Signs of water seen on Mars

New York Times : Although no pools of standing water have yet been seen on Mars, waterlogged molecules have been detected on its surface. In photographs captured by NASA’s Mars Reconnaissance Orbiter, Alfred McEwen of the University of Arizona and colleagues have seen what they term recurring slope lineae (RSL) at four different locations on Mars’s surface. The RSL have been noticed to lengthen during warm seasons and recede when the temperature drops, a pattern consistent with the flow of liquid water. The researchers have also found evidence of hydrated salts—which lower the freezing point of water—at all four locations when the RSL are most extensive. If Mars indeed has water, it could also harbor living organisms. That possibility poses problems for current and future spacecraft, which could contaminate Mars’s surface with microbial specimens from Earth, and it will certainly factor into the selection of a landing site for NASA’s next Mars rover, scheduled to launch in 2020.