Found in Morocco in 2011, NWA 7034 or ‘Black Beauty’ is a Martian meteorite that has interested scientists for some time, due to characteristics that make it unlike the other 100 or so known Martian meteorites discovered on Earth.
Now, new research suggests that NWA 7034 may in fact represent the Red Planet’s predominant geological make-up.
Prior to NWA 7034’s discovery, all known Martian meteorites were classed as shergottites, nakhlites or chassignites.
This ‘SNC’ classification uses names based on where the first meteorite in each category was discovered, but all three categories are different types of igneous rock, which is comprised of cooled volcanic material. NWA 7034, though, is different.
It is a ‘brecchia’: a mixture of different rock types, both igneous and sedimentary, welded together in a basaltic matrix.
To use an analogy, if SNC meteorites are lettuce, watercress and rocket, then NWA 7034 is a mixed salad containing both leaf and non-leaf ingredients.
Scientists have suspected for some time that this composition indicates that NWA 7034 originated in the Martian crust – and now analysis carried out at Brown University in the US suggests that this is indeed the case.
The research team, led by Kevin Cannon and Jack Mustard at Brown and Carl Agee at the University of Mexico, have published their findings in the journal Icarus.
Using a new hyperspectral imaging system developed by Massacussetts-based Headwall Photonics, they found that the spectral signature of the space rock was near-identical to that of the Red Planet itself, as measured from Martian orbiters, and a good match for rocks examined at the surface by the Opportunity and Curiosity rovers.
SNC meteorites, in contrast, have a slightly different spectral signature. This suggests that NWA 7034-like brecchias are common on Mars.
Although Mars is known as the Red Planet, its distinctive colouring is due to the dusty regolith that covers the surface.
As seen in the regions known as the ‘dark plains’, where this covering is thin, the rock beneath is dark – just like the Black Beauty meteorite.
This, say the researchers, correlates well with what we know of Mars’ geological history.
“Mars is punctured by over 400,000 impact craters greater than 1 km in diameter,” they write.
“Because brecciation is a natural consequence of impacts,” they write, “it is expected that material similar to NWA 7034 has accumulated on Mars over time.”