoing ground and aerial tests in late October 2016, in Challakere in the Chitradurga district of Karnataka. ISRO created roughly 10 craters on the surface to help assess the ability of the lander's sensors to select a landing site.
The mission's rover is called Pragyan (Sanskrit: प्रज्ञान, lit. 'Wisdom') Pronunciation (help·info)) with a mass of 27 kg (60 lb), would have operated on solar power. The rover was to move on 6 wheels traversing 500 meters on the lunar surface at the rate of 1 cm per second, perform on-site analyses and send the data to the lander, which would have relayed it to the Mission Control on the Earth. For navigation, the rover uses:
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 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 Pragyan rover was one lunar day, or around 14 Earth days, as its electronics were not designed to endure the frigid lunar night. However, its power system has a solar-powered sleep/wake-up cycle implemented, which could have resulted in longer service time than planned. Two aft wheels of the rover have the ISRO logo and the State Emblem of India embossed on them to leave behind patterned tracks on the lunar surface, which is used to measure the exact distance travelled, also called visual odometry.
ISRO selected eight scientific instruments for the orbiter, four for the lander, and two for the rover. While 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.
Dual Frequency L and S bandSynthetic 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).
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.
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.
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.
Chandrayaan-2 launch was initially scheduled for 14 July 2019, 21:21 UTC (15 July 2019 at 02:51 IST local time). However, the launch was aborted 56 minutes and 24 seconds before launch due to a technical glitch, so it was rescheduled to 22 July 2019. Unconfirmed reports later cited a leak in the nipple joint of a helium gas bottle as the cause of cancellation.
Finally Chandrayaan-2 was launched on-board the GSLV MK III M1 launch vehicle on 22 July 2019 at 09:13 UTC (14:43 IST) with better-than-expected apogee as a result of the cryogenic upper stage being burned to depletion, which later eliminated the need for one of the apogee-raising burns during the geocentric phase of mission. This also resulted in the saving of around 40 kg fuel onboard the spacecraft.
Immediately after launch, multiple observations of a slow-moving bright object over Australia were made, which could be related to upper stage venting of residual LOX/LH2 propellant after the main burn.
After being placed into a 45,475 × 169 km parking orbit by the launch vehicle, the Chandrayaan-2 spacecraft stack gradually raised its orbit using on-board propulsion over 22 days. In this phase, one perigee-raising and five apogee-raising burns were performed to reach a highly eccentric orbit of 142,975 × 276 km followed by trans-lunar injection on 13 August 2019. Such long Earth-bound phase with multiple orbit-raising manoeuvres exploiting the Oberth effect was required because of the limited lifting capacity of the launch vehicle and thrust of the spacecraft's on-board propulsion system. A similar strategy was used for Chandrayaan-1 and the Mars Orbiter Mission during their Earth-bound phase trajectory. On 3 August 2019, the first set of Earth images were captured by the LI4 camera on the Vikram lander, showing North American landmass.
After 29 days from its launch, the Chandrayaan-2 spacecraft stack entered lunar orbit on 20 August 2019 after performing a lunar orbit insertion burn for 28 minutes 57 seconds. The three-spacecraft stack was placed into an elliptical orbit that passes over the polar regions of the Moon, with 18,072 km (11,229 mi) aposelene and 114 km (71 mi) periselene. By 1 September 2019 this elliptical orbit was made nearly circular with 127 km (79 mi) aposelene and 119 km (74 mi) periselene after four orbit-lowering maneuvers followed by separation of Vikram lander from the orbiter on 7:45 UTC, 2 September 2019.
Vikram began its descent at 20:08:03 UTC, 6 September 2019 and was scheduled to land on the Moon at around 20:23 UTC. The descent and soft-landing were to be done by the on-board computers on Vikram, with mission control unable to make corrections.
The initial descent was considered within mission parameters, passing critical braking procedures as expected, but the lander's trajectory began to deviate at about 2.1 kilometres (1.3 mi; 6,900 ft) above the surface. The final telemetry readings during ISRO's live-stream show that Vikram's final vertical velocity was 58 m/s (210 km/h) at 330 meters above the surface which, according to the MIT Technology Review, is "quite fast for a lunar landing." Initial reports suggesting a crash were confirmed by ISRO chairman K. Sivan, stating that the lander location was found and that "it must have been a hard landing".
Radio transmissions from the lander were tracked during descent by analysts using a 25-meter radio telescope owned by the Netherlands Institute for Radio Astronomy. Analysis of the doppler data suggests that the loss of signal coincided with the lander impacting the lunar surface at a velocity of nearly 50 metres (160 ft) per second (as opposed to an ideal 2 metres (6.6 ft) per second touchdown velocity).
The powered descent was also observed by the Lunar Reconnaissance Orbiter using its Lyman-Alpha Mapping Project (LAMP) instrument to study changes in the lunar exosphere due to exhaust gases from the lander's engines.
The mission's orbiter used thermal imaging to locate the lander. Unconfirmed reports, citing an ISRO official, stated that the lander was intact, but there has been no official announcement by ISRO on the lander's physical condition.
ISRO's Chairman, K. Sivan, tasked senior scientist P. S. Goel to head the Failure Analysis Committee to look into the causes of the failure. As of 8 September 2019, ongoing efforts are being made by ISRO in hopes to restore communications with Vikram, while NASA's Lunar Reconnaissance Orbiter (LRO) is scheduled to fly over and acquire optical images for ISRO on 17 September 2019.
The orbiter part of the mission, with eight scientific instruments, remains operational, and will continue its seven-year mission to study the Moon.
A view of Mission Operations Complex (MOX-1), ISTRAC prior to the fourth Earth-bound burn.
Key scientists and engineers involved in the development of Chandrayaan-2 include:
^Monier Monier-Williams, A Sanskrit-English Dictionary (1899):
candra: "[...] m. the moon (also personified as a deity Mn. &c)"
yāna: "[...] n. a vehicle of any kind , carriage , waggon , vessel , ship , [...]"
^"Chandrayaan-2 FAQ". Retrieved 24 August 2019. The name Chandrayaan means “Chandra- Moon, Yaan-vehicle”, –in Indian languages (Sanskrit and Hindi), – the lunar spacecraft.
^"ISRO developing vehicle to launch small satellites". Frontline. Retrieved 29 August 2018. Making a throttleable engine of 3 kilonewtons or 4 kilonewtons is a totally new development for us. But we wanted to make use of available technologies. We have a LAM [liquid apogee motor] with a 400 newton thruster, and we have been using it on our satellites. We enhanced it to 800 newtons. It was not a major, new design change.
^"Chandrayaan-2: First step towards Indians setting foot on moon in near future". The New Indian Express. Retrieved 8 July 2019. As solar energy powers the system, a place with good visibility and area of communication was needed. Also, the place where the landing takes place should not have many boulders and craters. The slope for landing should be less than 12 degrees. The South pole has a near-flat surface, with good visibility and sunlight available from the convenience point of view,
^Elumalai, V.; Kharge, Mallikarjun (7 February 2019). "Chandrayaan – II"(PDF). PIB.nic.in. Archived from the original(PDF) on 7 February 2019. Retrieved 7 February 2019. Lander (Vikram) is undergoing final integration tests. Rover (Pragyan) has completed all tests and waiting for the Vikram readiness to undergo further tests.
^Annadurai, Mylswami; Nagesh, G.; Vanitha, Muthayaa (28 June 2017). ""Chandrayaan-2: Lunar Orbiter & Lander Mission", 10th IAA Symposium on The Future of Space Exploration: Towards the Moon Village and Beyond, Torin, Italy". Archived from the original on 29 June 2017. Retrieved 14 June 2019. Mobility of the Rover in the unknown lunar terrain is accomplished by a Rocker bogie suspension system driven by six wheels. Brushless DC motors are used to drive the wheels to move along the desired path and steering is accomplished by differential speed of the wheels. The wheels are designed after extensive modelling of the wheel-soil interaction, considering the lunar soil properties, sinkage and slippage results from a single wheel test bed. The Rover mobility has been tested in the Lunar test facility wherein the soil simulant, terrain and the gravity of moon are simulated. The limitations w.r.t slope, obstacles, pits in view of slippage/sinkage have been experimentally verified with the analysis results.
^India Heads to the Moon With Chandrayaan 2. David Dickinson, Sky & Telescope. 22 July 2019. Quote: "Vikram carries a seismometer, thermal probe, and an instrument to measure variation and density of lunar surface plasma, along with a laser retro-reflector supplied by NASA's Goddard Spaceflight Center."