dark streaks – Behind The Black

Boiling water on Mars

May 2, 2016 9:06 am Robert Zimmerman

Scientists now think that the dark streaks they see seasonally develop on Martian slopes are caused when frozen underground water brine is exposed to the atmosphere so that the water boils off, leaving the salt.

More here, including videos of their Earthbound experiments. On Earth, the boiling water caused avalanches and streaks, but because of the higher gravity they were not as long.

One comment

Scientists have found more evidence that the streaks on Martian hillsides that darken in warm weather are caused by melting groundwater flowing downhill.

March 20, 2012 8:36 am Robert Zimmerman

Liquid water on Mars! Scientists have found more evidence that the streaks on Martian hillsides that darken in warm weather are caused by melting groundwater flowing downhill.

Last summer, the team pointing the HiRISE camera on the NASA Mars Reconnaissance Orbiter (MRO) dropped that bombshell: it had identified 7 confirmed and 12 likely sites that contained hundreds of narrow streaks on steep slopes inside crater walls. During warmer seasons, as temperatures rose as high as 27 degrees Celsius, the streaks darkened, and then faded again. Salts could allow brines to be liquid at these temperatures. Today at the Lunar and Planetary Science Conference in The Woodlands, Texas, the HiRISE team announced that it now has doubled it stash of streaks, with the identification of 15 confirmed and 23 likely sites, all in the mid-latitudes of the Southern Hemisphere.

Additional analysis of the spectrographic data also suggests that water could be the cause of the darkening.