NWA 1068: Dark meteoritic rocks stand out in the snow and sand
Scientists have found five new Martian meteorites.
The new rocks, which were blasted off the Red Planet in the distant past only to land on Earth at a later date, were recovered by expeditions to Antarctica and the hot deserts of Oman and the Sahara.
They bring the number of known stones from Mars to just 24. Scientists are fascinated by the rocks because they contain chemical clues about Martian history and the possibility that the planet once possessed oceans of water and life.
The recent cache includes six specimens, but two are believed to be chunks from the same meteorite. One of the pair weighs 13.7 kilograms (30 pounds) and is the second largest Mars meteorite fragment ever recovered.
Antarctica and the world's deserts have proved fruitful hunting grounds for meteorite collectors. The dark rocks from space are easier to pick out on snowy and sandy landscapes.
Martian suspect
One of the rocks was picked up by veteran Mars rock finders Bruno Fectay and Carine Bidaut of France. They found one now catalogued as NWA 1068, in the Western Sahara.
It is estimated that 20,000 meteoroids strike the Earth every year, but only a few come from Mars. The most controversial Martian meteorite is undoubtedly ALH 84001 which was found in Antarctica. It is thought by some scientists to contain fossilised evidence of microbial life.
The Mars rocks are thought to have been expelled from the Red Planet eons ago by a comet or asteroid collision. After floating through space, these rocks would have landed on Earth - one as recently as a few decades ago.
Scientists are confident they come from Mars because of their relatively young age (less than 1.5 billion years old), their texture and the masses of their constituent atoms (like oxygen), which are found in ratios not seen in rocks on Earth or on the Moon.
There are about 22,000 meteorites catalogued worldwide. These are mostly pieces from asteroids and their ages all cluster around 4.5 billion years old.
Images are copyright of Bruno Fectay and Carine Bidaut