This image combines a photograph of seasonal dark flows on a Martian slope with a grid of colors based on data collected by a mineral-mapping spectrometer observing the same area. (NASA/JPL-Caltech/UA/JHU-APL)
Water may today exist on Mars, according to new clues revealed by spacecraft orbiting the Red Planet, what NASA describes as “dark, finger-like markings that advance down Martian slopes when temperatures rise.”
The markings, which researchers have dubbed recurring slope lineae or RSL, correspond to seasonal and temperature changes on Mars. They occur “only on the sun-facing slopes on Mars and only in the summertime, basically the few times and places where it might be warm enough for water to be liquid, at least for a short time before it boils away,” James Wray, a Georgia Institute of Technology professor, told weather.com.
Wray and graduate student Lujendra Ojha studied 13 confirmed sites of RSL using images from NASA’s CRISM instrument to look for signatures of water. (Three years ago, they discovered the RSL using another NASA instrument, the High Resolution Imaging Science Experiment.) They didn’t find what they were looking for — exactly.
No water, but also no proof that what they were seeing doesn’t require liquid water to happen, Wray said. “So far, no one has come up with an explanation for these that doesn’t require liquid water.”
“We still don’t have a smoking gun for existence of water in RSL,” reiterated Ojha, in a news release, “although we’re not sure how this process would take place without water.”
Confirming the presence of water on Mars would undoubtedly be huge, namely because — at least within framework we can understand — it’s fundamental for sustaining life. “That’s why NASA has taken this approach of follow the water,” Wray said. “For looking for Martian life, it’s important.” It’s also important for future missions to Mars, he added, noting it would be easier for astronauts to not have to cart along all the water they need.
The answer could be as simple as looking at data from a different time of day, in the early morning, once Mars has warmed up from the frigid night and before it gets too dry. Or, if we could land there, that would help, too. “If you go to the beach, you can tell the difference between wet sand and dry sand pretty easily, and if we were on the surface at these [RSL] locations, we could do that,” Wray said.
Of course, that comes with its own complications, in the form of stowaway microbes that could inadvertently colonize the Red Planet, and then we’d have difficultly knowing whether they were there already or whether we brought them. Either way, Wray said this is an exciting time to be studying Mars. “It’s great news to be finding some possibility, a likelihood even perhaps, of liquid water on the surface today and all the implications that has.”
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The ESO 3.6-meter telescope at La Silla observatory in Chile, during observations. (ESO/S. Brunier)