Ellie Kemp
The results of a study into thousands of 'slopes' found by NASA on Mars' surface has left scientists surprised.
The planet, roughly half the size of the Earth, has had curious researchers scratching their heads since it was first observed in 1610.
And while SpaceX founder Elon Musk hopes to one day colonize Mars, there's still so much we don't know about it.
Or so much that could still be disproven - like these dark, long streaks which were first discovered by the space agency's Viking 1 spacecraft in the late 1970s.
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What exactly they were continued to remain a mystery for around two decades, NASA said, but we now know there are two types: long-lasting 'slope streaks' that slowly fade over years, and seasonal 'recurring slope lineae' (RSLs) that appear in the warm season and vanish again.
Although Mars today is bitterly cold and dry - around -83°F, NASA says - high-resolution images suggest it once had flowing water.
We’ve even seen subsurface ice exposed by a meteoroid in 2021.
Some researchers reckon thick, briny meltwater or salty ice seeping from below could be behind those mysterious streaks, NASA explains.
But a recent study by Brown University and the University of Bern did not support the idea that water caused the streaks, after all.
The researchers examined more than 86,000 high-resolution photos from one of the most powerful imaging platforms; the Context Camera aboard NASA’s Mars Reconnaissance Orbiter.
Using AI machine learning, scientists Adomas Valantinas and Valentin Bickel identified more than 500,000 individual slope streaks.
“Once we had this global map, we could compare it to databases and catalogs of other things like temperature, wind speed, hydration, rockslide activity and other factors,” said Bickel, a post-doctoral fellow at the Center for Space and Habitability at the University of Bern.
“Then we could look for correlations over hundreds of thousands of cases to better understand the conditions under which these features form.”
And while scientists previously believed the phenomenon was caused by water, instead, the streaks were found to have formed in dusty, warm areas near the equator.
The streaks often appeared when there was more dust and stronger winds; the likely explanation being that the streaks are caused when fine layers of dust slide down slopes, triggered by wind, small earthquakes, or even meteoroid impacts.
“A big focus of Mars research is understanding modern-day processes - including the possibility of liquid water on the surface,” said Valantinas, a postdoctoral researcher at Brown University.
“Our study reviewed these features but found no evidence of water. Our model favors dry formation processes.”
This gives NASA and other scientists greater insight into how Mars works, helping to better their understanding of one of the most complex planets in our solar systems.
Reacting to photos of these striking marks in the r/SpacePorn community on Reddit, people were left in awe.
One person commented: “I was wondering if it was a real photo because it reminds me so much of a painting with how clean those streaks look from afar. But it's fascinating that we can take such high quality photos of Mars.”
A second social media user reckoned: “Looks like a spore print.”
While a third quipped: “Don't show me a closeup of the underside of mushroom and tell me its space.”