Featured Research

from universities, journals, and other organizations

Scientists Find Further Evidence Of Ancient Microbial Life On Mars In Meteorite

Date:
February 27, 2001
Source:
NASA/Ames Research Center
Summary:
An international team of researchers has discovered compelling evidence that the magnetite crystals in the martian meteorite ALH84001 are of biological origin. The researchers found that the magnetite crystals embedded in the meteorite are arranged in long chains, which they say could have been formed only by once-living organisms.

An international team of researchers has discovered compelling evidence that the magnetite crystals in the martian meteorite ALH84001 are of biological origin.

Related Articles


The researchers found that the magnetite crystals embedded in the meteorite are arranged in long chains, which they say could have been formed only by once-living organisms. Their results are reported in the Feb. 27 Proceedings of the National Academy of Sciences.

"The chains we discovered are of biological origin," said Dr. Imre Friedmann, an NRC senior research fellow at NASA's Ames Research Center in California's Silicon Valley and leader of the research team. "Such a chain of magnets outside an organism would immediately collapse into a clump due to magnetic forces," he said.

The chains were formed inside organic material whose structure held the crystals together. "The end result looks somewhat like a string of pearls," Friedmann noted. Each magnetite crystal in the chain is a tiny magnet, approximately one-millionth of an inch in diameter. Magnetite is an iron oxide, similar to iron rust.

The chains may have served as 'compasses' for the host magnetotactic bacteria, so named because they navigate with the help of the magnetic crystal chains inside their bodies. The chains were preserved in the meteorite long after the bacteria themselves decayed.

The researchers say the magnetite chains probably were flushed into microscopic cracks inside the martian rock after it was shattered by an asteroid impact approximately 3.9 billion years ago. This cataclysmic event on Mars' surface also may have killed the bacteria. The same, or a later, asteroid impact ejected the rock, now a meteorite, into space.

Another NASA research group, led by Kathie Thomas-Keprta of NASA's Johnson Space Center, report in the same issue of PNAS that the magnetite crystals inside the meteorite are similar to those formed by 'modern' magnetotactic bacteria now living on Earth. The team studied only single crystals, however, not the elusive chain-like structures.

Friedmann's team discovered the crystal chains using a technique that enabled them to 'see' the tiny chains inside the meteorite without destroying them. Besides the chain-like formation, the team discovered that individual crystals are of similar size and shape, do not touch each other and that the chains themselves are flexible, further evidence of biological origin.

"Until now, studying life has been like trying to draw a curve using only one data point -- life on Earth," said Friedmann. "Now we have two data points to draw life's curve." The next step is to find the remains of the bacteria themselves, he said.

The fact that a small (about 4-pound) meteorite from a planet contains large numbers of bacteria suggests that such bacteria were widespread on the surface of Mars, the researchers say. A stone of similar size from Earth would contain many bacteria.

In addition, since magnetotactic bacteria require low levels of oxygen, this finding indicates that photosynthetic organisms, the source of oxygen in the atmosphere, must have been present and active on Mars 3.9 billion years ago.

"Finding evidence of life on Mars is one of the central problems in astrobiology research today," said Dr. Michael Meyer, head of NASA's astrobiology program, which funded the research.

In addition to his fellowship at NASA Ames, Friedmann, who is best known for discovering microorganisms living inside desert rocks, is professor emeritus of biological science at Florida State University. Members of the research team include Dr. Jacek Wierzchos (University of Lleida, Spain), Dr. Carmen Ascaso (CSIC, Madrid, Spain), and Dr. Michael Winkelhofer (University of Munich, Germany).

The meteorite ALH84001 was found in the Allen Hills region of Antarctica in 1984 by researchers supported by the National Science Foundation's Antarctic Search for Meteorites Program, a joint effort by the NSF, the Smithsonian Institution and NASA. Case Western Reserve University in Cleveland manages the program.

Full text of the research paper is available at: http://www.pnas.org Images of the magnetite chains inside the ALH84001 meteorite and, for comparison, inside a modern magnetotactic bacterium are at: http://amesnews.arc.nasa.gov/releases/2001/01images/magneticbacteria/ bacteria.html

Ames Research Center is NASA's lead center for astrobiology, the study of the origin, evolution, dissemination and future of life in the universe. NASA Ames is the location of the central offices of the NASA Astrobiology Institute, an international research consortium.


Story Source:

The above story is based on materials provided by NASA/Ames Research Center. Note: Materials may be edited for content and length.


Cite This Page:

NASA/Ames Research Center. "Scientists Find Further Evidence Of Ancient Microbial Life On Mars In Meteorite." ScienceDaily. ScienceDaily, 27 February 2001. <www.sciencedaily.com/releases/2001/02/010227073558.htm>.
NASA/Ames Research Center. (2001, February 27). Scientists Find Further Evidence Of Ancient Microbial Life On Mars In Meteorite. ScienceDaily. Retrieved November 25, 2014 from www.sciencedaily.com/releases/2001/02/010227073558.htm
NASA/Ames Research Center. "Scientists Find Further Evidence Of Ancient Microbial Life On Mars In Meteorite." ScienceDaily. www.sciencedaily.com/releases/2001/02/010227073558.htm (accessed November 25, 2014).

Share This


More From ScienceDaily



More Space & Time News

Tuesday, November 25, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Feast Your Eyes: Lamb Chop Sent Into Space from UK

Feast Your Eyes: Lamb Chop Sent Into Space from UK

Reuters - Light News Video Online (Nov. 25, 2014) Take a stab at this -- stunt video shows a lamb chop's journey from an east London restaurant over 30 kilometers into space. Rough Cut (no reporter narration). Video provided by Reuters
Powered by NewsLook.com
Soyuz Spacecraft Docks With International Space Station: NASA

Soyuz Spacecraft Docks With International Space Station: NASA

AFP (Nov. 24, 2014) A Russian Soyuz spacecraft carrying Italy's first female astronaut safely docks with the International Space Station, according to NASA. Duration: 00:40 Video provided by AFP
Powered by NewsLook.com
Multi-National Crew Safely Docks at Space Station

Multi-National Crew Safely Docks at Space Station

Reuters - US Online Video (Nov. 24, 2014) A Russian Soyuz rocket delivers a multi-national trio to the International Space Station. Rough Cut (no reporter narration). Video provided by Reuters
Powered by NewsLook.com
Raw: Soyuz Docks With Int'l Space Station

Raw: Soyuz Docks With Int'l Space Station

AP (Nov. 23, 2014) A Russian capsule carrying three astronauts from Russia, the United States and Italy has arrived at the International Space Station. (Nov. 23) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Space & Time

Matter & Energy

Computers & Math

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins