By now, there is no doubt that liquid water flows on Mars. On September 28, 2015, NASA released evidence confirming that water flows on Mars, today. Following the discovery of dark streaks on the walls of Garni crater on Mars, its mission identified they were formed by, most likely, salty water. These streaks seemed to appear during warm seasons, when temperatures were above minus 10 degrees Fahrenheit, and faded during the cooler season temperatures. Recurring Slope Lineae, or RSL, have been documented in dozens of other sites on Mars. Even tough these are no gushing flows of water, it counts as evidence of the previous existence of bigger sources of water.
What happened? Where did all the water go?
NASA’s MAVEN (Mars Atmosphere and Volatile Evolution) mission identified the process for wich Mars became a cold and arid planet. On 2010 in the AGU journal Geophysics Research Letters, scientists reported Mars was losing its atmosphere by bursts of solar wind. Unlike Earth, Mars’ smaller magnetosphere is not able to protect it from these solar pulses. MAVEN data showed that erosion of Mars’ atmosphere happens the most during solar storms. Over time, this strip of the atmosphere has made the Mars we know today. Which then lead scientist to infer that billions or years ago, Mars may have had a thicker atmosphere, just like Earth’s -it may have been thick enough to keep the planet warm and able to support liquid water.
The loss of Mars’ atmosphere was the significant event that led to the change of the Mars’ climate. In some regions of the planet, traces of valleys carved by rivers and mineral deposits resemble those on Earth.
Other research may support the idea that Mars was once a prolific planet. In a 2000 expedition by the Japanese Antartic Research Expedition, a Martian meteorite was found to have special micro features that resembled “bio-alteration textures observed in terrestrial basaltic glasses”. It was also found to have nanometer-to-micrometer-sized spherules within the layer of the meteorite which were composed of a significantly higher amount of carbon content compared to the surrounding layers. These textural compositions imply the possibility that these features were formed by biological activity, similar to terrestrial clay. Although the possibility still remains that the Martian meteorite may have been contaminated, further studies will continue.
In a recent study, scientists looked into the impact crater Lyot and the vast network of water-carved valleys on its flanks. According to climate history models of Mars, ice was located in the mid-latitude where Lyot’s crater is located. The ice layers could have been between 20 to 300 meters thick. The impact would have blasted heated rock to 250 degrees Fahrenheit or more, melting thousands of cubic kilometers of water which then carved the valleys. this research provided the evidence to the idea that water could have occurred without the need for a habitable, warm atmosphere.
Where is the water now?
In November 2016, NASA reported a large underground body of water ice. It’s estimated to hold as much water as Lake Superior. Shallow Radar (SHARAD) on NASA’s Mars Reconnaissance Orbiter, examined the Utopia Planitia. The deposit lays 3 to 33 feet underneath the surface. It ranges from 260 feet to 560 feet thick and is composed of a mixture of water ice, dust or larger rocky particles.
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