The search for life on Mars has been a long a confusing one. Inconclusive experiments abound, but one thing is certain – there is definitely organic material on the Red Planet. Now, a new study in Nature has confirmed that finding and showed just how complex that organic material actually is.
Understanding what this new study means requires understanding some of the backstory as to why it is important. Viking, one of the early landers on the Red Planet back in the 1970s, had an experimental result that puzzled scientists at the time – a few chemicals made it look like the sensor had been contaminated with cleaning fluids. It wasn’t until decades later, in 2008, that the Phoenix lander found perchlorate in the Martian regolith that it became clear that the Viking lander hadn’t detected cleaning materials – it had seen organic material that had been reacting with perchlorate in its sample.
Phoenix also directly measured organics in the Martian soil – notably methane, one of Earth’s most common organic materials. Curiosity also contributed with a clear detection of organics in 2012. But more recently, another, more capable rover arrived on the scene.
Perseverance landed on Mars in 2021 and has served as the basis for much of the ongoing burst of research about the planet. That includes the latest Nature study, which utilized the Scanning Habitable Environments with Raman and Luminescence for Organics and Chemicals (SHERLOC) instrument on the rover.
SHERLOC scans a target from about 2 inches away using techniques, including deep ultraviolet Raman and fluorescence spectroscopy, which can help differentiate types of organic materials in the object being scanned. What the instrument found surprised Dr. Amy Williams of the University of Florida (UF) and her fellow experts in organic chemistry.
According to a press release from UF, signs appeared in SHERLOC’s data that were “consistent with molecules linked to aqueous processes” according to a press release from UF. In other words, some organic materials that SHERLOC collected data on were created underwater.
That might not come as a big surprise, given that Jezero Crater, Perseverance’s landing spot, was specifically selected as it was thought to be a dried-up lake bed. However, there was variability in different areas of the crater that hinted at a more complex organochemical system than the scientists initially thought.
As with all articles focused on organics on Mars, we must include a disclaimer that this does not mean that Martian life created these organic compounds. Plenty of geochemical processes can do so, and the general consensus of Perseverance’s scientific teams is that all the organic signatures they have seen so far can be attributed to creation by non-biological processes.
But, as Dr. Williams puts it in the press release, “We are just now scratching the surface of the organic carbon story on Mars.” Despite 50+ years of data collection, most of that story still needs to be written. And, despite some recent setbacks in the development of the Mars Sample Return, Perseverance’s follow-up mission, there will be plenty of other opportunities to study these compounds on the Red Planet in the future.
UF – Study Reveals Evidence of Diverse Organic Material on Mars
Sharma et al – Diverse organic-mineral associations in Jezero crater, Mars
UT – Perseverance Has Collected Samples from One of the Best Places to Search for Ancient Life on Mars
UT – What Happens if Perseverance Finds Life on Mars?
Perseverance taking a look at its surroundings with its Mastcam.
Credit – NASA / JPL-Caltech / MSSS