[meteorite-list] Martian Meteorite Not Evidence of Extraterrestrials, Scientists Say

[JoshuaTreeMuseum]

Not only is there no evidence of life on the surface of Mars, there's also 
no evidence in Martian meteorites:

http://www.space.com/scienceastronomy/mars-meteorite-extraterrestrial-life-atmosphere-101201.html


      Martian Meteorite Not Evidence of Extraterrestrials, Scientists Say
      By Charles Q. Choi
      SPACE.com Contributor
      posted: 02 December 2010
      09:30 am ET


What some argue is evidence of ancient life in a meteorite from Mars could 
have a simple chemical explanation, scientists now suggest.

These findings could also shed light on of the tricky chemistry going on in 
the atmospheres of both Mars and Earth.

Impacting space rocks on Mars over the years have hurled debris off the 
planet, some of which has landed on Earth. One such rock - the 3.9 
billion-year-old meteorite known as ALH84001 - had globular, micron-sized 
carbonate particles seemingly arranged in chains that some thought must have 
been made by ancient Martian life.

Ads by GoogleThe 9mm is No DefenseDiscover What Self Defense Masters & The 
Army Don't Want You To Know www.CloseCombatTraining.comWhat is Quantum 
Jumping?Discover Why Thousands of People are "Jumping" to Change Their Life 
www.QuantumJumping.comHowever, researchers have now discovered a new way to 
form carbonates on Earth without interference from biological organisms. 
They suggest this process likely takes place on Mars as well.

Unusual oxygen type

The carbonates seen in ALH84001 possessed unusually high levels of the 
isotope oxygen-17. (An oxygen atom has eight protons in its nucleus, and 
while most of these also have eight neutrons, oxygen-17 has nine.)

Atmospheric chemist Robina Shaheen at the University of California at San 
Diego discovered anomalously high levels of oxygen-17 in carbonates found on 
dust grains, aerosols and dirt on Earth as well. This hinted that a chemical 
process common to both planets might be at work.

Shaheen calculated that ozone in the atmosphere could interact with 
oxygen-bearing mineral aerosols from dust and other sources to form hydrogen 
peroxide and carbonates possessing this same oxygen-isotope anomaly. "What 
she found is that the tiny little layer on the outside of the grain is where 
this chemistry all happens," said researcher Mark Thiemens, a planetary 
scientist at the University of California at San Diego.

Shaheen's analysis of the carbonates in ALH84001 suggested they could have 
been formed on aerosols in the ancient Martian atmosphere. NASA's Phoenix 
lander recently detected carbonates linked with particulates in the dusty 
atmosphere of Mars. "We think it might be this same mechanism that is 
operating," she said.

Although the researchers think the carbonate particles seen in ALH84001 are 
probably not biological in origin, "that doesn't mean that life is 
impossible on Mars," Thiemens cautioned.

This chemical process might not only shed light on the past and present of 
Mars, but it could also do the same for our planet as well. For instance, 
current models of atmospheric processes on Earth assume that the mixing of 
large volumes of gases drives the chemistry of the Earth's atmosphere. This 
new work might force a rethinking of this idea, scientists said, especially 
as the Earth's atmosphere becomes warmer and dustier due to climate change, 
providing more opportunities for this kind of chemistry to take place on 
aerosols.

"The chemical transformations aerosols can undergo could make them seeds for 
cloud formation when before we thought they could not, which has huge 
implications regarding the water cycle and probabilities of rain," Shaheen 
told SPACE.com.

Window into Earth's past

Scientists could also peer into Earth's atmosphere as it was in the past, 
particularly its oxygen levels, by examining carbonates found in rocks that 
are hundreds of millions of years old, researchers said. This could provide 
a window to early Earth far beyond the 60,000 years or so back that 
scientists can now study via ice core samples.

"We've found a new way to measure the earth's atmosphere for time periods 
when we previously could not do it," Thiemens said. "What happened to ozone 
and oxygen levels 65 million years ago during the Cretaceous-Tertiary period 
when the dinosaurs and many other forms of life were killed in a mass 
extinction? Who died first? Did the food chain disappear before the 
dinosaurs? What happened 251 million years ago during the Permian-Triassic 
period, the most severe extinction of life on Earth, when 85 percent of life 
disappeared and no one knows why? There's no record of what happened in the 
atmosphere. But if you can find a record of what happened to oxygen levels, 
you can answer questions like that."

Ancient carbonate might even shed light on the origins of complex life, 
Thiemens said.

"If you want to understand the origin and evolution of complex life, oxygen 
is your number one culprit," Thiemens told SPACE.com. "The most interesting 
time carbonates might be able to look at would be about 500 million years 
ago, back when the Earth was frozen solid. Prior to that time, there's no 
life except algae and bacteria. After that, all this life that depends on 
oxygen appears, and how that happened is something that's still uncertain."

Shaheen, Thiemens and their colleagues detailed their findings online Nov. 8 
in the journal Proceedings of the National Academy of Sciences.

--------------------------

 I was reading the dictionary, I thought it was a poem about everything. 
(SW)

Phil Whitmer