Artificial intelligence has helped pinpoint the exact origin site of the oldest Martian meteorite, in a discovery researchers say provides clues about the planet’s early history.
The meteorite, commonly known as “Black Beauty” and officially called Northwest Africa 7034, contains the oldest known Martian igneous material, which is approximately 4.5bn years old. It was found in the Sahara Desert in 2011.
Researchers have now identified its origin from a crater in the Terra Cimmeria-Sirenum province of Mars’ southern hemisphere.
Dr Anthony Lagain of Curtin University, the study’s lead author, said Black Beauty was ejected to earth by an asteroid impact on the surface of Mars around five to 10m years ago.
The meteorite’s origin crater on Mars has been named Karratha, after the Western Australian mining town – in keeping with naming conventions set out by the International Astronomical Union that stipulate small craters must be named after cities on Earth with a population less than 100,000.
“Since Black Beauty contains the oldest mineral we’ve been able to date from Mars, I thought a city from Western Australia would be a good idea,” Lagain said.
“I decided to name it Karratha because Karratha is very close to the Pilbara region, where the oldest rocks on Earth are.”
To identify the meteorite’s most likely origin site, researchers used a machine learning algorithm to analyse the size and distribution of 94m impact craters on the surface of Mars. The AI assessed tens of thousands of images taken by the Mars Reconnaissance Orbiter’s context camera.
Of 19 candidate craters, the team narrowed the origin site down to one that had characteristics matching the meteorite’s properties.
Lagain said locating Black Beauty’s origins was motivated by a desire to understand the early geological history of Mars.
“Some minerals in the meteorites are as old as 4.5bn years old, so pretty much the age of the planet itself.”
“When you analyse the surface [around the Karratha crater] you realise that the composition of this region … is very close to what we find on Earth for the continents. It might indicate that this region might be the relic of very old continents on Mars.”
“We know very little about the early evolution of planets, including the Earth,” Lagain said. “On Earth we’ve got plate tectonics, we’ve got a lot of erosion, which makes it very hard to find very old rocks.”
Black Beauty is a breccia, comprised of multiple rock types cemented together – the only sample of its kind on Earth. It was initially thought to be around 2.1bn years old.
The research was published in the journal Nature Communications.
