What is Mars to us Earthbound humans?
There is the Mars of fancy, so often employed by generations of science fiction writers. Edgar Rice
Burroughs set his Barsoom novels there, and his action-packed Red Planet was home to naked princesses,
telepaths, six-legged cats, and a Civil War superhero, transported from Earth and named John Carter.
H.G. Wells’ Martians looked across the desolation of space at our blue-green home with “envious eyes”
and launched their “War of the Worlds” against us. Percival Lowell, the great 19th Century astronomer
who discovered Pluto, believed he could see canals on the Red Planet’s surface, through the limited
Earthbound telescopes that were available to him at the time.
There is the Mars of fact, boasting an apocalyptic topography photographed in thrilling detail by the CTX
(Context Camera), orbiting 250 miles above the planet’s chilly surface. NASA’s robot rovers have
trundled across parts of a world rich in supersized features: a volcano (Olympus Mons) as large as
Arizona; a meteorite crater (Hellas Planatia) with a diameter so vast it is greater than the driving distance
from Dallas to Washington, DC. Planetary scientists have found abundant evidence of frozen water on
Mars; an ancient stream bed in the Gale Crater suggests there was once “a vigorous flow” of water there.
We know that, on our planet at least, water breeds life and there are many who believe we will one day
find fossil evidence of long-ago primitive life on Mars.
And then there is the real Mars, the actual Mars, the tangible Mars, that a fortunate few can actually hold
in their hands — meteorites from the Red Planet.
We know that Northwest Africa (NWA) 8159 and the 234 other listed Martian meteorites journeyed here
from Mars because of the robot Viking spacecraft that landed on the Red Planet in 1976. Six years after
those landings, Drs. Johnson and Bogard were studying an unusual meteorite with a most unusual name
— Elephant Moraine 79001, which had been found in Antarctica in 1979. Astonishingly, the two
scientists discovered that tiny amounts of gas trapped within 79001 were a close match to the thin
atmosphere of Mars, as recorded by the Viking landers. This experiment has been confirmed by looking
at gaseous inclusions from several other Martian meteorites, clearly indicating their origin point. And
what a fiery and furious life NWA 8159 and its “cousins” have led! Blasted off the surface of their home
planet by other meteorite impacts (the impactors likely being large asteroid fragments), they wandered in
space until encountering our planet. There were super-heated in our atmosphere — as meteors or shooting
stars — before falling to Earth and later being found, as a result of luck or diligent searching.
At the time of writing (June, 2019) there were 61,316 different meteorites listed in the “Meteoritical
Bulletin.” That number represents the total of all meteorites officially recognized by academia in the
history of the science of meteorite study (meteoritics). Of these, a scant 235 are Martian meteorites,
making them among the most scarce commodities that any human has ever owned or touched. Of the 235
known Martians, the vast majority belong to the SNC class, that being an acronym for three celebrated
Martian meteorites: Shergotty (fell Bihar, India, 1865); Nakhla (fell Al Buhayrah, Egypt, 1911);
Chassigny (fell Champagne-Ardenne, France, 1815). The rare Martian polymict breccias account for
another 17 recognized Martians. And, relevant to this extraordinary lot, the “Meteoritical Bulletin” lists
two meteorites from Mars that exist all by themselves — literally in a class of their own. One is the OPX
class, whose sole listed member is the puzzling Alan Hills 84001 meteorite which, after being discovered
in Antarctica, caused a worldwide sensation when some researchers believed they had found signs of
fossilized life within it. Examples of that meteorite are not available for sale to collectors. The other class
with a sole intriguing member is described as “Martian (augite-basalt)” in the bulletin. The meteorite
itself is NWA 8159 and only 149.4 grams are known to exist in all of the world.
“Main mass” is a scientific term used to describe the largest single extant piece of a specific meteorite. For example, the main mass of Clarendon (c), found in Texas in 2015, is a whopping 345 kg, but smaller pieces were also recovered and all of those are believed to have weathered off from it. We often think of a main mass as being very large, but a main mass can be of almost any size, depending on how much of that particular meteorite was recovered in the field and how much remains intact today.
When a new meteorite is discovered and submitted for classification, a sample (typically about 20 grams) is removed and sent to the institution carrying out the analysis. That removed sample becomes known as the “type specimen” and it remains permanently with the classifying institution. If no other meteorites are determined to be a match to the new discovery, the remaining and larger portion becomes known as the main mass. In the majority of cases, we would expect that mass to be cut up into smaller pieces and sold, traded, or sent to additional institutions for further study.
After the single NWA 8159 stone was found in Morocco it was brought to the United States in 2013 and
sent to the Institute of Meteoritics at the University of New Mexico, Albuquerque for classification. It its official writeup, NWA 8159 was described by the submitting scientist as “a fine grained olivine-bearing
augite basalt that does not appear to be a SNC type although there are some aspects of it that resemble
SNC.” Its primary composition is ~48–50% augite, ~37–40 % plagioclase, with lesser amounts of olivine,
magnetite, and orthpyroxene.
Further analysis conducted during 2015 resulted in reports of “shock-melt veins of unique texture” and
noted the presence of “high-pressure mineral phases including majoritic garnet, stishovite, coesite,
tissinite, and ahrensite.
While a small number of representative pieces of NW 8159 were made available to academia and
collectors, the mass has remained largely intact since its discovery. The few pieces that were released
have been studied by academia and cherished by collectors, and were acquired at an extremely high
dollar-per-gram rate, indicating the rarity of this meteorite and, indeed, this meteorite class.
The rigorous and repeated studies conducted on NWA 8159 by various experts have determined
unequivocally that it is a piece of the Red Planet and, in addition, a very rare type indeed, which appears
to be unlike most, or possibly all, other known Martian meteorites.
We are pleased to offer the main mass (largest known extant piece) of the Martian augite basalt
meteorite, Northwest Africa 8159. An important and fascinating offering, it is a meteorite of such
uniqueness and value that one might say it is a world-class specimen … on two different worlds.