How Chandrayaan-1 helped to confirm and reconfirm water on the moon

Written by Amitabh Sinha
| Pune |

Updated: August 22, 2018 14:15:26 pm

Chandrayaan, Chandrayaan-1 mission, moon water, water on moon, Indian moon mission, Chandrayaan moon mission, NASA, ISRO, chandrayaan 2 mission NASA said that the ice deposits had been divided into clearances and could "be of old". (File)

On Tuesday, the American space agency NASA announced that a team of scientists, while studying data generated by an instrument that traveled the Indian spaceship Chandrayaan-1 in 2008, directly & # 39; definite evidence & # 39; of water ice on the surface of the moon had been observed. NASA said that the ice deposits had been divided into clearances and could "be of old".

"M3 (NASA & # 39; s Moon Mineralogy Mapper) aboard the spaceship Chandrayaan-1 … was uniquely equipped to confirm the presence of solid ice on the moon, gathering data that not only picked up the reflective properties that we of ice, but was also able to measure the distinctive way in which molecules absorb infrared light, so that it can distinguish between liquid water or vapor and solid ice, "NASA said in a statement.

Although NASA & # 39; s announcement is based on the results of a new study, published in the Proceedings of the National Academy of Sciences, this is not the first time that evidence of water on the moon has been found. It is also not the first time that the contribution of Chandrayaan-1 is recognized when establishing such evidence.

First confirmation

In September 2009, data from the same M3 instrument was used to announce "unambiguous evidence" for the presence of water over the lunar surface. This announcement was made after M3 data had been confirmed by observations from NASA & # 39; s EPOXI spacecraft as it passed the moon on its way to comet Hartley 2 and a re-evaluation of the data produced by a spectrometer onboard Cassini spacecraft in 1999. The data from ISRO's hyperspectral imager, an instrument used for minerals mapping, also aboard Chandrayaan-1, added the evidence.

Distribution of surface ice (blue) on the south side of the moon (left) and the north pole of the moon, detected by the NASA M3 instrument aboard Chandrayaan-1. (Source: NASA)

That announcement was seen as the final confirmation of water on the moon, something that had been assumed since the first lunar missions in the 1960s and 1970s. Water molecules were mostly found in the polar regions of the moon.

Days after that announcement, ISRO said that another instrument on Chandrayaan-1, the Moon Impact Probe or MIP, had provided convincing evidence of water on the moon. ISRO said that this evidence was available at least a few months before NASA announcement. MIP, a cube-shaped instrument weighing 35 kg on all sides with the tricolor, is the first Indian object to land on the moon.

G Madhavan Nair, president of ISRO during the launch of Chandrayaan-1, explained why the agency could not publish the findings of the MIP: "There was an instrument within MIP that was supposed to determine the moisture content in the lunar surface. a clear signature (of the presence of water), but unfortunately there were some calibration anomalies in the data that prevented us from quantifying the amount of water content, which meant we were not in a position to publish the results. "However, Nair said the data of the hyperspectral imager were very useful to determine the presence of water.


After 2009, several studies have pointed to the presence of water in various forms. Most of these used the same datasets as used for the 2009 announcement.

For example, in August 2013, a team of American scientists looked at the same M3 data and detected magmatic water, "or water that originates within the moon" on the moon surface. A NASA statement said it represented the "first detection of this form of water from the lunar orbit of the moon".

Last year, another team used M3 data and produced the first map of water distribution on the lunar surface, showing that it was scattered across the moon and not just in the polar regions.

In February of this year, NASA reported a new analysis of data from two lunar missions that suggested new evidence that water across the surface was "widespread". It said that the water seemed "present day and night, although it is not necessarily easily accessible".

The latest discovery, that of solid ice, brings these discoveries forward. "Most of the rediscovered water ice lies in the shadow of craters at the poles, where the warmest temperatures never exceed -250 ° F (-150 ° C), because of the very small tilt of the Moon's rotation axis. sunlight never this region's, "according to the NASA statement.

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