A NASA-funded study, led by University geology professor Bruce Fouke, has determined that a certain type of pasta-looking rock could be indicative of past life on the red planet. 

These fettuccine-like rocks are a subset of Travertine, a type of banded sedimentary rock that is made up of calcium carbonate. Their fibrous appearance is a testament to how they were formed; the rocks are a result of Sulfurihydrogenibium yellowstonense, or Sulfuri bacteria’s tendency to form in long threads. The bacteria bind together to form cables around which calcium carbonate crystallizes. This effect creates the rock’s pasta-like appearance.

Since the rocks formed around Sulfuri bacteria are very unique in appearance even compared to other types of travertine rock, rovers on Mars could easily identify them on the Martian surface. If the fettuccine-looking rocks were to be found on the surface of Mars, it would be evidence for life to have existed on the planet. In order to confirm that Sulfuri could have survived on the Martian landscape, the team studied the metabolic needs of the bacterium.

“Instead of breathing oxygen like we do, they actually like to breathe sulfur in the form of sulfide,” Fouke explained. “It’s quite resourceful. It has multiple metabolisms, and what I mean by that is that we as humans, the scientific way to describe it, need to eat organic matter that was previously formed by plants or animals…that’s the only way we operate. But it’s not uncommon for some of these Sulfuri filaments to be able to do upwards of five, six or seven metabolisms. It can go all the way from ancient forms of rudimentary photosynthesis all the way to being like us, eating Snickers and breaking it down with oxygen.”

Because of the bacteria’s flexibility as being both an autotroph and heterotroph, as well as its ability to tolerate ultraviolet light and low oxygen levels, the research team concluded that Sulfuri would have had the proper conditions to exist on the Martian surface. Paired with the fact that the rocks formed by Sulfuri have a distinctive appearance resembling pasta, these rock formations would be an easy way to detect the presence of microbial life on other planets. 

“When we go to another planet and look for life, we want to be able to collect just the right rocks, and that’s not an easy task because there are all kinds of rocks on Mars and other places,” Fouke said. “But if you tell the rover and search with it to find these kinds of sinuously shaped travertines…that allows us to then have a very specific search of what to come home with.”

In order to study the Sulfuri formations, the research team traveled to the Mammoth Hot Springs in Yellowstone National Park, where they collected samples of the rock. “The results that we’re getting from Yellowstone have allowed us to understand how similar types of processes, not in hot water, but other environments, operate throughout the planet,” Fouke said. “So we use Yellowstone as a natural laboratory to understand how life has evolved, how life first emerged, how life makes a living and also life’s interaction with minerals. Here it’s calcium carbonate, and we have our bones which are very similar to that. So we do our laboratory work in Yellowstone and then we apply the results directly to other systems.”

The team’s research findings on the Sulfuri travertine rocks are currently in active use by NASA to search for similar rocks on the Martian surface. But the findings haven’t only been used to search for life in space; the specific form of calcium carbonate called aragonite found in the Sulfuri travertines is the same mineral used by corals to grow their skeletons in warm and shallow tropical seas. The research done at the Mammoth Hot Springs has also, therefore, led to new information about corals, and how they will be affected by the rise in sea surface temperature due to global warming.

“It’s extremely cross-disciplinary work,” said Fouke. “I’m a geologist, and also now a professor in microbiology and work in the genomics institute. [The University of] Illinois is very unique in having the capacity and the interest in having very strong cross-disciplinary research going on. It’s a very unique and important part of our campus.”

Fouke also mentioned his optimism for the future of how prevalent cross-disciplinary research will become. “That’s what’s so exciting about your generation and future generations, is that everything is connected.”

Professor Fouke himself is a testament to this, having worked not only with travertines and coral reefs, but also researching the formation of kidney stones in humans. He also researched the timing and hydrology of the last flow of water in the aqueducts of ancient Rome. The variety of Fouke’s work goes to show that all the disciplines of science are inseparable from one another; researching calcium carbonate in hot springs can both help us understand the structure of coral reefs and to search for life in the universe. 

As the divide between disciplines grows fainter, it’s certain that many of today’s findings will allow for applications across several fields, even those that at first glance seem far removed from others.

Natalie is a junior in LAS. 

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