A New Martian Biosignature?

TL;DR

Oxygen may be a new Martian biosignature because its seasonal behavior resists the abiotic explanations examined by researchers and could correlate with methane. The SAM instrument measured oxygen averaging about 0.16 percent, rising higher than predicted in spring and summer and falling below expectations in winter. Formaldehyde, complex organics, unusual carbon isotopes, possible stromatolites, and Viking results add clues, but not proof, making the evidence worth examining further.

Transcript

Mars is often seen as the most likely place in the solar system to have, or have had, life. This could be indigenous life, or life that was delivered either to Mars through Panspermia, or perhaps more intriguingly from Mars to here. Are we Martians? And while there are plenty of candidates for other life in the solar system, Mars is the one that mo... Read More

Key Insights

• 🚚 Mars is considered a potential place to find life, either indigenous or delivered through Panspermia.
• 🇲🇭 The presence of methane and oxygen on Mars, with their peculiar behavior and seasonal patterns, suggests the possibility of biological activity.
• 🛟 Other biosignatures such as formaldehyde, complex organics, carbon isotopes, and potential stromatolites provide further clues about the potential for life on Mars.
• 🛟 The Viking landers' labeled release experiment yielded positive detections of microbial life on Mars, reinforcing the notion of past or present life on the planet.

Questions & Answers

Q: Why is oxygen considered a possible new Martian biosignature?

The SAM instrument found that oxygen followed an unusual seasonal pattern, rising higher than predicted in spring and summer and falling below expected levels in winter. Because the effect also varied each year and examined abiotic explanations did not account for it, biological activity remains a possibility rather than a confirmed cause.

Q: How much oxygen is present in the Martian atmosphere?

The transcript says oxygen averages about 0.16 percent in Mars’s atmosphere. Although the concentration is never very high, its unexpected seasonal changes make it scientifically interesting.

Q: How does methane behave on Mars?

Methane levels rise significantly during the Martian summer, and unexplained spikes have also been reported. Its seasonal behavior differs from that of other gases, which the transcript says looks more consistent with life than ordinary abiotic atmospheric variation and weighs against volcanism as the source.

Q: Do oxygen and methane prove that life exists on Mars?

No. Neither gas requires biology to form, but correlated changes in their levels could constitute a possible, potentially strong biosignature. The oxygen pattern deepens the mystery but is described as not being a definitive biosignature.

Q: Which non-biological explanations for Martian oxygen were examined?

Researchers considered whether carbon dioxide or water vapor might be split in the Martian atmosphere. According to the transcript, these mechanisms did not explain the observed oxygen effect, while its year-to-year variation also made ordinary abiotic atmospheric variation less likely.

Q: What other possible Martian biosignatures have been reported?

The transcript identifies formaldehyde, complex organics, unusual proportions of carbon 13 and carbon 12, and rover images resembling stromatolites or fossil bacterial mats. Each could have a non-biological explanation, so they remain clues rather than proof.

Q: What did the Viking labeled release experiment detect on Mars?

NASA’s Viking landers arrived at Mars in 1976 with direct life-detection experiments, and the labeled release experiment produced positive detections of microbial life. Whether those results represented life or false positives caused by Martian soil chemistry has remained disputed.

Q: When and where were formaldehyde and complex organics found on Mars?

Researchers using Mars Express found formaldehyde in the Martian atmosphere in 2005; it could arise from methane oxidation or life, though the chemical route would require greater geological activity than Mars appears to have. In 2018, Curiosity found complex organics in quantity in Gale Crater, possibly preserved from a younger and more habitable Mars.

Summary & Key Takeaways

• Methane is present on Mars, with levels that fluctuate during different seasons, raising the possibility of its biological origin.

• Oxygen, another potential biosignature, follows a different pattern compared to other gases on Mars, indicating the influence of a biological process.

• Other possible biosignatures supporting the existence of life on Mars include formaldehyde, complex organics, strange carbon isotopes, and rover images of potential stromatolites.