While many may be familiar with Mars' dusty red surface from the glow it gives, or even the dust-covered mountains traversed by Mars rovers in the past, a new study of a meteorite found in the Moroccan desert has researchers believing that a far different image of the planet lies just below the thin red dust.
Meteorite NWA 7034, better known as "Black Beauty", is a metamorphic rock found years ago in the Moroccan desert and is unlike other rocks found here on Earth. Dated back to 4.4 billion-years-ago, the shiny rock is believe to be a chunk of the Martian crust, and according to a new study published this week in the journal Icarus, may represent what predominantly lies underneath the red dust on Mars.
Utilizing data gathered by spectroscopy of both the meteorite and of the Martian dark plains, where the planet's red dust has thinned enough to expose the black crust beneath, researchers Jack Mustard and Kevin Cannon from Brown University now believe that "Black Beauty" represents a "bulk background" of the rocks beneath the Martian surface.
When the team began its analysis in 2011, the initial chemical composition made it evident to researchers that the meteorite had originally come from Mars. But unlike any other Martian meteorite ever found, "Black Beauty" represented an entirely new class of rock. Known as a "breccia", a metamorphic mashup of other rock types bound together in a basaltic matrix much like lava rock, the meteorite represents something different than what researchers have ever seen from the red planet's surface, while still contain trace evidence of its sedimentary components.
And with their new data Cannon and Mustard hoped to clear up the longstanding mystery of what lies beneath Mars' red dust.
"Most samples from Mars are somewhat similar to spacecraft measurements" Mustard says. "But annoyingly different."
Utilizing new spectroscopy techniques, which included the use of a hyper spectral imaging system, the researchers were able to gain detailed spectral imaging of the entire sample rather than just a small portion. This new imaging technique allowed researchers to develop a clear picture of what lies in Mars' dark plains, suggesting that large regions of its crust are predominantly brecciated rocks.
"Other techniques give us measurements of a dime-sized spot. What we wanted to do was get an average for the entire sample" Cannon says. "That overall measurement was what ended up matching the orbital data."
"This [study shows] 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."
Though metamorphic rocks occur here on Earth as the molten lava rises from the inner mantle and cools along the Earth's crust, researchers believe that breccia like "Black Beauty" are likely attributed to another cause on the red planet. Mustard says that the "dark, messy and beautiful" rocks make far more sense considering Mars' impact history, and while the red sediment covers large plains of the planet, there's likely far more brecciated rocks to find.
"Mars is punctured by over 400,000 impact craters greater than 1 km in diameter..." Mustard says. "Because brecciation is a natural consequence of impacts, it is expected that material similar to NWA 7034 has accumulated on Mars over time."
