Scientists puzzling over some odd dark spots on Mars may finally have shone a light on the mystery.
In a new paper, published March 26 in the academic journal Geology, study authors Briony Horgan and James Bell of Arizona State University in Tempe found evidence that the Martian blemishes are likely to be made of sand-like particles of glass, similar in composition to obsidian.
For the authors, the glass is much more than decoration—its presence may hint at mineral-rich liquid water in Mars' past.
By analogy with glass-rich sand dunes found in Iceland, Horgan and Bell proposed that the Martian glass, concentrated in the region known as the northern lowlands, may have come about by an explosive volcanic event, which would have occurred when magma came in contact with ice or water.
"If these things were created by magma ice interactions, they would have caused huge outflows of hot, chemically rich liquid water, which would have created a habitable environment which is one of the big drivers for the Mars Program today," Horgan told Discovery News.