Credit: NASA/JPL/UArizona

A super-powerful camera on NASA’s Mars Reconnaissance Orbiter has captured new imagery of slope streaks on the Red Planet. The sharp-shooting High Resolution Imaging Science Experiment (HiRISE) snagged a set of new dark streaks.

Slope streaks are common in the tropics of Mars. Once thought to be caused by flowing water, most scientists now believe that they are avalanches of dust, explains HiRISE team member Paul Geissler of the U.S. Geological Survey.

“They are typically darker than their surroundings and often fan outwards downslope. This suggests that the dust sediment is sticky, so that the avalanche broadens as it flows downhill,” Geissler explains on the HiRISE website at the University of Arizona.

Time scales

“Slope streaks are known to fade over time, but the slope streaks at this monitoring site in Arabia Terra go beyond that. Here, old slope streaks appear to be brighter than the surrounding terrain,” Geissler adds.

Comparative HiRISE images taken in 2008 and in 2019 show very few changes in the dark and bright streaks.
Credit: NASA/JPL/UArizona

Comparing HiRISE images taken in 2008 and in 2019 show very few changes in the dark and bright streaks.

“We can see three new dark streaks in our more recent image,” Geissler says. “These were the only changes spotted among the hundreds of streaks observed in the monitoring site, suggesting that new streak formation and fading take place on time scales of at least decades.”

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