Selfie of Curiosity Mars rover on the prowl.
Credit: NASA/JPL-Caltech/MSSS

NASA’s Curiosity Mars rover recently discovered thiophenes on the Red Planet. These organic compounds would be consistent with the presence of early life on Mars, reports Washington State University’s (WSU) Schulze‑Makuch and Jacob Heinz with the Technische Universität in Berlin.

“We identified several biological pathways for thiophenes that seem more likely than chemical ones, but we still need proof,” Dirk Schulze‑Makuch said in a WSU statement. “If you find thiophenes on Earth, then you would think they are biological, but on Mars, of course, the bar to prove that has to be quite a bit higher.”

Dirk Schulze-Makuch Credit: NASA/Bill Ingalls

Warmer, wetter world

Thiophene molecules have four carbon atoms and a sulfur atom arranged in a ring, and both carbon and sulfur, are bio‑essential elements. Yet Schulze‑Makuch and Heinz could not exclude non‑biological processes – such as meteor impacts — leading to the existence of these compounds on Mars.

In the biological scenario, bacteria — which may have existed more than three billion years ago when Mars was warmer and wetter — could have facilitated a sulfate reduction process that results in thiophenes. There are also other pathways where the thiophenes themselves are broken down by bacteria.

Credit: Bryan Versteeg

Moving microbe

While the Curiosity rover has provided many clues, it uses techniques that break larger molecules up into components, so scientists can only look at the resulting fragments.

“As Carl Sagan said ‘extraordinary claims require extraordinary evidence,’” Schulze‑Makuch said. “I think the proof will really require that we actually send people there, and an astronaut looks through a microscope and sees a moving microbe.”

For more information, go to the Heinz/ Schulze‑Makuch research in the journal Astrobiology  — “Thiophenes on Mars: Biotic or Abiotic Origin?” — by going to:

https://liebertpub.com/doi/10.1089/ast.2019.2139

Also go to:

NASA Finds Ancient Organic Material, Mysterious Methane on Mars

https://www.nasa.gov/press-release/nasa-finds-ancient-organic-material-mysterious-methane-on-mars

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