February 28, 2014
NASA Scientists Find Evidence Of Water In Martian Meteorite
Lawrence LeBlond for redOrbit.com - Your Universe Online
Evidence of water and life on Mars is a hotly debated topic that has been ongoing for decades. While most scientists agree that Mars had an abundant source of water in its ancient past, there has only been limited evidence that life may have once existed on the Red Planet.
However, scientists from NASA’ Johnson Space Center in Houston and the Jet Propulsion Laboratory in Pasadena, California have found evidence of past water movement in a Martian meteorite, reviving the debate over life on Mars.
In a Science paper published in 1996, JSC scientists David McKay, Everett Gibson and Kathie Thomas-Keptra announced the discovery of biogenic evidence in the Allan Hills 84001 meteorite.
In a new study, published in the journal Astrobiology, the same team members, now led by Lauren White, of JPL, focused on structures deep within a 30-pound Martian meteorite known as Yamato 000593. The team reported that “newly discovered different structures and compositional features within the larger Yamato meteorite suggest biological processes might have been at work on Mars hundreds of millions of years ago.”
"While robotic missions to Mars continue to shed light on the planet's history, the only samples from Mars available for study on Earth are Martian meteorites," White said in a statement. "On Earth, we can utilize multiple analytical techniques to take a more in-depth look into meteorites and shed light on the history of Mars. These samples offer clues to the past habitability of this planet. As more Martian meteorites are discovered, continued research focusing on these samples collectively will offer deeper insight into attributes which are indigenous to ancient Mars. Furthermore, as these meteorite studies are compared to present day robotic observations on Mars, the mysteries of the planet's seemingly wetter past will be revealed."
Analyses of the meteorite found that it was formed around 1.3 billion years ago from a lava flow on the Red Planet. During an impact on Mars some 12 million years ago, the rock was ejected from the planet’s surface and into space. The meteorite traveled in space for millions of years before crashing to Earth, specifically in Antarctica, about 50,000 years ago.
A Japanese expedition discovered the meteorite on the Yamato Glacier in Antarctica in 2000 and has been classified as a nakhlite, a subgroup of Martian meteorites.
White and colleagues have found two distinct sets of features in the rock associated with Martian-derived clay. They discovered tunnel and micro-tunnel structures that thread their way throughout the meteorite. The micro-tunnels displayed “curved, undulating shapes consistent with bio-alteration textures observed in terrestrial basaltic glasses, previously reported by researchers who study interactions of bacteria with basaltic materials on Earth.”
The second set of features consist of nanometer- to-micrometer-sized spherules sandwiched between layers within the rock and are distinct from carbonate and the underlying silicate layer. The composition of Y000593’s spherules show that they are significantly enriched in carbon compared to the nearby surrounding iddingsite layers.
Strangely enough, the distinct features in the Y000593 meteorite, which were recovered some 50,000 years after impacting Earth, are very similar to those from another sample – the Nakhla meteorite that fell in Egypt in 1911 and collected shortly after impact.
The team said they cannot exclude the possibility that the carbon-rich regions in both sets of features may be the product of abiotic mechanisms. However, textural and compositional similarities to features found in Earth-based samples, which have been interpreted as biogenic, imply that the Martian features were likely formed by biotic activity
"The unique features displayed within the Martian meteorite Yamato 000593 are evidence of aqueous alterations as seen in the clay minerals and the presence of carbonaceous matter associated with the clay phases which show that Mars has been a very active body in its past," said Gibson in a statement. "The planet is revealing the presence of an active water reservoir that may also have a significant carbon component.
"The nature and distribution of Martian carbon is one of the major goals of the Mars Exploration Program. Since we have found indigenous carbon in several Mars meteorites, we cannot overstate the importance of having Martian samples available to study in earth-based laboratories. Furthermore, the small sizes of the carbonaceous features within the Yamato 000593 meteorite present major challenges to any analyses attempted by remote techniques on Mars," Gibson added.
"This is no smoking gun," said White. "We can never eliminate the possibility of contamination in any meteorite. But these features are nonetheless interesting and show that further studies of these meteorites should continue."
McKay, who led the team that studied the ALH84001 meteorite, died last year.