Welcome to this week’s edition of The Intelligence Brief… this week, we’ll be turning our focus toward an underreported study involving a surprise discovery on the Red Planet. This involves 1) a curious discovery by the Curiosity rover, and how that relates to 2) the search for life on Mars, 3) what the recent findings suggest about the possible existence of life on ancient Mars, and 4) why the question of biology shouldn’t be ruled out entirely.
QUOTE OF THE WEEK
“In our time this search for extraterrestrial life will eventually change our laws, our religions, our philosophies, our arts, our recreations, as well as our sciences. Space, the mirror, waits for life to come look for itself there.“
And with that out of the way, it’s time once again to get up to speed on new developments taking place on the Red Planet, and why one recent discovery had a few astrobiologists wondering “what if?”
Curiosity Makes a Curious Discovery
Just a few weeks ago, NASA made an intriguing announcement about something unusual detected by the Curiosity rover during its analysis of powdery samples it had gathered from the Martian surface.
Although Perseverance has been getting most of the attention since its arrival on the Red Planet last spring, its predecessor, Curiosity, has remained in operation at its location in Gale Crater since its arrival as part of the Mars Science Mission (MSL) on August 6, 2012. And during its recent analysis of a collection of Martian rock samples, Curiosity was able to detect a unique type of carbon that, on Earth, is recognized for its appearance in association with biological processes.
That’s right, you read correctly: biological. But while Curiosity’s recent discovery is certainly promising, how likely is it that one of our Martian rovers may have found evidence of what scientists have long hoped for: evidence of life beyond Earth?
The Search for Life on Mars
Whether extinct or still extant, the search for life on Mars is one of astrobiology’s greatest pursuits, and if ever confirmed, would represent one of the most significant scientific discoveries of all time. Given its barren appearance, it’s hard to look at Mars as it appears today and think of it as the kind of place that would be teeming with life. However, that wasn’t always the case; billions of years ago, Mars was very likely a warmer, wetter place than it is right now, and would have possessed an atmosphere of carbon dioxide, making it a far better home for any prospective life than it currently is.
Add to this the fact that Mars would have been going through its more habitable phase around the same time that life is believed to have first begun to develop in primordial springs here on Earth, and it seems all the more plausible that the Red Planet might have once been home to its own varieties of simple organisms.
Of course, things changed at some point along the way, and the differences between the environments on Earth and its nearest planetary neighbor gradually became vastly different over time. While it seems unlikely that Mars as it now exists could still be home to life, there is still a better chance that evidence of life at an earlier time will be found on Mars than in other locations throughout our solar system.
So, what did Curiosity recently find, and does it move us any closer toward understanding whether the ancient Martian landscape could have ever been hospitable for life?
Although the recent analysis by Curiosity has certainly garnered attention from NASA, there are a range of reasons why this variety of carbon might have turned up on Mars. Unfortunately, these don’t all necessarily involve the presence of life.
Paul Mahaffy, who retired from NASA’s Goddard Space Flight Center last December, had previously served as the principal investigator of the Sample Analysis at Mars (SAM) chemistry lab aboard Curiosity. Mahaffy says that while the discovery of a rich form of carbon associated with life on Earth is certainly promising, scientists “would really need more evidence to say we’ve identified life.”
Right now, Mahaffy says his former NASA colleagues are “looking at what else could have caused the carbon signature we’re seeing, if not life.”
Even if the discovery doesn’t point to evidence of ancient life on Mars, it will likely present new data that will be useful in terms of understanding how organic processes occur on Mars, as compared to similar processes on Earth.
According to a paper published in Proceedings of the National Academy of Sciences on January 25 that expanded on the recent findings, carbon isotopes that were detected in methane baked off during part of the analysis process (called pyrolysis) appeared to “show remarkable variation indicating different origins for the carbon evolved from different samples.”
The paper’s authors suggested three different ways this “highly fractionated” carbon might have ended up on Mars, which all appear to have one thing in common: that “Martian carbon cycling is quite distinct from that of the present Earth.” In other words, processes that give rise to the formation of a unique variety of carbon on Mars are likely to be quite different from how they occur here on Earth.
However, that doesn’t necessarily preclude the possibility that ancient Martian lifeforms might have played a role in what NASA scientists with the recent carbon study were seeing.
“The hardest thing is letting go of Earth,” said Goddard astrobiologist Jennifer L. Eigenbrode, one of the study’s participants, in a recent post at NASA’s Mars Exploration Program page.
According to Eigenbrode, “We need to open our minds and think outside the box,” which is precisely what she and her coauthors attempted to do in the January 25 PNAS paper; and of the three possible explanations the paper presents, one does still focus on the possibility of life.
In one scenario the paper examines, the distinctive carbon signatures detected by Curiosity might stem from a process where methane released into the ancient Martian atmosphere by bacteria could have been transformed into more complex molecules through exposure to ultraviolet light. The converted molecules would thereafter have fallen back to the surface, and remained there preserved within the rocks collected by Curiosity.
Although the other explanations the paper examines do not involve the presence of ancient bacteria to account for the unique carbon signatures, Christopher House, the study’s lead author, notes that “All three explanations fit the data,” and that scientists will require “more data to rule them in or out.”
While the current analysis by the Curiosity team falls short of providing evidence of life on Mars, the ongoing search may soon get a helping hand from the Perseverance rover, which will be collecting samples to be returned to Earth for future study. Thus, it could yet prove that in the years ahead, additional analysis of Martian samples brought back to Earth could present even more promising results, some of which may point to evidence of life that once thrived on Earth’s nearest neighbor.
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