Chemical Signature Hidden in Lunar Rocks Hints at Oxygen in The Ancient Moon

Researchers used electron microscopy on an Apollo 17 ilmenite sample and found about 15% of titanium in a 3+ charge state.

Trivalent titanium implies lower oxygen availability when the rock crystallized around 3.8 billion years ago.

The team identified over 500 prior ilmenite analyses that could be reexamined and plans experiments to quantify the Ti3+–oxygen link.