Chandrayaan-2 Explained


  • A day after it announced the launch date for the Chandrayaan-2 mission, the Indian Space Research Organisation (ISRO) said it intended to build a permanent station in space in the next five to seven years. It seems to be a logical step forward, after the exploratory missions to the Moon (Chandrayaan -1) and Mars (Mangalyaan), the upcoming Lander and Rover mission to Moon (Chandrayaan-2), the declared human space flight before 2022 (Gaganyaan), and a possible, still undeclared, human mission to the Moon sometime later.
  • With these missions, ISRO has also been signalling a distinct change in its priorities — henceforth, it would be an agency engaged mainly in space and inter-planetary exploration, while other ventures like commercial satellite launches would only be secondary activities. Much would, however, depend on the success of Chandrayaan-2 and Gaganyaan.


  • A natural sequel to Chandrayaan-1, an Orbiter mission launched in October 2008, Chandrayaan-2 has taken a long way coming. It was originally scheduled to be launched in 2012, but at that time the lander module was supposed to come from Russian space agency Roskosmos. The Russians, however, withdrew after their similarly designed lander for another mission developed problems in 2011. That left it on ISRO to design, develop and build the lander on its own, which has taken a few years.
  • Now, it is expected to produce much more science than Chandrayaan-1 could. Chandrayaan-1, ISRO’s first exploratory mission to moon, was designed to just orbit the Moon and make observations with instruments on board. The closest the spacecraft came was in an orbit 100 km from the Moon surface.
  • For largely symbolic reasons, though, the Chandrayaan-1 mission did send one of its instruments, called Moon Impact Probe, or MIP, a 35-kg cube-shaped module with the Indian tricolour on all its sides, to crash-land on the Moon’s surface. ISRO later claimed data sent by MIP on its way to the Moon had shown evidence of presence of water, but it could not publish those findings because of anomalies in calibration.
  • The confirmation for water had come through studies on data produced by another instrument onboard the Chandrayaan-1 spacecraft, the M3 or Moon Mineralogy Mapper, that had been put by NASA.
  • Chandrayaan-2 consists of an Orbiter, Lander and Rover, all equipped with scientific instruments to study the moon. The Orbiter will once again orbit from 100 km away, while the Lander and Rover modules will separate and make a soft-landing on the surface. ISRO has named the Lander module Vikram, after Vikram Sarabhai, and the Rover module Pragyaan, meaning wisdom.

The Lander

  • The Lander is the distinguishing feature. It is the first time that ISRO is attempting to soft-land a module in extra-terrestrial space. The main challenge is in controlling its speed as it approaches the surface. Once the Lander and the Rover, enter the Moon’s gravity, they would be in a state of free fall. That could end in crash-landing and destruction of instrument; because of lack of air to provide drag, these instruments cannot make use of parachute-like technologies. Instead, the Lander fires thrusters in the opposite direction to slow down. To enable a smooth landing, the speed of the Lander just ahead of touchdown should be 1 m/s (3.6 km/h) or less.
  • Once on the Moon, the Rover, a six-wheeled solar-powered vehicle, will detach itself and slowly crawl on the surface, making observations and collecting data. It will be equipped with two instruments, and its primary objective will be to study the composition of the surface near the lunar landing site, and determine its abundance of various elements.
  • The 1471-kg Lander, which will remain stationary after touching down, will carry three instruments that will mainly study the moon’s atmosphere. One of these will also look out for seismic activity.
  • While the Lander and Rover are designed to work for only 14 days (1 lunar day), the Orbiter, a 2,379-kg spacecraft with seven instruments on board, would remain in orbit for a year. It is equipped with different kinds of camera to take create high-resolution three-dimensional maps of the surface. It also has instruments to study the mineral composition on moon and the lunar atmosphere, and also to assess the abundance of water.

Uncharted territory

  • With Chandrayaan-2, India will become only the fourth country to land a spacecraft on Moon. So far, all landings, human as well as non-human, have been in areas close to the Moon’s equator. That was mainly because this area receives more sunlight, which is required by solar-powered instruments. In January this year, China landed a lander and rover on the Moon’s far side (not facing the Earth). This was the first time any landing had taken place on that side. The Chinese mission, Chang’e 4, was designed to function for three lunar days but has already entered its fifth lunar night.
  • Chandrayaan-2 will make a landing at a site where no earlier mission has gone, near the south pole of the Moon. The unexplored territory offers an opportunity for the mission to discover something new. Incidentally, the crash-landing of the MIP from Chandrayaan-1 had happened in the same region of the Moon.
  • The south pole of the Moon holds possibility of presence of water. In addition, this area is also supposed to have ancient rocks and craters that can offer indications of history of the Moon, and also contain clues to the fossil records of early solar system.
    Space Station
  • ISRO has not announced any date for establishing a space station. And that is because it would crucially depend on the success of Gaganyaan which will demonstrate the agency’s capability to send astronauts and bring them back safely. Until a human space flight becomes successful, the space station would be meaningless.
  • As of now, only NASA’s International Space Station is operational. Before that, the Mir station built by the erstwhile Soviet Union was the only such facility available. China is the only other country to have a space station programme, and it has tested out technologies through two Tiangong spacecraft. It is not yet ready to support habitation for astronauts.


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