Topic: Mars Meteor carbon not a terrestrial contaminant, further structure suggests...

[Stormbringer]

New Viewing Technique Bolsters Case For Life On Mars

Using the FIB microscope, scientists were able to detect tiny carbon structures suggesting the possibility that tiny organisms once inhabited the Martian meteorite called Nakhla.
by Staff Writers
Houston, Texas (SPX) Feb 8, 2006
New examinations of a Martian meteorite found nearly a century ago have strengthened the possibility that the red planet once harbored life.
"I don’t understand the sample completely just yet, but it’s exciting," research team member Kathie Thomas-Keprta told SpaceDaily.com.

The sample in question is from a meteorite named Nakhla, which was found in the Egyptian desert in 1911, and which has been held since by the Natural History Museum in London. A new examination of Nakhla has produced a very strong indication that it might have been imbedded with organic carbon - an absolute necessity for life - that did not originate on Earth.

Keprta, a specialist in microscopy techniques and a contractor for NASA at the Johnson Space Center, said she and colleagues recently obtained pristine samples of the rock -which is thought to be 1.3 billion years old - to probe its structure using the latest optical examination techniques.

"We have known for a long time about its carbon content via chemical analysis," she explained, "but up to now no one has been able to locate it."

The team took a tiny, polished piece of the meteorite only 30 micrometers thick that was sealed in epoxy and applied a technique called focused-ion-beam microscopy, or FIB, to carve out a small rectangle from the sample, and another technique called transmission electron microscopy, or TEM, to identify the deposits of carbonaceous material.

"For the first time, we can find the exact area" on Nakhla that harbors the carbon," Thomas-Keprta said. Further analysis by secondary ion mass spectroscopy, or SIMS, identified the sample as composed of carbon 13, which she said could only have come from an extraterrestrial source, not from any earthbound contamination.

All life on Earth contains some quantity of the isotope carbon 14, but no carbon 13.

The deposits, which Thomas-Keprta described as "shrubby," resemble similar structures on Earth created by the actions of ancient microorganisms that lived within volcanic rocks on the ocean floor.

Thomas-Keprta and colleagues will present their findings next month at the Lunar and Planetary Science Conference in Houston. The team includes scientists who also presented evidence for microbial life in another Martian meteorite - ALH84001, which was found in Antarctica - in 1998.

All Martian meteorites are thought to have been ejected from the red planet’s surface during ancient impacts. The meteorites drifted in interplanetary space until captured by Earth’s gravity and dragged down to the surface.

[Nemesis]

Link to full article

It seems that their are still people working on this one.

Other scientists have argued instead that the magnetite in ALH84001 was likely caused by inorganic processes, and that those same processes can be recreated artificially in the laboratory by heating carbonates in a process known as thermal decomposition, forming magnetite identical to that found in the Mars meteorite.

In this new study, the JSC research team reassessed the leading alternative non-biologic hypothesis that heating or shock decomposition produced the magnetites. The authors argue that their new results do not support the heating hypothesis for the formation of the magnetites. They conclude that the biogenic explanation is a more viable hypothesis for the origin of the magnetites.

"We believe that the biogenic hypothesis is stronger now than when we first proposed it 13 years ago," said Gibson, NASA senior scientist.

These new shapes, seen with a scanning electron microscope, are termed biomorphs because of their close resemblance to known, biologically produced features on Earth. The biomorphs observed in the meteorites will be the focus of the JSC team with more detailed studies, including chemical and isotopic analyses.

[Sirgod]

Nice Necro bump. I need to write Stormbringer some time also.

Stephen

[Nemesis]

It wasn't dead, it was pining for the fjords.

[Sirgod]

Maybe it was napping?

Still good read at your link.

Stephen