Image courtesy of Science/AAAS
Many of the rougly 150 Martian meteorites that have been found on Earth may have been launched into space during the impact that created the Mojave Crater on Mars.
The minerals in the meteorites, called shergottites, are similar to those found in the crater, and the age of the crater — which is at least 3 million years old — matches evidence of when the meteorites were ejected. But the meteorites may have crystalized as far back as 4.3 billion years ago, making them, along with the Allan Hills 84001 meteorite, among the oldest known material from Mars, scientists report March 6 in Science.
Other estimates pin the age of the rocks at less than 600 million years, but the younger appearance could be explained by melting during impact, the scientists say.