For anyone who thought “aliens!” the moment you heard that those mysterious streaks on the surface of Mars could be evidence of water flowing on the surface, that idea is about to dry up.
Apparently Mars is more Jakku than Endor (for all you Star Wars fans out there). Recurrent slope lineae or RSLs, the strange dark flow lines that appear and vanish seasonally on the Red Planet, met with much controversy back in 2011 when they were first discovered and assumed to be caused by liquid water which could be swimming with microbial alien life-forms. Photos from the NASA Mars Reconnaissance Orbiter (MRO) are telling scientists something else.
RSLs aren’t nearly as characteristic of streams as they are of dunes. MRO beamed back shots from its High Resolution Imaging Science Experiment (HiRISE) camera that revealed they only exist on slopes steep enough for particles to flow downwards, creating ridges that can easily be mistaken for their mirror images on Earth, which are carved out by what every alien hunter was hoping for—liquid water. RSLs extend downhill in warmer weather and start to disappear as temperatures drop, much like water on our planet freezes in the winter and later trickles down as it melts. H2O is the only thing on Earth that can create these veins on the surface. Except this is Mars, and even scientists have no idea what kind of weather can pull off the same thing on its supposedly bone-dry surface.
“The preference for warm seasons and the detection of hydrated salts are consistent with some role for water in their initiation,” said Colin Dundas of the U.S. Geological Survey's Astrogeology Science Center, who led a study with findings recently published in Nature Geoscience. “However, liquid water volumes may be small or zero, alleviating planetary protection concerns about habitable environments.”
Even with hydrated salts (which have water molecules bound to their crystal structure) previously observed in some of the RSLs, it is highly unlikely there is enough liquid water around to spawn extraterrestrial microbes. The brutal Martian environment, attacked by killer radiation from solar storms, is hardly a place you’d expect there to be an abundance of water, much less organisms thriving in it. Its atmosphere has been all but obliterated. How Martian RSLs come into being and then ghost as mysteriously as they appeared remains unknown.
"Full understanding of RSL is likely to depend upon onsite investigation of these features," MRO Project Scientist Rich Zurek of NASA's Jet Propulsion Laboratory believes. “In particular, a full explanation of how these enigmatic features darken and fade still eludes us.”
Getting an onsite macro view that could shed light on this phenomenon doesn’t end at programming the computer brain of a spacecraft or beaming it commands. Precautions would have to be taken so microbes from Earth don’t contaminate the samples and convince a team of overexcited scientists that there is definitely live breeding on Mars. Monitoring them throughout the day could also give further insight into their behavior.
For anyone feeling down about the improbability of aliens on the surface, just remember that we’re getting ready to probe deeper.