Astronomers have found patches of frost scattered around the moon’s north and south poles which could one day provide a source of water for human visitors. The scientists spotted the tell-tale signature of frozen water in infrared measurements taken by Nasa’s moon mineralogy mapper, an instrument that flew on India’s Chandrayaan-1 mission to the moon a decade ago.
The freshly-analysed data show that water ice lurks on the ground in some spots near the moon’s polar regions that are permanently in the shade and so sheltered from the heat of the sun’s rays. Most of the ice was found near the moon’s south pole around a cluster of craters named after scientists and explorers, including Haworth, Shoemaker, Sverdrup and Shackleton. In the north, the patches of ice appeared to be more isolated, according to Shuai Li at the Hawaii Institute of Geophysics and Planetology in Honolulu. Follow-up measurements of the ice patches found that they tended to form where the surface temperature never crept above -163C, but temperature alone was not enough to guarantee frozen water: only 3.5% of the shadowy areas the scientists checked for water revealed notable signs of ice.
The images are the first “direct and definitive evidence” of water ice that is exposed on the surface of the moon, according to a report in the Proceedings of the National Academy of Sciences. “These ice deposits might be utilised as an in-situ resource in future exploration of the moon,” the authors write. The Indian Space Agency launched its Chandrayaan-1 mission to the moon in 2008 and was swiftly rewarded with evidence of frozen water on the lunar surface a year later. Rather than sheets of ice on the surface, the water is thought to exist as water molecules bound to grains of moon dust. Soon after the Indian feat, Nasa crashed a spacecraft into the 100km-wide Cabeus crater which is in the permanent shade on the moon’s south pole. The intentional act of lunar violence threw up a plume of debris from which scientists were able to confirm the presence of water on the moon.
Credit: Ian Sample for The Guardian, 20 August 2018.