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UA researchers look for life outside of Earth

An astronomer, a geoscientist and a biologist walk into a room. No, it’s not the beginning of a joke — this is a typical astrobiology meeting. At the UA, the highly interdisciplinary astrobiology program researches everything from extremophiles to exoplanets in an attempt to study life in the universe.

The search for life in space, however, begins at home with the examination of extreme life forms and conditions on earth.

“If you want to know what life in the universe might look like, you have to know [what] the full boundaries of terrestrial biology [are], and we haven’t really found them yet,” said Chris Impey, a professor of astronomy.

The examination of life on earth has lead to discoveries of life in many places that seemed impossible, including deep mine shafts and beneath ice sheets.

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“We can find life in basically every possible niche on earth,” said Daniel Apai, an assistant professor of planetary sciences and an astrobiologist. “That also encourages a search … for life beyond earth and beyond the solar system.”

Based on discoveries made on earth, the most likely life forms in space are probably microbes and viruses, according to Gary Trubl, a fourth-year graduate student studying soil, water and environmental sciences.

“People think we’re looking in space and we’re looking for these big animals,” Trubl said. “But really, we’re trying to understand the origin of life, what makes a planet habitable, what nutrients are essential for life, and we’re specifically looking for microbes or viruses.”

In the past, scientists have looked to Mars and Europa — one of Jupiter’s moons — as possible sources of life. Now, astronomers have been able to find earth-like planets around other stars. Apai’s research includes finding and mapping exoplanets, which are planets that don’t orbit the sun and instead orbit another star.

Finding exoplanets is very difficult compared to finding stars, Apai explained. The signal given off by planets is very weak, especially when compared to the brightness of the stars they orbit. He compared it to trying to find a firefly on a lighthouse.

For years, many people didn’t even think it was possible to find exoplanets. In the past decade, it has become easier to do so, and more planets found every day.

”It’s a co-evolution of technology [and] computational resources, but also ideas and a little bit of ingenuity,” Apai said.

However, even though there may be life on some exoplanets, demonstrating the presence of it is a hard experiment, Impey said.

Assuming a carbon-based life form with similar nutrient and energy needs as life on Earth, the cheapest and most effective way to demonstrate life elsewhere is to look for a biosignature, Trubl said. A biosignature consists of gases such as methane that produce specific isotopic signatures that we know come from life, according to Trubl.

Even if life is out there, that doesn’t guarantee researchers will be able to find it.

“Space is very large,” Impey said. “Life could be out there, but we could still be isolated by time and space.”

Despite these challenges, the future of astrobiology is bright. Researchers remain optimistic and there appears to be increased public interest.

“People have been asking the question of whether there is life on other planets for 2000 years,” Apai said, “but now the question has moved from philosophy to science.”

—Follow Amy Nippert @DailyWildcat


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