Daily Answer Writing
10 September 2021

Q. Examine the successes that Chandrayan 2 has achieved over the course of its mission.  (150 Words)

  • Source: The Indian Express - Page 15/Explained: What Chandrayaan-2 has sent
  • GS 3: Science and Technology 


Approach Answer:

Introduction: Chandrayan II was launched in 2019 which contained an Orbiter, a Lander & and a 25kg rover. The Orbiter had a circular orbit around the moon which was aimed at creating a spectral image of moon. Lander Vikram, Named after Dr. Vikram Sarabhai, was to function for 1 lunar day or 14 earth days and perform on-site chemical analysis on the Lunar South Pole, where Chandrayan-I had confirmed the presence of water. Rover Pragyan, a 6 wheeled  robotic vehicle could travel up to 500m using battery powered Solar energy.


Ultimate failure of the mission:

    • The Landing failed: It failed to make a soft-landing on the lunar surface. The lander and rover malfunctioned in the final moments and crash-landed, getting destroyed in the process.
    • Rover couldn't start: Eventually after the hard landing the Rover couldn't be communicated with.
    • ISRO couldn't demonstrate the soft landing capability: Which is essential for any future human mission on moon.


However, the Orbiter had functioning normally, and had send back data from the various instruments on board which has added to our knowledge about the Moon and its environment.


Partial Success:

    • Spectroscopy in greater detail than Chandrayan-I: The eight instruments onboard studied in more detail the elemental composition of the lunar surface and environment, assess the presence of different minerals, and do a more detailed mapping of the lunar terrain.
      • Sources of water. Primordial rock, Water-bearing comets, Hydrogen ions in solar wind chemically combine with Oxygen atoms present in lunar mineral surface.
    • Most Precise study of WATER MOLECULE till date: The instrument used on Chandrayaan-1 to detect water was not sensitive enough to detect whether the signals came from the hydroxyl radical (OH) or the water molecule. The Imaging Infra-Red Spectrometer (IIRS) on board Chandrayaan-2 has been able to distinguish between hydroxyl and water molecules, and found unique signatures of both.
    • Water on surface apart from just Lunar South Pole: Chandrayaan-I had found water only on Lunar South Pole, whereas, Chandrayaan-2 has now found signatures of water at all latitudes, including the water ice at the North Pole and south Pole and water at the far side of the moon. Although its abundance varies from place to place. 
    • MINOR ELEMENTS: The Large Area Soft X-Ray Spectrometer (CLASS) has measured the Moon’s X-ray spectrum to examine the presence of major elements. It has detected the minor elements chromium and manganese for the first time. This can help us understand the magmatic evolution on the Moon and deeper insights into the nebular conditions as well as planetary differentiation.
    • Studying Geo-tail: CLASS has detected charged particles on Moon’s soil, during the orbiter’s passage through the “Geotail”. The Geotail is a region in space that allows the best observations. The region exists as a result of the interactions between the Sun and Earth.
    • Mapping of Lunar Surface: CLASS has mapped nearly 95% of the lunar surface in X-rays for the first time.
    • STYUDYING THE SUN: Solar X-ray Monitor (XSM), has studied the Moon through the radiation coming in from the Sun and has collected information about solar flares. XSM has observed a large number of microflares outside the active region for the first time.
    • Studying the depth of regolith:  it has explored the permanently shadowed regions as well as craters and boulders underneath the regolith, the loose deposit comprising the top surface extending up to 3-4m in depth.


Greater Significance:

    • Expansion of Knowledge about the Moon: It paves the path for future Moon missions. Four aspects — mineralogical and volatile mapping of the lunar surface, surface and subsurface properties and processes involved, quantifying water in its various forms across the Moon surface, and maps of elements present on the moon — will be key for future scope of work.
    • Selection of future landing and drilling sites: Since, it has explored the permanently shadowed regions as well as craters and boulders underneath the regolith, it can help in future selection of landing site.
    • Helping Other space agencies: For example, Japan Aerospace Exploration Agency (JAXA)-ISRO collaboration Lunar Polar Exploration (LUPEX) mission scheduled for launch in 2023/2024 would use this data. NASA’s Artemis missions plan to enable human landing on the Moon beginning 2024 and target sustainable lunar exploration by 2028. The Chinese Lunar Exploration Programme too plans to establish a prototype of the International Lunar Research Station (ILRS) at the lunar south pole and build a platform supporting large-scale scientific exploration.


Conclusion: The Chandrayaan-II mission was a 95% success in terms of the number of goals achieved by the mission according to ISRO. The accident was caused by a relatively small error that has been identified and corrected and would be addressed in Chandrayaan-3, planned for next year. It is expected to have only a lander and rover, and no Orbiter, which can boost pave the way for future manned mission.

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