Martian life on earth?

A cave in the Oregon Cascades may very well contain clues to ancient life on Mars, according to a paper published by Dr. Radu Popa, a Portland State researcher and associate professor of biology.

According to Popa’s paper, the South Ice Cave, located in central Oregon, sits at an elevation of 5,019 feet and isn’t actually a cave. It is a basalt lava tube, a common type of volcanic rock. Upon analysis, the volcanic rock shows evidence of fossilized bacteria that can survive in extreme conditions. The temperature in the cave can be as low as five degrees Celsius, and its physical environment is similar to that of Martian volcanoes.

Popa has taught at PSU for five years, but his research goes back to 1994 when, along with Dr. Martin Fisk from Oregon State University’s College of Ocean Ecology and Biogeochemistry, Popa collaborated on a project for NASA. The project looked at the microbe that lives in the olivine crystal inside basalt rock.

The microbe was discovered in a rock found in Egypt in 1930. Popa said that fossils of the bacteria—Pseudomonas sp. HerB—can be seen under a microscope as they eat their way through the olivine crystal, creating entrances called microchannels. These microchannels were the first clue to the existence of ancient life on Mars.

“The question becomes: can we prove that the microbes that make this channel also exist on earth?” Popa asked.

To answer the question, Popa and his team of four other people traveled to the ice caves in the summer of 2008 to collect rock samples. The group hauled all of their own equipment as they crawled through tight, dark spaces inside the caves, some of which were filled with debris, mud and ice up to the ceiling.

Amy Smith, a former master’s student in the biology department at PSU, collaborated on the research. She said the experience was unnerving and at times scary, citing a moment when she suspected a wild animal might have been living in one of the caves.

Finding connections between Earth and Mars is challenging, but according to Popa, the main difficulty is in knowing the right questions to ask.

“We’ve been asking the wrong question since 2004. We’re just lucky to ask the right question in 2009 and the moment we knew, the answer was right there before us,” Popa said.

Popa and the researchers now know that microbes exist on earth in places that share similar physiology with Mars—places like the ice caves. When researchers isolated the microbe, they noticed that in near-freezing temperatures and low-oxygen conditions, the microbes consume iron within the olivine crystal for energy.

Smith, who is now a first-year doctorate student at OSU, said that the research is important because they now can identify these “biosignatures” left by the bacteria on the minerals. This gives scientists an idea of what to look for when NASA sends a rover to Mars.

In an article published in the scientific journal Astrobiology in 2011, researchers said organisms that consume olivine may have been the earliest Martian colonists. Popa said, however, that the chances of finding organisms that are still alive today are small, since the environmental conditions need to be comparable to those on the surface of Mars, and those conditions aren’t met on Earth.

In addition to researching olivine-consuming microorganisms, Popa is also working on research that uses microbes and black soldier fly larvae to assist in the processing of biodegradable waste, to convert organic waste into fuel, and for livestock feed. More information on this research can be found on Popa’s website, www.dipterra.com.