Follow the nitrogen to extraterrestrial life

May 04, 2006

The narrow search for water may miss important clues, say USC geobiologists
The great search for extraterrestrial life has focused on water at the expense of a crucial element, say geobiologists at the University of Southern California.

Writing in the Perspectives section of the May 5 issue of Science, four USC researchers propose searching for organic nitrogen as a direct indicator of the presence of life. Nitrogen is essential to the chemistry of living organisms.

Even if NASA were to find water on Mars, its presence only would indicate the possibility of life, said Kenneth Nealson, Wrigley Professor of earth sciences in the USC College of Letters, Arts and Sciences.

"It's hard to imagine life without water, but it's easy to imagine water without life," Nealson said.

The discovery of nitrogen on the Red Planet would be a different story.

"If you found nitrogen in abundance on Mars, you would get extremely excited because it shouldn't be there," Nealson said.

The reason has to do with the difference between nitrogen and carbon, the other indispensable organic element.

Unlike carbon, nitrogen is not a major component of rocks and minerals. This means that any substantial organic nitrogen deposits found in the soil of Mars, or of another planet, likely would have resulted from biological activity.

Dimming the hopes of life-on-Mars believers is the makeup of the planet's atmosphere. The abundant nitrogen in Earth's atmosphere is constantly replenished through biological activity. Without the ongoing contribution of living systems, the atmosphere slowly would lose its nitrogen.

The extremely low nitrogen content in the Martian atmosphere suggests that biological nitrogen production is close to zero.

However, the authors write, it is possible that life existed on Mars at some hypothetical time when nitrogen filled the atmosphere.

Co-author Douglas Capone, Wrigley Professor of environmental biology in USC College, said NASA should establish a nitrogen detection program alongside its water- seeking effort. He noted that next-generation spacecraft will have advanced sampling capabilities.

"What we're suggesting here is basically drilling down into geological strata, which they're going to be doing for water anyway," Capone said.

"The real smoking gun would be organic nitrogen."

Said Nealson: "If your goal is to search for life, it would be wise to include nitrogen."

In their acknowledgments, the authors thanked the students of the Spring 2004 Geobiology & Astrobiology course at USC, with whom Nealson and Capone began their discussion on how to search for life outside earth.

"That's really what stimulated this [paper]," Nealson said.

Source: University of Southern California

Explore further: NASA astronaut memorial stirs memories for shuttle veteran (Update)

add to favorites email to friend print save as pdf

Related Stories

Drought led to massive 'dead zone' in Lake Erie

Jan 06, 2015

Lake Erie just can't catch a break. The lake has experienced harmful algal blooms and severe oxygen-depleted "dead zones" for years, but now a team of researchers led by Carnegie's Anna Michalak and Yuntao ...

Hunting for dark matter in a gold mine

Dec 09, 2014

"What really impressed me was the trip down," said astrophysicist James Buckley, PhD, speaking of the vertical mile he traveled to get to the site of an underground dark-matter experiment. "You can see you're ...

Orion test sets stage for ESA service module

Dec 08, 2014

Today's flight and splashdown of NASA's first Orion spacecraft paves the way for future human exploration beyond low orbit powered by ESA's European Service Module.

Recommended for you

Scientists launch CubeSats into radiation belts

15 hours ago

Twin, pintsized satellites built in part at the University of New Hampshire's Space Science Center will be launched into orbit from Vandenberg Air Force Base in California at 9:20 a.m. (EST) Thursday, January ...

Cassini catches Titan naked in the solar wind

15 hours ago

(Phys.org)—Researchers studying data from NASA's Cassini mission have observed that Saturn's largest moon, Titan, behaves much like Venus, Mars or a comet when exposed to the raw power of the solar wind. ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.