Lunar water is water that is present on the Moon. Liquid water cannot persist at the Moon’s surface, and water vapor is decomposed by sunlight, with hydrogen quickly lost to outer space. However, scientists have since the 1960s conjectured that water ice could survive in cold, permanently shadowed craters at the Moon’s poles.
Scientists are still confused about the amount of water present on Moon, our closest cosmic neighbor. Some scientists say that water is present on Moon in a particular region while others claim that water on Moon is widespread. But a recent study looked at the data from two lunar missions and concluded that water is present widely across the lunar surface and is not confined to a particular region or a specific terrain. Although water is widely distributed and present day and night on Moon, getting access to it is pretty difficult, as informed by the study.
The lead of the study, Joshua Bandfield, a senior research scientist with the Space Science Institute in Boulder, Colorado, said, “We find that it doesn’t matter what time of day or which latitude we look at, the signal indicating water always seems to be present.” Bandfield further said that the presence of water does not appear to be dependent on the composition and water and it sticks around on the lunar surface. The latest findings will prove to be beneficial in understanding the origin of water on Moon and also it’s possible to be used as a resource on Moon. If it is found out that water is accessible on Moon, then it will definitely boost up the human exploration mission for Moon as well as Mars.
Previous researchers suggested that water is present mainly at the polar altitudes of Moon and the waters signal strength varies according to the lunar day. So, the scientists hypothesized that that water molecule could “hop” across the lunar surface until they move into cold traps in the dark reaches of craters near the north and south poles of Moon. These cold traps can keep the water and another volatiles stable for several billion years. All these studies were based on the measurements remote-sensing instruments. These instruments measure the strength of sunlight reflected off the lunar surface and from this, the scientists estimated the strength of water.
But, Bandfield and his team followed a different method to incorporate temperature information and created a detailed model by using measurements taken by the Diviner instrument fitted on NASA’s Lunar Reconnaissance Orbiter, or LRO. The research team then applied this temperature model to data collected by the Moon Mineralogy Mapper fitted to India’s Chandrayan-1 orbiter. The results suggested that water on Moon is not limited to a specific surface and it is widely spread across the surface in relatively immobile form.
“By putting some limits on how mobile the water or the OH on the surface is, we can help constrain how much water could reach the cold traps in the polar regions,” said Michael Poston of the Southwest Research Institute in San Antonio, Texas.
The researchers are still discussing what the findings tell them about the source of the Moon’s water. The results point toward OH and/or H2O being created by the solar wind hitting the lunar surface, though the team didn’t rule out that OH and/or H2O could come from the Moon itself, slowly released from deep inside minerals where it has been locked since the Moon was formed.
Water, water, everywhere, but is there a drop to drink? Data from 2 lunar missions finds evidence that the Moon’s water is widely distributed across the surface. If the Moon has enough accessible ?, it could be an essential resource to future explorers: https://t.co/4NuyjtO4uS pic.twitter.com/VlkTTKJqcp
— NASA (@NASA) February 24, 2018
“Some of these scientific problems are very, very difficult, and it’s only by drawing on multiple resources from different missions that are we able to hone in on an answer,” said LRO project scientist John Keller of NASA’s Goddard Space Flight Center in Greenbelt, Maryland.
LRO is managed by NASA’s Goddard Space Flight Center in Greenbelt, Maryland, for the Science Mission Directorate at NASA Headquarters in Washington, D.C. JPL designed, built and manages the Diviner instrument.
Below is the extract of the study
Remote-sensing data from lunar orbiters have revealed spectral features consistent with the presence of OH or H2O on the lunar surface. Analyses of data from the Moon Mineralogy Mapper spectrometer onboard the Chandrayaan-1 spacecraft have suggested that OH/H2O is recycled on diurnal timescales and persists only at high latitudes. However, the spatial distribution and temporal variability of the OH/H2O, as well as its source, remain uncertain. Here we incorporate a physics-based thermal correction into the analysis of reflectance spectra from the Moon Mineralogy Mapper and find that prominent absorption features consistent with OH/H2O can be present at all latitudes, local times and surface types examined. This suggests the widespread presence of OH/H2O on the lunar surface without significant diurnal migration. We suggest that the spectra are consistent with the production of OH in space-weathered materials by the solar wind implantation of H+ and formation of OH at crystal defect sites, as opposed to H2O sourced from the lunar interior. Regardless of the specific composition or formation mechanism, we conclude that OH/H2O can be present on the Moon under thermal conditions more wide-ranging than previously recognized.
Following is an excerpt from Wikipedia on Lunar Water
Lunar water is water that is present on the Moon. Liquid water cannot persist at the Moon’s surface, and water vapor is decomposed by sunlight, with hydrogen quickly lost to outer space. However, scientists have since the 1960s conjectured that water ice could survive in cold, permanently shadowed craters at the Moon’s poles. Water molecules are also detected in the thin layer of gases above the lunar surface.
Water (H2O), and the chemically related hydroxyl group (-OH) can also exist in forms chemically bound as hydrates and hydroxides to lunar minerals (rather than as free water), and evidence strongly suggests that this is indeed the case in low concentrations over much of the Moon’s surface. In fact, adsorbed water is calculated to exist at trace concentrations of 10 to 1000 parts per million. In 1978 it was reported that samples returned by the Soviet Luna 24 probe contained 0.1% water by the mass sample. Inconclusive evidence of free water ice at the lunar poles was accumulated from a variety of observations suggesting the presence of bound hydrogen.
On 18 November 2008, the Moon Impact probe was released from India’s Chandrayaan-1 at a height of 100 kilometers (62 mi). During its 25-minute descent, the impact probe’s Chandra’s Altitudinal Composition (CHACE) recorded evidence of water in 650 mass spectra gathered in the thin atmosphere above the Moon’s surface. In September 2009, NASA payload Moon Mineralogy Mapper onboard Chandrayaan-1 detected water on the Moon surface and hydroxyl absorption lines in reflected sunlight. In November 2009, NASA re-confirmed water on the moon with its LCROSS space probe which detected a significant amount of hydroxyl group in the material thrown up from a south polar crater by an impactor; this may be attributed to water-bearing materials – what appears to be “near pure crystalline water-ice”. In March 2010, it was reported that the Mini-SAR onboard Chandrayaan-1 had discovered more than 40 permanently darkened craters near the Moon’s north pole that are hypothesized to contain an estimated 600 million metric tonnes (1.3 trillion pounds) of water-ice.
Water may have been delivered to the Moon over geological timescales by the regular bombardment of water-bearing comets, asteroids, and meteoroids or continuously produced in situ by the hydrogen ions (protons) of the solar wind impacting oxygen-bearing minerals.
The search for the presence of lunar water has attracted considerable attention and motivated several recent lunar missions, largely because of water’s usefulness in rendering long-term lunar habitation feasible.