Secrets of the Moon's Permanent Shadows Are Coming to Light

[Judi Lynn]

JUL 3, 2022 8:00 AM

Robots will venture into the sunless depths of lunar craters to find ancient water ice, while studies find hints about how water arrives on rocky worlds.



ON OCTOBER 9, 2009, a 2-ton rocket smashed into the moon traveling at 9,000 kilometers per hour. As it exploded in a shower of dust and heated the lunar surface to hundreds of degrees Celsius, the jet-black crater into which it plummeted, called Cabeus, briefly filled with light for the first time in billions of years.

The crash was no accident. NASA’s Lunar Crater Observation and Sensing Satellite (LCROSS) mission aimed to see what would be kicked up from the lunar shadows by the impact. A spacecraft trailing the rocket flew through the dust plume to sample it, while NASA’s Lunar Reconnaissance Orbiter observed from afar. The results of the experiment were astonishing: Scientists detected 155 kilograms of water vapor mixed into the dust plume. They had, for the first time, found water on the moon. “It was absolutely definitive,” said Anthony Colaprete of NASA’s Ames Research Center, the principal investigator of LCROSS.

The moon isn’t an obvious reservoir of water. “It’s really weird when you stop to think about it,” said Mark Robinson, a planetary scientist at Arizona State University. Its lack of atmosphere and extreme temperatures should cause any water to almost instantly evaporate. Yet about 25 years ago, spacecraft began to detect signatures of hydrogen around the moon’s poles, hinting that water might be trapped there as ice. LCROSS proved this theory. Scientists now think there’s not just a bit of water ice on the moon; there are 6 trillion kilograms of it.

Most of this ice resides in peculiar features at the moon’s poles called permanently shadowed regions (PSRs). These are craters like Cabeus into which the sun can’t reach, because of the geometry of the moon’s orbit. “They’re in permanent darkness,” said Valentin Bickel, a planetary scientist at the Max Planck Institute for Solar System Research in Germany.

More:
https://www.wired.com/story/secrets-of-the-moons-permanent-shadows-are-coming-to-light/

[dpibel]

1. Sounds big but...

My quick search tells me that there are a trillion kilos of water in a cubic kilometer.

Which is to say all that water they're guessing is on the moon amounts to 6 cubic kilometers.

For a quick notion of how much that is: Lake Erie holds 480 cubic kilometers of water.

[localroger]

2. It's not a lot from a planetary perspective, but it's a lot for colony builders

Every gram of water that's already there is a gram that doesn't have to be brought from Earth to support life.