Downside To Lunar Water

The recent discovery of substantial amounts of water on the Moon excited those who want to build manned lunar bases, but it seems that water could also make lunar optical astronomy more challenging.

For decades, astronomers have dreamed of building huge optical telescopes on the Moon, taking advantage of the low gravity and perpetually cloudless sky to probe the mysteries of the universe. That was when the Moon was thought to be dry as chalk, however. Water is a complication. Sunlight breaks water down to hydrogen and hydroxyl, which could distort images taken by huge lunar scopes. Of course, Earth-based telescopes have been made more productive by using techniques that factor out the distortions caused by Earth's atmosphere. That atmosphere is thicker and more active than hydroxyls around the Moon would be, so there's every chance such lunar distortions could be overcome.

Radio astronomy-- especially from the far side of the Moon, where the bulk of the Moon would block radio noise from Earth-- would not be affected by hydroxyl distortion, and therefore retains incredible promise as a lunar-based science.