Scientists have created the first map of water trapped in the uppermost layer of the Moon’s soil which may prove useful to future lunar explorers using data from an instrument aboard India’s Chandrayaan-1 spacecraft. The study, published in the journal Science Advances, builds on the initial discovery in 2009 of water and a related molecule hydroxyl, which consists of one atom each of hydrogen and oxygen in the lunar soil.
Scientists from Brown University in the US used a new calibration of data taken from NASA’s Moon Mineralogy Mapper, which flew aboard Chandrayaan-1 spacecraft, to quantify how much water is present on a global scale. Now that we have these quantitative maps showing where the water is and in what amounts, we can start thinking about whether or not it could be worthwhile to extract, either as drinking water for astronauts or to produce fuel.
The water concentration reaches a maximum average of around 500 to 750 parts per million in the higher latitudes. That is less than what is found in the sands of Earth’s driest deserts. The researchers said that the way the water is distributed across the Moon gives clues about its source. The distribution is largely uniform rather than splotchy, with concentrations gradually decreasing toward the equator. The study also found that the concentration of water changes over the course of the lunar day at latitudes lower than 60 degrees, going from wetter in the early morning and evening to nearly bone dry around lunar noon. The fluctuation can be as much as 200 parts per million.