Curiosity images tiny, strange tube-like structures on Martian surface
Features could have geological or biological origins.

Laurel Kornfeld | Apr 19, 2018

Strange, tiny tube-like structures are visible in the first 2018 photos of the Vera Rubin Ridge along Mars' Mount Sharp captured by NASA's Curiosity rover.

Captured by the rover's Mars Hand Lens Imager (MAHLI), the structures, which range from 0.08 to 0.2 inches wide, are intriguing because they resemble trace fossils--fossils that show the imprint of an organism rather than the organism itself) seen on Earth.

That similarity led the Curiosity mission team, which first observed the features in black and white, to re-visit the site and image them with the MAHLI color camera on the rover's arm.

"This site was so interesting that we backtracked to get to where the rover was parked for this plan," said planetary geologist and Curiosity mission team member Christopher Edwards of Northern Arizona University in Flagstaff.

"In the work space in front of the rover, we have some very peculiar targets that warranted some additional interrogation."

The tube-like features, which appear angular in many dimensions, could be produced by either geological or biological processes.

Crystals within rock could leave impressions or molds when they dissolve, noted Curiosity project scientist Ashwin Vasavada of NASA's Jet Propulsion Laboratory (JPL) in Pasadena, California.

Such molds, produced by the same processes, are found on Earth.

A biological origin would be the result of a process known as bioturbation or the disturbing of sediments caused by burrowing creatures such as worms.

"Bioturbation at the scale of the features seen in the Curiosity imagery would imply macroscopic multicellular organisms at work, so something that would have evolved far beyond unicellular life. To claim that we're seeing bioturbation on Mars--which I did not say--would be an extraordinary claim," emphasized Pascal Lee, a planetary scientist at both the Mars Institute and the SETI (Search for Extraterrestrial Intelligence) Institute in Mountain View, California.

Without the ability to search for organics in the surface materials at a laboratory, it is difficult for scientists to determine whether the crystallization process that produced these features was geological or biological.

Mission scientists hope to find answers or at least clues from studying the features with Curiosity's Chemistry and Camera (ChemCam) and its Alpha Particle X-Ray Spectrometer (APXS).

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