University of Houston - 15 April 2010
New Information about Martian Meteorites Discovered by UH Professor
Through the study of a popular Martian meteorite’s age, a University of Houston professor and his team have made significant discoveries about the timeline of volcanic activity on Mars.
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ALH84001 is a thoroughly studied, well-known Martian meteorite. This stone is unique among Mars rocks available for study on Earth, since its formation age is more than 2.5 billion years older than any other recognized Martian meteorite, giving scientists the only sample of material formed early in Mars’ history. Data from this rock may help geologists better understand, through analogy, the processes of early Earth evolution.
Lapen and his colleagues’ data showed that the true age of this meteorite is 4.091 billion years old, about 400 million years younger than earlier age estimates. They concluded that this stone formed during an important time when Mars was wet and had a magnetic field, conditions that are favorable for the development of simple life. This finding precludes ALH84001 from being a remnant of primordial Martian crust, as well as confirming that volcanic activity was ongoing in Mars over much of its history.
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Space.com - 15 April 2010
Famous Martian meteorite younger than thoughtThe oldest known Martian meteorite – a space rock that fell to Earth – is some 400 million years younger than originally thought. It formed about 4.091 billion years ago, a time when the red planet was wet and had a magnetic field, a new study suggests.
Studying this chunk of ancient Mars, which reflects the volcanic processes and bombardment by space debris, could help scientists better understand Mars' early evolution, as well as Earth's.
The meteorite, dubbed ALH84001, was found during a snowmobile ride on Dec. 27, 1984 in the Far Western Icefield of Allan Hills in Antarctica.
Many other Martian meteorites have been found in Antarctica, as well as in remote regions of Africa, but ALH84001 is the "oldest by billions of years," said Tom Lapen of the University of Houston, who conducted the new study of the meteorite. It's about 2.5 billion years older than other Mars meteorites, which get kicked up from the surface of Mars by space rock impacts, flung into space, and then eventually hit Earth.
Science News - 15 April 2010
APOD: ALH84001: A Meteorite From Mars (1996 Aug 17)The oldest known Martian meteorite isn’t so old after all. Though it’s still the oldest chunk of Mars scientists have ever found, new research suggests the Allan Hills meteorite — officially known as ALH84001 — is about 400 million years younger than previously estimated.
A new analysis published in the April 15 Science pegs the meteorite’s age at a mere 4.091 billion years. Previously the meteorite was commonly accepted to have formed 4.51 billion years ago, when the planet’s surface was still solidifying out of its primordial magma ocean. But the new age indicates the rock would have formed during a later, chaotic period when Mars was being pummeled by meteorites that fractured and shocked the planet’s solid surface.
The Allan Hills meteorite has been a lightning rod for controversy since scientists announced in 1996 that it might hold fossils of Martian bacteria. The scientific community has since mostly abandoned that idea, as one by one every line of evidence for life has been given a non-biological explanation.
http://asterisk.apod.com/viewtopic.php?f=9&t=17921