Do aliens exist? Are aliens green? Do they ride in UFOs?

These questions have plagued people on Earth for years, and have often been accepted as mythical fantasy rather than verifiable fact. However, the concept of aliens may be closer to reality than you think—and one place in consideration for aliens is Mars.

A new study conducted by NASA on January 17, 2022, shockingly discovered that large amounts of carbon-12 were found in powdered rock on Mars. Since carbon-12 is known as life’s most important isotope, many scientists believe that the discovery of carbon can imply that there was, at one point, the presence of ancient biological life. 

How was NASA able to realize that there was carbon hidden in the rock? NASA was able to collect various rock samples by sending the Curiosity rover to Mars in 2012, where it traversed the Gale Crater. The rover employed a robotic arm to amass rock samples from under the surface of Mars, and the samples were then exposed to high heat, resulting in a release of carbon gas from the rock. One of the rover’s tools then utilized the gas to measure isotopes from the carbon, and the isotopes can help scientists determine whether there were carbon-related activities in the past. Researchers were surprised to find the carbon-12 isotope in these samples, because the atmosphere on Mars and meteorites that have struck the planet do not contain the same levels of carbon.

Christopher House, a Curiosity scientist who led the study, stated that “processes that would produce the carbon signal we’re detecting on Mars are biological.” However, he also added that “We have to understand whether the same explanation works for Mars, or if there are other explanations, because Mars is very different.” There are three crucial theories scientists have proposed that can explain the presence of carbon-12 in the rock. 

One theory proposed by researchers explores the biological explanation for such a phenomenon. House stated that “The amounts of carbon-12 and carbon-13 in our solar system are the amounts that existed at the formation of the solar system. Both exist in everything, but because carbon-12 reacts more quickly than carbon-13, looking at the relative amounts of each [isotope] in samples can reveal the carbon cycle.” When the rock samples were discovered, researchers quickly realized that the samples contained enriched carbon-12 but low levels of carbon-13. This biological theory suggests that bacteria may have released methane gas into the environment, where Ultraviolet light then transformed this gas into larger, more complex molecules that settled on the exterior of the rock. Thus, the molecules stayed in the rocks collected by the Curiosity rover. However, when NASA discovered methane gas on Mars in 2019, they were unable to discern whether the methane produced resulted from biological processes or not. House explained that “The samples [that are] extremely depleted in carbon-13 are a little like samples from Australia taken from sediment that was 2.7 billion years old. Those samples were caused by biological activity when methane was consumed by ancient microbial mats, but we can’t necessarily say that [is the case] on Mars because it’s a planet that may have formed out of different materials and processes than Earth.” 

Besides the biological theory, there remain two alternative non-biological explanations identified in the study. One theory indicates that the carbon signals resulted from an interaction of ultraviolet light and carbon dioxide gas in the atmosphere, which could have produced carbon-containing molecules that settled on the rock. 

The other explanation suggests that the carbon was derived from a cosmic event from millions of years ago, but there is limited evidence for this theory. During the event, the solar system passed through a molecular dust cloud that deposited dust on various planets, which contained the same carbon found in the rock samples. However, the dust should also be found on Earth as well, but evidence of it on Earth is nearly nonexistent. Furthermore, Glaciers are necessary for that argument to work on Mars, and there is limited evidence that there were ever glaciers in the Gale crater. 

Fundamentally, carbon-12 discovered on Mars could have an indication of past life, but we still lack the evidence necessary to confirm such a claim. House admits that “All three explanations fit the data…We simply need more data to rule them in or out.”

Bibliography

“EarthSky | Scientists Find Carbon-12, Life’s Most Crucial Isotope, on Mars,” January 21, 2022. https://earthsky.org/space/scientists-find-carbon-12-13-isotope-on-mars/.

“Study: Mars Rock Contains Carbon ‘Signals’ Possibly Linked to Life.” VOA, https://learningenglish.voanews.com/a/study-mars-rock-contains-carbon-signals-possibly-linked-to-life/6405728.html. Accessed 3 Apr. 2022.

Shekhtman, Svetlana. “NASA’s Curiosity Rover Measures Intriguing Carbon Signature on Mars.” NASA, 14 Jan. 2022, http://www.nasa.gov/feature/goddard/2022/nasa-s-curiosity-rover-measures-intriguing-carbon-signature-on-mars.