CUATRO CIÉNEGAS, Mexico — Studying Mars usually involves tilting one’s head up toward the heavens, but not here in the Chihuahuan Desert, where the vast, scorching plain is so inhospitable — and so Mars-like — that scientists seeking insight into that distant planet look down at their feet.

Largely arid and extremely hostile, Cuatro Ciénegas is inhabited by organisms able to survive on few nutrients, high salinity, soaring temperatures and high ultraviolet radiation. Scientists say such an environment resembles that of Mars billions of years ago.

And the gypsum dunes in the valley, blindingly white in the afternoon sun, are not unlike the Gale crater on present-day Mars, where NASA’s Curiosity rover is scheduled to land in August, scientists say.

A team of researchers piled into a caravan of off-road vehicles last month and drove for hours across the valley, in the northern Mexican state of Coahuila. They searched for the pockets of water that may house their study subjects: microbes, bacteria and fish that survived in an environment similar to one scientists say Mars once had.