Scientists have identified a never-before-seen type of meteorite from Mars that has 10 times more water and far more oxygen in it than any previous Martian sample.
The meteorite was found in the Sahara Desert in 2011 and has the official name of Northwest Africa 7034. It is a small basaltic rock -- nicknamed “Black Beauty” – which means it formed from rapidly cooling lava. The meteorite is about 2.1 billion years old, from a period known as the Martian Amazonian epoch, and provides scientists with their first hands-on glimpse of this era.
Around 110 Martian meteorites have been found on Earth. Most were probably blown off the Red Planet during a large asteroid impact and subsequently crashed on our own world. The majority are relatively young, though the famous Allan Hills 84001, which some scientists believe contains traces of ancient Martian bacteria, is more than 4 billion years old.
Almost all other Mars rocks on Earth fall into a category known as the SNC group (Shergottites, nakhlites, and chassignites). Curiously, most SNC meteorites don’t seem to match up with the current crust composition of Mars, suggesting they came from the deeper interior or somewhere else. The newly discovered meteorite is different in that it has a composition that very closely lines up with the geochemistry seen at Gusev crater by the Spirit rover.
Scientists analyzed the rock through several methods. When the meteorite was heated to high temperature, hydrated minerals inside it released their water. NWA 7034 released an order of magnitude more water than any SNC meteorite, and gave off different isotopes of oxygen, which appeared in a ratio unlike any other Martian rock. One explanation for the oxygen ratio is that Mars once had isolated reservoirs of oxygen in its crust.
In addition to providing information about Mars’ ancient past, NWA 7034 may help scientists better understand the minerals and geology currently being explored by NASA’s Curiosity rover. The findings appeared Jan. 3 in Science.
Image: NASA
