Future human exploration and habitation on the moon rely on the presence of water hiding out in shadowy craters on the lunar surface. Past missions have provided good evidence that there’s water ice in there, but now we have absolute confirmation that ice exists on the surface thanks to India’s Chandrayaan-1 spacecraft. Technically, we had the evidence almost a decade ago and no one noticed until now.
Astronauts can, of course, take all the water they need for a short or medium-term mission to the moon. However, establishing a long-term presence on the moon would benefit from having a local source of water, which is costly to transport into space. Water is necessary for human survival, but you can also split it into hydrogen and oxygen for use as rocket fuel. That could make a moon base ideal as a refueling depot for missions to the outer solar system.
Even if the moon has ice, it’s no good to us if it’s not accessible. That’s where the Chandrayaan-1 spacecraft comes in. This mission studied the moon in 2008 and 2009. Among its various instruments was the NASA-designed Moon Mineralogy Mapper (M3). A new analysis of the data from M3 led by Shuai Li of the University of Hawaii and Brown University has revealed previously undetected ice deposits.
The team spotted the reflectance of ice in craters near the north and south poles. To confirm, the team used infrared scan data from the probe that showed distinctive absorption consistent with water ice. In these regions within 20 degrees of the poles, there are large swaths of the surface that are never exposed to sunlight. However, the team calculates that only 3.5 percent of these “cold traps” actually have detectable amounts of ice, and it’s much more common around the south pole. That means lunar ice is more scattered than the ice we’ve detected on Mercury or the dwarf planet Ceres.
In 2009, a NASA mission called the Lunar Crater Observation and Sensing Satellite (LCROSS) launched an impactor into one of these craters. The orbiting probe detected the signature of water ice in the ejecta, but that only proved there was ice present. The new data adds the crucial detail that ice is present on the surface. Any more than a few millimeters deep, and it becomes much harder to harvest and utilize ice on the moon.
Now we know where to find water on the moon, but it’s up to NASA and other space agencies to figure out how to utilize it.
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