NASA’s steady reconnaissance of Mars with the Curiosity rover has produced another major discovery: evidence of an ancient lake — with water that could plausibly be described as drinkable — that was part of a long-standing, wet environment that could have supported simple forms of life.
Scientists have known that the young Mars was more Earthlike than the desert planet we see today, but this is the best evidence yet that Mars had swimming holes that stuck around for thousands or perhaps millions of years. (It would have been very chilly — bring a wet suit.)
Scientists had announced this year that they’d found signs of an ancient, fresh-water lake within Gale Crater, but the new reports provide a much more detailed analysis, including the first scientific measurements of the age of rocks on another planet. The research suggests that Martian winds are sand-blasting rock outcroppings and creating inviting places to dig into rocks that may retain the kind of organic molecules associated with ancient microbes.
Gale Crater is in an area with rocks about 4.2 billion years old. The lake, which scientists think existed a little more than 3.5 billion years ago, was roughly the size and shape of one of New York’s Finger Lakes. The freshwater lake may have come and gone, and sometimes been iced over, but the new research shows that the lake was not some momentary feature, but rather was part of a long-lasting habitable environment that included rivers and groundwater.