Post by Hill on Oct 19, 2015 18:10:17 GMT
Fairly early on in its explorations of the Martian surface, the Mars Reconnaissance Orbiter (MRO) photographed what seemed to be seasonal streams running down steep slopes in various localities. I originally mentioned it HERE in the now-archived Google Earth Community Forums. The planetary geologists had reason to be cautious about claiming the rivulets were caused by water because the low atmospheric pressure on Mars would supposedly immediately cause liquid water to boil off to vapor.
But further study shows that is the water is very salty, it may be able to run downslope.
Small crater in the Amazonas Planitia region
" Using an imaging spectrometer on MRO, researchers detected signatures of hydrated minerals on slopes where mysterious streaks are seen on the Red Planet. These darkish streaks appear to ebb and flow over time. They darken and appear to flow down steep slopes during warm seasons, and then fade in cooler seasons. They appear in several locations on Mars when temperatures are above minus 10 degrees Fahrenheit (minus 23 Celsius), and disappear at colder times."
"These downhill flows, known as recurring slope lineae (RSL), often have been described as possibly related to liquid water. The new findings of hydrated salts on the slopes point to what that relationship may be to these dark features. The hydrated salts would lower the freezing point of a liquid brine, just as salt on roads here on Earth causes ice and snow to melt more rapidly. Scientists say it’s likely a shallow subsurface flow, with enough water wicking to the surface to explain the darkening." SOURCE
But further study shows that is the water is very salty, it may be able to run downslope.
Small crater in the Amazonas Planitia region
" Using an imaging spectrometer on MRO, researchers detected signatures of hydrated minerals on slopes where mysterious streaks are seen on the Red Planet. These darkish streaks appear to ebb and flow over time. They darken and appear to flow down steep slopes during warm seasons, and then fade in cooler seasons. They appear in several locations on Mars when temperatures are above minus 10 degrees Fahrenheit (minus 23 Celsius), and disappear at colder times."
"These downhill flows, known as recurring slope lineae (RSL), often have been described as possibly related to liquid water. The new findings of hydrated salts on the slopes point to what that relationship may be to these dark features. The hydrated salts would lower the freezing point of a liquid brine, just as salt on roads here on Earth causes ice and snow to melt more rapidly. Scientists say it’s likely a shallow subsurface flow, with enough water wicking to the surface to explain the darkening." SOURCE
