Alien life is almost certainly out there somewhere, but because it's most likely microscopic, it probably won't be easy to spot. Instead we might need to keep an eye out for other biomarkers, which could be detected in the atmosphere, soil or water of a planet. Now, researchers at the University of Illinois have come up with a new and fairly obvious sign of life: pasta-shaped rocks.
Modern-day Mars is a hellish world for most life as we know it. Liquid water and molecular oxygen are extremely scarce, and the surface is constantly bombarded with cosmic radiation. Conditions were probably better in the distant past, but even then they might not have been up to Earth standards.
That said, microbes have turned up in some of the most inhospitable places ever discovered here on Earth, so they can't be ruled out on other planets. And according to researchers on a new study, one of the best contenders also happens to leave a very obvious mark in rocks.
Named Sulfurihydrogenibium yellowstonense (or just Sulfuri for short), the bacterium could thrive on planets we might dismiss as too hostile. Here on Earth it makes its home in bubbling hot springs, it isn't bothered by ultraviolet light, and instead of oxygen it can make do with sulfur and carbon dioxide.
But its best trait is its distinctive fingerprint. When Sulfuri bacteria gather in fast-flowing water, they tend to latch onto each other in a chain, forming thin, wispy strands of material that look like pasta.
"They form tightly wound cables that wave like a flag that is fixed on one end," says Bruce Fouke, lead researcher on the study. "These Sulfuri cables look amazingly like fettuccine pasta, while further downstream they look more like capellini pasta."
Of course, the chances of finding flowing water full of Sulfuri bacteria on Mars today are extremely slim. But the good news is that their presence can be seen long after the organisms themselves have died. Calcium carbonate has been known to crystallize around the fibrous bugs, creating filamentous rocks that look like they're covered in angel hair pasta.
In fact, as part of the study the team found that proteins on the surface of the bacteria are responsible for speeding up the rate of crystallization. Amazingly, that can happen up to a billion times faster than in any other natural environment on Earth, the researchers say.
"This should be an easy form of fossilized life for a rover to detect on other planets," says Fouke. "If we see the deposition of this kind of extensive filamentous rock on other planets, we would know it's a fingerprint of life. It's big and it's unique. No other rocks look like this. It would be definitive evidence of the presences of alien microbes."
This could give future rovers, like Mars 2020 and ExoMars, a new target to keep an eye out for.
The research was published in the journal Astrobiology. The movement of the Sulfuri strands can be seen in the video below.
Source: University of Illinois