It’s quite moving to hold a piece of Mars in your hands… to reflect on its incredible interplanetary journey, and the science that gives confidence as to the origin of this unusual piece of rock.
The perimeter exhibits a fusion crust from the heat of entry into the Earth’s atmosphere. It is a fresh sample of NWA 6963, an igneous Martian shergottite meteorite found in September 2011 in Morocco. Meteorites are often labeled NWA for North West Africa, not because they land there more often, but because they are easy to spot as peculiar objects in the desert sands. (It’s like searching for your car keys where the streetlight shines bright).
From the geochemistry and various isotopes, we can deduce the origin and transit time of interstellar objects (a bit like Carbon-14 dating for formerly living artifacts on Earth). The 99 meteorites from Mars exhibit precise elemental and isotopic compositions similar to rocks and atmosphere gases analyzed by spacecraft on Mars, starting with the Viking lander in 1976. Compared to other meteorites, the Martians have younger formation ages, unique oxygen isotopic composition (consistent for Mars and not for Earth), and the presence of aqueous weathering products. A trapped gas analysis concluded that their origin was Mars quite recently, in the year 2000.
The formation ages of meteorites often come from their cosmic-ray exposure (CRE), measured from the nuclear products of interactions of the meteorite in space with energetic cosmic ray particles. This one is particularly young, having crystallized only 180 million years ago, suggesting that volcanic activity was still present on Mars at that time. Volcanic flows are the youngest part of a planet, and this one happened to be hit by an meteor impact, ejecting the youthful Mars (much like the 211-year old lava flow I am sitting on now).
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