NASA announced on Monday that it has uncovered evidence of recent flowing water on the Martian surface. The evidence of hydrated salt left behind by the flowing water was discovered by the high-resolution camera onboard the Mars Reconnaissance Orbiter. The deposits were manifested by what scientists call “recurrent slope linae”, or R.S.L.s. The RSLs are dark streaks that have been noted along the slopes of craters, canyons, and mountains. The streaks lengthened during the summer and contracted during the winter on the Red Planet.
The fact that these streaks were hydrated salts was uncovered after reviewing readings from a spectrometer. The findings suggest that the water is heavily permeated with salt, something that makes sense as salt lowers the freezing point of water.
The best theory about the source of the water is that it seeps from underground aquifers, which freeze during the winter and then melts during the summer, seeping up from beneath the soil. An alternate theory is that the water might actually condense from the surrounding atmosphere, but this would be dependent on Mars being more humid near its surface than hitherto has been thought by scientists.
Scientists have long known that water exists on Mars. Much of the stuff is frozen at the Martian ice cap. Also, it has long been theorized that water existed beneath the Martian surface. Today’s findings are proof that subsurface Martian water exists.
Water was far more abundant on Mars billions of years ago when it likely had rivers, lakes, and even oceans. But as the Martian atmosphere leached away into space, much of the water likely left with it, broken up by sunlight into its hydrogen and oxygen components, or became frozen at the poles and in underground deposits.
The reason that NASA is so excited about surface flowing water is that where liquid water exists, so might life, albeit in simple, bacterial form, according to the New York Times. The discovery of extraterrestrial life, having evolved beyond Earth, has been the Holy Grail of scientists since before the space age began. However, as Chris MacKay notes, the water traces on the Martian surface is likely a poor place to look for life. The water would just be too salty to sustain life. Other scientists are not so sure.
Paradoxically, the regions where the RSLs have been found have been declared off limits from NASA probes, both current and future. The reason for this prohibition is that rovers such as the Curiosity and the future Mars 2020 may have Earth microbes that could contaminate the RSL deposits. Some close up examination will have to be developed to confirm or rule out the presence of life, however,