Aliens among us? ASU prof aims to find out

Aliens may be living among us.

Lurking in nuclear waste pools. Breeding in acidic lakes. Or creeping underground devoid of oxygen and light.

This may sound like a teaser for a science-fiction movie, but it is the subject of a scientific paper written by Arizona State University Professor Paul Davies that is appearing in next month's Astrobiology journal.

In the paper, titled "Signatures of a Shadow Biosphere," Davies calls on scientists to broaden their scope when examining living things. He urges them to go beyond the methods they usually employ and be open to the existence of "weird" life or "life as we don't know it."

"In effect, I'm trying to raise the consciousness of the scientific community to the possibility that life on Earth may have had more than one origin," he said. "If 'weird' life is proven to exist, it would be the biggest thing since Darwin."

Davies' aliens are not likely to be one-eyed purple people eaters. The majority of Earth's organisms are unseen by the naked eye. Therefore, these aliens are more likely to be microorganisms or microbes.

Alien microbes would be easiest to spot if found in severe temperatures or brutal landscapes, Davies said, which is possible if they arose independently of known life.

Life as we know it has a standard biochemistry and genetic code. For example, every known living species uses DNA. But alien life may not have DNA at all. It could therefore inhabit toxic lakes, scorching deserts, or the freezing plains of the Arctic. If microbes are found living amid these conditions, there is a good chance they could be alien, Davies said.

To prove his hypothesis, Davies proposes a "mission to Earth." He wants to explore areas with severe temperatures or pressures - places uninhabited by known living things. These locations could potentially be home to alien life - or as Davies put it, a "shadow biosphere."

One of these places is the arsenic-rich Mono Lake, near Yosemite National Park in California. Davies believes some of the billions of microbes living in the lake could be alien.

Known life is based on oxygen, carbon, hydrogen, nitrogen, sulfur and phosphorous. Perhaps alien life thrives off arsenic instead of phosphorous, Davies said. Arsenic is poisonous to humans, but it could serve as a replacement because "most of the jobs that can be done by phosphorus can be done by arsenic."

There have been explorations of the lake before. But the problem is that scientists don't know how alien life looks or acts under the microscope, Davies said. Biochemical processes would not be the same for alien organisms as they would be for known organisms. By definition, they have a different makeup and metabolism. Davies wants scientists to be conscious of this when studying their slides.

"Our techniques are customized to the biochemistry of known life," Davies said. "Might (life) exist on Earth today in extreme environments and remain undetected?"

At the core of Davies' argument is the possibility that life on Earth emerged more than once - most likely about 500 million to 700 million years after the Earth was formed. During this period, Davies said, organisms could have hitched a ride on a meteor from Mars and thrived here on Earth. In another hypothetical, life could have started many times on both Earth and Mars.

Chris McKay, planetary scientist at NASA-Ames Research Center, said there is a growing interest in Davies' hypothesis. McKay, who co-authored the article, said when scientists looked at a culture under a microscope 20 years ago, they could see only 1 percent of the microbes that they can see now.

McKay and Davies are now hoping to make another breakthrough.

McKay said that the way things stand now, life on Earth is seen as a "cosmic fluke." If alien life is found, it "will provide a fundamental new insight into life," he said. He hopes the forthcoming paper will provide scientific rationale for laboratories to obtain funding for research to move the hypothesis forward.

Along with Davies and McKay, there are four other co-authors. In all, there are cosmologists, chemists and even a philosopher signed on to the paper. One co-author, Felisa Wolfe-Simon, a geobiochemist studying at Harvard University, said the group wanted to bring people together with diverse backgrounds, so they could have a well-rounded, fully informed hypothesis.

"We're at a point in science, where one person just can't be a renaissance person," she said. "You need to have input from people of all walks of science."

Scientists have long been intrigued by the possibility of finding alien life. Just last week, NASA launched the telescope, Kepler, into outer space. Kepler's mission is to find out if there are other worlds like Earth in the universe. The hope is to find life on other planets. It will last more than three years and cost about $600 million.

Davies is quick to point out that his proposed search for aliens is not complex - or costly.

"There are plenty of places to trawl here," he said. "After all, what's more Earth-like than Earth?"