Follow the nitrogen to extraterrestrial life

May 4, 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: Scientists launch project to tackle global 'clean cold' challenge

Related Stories

Laboratory perfects metal powders for manufacturing

January 12, 2017

Iver Anderson and Emma White, metallurgists at Ames Laboratory, like to show off samples of metal powders encapsulated in custom-made hourglasses to visitors. Dull gray, the powders are barely remarkable in and of themselves, ...

$1M dead zone contest: 5 finalists from AUS, Calif, Ill, NY

December 24, 2016

Teams from Australia, New York and California are among five finalists in Tulane University's $1 million contest to find ways to fight "dead zones" where water holds too little oxygen to support life. There are hundreds of ...

New leaf study sheds light on 'shady' past

December 19, 2016

A new study led by a research scientist at the Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab) highlights a literally shady practice in plant science that has in some cases underestimated plants' ...

Recommended for you

Galaxy murder mystery

January 17, 2017

It's the big astrophysical whodunnit. Across the Universe, galaxies are being killed and the question scientists want answered is, what's killing them?

ALMA reveals sun in new light

January 17, 2017

New images from the Atacama Large Millimeter/submillimeter Array (ALMA) reveal stunning details of our Sun, including the dark, contorted center of an evolving sunspot that is nearly twice the diameter of the Earth.

0 comments

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.