By Ron Cowen
The Phoenix Mars Lander has been entombed in ice on the Red Planet since November, but the extraordinarily salty tale it has told endures. The surprisingly high concentration of perchlorate salts found in the Martian polar soil by Phoenix’s wet chemistry lab last year — as much as a few percent — could mean that shallow, extremely briny reserves of water lie just below much of the Martian surface, several researchers will report next week at the annual Lunar and Planetary Science Conference in The Woodlands, Texas.
“There seems to be at least a possibility that we have liquid water in the near subsurface over much of the planet,” comments astrobiologist Christopher Chyba of Princeton University, not a member of the Phoenix teams. “That’s a pretty startling change in the way we think about Mars.”
Perchlorates are unique among salts because they can keep water liquid at temperatures as low as –68° Celsius, close to the minimum temperature at the Phoenix landing site last May, when the craft arrived in the arctic region.