A UNIQUE meteorite that fell on a Soviet military base in Yemen in 1980 may have come from one of the moons of Mars. Several meteorites from the Red Planet have been found on Earth, but this could be the only piece of Martian moon rock.
Andrei Ivanov, who is based at the Vernadsky Institute of Geochemistry and Analytical Chemistry in Moscow, Russia, spent two decades puzzling over the fist-sized Kaidun meteorite before he decided that it must be a chip off Phobos, the larger of the two Martian moons (Solar System Research, vol 38, p 97). 鈥淚 can鈥檛 find a better candidate,鈥� Ivanov told 快猫短视频.
The Kaidun meteorite is like no other in the world 鈥� and 23,000 of them have been catalogued. It is made of many small chunks of material, including minerals never seen before.
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Working with Michael Zolensky of the NASA Johnson Space Center in Houston, Texas, Ivanov used an electron microscope to look at the space rock鈥檚 crystal structure, peered through its minerals using X-rays and vaporised fragments to catalogue the elements inside. And every sample turned out to be something 鈥渘ew and weird鈥�, says Zolensky.
Among the odd materials in the meteorite were two fragments of volcanic rock 鈥� which only forms in massive, planet-like bodies with a core, mantle and crust. But much of the meteorite is a kind of carbon-rich material that only occurs in asteroids.
Zolensky thinks this paradox could be resolved if the meteorite comes from a Martian moon. Both Phobos and Deimos are thought to be asteroids captured by Mars as they wandered through space. That would explain the carbonaceous material.
And the pieces of volcanic rock could be bits of Mars, thrown into orbit when other asteroids crashed into the planet. Phobos is the more likely candidate: it orbits only 6000 kilometres from the planet鈥檚 surface, much closer than Deimos, and so has probably mopped up a lot more fragments of Mars rock.
The idea is plausible, if somewhat speculative, says Sara Russell, a meteorite expert at the Natural History Museum in London. 鈥淭here have been no landers sent to Phobos and so almost nothing is known about the composition and geology of this body.鈥� Zolensky thinks that an unusual asteroid could have been the source.
Hope of resolving the mystery rests with the European Space Agency, which has been asked by UK scientists to consider sending a mission to Phobos as part of its Mars exploration programme.