"Hydroxyls can form when hydrogen in the solar wind flux hits the minerals in the rocks on the lunar surface," said Klima.
"That tends to happen in cooler areas, and there have been signs that it migrates with the lunar day. So basically when it's cooler it will form and stick to the surfaces, and when it gets warmer later in the lunar day it will move."
When Klima first detected hydroxyl in her spectroscopic readings, she assumed it was solar wind generated surface hydroxyls, similar to what had been seen previously.
"But looking at the crater in more detail and at different times during the lunar day, I found there was no change in the hydroxyl signature," said Klima.
Going Deeper Klima and colleagues were also unable to detect any hydroxyls in the surrounding lunar soil. The only hydroxyls were in the crater's central peak, indicating that it had been dredged up from deep underground.
"It was only in the center of the crater where the rocks from the deepest part of that area had been brought up to the surface, that we saw this hydroxyl signature," said Klima.