An impact crater on Mars, revealing dark material beneath reddish dust.
NASA/JPL-Caltech/University of Arizona
Six Martian meteorites have been traced back to where they erupted from Martian craters millions of years ago, and knowing the origins of these alien rocks can help place them in context and provide insight into the history of the Red Planet.
“Identifying the impact launch site of Martian meteorites has long been a challenging goal,” Hap McSween “There have been a number of attempts published, but none have been convincing,” said John F. Kennedy, a researcher at the University of Tennessee, Knoxville, who was not involved in the study.
When a rock hits Mars or any other planet, it can send debris flying, some of which may drift through space and eventually hit Earth as a meteorite. Anthony Lagein Researchers from Curtin University in Australia used advanced modelling that matches what we know about Mars’ millions of craters and the ages of six meteorites that have broken off from the planet’s surface.
“There are about 80,000 craters on Mars that are larger than two miles in diameter, so there are about 80,000 craters that could be the source of these meteorites,” Ragain says. The researchers’ model narrowed down the possible sources to about 20. They then looked at the rocks’ structure to see how suddenly they were subjected to force when they were hurled into space, and fed that into another model of the craters themselves. This allowed them to determine the meteorite’s original source and how deep it was buried before falling to Earth.
All meteorites are igneous rocks, meaning they are pieces of solidified lava. Pete Mouginis Mark Researchers from the University of Hawaii at Manoa say that while there are doubts about whether the characteristics of the lava flows in these craters are an exact match for meteorites, if these craters are indeed the source of the rocks, they could tell us a lot about volcanism on Mars.
In particular, two of the meteorites thought to have come from the same crater suggest that the region has been volcanically active for longer than previously thought. “This may force us to rethink the ‘plumbing systems’ we think exist inside Martian volcanoes and how they can remain molten for such long periods of time,” Mouzinis-Mark says.
Only about 200 Martian meteorites exist on Earth, making them the only Martian rocks available for researchers to study in detail. NASA’s planned mission to return samples directly from Mars faces serious problems. This can lead to significant delaysThese rocks therefore may be our only chance to study Martian materials in a state-of-the-art laboratory. “We have six Martian meteorites here, from five locations, so it’s like we get five sample return missions for free,” Ragain says. Further study of these samples could not only tell us about the evolution of Mars, but also help guide future exploration to the most scientifically interesting places on the surface.
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