New images beamed back by the Mars Reconnaissance Orbiter (MRO), which has been circling the Red Planet since 2006, have produced the first compelling evidence of flowing, salty water on the Martian surface. Water may mean biology and biology, of course, would mean Martians.
There’s been little doubt in recent years that Mars was once very wet. Mineral deposits, ancient shorelines, dried up lake beds and long-empty waterways all attest to the sloshingly aquatic place the planet once was. Most of the water was lost to space due to Mars’s low gravity and tenuous atmosphere. Anything that was left contracted into ice coverings in the northern and southern latitudes and perhaps retreated into the soil. If anything warm and liquid existed deeper underground — serving as a potential stew pot for organisms — there was no way of knowing.
The MRO appears to have changed that. In a paper published this week in the journal Science and announced at a press conference at NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, mission scientists revealed the appearance of seasonal streaks at key points on the Martian surface, looking for all the world like the tracks of water rivulets running down-slope, collecting at the base of the incline and then evaporating back into the atmosphere.“Since the MRO arrived at Mars our overarching theme has been ‘follow the water,'” says mission scientist Mike Meyer. “Now we may be catching Mars in the act. We have found repeated and predictable evidence of water flowing on the surface.”
There are a lot of things about the images that make a powerful — if not yet seal-the-deal definite — case for water. For one thing, there’s the seasonality. The water appears only in the Martian spring and summer when surface temperatures may range from a low of 10 below zero F to a balmy 80 above (-23 to 27°C) — and only in the planet’s mid-latitudes, as opposed to the permanently frozen far north and south.
“These flows occur close to the equator,” says MRO team member Phil Christensen. “They’re at a latitude at which it’s actually possible for water to exist.” JPL images also show the events occurring over three full Martian years — a repeatability that only makes the case stronger.
Just as important as the presence of the water is the overwhelming evidence that it’s salty — a key feature of the seawater in which Earthly life emerged. Salt exists in deposits and dustings over much of the surface of Mars, which is consistent with a world that was once so watery. What’s more, while ordinary water could not flow at temperatures below 32 F (0 degrees C), densely concentrated salt water has a much lower freezing point, making it possible for it to remain liquid deep into the mid-latitude’s lower temperature ranges. So concentrated may this Martian brine be that it would actually flow more like syrup than water.
Just what shape the subsurface water deposits might take is impossible to say with certainty, but Lisa Pratt, a mission scientist, thinks there’s a lot to learn from the closest Earth analogs we have to this part of the Martian surface: the Siberian permafrost. There, she says, subsurface water collects either in fracture networks or in small pockets called cryopegs. Once the Martian water grows warmer and begins to leak out of these deposits, it would seep up first to what’s known as a photic zone, a think film of surface soil where warmth from the sun could allow biological activity to take place.
Not every instrument aboard the MRO agreed entirely with the findings of the cameras. The ship’s spectrometer, which would be expected to find the elemental signature of water when it scanned the rivulet zones, came up empty, but that could simply be a matter of timing. Atmospheric pressure on the surface of Mars is just 1% of what it is at sea level on Earth. Even in the biting cold, this would cause fresh water simply to boil away.
“Salty water wouldn’t boil,” says MRO team member Alfred McEwen, “but it would evaporate very quickly.” By the time the spectrometer could take a bead on the streaks, the water that formed them would be gone.
JPL is already planning Earth-based experiments in which soil and brine of similar composition can be studied for clues to exactly what’s going on Mars. A European-American Missions set to launch in 2016 will orbit Mars looking for trace gas emissions, particularly methane and oxygen molecules, both of which could be the byproducts of biological processes. The Curiosity rover, a Mars car about the size of an SUV, will launch in November as well, but NASA cautions that it won’t be able to investigate the sites up close. Its planned landing site is too far from where the streaks have been seen and it was not built to navigate the steep, 35-degree slopes where the rivulets are forming.
This is the most interesting proof found till date about the presence of water in mars
Report frm September,2008
The universe has many secrets hidden inside we just need to explore them!!!