Through remote controlled probes scientist have learned much about the planet Mars. But we have yet to receive any samples back to Earth from there. We know the composition of the atmosphere of Mars and we have analyzed the rocks recently and currently are testing the frozen soil. But it is through a handful of meteorites from Mars found on Earth that we have our only direct contact with the Red Planet.
The three Martian meteorites recognized as very distinct from each other were Shergotty, Nakhla, and Chassigny. The form a grouplet of planetary meteorites know simply as the SNC group. Mars meteorites are now mostly placed into one of these three types.
How do scientist know that a rock originated on Mars? Well it is not that difficult today. when rocks form they sometimes trap gas from the atmosphere inside. As it turns out the many rare gases like neon and argon and others have a variety of isotopes with are present along with the normal atoms. It is by measuring the ratios of these isotopes as well as other means that a match to Mars is clearly established.
Mars meteorites will always be rare. The mechanism to launch the rocks from that world and get them to ours makes large amounts getting to Earth unlikely. But fortunately for meteorite collectors some Martian meteorites have been found in recent years and it is now possible to acquire pieces of these rare stones.
Click on the links below for more information on Mars meteorites.