Boffins have dated a piece of Martian meteorite they reckon is the oldest bit of the planet ever collected.
Martian meteorite NWA7533*
Radioactive analysis of the zircons in NWA7533, a meteorite found in Northwest Africa, have revealed that the rock is around 4.4 billion years old – so it was formed just 100 million years after Mars itself. In planetary terms, this is very young indeed.
Florida State University’s Muni Humayun and his team investigated the rock using sophisticated mass spectrometers and found that it also contains trace metals like iridium that put its origin in the elusive cratered area of Mars’ southern highlands.
“This cratered terrain has been long thought to hold the keys to Mars’ birth and early childhood,” Humayun explained.
The meteorite is not only a part of the Red Planet’s ancient crust, but it’s also the first sample to come from this area. Using the rock, the researchers have already been able to figure out the thickness of Mars’ crust and confirm what spacecraft measurements have indicated, that the planet didn’t experience a giant impact that melted the entire planet in its early history.
“We now know that Mars had a crust within the first 100 million years of the start of planet building, and that Mars’ crust formed concurrently with the oldest crusts on Earth and the Moon,” Humayan said.
Rather strangely, dating measurements on another meteorite fragment from the same impact, known as NWA7034 or Black Beauty, found that it was just 2.1 billion years old. That research used rubidium dating rather than uranium testing to age the rock and it’s possible that the original whole meteorite was actually an amalgamation of several different kinds of stone, which would lead to different ages.
The full study, “Origin and age of the earliest Martian crust from meteorite