Chandrayaan-2: India's Orbiter-Lander-Rover Mission
An illustration of India's Chandrayaan-2 lunar spacecraft.
Credit: ISRO

Chandrayaan-2 is India's planned second mission to the moon, which is expected to launch in 2018. It is a follow-up mission from the Chandrayaan-1 mission that assisted in confirming the presence of water/hydroxyl on the moon in 2009. Chandrayaan-2 will launch from the Satish Dhawan Space Center in Sriharikota, India, aboard a Geosynchronous Satellite Launch Vehicle (GSLV) rocket.

According to the Indian Space Research Organization (ISRO), the new mission will consist of an orbiter, a lander and a rover. The orbiter will perform mapping from an altitude of 100 kilometers (62 miles), while the lander will make a soft landing on the surface and send out the rover.

Initially, ISRO planned to partner with Russia to perform Chandrayaan-2. The two agencies signed an agreement in 2007 to launch the orbiter and lander in 2013. Russia later pulled out of the agreement, however, according to a news report from The Hindu. The Russian lander's construction was delayed after the December 2011 failure of Roscosmos' Phobos-Grunt mission to the Martian moon of Phobos, the report stated. 

Russia subsequently pulled out of Chandrayaan-2 altogether, citing financial issues. Some reports stated that NASA and the European Space Agency were interested in participating, but ISRO proceeded with the mission on its own.

The Chandrayaan-2 orbiter will circle the moon and provide information about its surface, ISRO stated. "The payloads will collect scientific information on lunar topography, mineralogy, elemental abundance, lunar exosphere and signatures of hydroxyl and water-ice," ISRO said on its website. The mission will also send a small, 20-kilogram (44 lbs.), six-wheeled rover to the surface; the rover will move semi-autonomously, examining the lunar regolith's composition.

This is the list of instruments on the orbiter, according to the Planetary Society:

  • Terrain Mapping Camera 2 (TMC-2), which will map the lunar surface in three dimensions using two on-board cameras. A predecessor instrument called TMC flew on Chandrayaan-1.
  • Collimated Large Array Soft X-ray Spectrometer (CLASS), which will map the abundance of minerals on the surface. A predecessor instrument called CIXS (sometimes written as C1XS) flew on Chandrayaan-1.
  • Solar X-ray Monitor (XSM), which looks at emissions of solar X-rays.
  • Chandra's Atmospheric Composition Explorer (ChACE-2), which is a neutral mass spectrometer. A predecessor instrument called CHACE flew on Chandrayaan-1's Moon Impact Probe.
  • Synthetic Aperture Radar (SAR), which will map the surface in radio waves. Some of its design is based on Chandrayaan-1's MiniSAR.
  • Imaging Infra-Red Spectrometer (IIRS), which will measure the abundance of water/hydroxl on the surface.
  • Orbiter High Resolution Camera (OHRC) to examine the surface, particularly the landing site of the lander and rover.

The lander's instruments include:

  • Instrument for Lunar Seismic Activity (ILSA), to look for moonquakes.
  • Chandra's Surface Thermophysical Experiment (ChaSTE), to examine the surface's thermal properties.
  • Radio Anatomy of Moon Bound Hypersensitive ionosphere and Atmosphere (RAMBHA-Langmuir Probe), to look at plasma density on the surface.

The rover will carry two science instruments to look at the composition of the surface: the Laser-Induced Breakdown Spectroscope (LIBS) and the Alpha Particle X-Ray Spectrometer (APXS).

Chandrayaan-2's lander and rover are targeted for a location about 600 kilometers (375 miles) from the south pole, which would be the first time any mission touched down so far from the equator, according to a January 2018 article in Science magazine. ISRO plans to use the experience for more challenging missions in the future, such as touching down on an asteroid or Mars, or sending a spacecraft to Venus, IRSO chair Kailasavadivoo Sivan said in the article.

The lander is expected to last about one lunar day, or 14 Earth-days; it is unclear if it will revive after falling into the darkness of a lunar night. Its measurements of moonquakes would provide more data after the information collected by the human Apollo missions in the 1960s and 1970s, according to Science. Meanwhile, the terrain explored by the rover is of great scientific interest due to the rocks' old age; at 4 billion years old, scientists say the zone likely is composed of an ancient magma ocean.

While NASA is not directly participating in this mission, the measurements taken by Chandrayaan-2 could be a help for future lunar missions. That is because in late 2017, the agency was tasked by the Trump administration to return humans to the moon in the coming years.

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