For anyone wondering, it’s pretty conclusive that Mars once had water on it. Here we have a new sign that ancient Mars was wet more recently.
“This is an exciting discovery because it extends the time range for liquid water on Mars, and the places where it might have supported life,” said CRISM principal investigator Scott Murchie of the Johns Hopkins Applied Physics Laboratory in Laurel, Md. “The identification of opaline silica tells us that water may have existed as recently as 2 billion years ago.”
Notice that this extends the range of time that Mars is thought to have harbored liquid water – in other words, the point isn’t to show confirmation of water in the history of Mars. That’s been known for quite some time, despite public perceptions.
“What’s important is that the longer liquid water existed on Mars, the longer the window during which Mars may have supported life,” Milliken said. “The opaline silica deposits would be good places to explore to assess the potential for habitability on Mars, especially in these younger terrains.”