NASA, wait, wait lemme put my drink down... NASA, you need to be searching for vanadium

Bio-boffins urge Red Planet life search to hunt for weird metal

his low-angle self-portrait of NASA's Curiosity Mars rover shows the vehicle at the site from which it reached down to drill into a rock target called "Buckskin." The MAHLI camera on Curiosity's robotic arm took multiple images on Aug. 5, 2015, that were stitched together into this selfie. Credit: NASA/JPL-Caltech/MSSS
NASA's Curiosity rover is currently exploring Mars

Scientists hoping to discover evidence of life on Mars should search for vanadium, a metallic element, according to a paper published in Astrobiology this month.

Vanadium is a silvery, malleable transition metal with an atomic number of 23 in the periodic table. It’s rarely found in nature, but on Earth it is known to occur in several types of minerals and in fossil fuel deposits.

A team of scientists believes that if Mars did support extraterrestrial life, it will probably be evidenced in the form of fossilized bacteria.

Craig Marshall, the paper’s lead author and an associate professor of geology at the University of Kansas in the US, said on Thursday: “You’ve got your work cut out if you’re looking at ancient sedimentary rock for microfossils here on Earth – and even more so on Mars.”

Some rocks have been sitting around Earth for over three billion years. Tectonic activity and realignment can damage them, and bury them into the crust where temperatures increase with depth, making them difficult to retrieve.

The ancient microfossils on Mars might be in a similar position, Marshall said. It’s easy to identify living bacteria as organisms, but as they become fossilized the biological elements are stripped away, and scientists will have to look for proof of their existence in other ways.

“You can see a steak looks biological – there’s blood dripping from it. Then, you put it in a pressure cooker for very long time, and you end up with charcoal. It could be abiotic charcoal, or it could be made from heat and pressure on organic materials. A lot of biological compounds get destroyed and ripped apart from heat and pressure, and you’re left with carbon residue. We can see this carbon with Raman spectroscopy.”

But sometimes it’s difficult to tell if carbon samples are the remnants of living matter or a product of other chemical processes. Marshall and his team of researchers offer another option: sniffing out vanadium instead.

The paper suggests using X‑ray fluorescence microscopy, which involves bombarding matter with X‑rays and exciting the material’s electrons. Ionized electrons leave the atom, and other electrons in higher electron shells rush to fill the gaps, emitting a characteristic energy that allows researchers to probe the electronic structure so they can see what elements are present.

The team used this technique to find vanadium in a type of microfossil called acritarchs collected on Earth. “Maybe we could look for a known biological element, like vanadium,” Marshall said. If the material looks like microfossil and contains carbon and vanadium, then it could be “a new way forward for finding out if something really was biology.”

“We tested acritarchs to do a proof-of-concept on a microfossil where there’s no shadow of a doubt that we’re looking at preserved ancient biology. The age of this microfossil we think is Devonian. These guys are aquatic microorganisms – they’re thought to be microalgae, a eukaryotic cell, more advanced than bacterial. We found the vanadium content you’d expect in cyanobacterial material.”

The research was done independently of NASA, but Marshall said “hopefully someone at NASA reads the paper” so that an independent team can consider vanadium for the Mars 2020 Rover mission, which will send a robot to drill the surface of Mars to sniff out microbial life. ®

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