The Curiosity rover stumbled upon yet another intriguing sight while trekking across the Red Planet. The robot’s first batch of 2018 Mars photos includes a puzzling image of bizarre “stick-like figures” etched in Martian rocks in a region of the Vera Rubin Ridge, a popular exploration target of NASA’s Curiosity rover.
The image was taken with the Mars Hand Lens Imager (MAHLI), a focusable color camera mounted on top of the Curiosity rover and which has the advantage of capturing tiny details, even smaller than a strand of hair. The gripping photo reveals small dark-toned rock formations, no longer than a quarter inch, and which closely resemble some sort of stick figures of undetermined origin.
The enigmatic stick-like figures are shrouded in mystery as scientists have yet to establish what they are. According to Ashwin Vasavada, Curiosity project scientist at NASA’s Jet Propulsion Laboratory in Pasadena, California, these “unique” rock formations are quite “tiny” — one to two millimeters (0.04 to 0.08 inches) wide, and up to 5 millimeters (0.2 inches) long.
These perplexing stick figures were initially photographed in black and white, Vasavada explains, and immediately piqued NASA’s interest. The fascinating nature of this discovery compelled the space agency to send the Curiosity rover back to the site and take more snapshots with the help of MAHLI, the scientist points out.
“These were unique enough, given the fact that we didn’t know they were there … [that] we thought we should go back,” Vasavada said in a statement for Inside Outer Space, cited by Space.com.
The Curiosity Rover Twitter account unveiled the enthralling image on January 4, stating the stick-like figures could be either crystals or minerals trapped inside cracks in the rock after minerals melted away.
Meanwhile, back on Mars… I’m checking out these stick-like figures. Each is about a quarter-inch long. Maybe they're crystals? Or they could be minerals that filled spaces where crystals dissolved away. Stay tuned! Science continues. pic.twitter.com/4oR70BVht3
— Curiosity Rover (@MarsCuriosity) January 4, 2018
Soon after the photo was posted on Twitter, people began taking turns at guessing what the mysterious stick figures are. Among the wildest suggestions, Newsweek notes the fossilized remains of a space dinosaur, Viking runes or even tire tracks.
One scientist, however, concurs with the hypothesis that the newfound stick-like figures could be signs of past life on Mars. Barry DiGregorio, a research fellow at the Buckingham Centre for Astrobiology in the United Kingdom, believes the Martian stick figures could be trace fossils — either biological material left behind by creatures alive a long time ago, or their actual fossilized remains.
“They look remarkably similar to Ordovician trace fossils I have studied and photographed here on Earth.”
“If not trace fossils, what other geological explanations will NASA come up with?” DiGregorio wonders.
Whether the stick-like figures on Mars were formed through geological or biological processes, Vasavada doesn’t dismiss the possibility that they could indeed be trace fossils. Nevertheless, the Curiosity project scientist acknowledges “we certainly won’t jump to that as our first interpretation.”
In a January 3 mission update, Curiosity team member Christopher Edwards described the stick-like figures as “very peculiar targets that warranted some additional interrogation,” detailing how the team decided to revisit the site and examine it further.
These unusual rock formations looked equally captivating from outer space, Edwards disclosed. Their location was also photographed from orbit by the Mars Reconnaissance Orbiter, whose High-Resolution Imaging Science Experiment camera detected a bluish hue in the area.
The Curiosity Rover Twitter account also released a larger image of the area, highlighting the spot where the dark-toned rock formations were found.
Here's a wider shot. The red box shows roughly where the close-up of the stick-like features goes. Note: this was taken from a different angle. More info at https://t.co/cfLajNkRVX pic.twitter.com/iNpc50Zcd4
— Curiosity Rover (@MarsCuriosity) January 4, 2018
Vasavada remarks the Martian stick figures seem to be angular in multiple dimensions, as shown by close-up looks at the images. He suggests this could indicate the bizarre formations are related to crystals in the rock, and might even be “crystal molds” left behind by dissolved crystals — a phenomenon also spotted on Earth.
“If we see more of them […] then we begin to say that this is an important process that’s going on at Vera Rubin Ridge,” he said.
To get a better grasp of what they’re dealing with, the Curiosity team is currently trying to identify the rocks’ chemical composition, by analyzing the stick figures with the rover’s Alpha Particle X-ray Spectrometer, as well as its ChemCam.
So far, going by the Mars Curiosity rover photo alone, “it’s hard to tell what the wiggly sticks are,” says Pascal Lee, a planetary scientist at the Mars Institute and SETI (Search for Extraterrestrial Intelligence) Institute in Mountain View, California. Yet he admits that “a strictly mineral origin is, of course, the most plausible.”