Spectroscopic measurements of a Martian meteorite called Northwest Africa (NWA) 7034 are a spot-on match with orbital measurements of the Red Planet’s dark plains, according to a new study published in the journal Icarus.
Northwest Africa 7034. Image credit: NASA.
NWA 7034, approximately 320 grams in weight, is a regolith breccia from Mars.
It was found in the Saharan Desert in 2011 and is estimated to be at least 2.1 billion years old.
Before NWA 7034, all known Martian meteorites – mainly igneous rocks which crystallized less than 200 million years ago – were classified as belonging to a group known as the SNC meteorites (consisting of the shergottite, nakhlite, and chassignite types). But NWA 7034 does not fit into any of the three SNC types.
Meteorite scientist Kevin Cannon of Brown University and his colleagues thought this meteorite might help to clear up a longstanding enigma – the spectral signal from SNC meteorites never quite match with remotely sensed specra from the surface of Mars.
“Most samples from Mars are somewhat similar to spacecraft measurements, but annoyingly different,” said co-author Dr Jack Mustard of Brown University.
After acquiring a sample of NWA 7034, the scientists used a variety of spectroscopic techniques to analyze it.
“What we wanted to do was get an average for the entire sample. That overall measurement was what ended up matching the orbital data,” Cannon said.
“The spectral match helps put a face on the dark plains of Mars, suggesting that the regions are dominated by brecciated rocks similar to NWA 7034.”
Because the dark plains are dust-poor regions, they’re thought to be representative of what hides beneath the red dust on much of the rest of the planet.
“This is showing that if you went to Mars and picked up a chunk of crust, you’d expect it to be heavily beat up, battered, broken apart and put back together,” Cannon said.
“That the surface of Mars would be rich in NWA 7034-like breccias makes a lot of sense, given what we know about Mars.”
“Mars is punctured by over 400,000 impact craters greater than 1 km in diameter. Because brecciation is a natural consequence of impacts, it is expected that material similar to NWA 7034 has accumulated on Mars over time.”
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Kevin M. Cannon et al. Evidence for a Widespread Basaltic Breccia Component in the Martian Low-Albedo Regions from the Reflectance Spectrum of Northwest Africa 7034. Icarus, published online January 29, 2015; doi: 10.1016/j.icarus.2015.01.016
