Future human exploration and habitation on the moon rely on the presence of water that is hidden in shadowy craters on the moon surface. Past missions have provided good evidence that there is water ice in it, but now we have absolute confirmation that ice on the surface occurs thanks to India's Chandrayaan-1 spacecraft. Technically, we had the evidence almost a decade ago and no one noticed it so far.
Astronauts can of course pick up all the water they need for a short or medium 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 to 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 lunar base ideal as a service station for missions to the outer solar system.
Even if the moon has ice, it is not good for us if it is not accessible. That is where the spaceship Chandrayaan-1 enters. This mission studied the moon in 2008 and 2009. Among the different instruments was the Moon Mineralogy Mapper (M3) designed by NASA. A new analysis of data from M3 led by Shuai Li from the University of Hawaii and Brown University has previously uncovered undetected ice supplies.
The team saw the reflection of ice in craters in the vicinity of the north and south poles. To confirm, the team used infrared scanning data from the probe that showed a distinctive absorption consistent with water ice. In these areas within 20 degrees of the poles, there are large areas 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 is much more common around the South Pole. This means that moon ice is more dispersed than the ice we observed on Mercury or the dwarf planet Ceres.
In 2009, a NASA mission, the Lunar Crater Observation and Sensing Satellite (LCROSS), launched an impactor in one of these craters. The circulation probe detected the signature of water ice in the ejecta, but that only proved that there was ice present. The new data add the crucial detail that ice is present on the surface. More than a few millimeters deep, and it is much harder to harvest and use ice on the moon.
Now we know where to find water on the moon, but it is up to NASA and other space agencies to find out how they can use it.
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