. 24/7 Space News .
Does Iron Contain A Life Signature
photo copyright AFP Madison - September 16, 1999 - Reading the narrow bands of iron found in some sedimentary rocks, scientists may have found a way to assess microbial populations across time and space, opening a window to the early history of life on Earth and possibly other planets.

Writing in the Friday, Sept. 17 issue of the journal Science, a team of scientists led by UW-Madison geochemist Brian L. Beard describes a geochemical signature in iron indicative of life.

If the technique is confirmed and refined, it could be used to trace the distribution of Earth's microorganisms in the distant past, and could help resolve disputes about the existence of past life on other planets such as Mars.

"This could be an ideal biosignature," Beard says in describing a set of iron isotope-sorting experiments designed to determine if iron found in different kinds of rocks has been metabolized by microorganisms.

Iron is vital to plant, animal and microbial life. Nearly all organisms ingest it in the course of daily life. If scientists can devise a method to distinguish between iron that has been processed by a living organism and iron that has not been metabolized, they will have a way to measure the distribution of microbes on Earth billions of years ago.

Because iron is common on the moon, planets and other objects in space, the technique could be used to detect signs of past life beyond our own planet.

Beard's group measured the isotopic composition of iron from two distinct sources: sedimentary rock and igneous rock. Sedimentary rock reflects the accumulation of sediments, including organic material and trace elements such as iron. Igneous rock is forged deep in the Earth at very high temperatures where life is absent. It also can contain iron.

Working in collaboration with scientists from NASA's Jet Propulsion Laboratory and the Institute for Great Lakes Study at UW-Milwaukee, the Wisconsin team sampled the isotopic composition of iron from the two sources by incinerating samples of iron and measuring charged particles from the reaction is a mass spectrometer, a device that sorts and counts ionized particles.

"Measurable isotopic variations can be seen," says Beard. "The mass differences are small, but large enough that a microorganism could have made the difference."

Isotopes from sedimentary rock, says Beard, match the isotopic signature of iron ingested and metabolized by bacteria in the lab: "What we found in the biological experiments was that microbes produce a measurable iron isotope fractionation. We wondered if inorganic processes might have the same effects, but we found that the isotopic composition of iron in igneous rocks is constant."

Knowing this, it may now be possible for scientists to look at sedimentary rock and gain a sense of the worldwide ebb and flow of microbial populations in the distant past, perhaps as far back as 2 billion years ago, when the Earth's oceans were full of soluble iron. Such insight may help show how life evolved on Earth.

"Iron has had a dramatic effect on how organisms have evolved," Beard says. "Microorganisms fight for iron and some have developed a chemical compound that allows them to grab iron and store it for future use."

Beard says his group next plans to apply the technique to a piece of the Mars Rock, a controversial meteorite that some scientists believe harbors evidence of past microbial life on the Red Planet. It could also be used to screen samples brought back to Earth from planned NASA missions to Mars.

Co-authors of the paper published in Science include Clark Johnson, a professor of geology and geophysics at UW-Madison; Lea Cox, Henry Sun and Kenneth Nealson of NASA's Jet Propulsion Laboratory in Pasadena, Calif.; and Carmen Aguilar of the Institute for Great Lakes Study at UW-Milwaukee.

  • Isotope Geochemistry Research
  • Radiogenic Isotope Laboratory

    Life and ExoWorlds at SpaceDaily

  • Europa: Cold, Wet and Dark
  • ETs Invade Computers
  • Not All Habitable Zones Are Created Equal
  • Are Life's Diamonds That Rare
  • ET's Will Dig Pink Floyd
  • Gaia Gets New Life As Gas Station
  • Did Supernova Zap Earth Life
  • Galactic Wide Gamma Ray Burst Inhibit Life
  • Life In The Void
  • Proto Asteroid Belt Spotted
  • Extra-Solar Multi Planet World Discovered
  • Masking Starlight In Search of Ozone Signatures
  • Early Extrasolar Analysis Favors Heavy Elements
  • ExtraSolar Planet With Earth-Like Orbit
  • Detecting Earth Like Planets
  • SETI Insensitive To Marconi
  • Origins Of Our Stellar History

    Related News Baskets at SpaceDaily

  • Space Science - SpaceDaily Special
  • SETI News - SpaceDaily Special
  • Exo Worlds - SpaceDaily Special

    Additional Offsite Links

  • David Pacchioli, "Worlds Beyond the Sun"
  • James F. Kasting - Habitable Climates
  • James F. Kasting - CO2 Clouds: Their Effect on Martian Paleoclimate
  • Calvin W. Johnson - Goldilocks and the Three Planets
  • Could Life Exist on Extra-Solar Planets?
  • Planets and Life
  • Life in the Milky Way and Beyond
  • Planetary Society - Scientists Explain Mars' Liquid Water
  • New Scientist - In the Dark
  • Raymond T. Pierrehumbert - Warming Early Mars With Carbon Dioxide

    Thanks for being here;
    We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain.

    With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords.

    Our news coverage takes time and effort to publish 365 days a year.

    If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.
    SpaceDaily Contributor
    $5 Billed Once

    credit card or paypal
    SpaceDaily Monthly Supporter
    $5 Billed Monthly

    paypal only

  • The content herein, unless otherwise known to be public domain, are Copyright 1995-2016 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement All images and articles appearing on Space Media Network have been edited or digitally altered in some way. Any requests to remove copyright material will be acted upon in a timely and appropriate manner. Any attempt to extort money from Space Media Network will be ignored and reported to Australian Law Enforcement Agencies as a potential case of financial fraud involving the use of a telephonic carriage device or postal service.