Scientists have identified
what they believe to be the first meteorite to originate from the
Martian crust, a 2.1-billion-year-old specimen that contains about 10
times more water than any other space rock from the Red Planet.
Discovered in the
Sahara,
the rock — called NWA 7034 — is unlike any of the 110-odd Martian
meteorites yet found on Earth, according to a report published online
Thursday by the journal Science. Experts said it provided an
unprecedented close-up view of the Martian surface and may help
scientists understand what
NASA's Curiosity and Opportunity rovers are seeing as they roam the terrain.
"This opens a whole new window on Mars," said Munir Humayun, a cosmo-chemist at Florida State University in
Tallahassee who was not involved in the study.
Though planetary scientists
have sent several spacecraft to Mars — most recently Curiosity, which is
equipped with an onboard chemical laboratory — there's no substitute
for a sample in hand, said study leader Carl Agee, director of the
Institute of Meteoritics at the University of New Mexico in Albuquerque.
Scientists on Earth can run sophisticated tests and glean a wealth of
information about the rock's history and the environment in which it
formed — tests no rover could do.
NWA 7034 came to Agee in 2011 by way of a meteorite collector who
bought it from a meteorite dealer in Morocco. The planetary scientist
said he was immediately struck by the 319.8-gram sample, which is about
the size of a baseball and twice as heavy.
Even though most space rocks become blackened on the outside during
their blazing descent through the Earth's atmosphere, they often remain
light on the inside. NWA 7034, on the other hand, was dark all the way
through, earning it the nickname "Black Beauty."
"I had never seen anything like it," Agee said.
Perplexed by the strange specimen, he put it on his bookshelf and let
it sit there for about a month as he wrestled with the best way to
approach his analysis. Once he got started, he examined the meteorite
for nearly a year.
At first, NWA 7034 appeared to be very un-Mars-like. Laser
fluorination revealed that its ratio of heavier-to-lighter oxygen
isotopes, usually a handy fingerprint of a meteorite's origins, didn't
match any of the Mars meteorites described in the scientific literature.
Those meteorites seemed to come from volcanic deposits formed deep
inside Mars, because their chemical makeup was different from the data
sent back by rovers and spacecraft examining the Red Planet's surface.
If Agee's team had looked no further, the space rock might have been
classified as an oddball piece of asteroid and quite possibly forgotten.
But rubidium-strontium dating indicated that NWA 7034 was just 2.1
billion years old — far too young to come from an asteroid.
Meteorites that come from asteroids are typically more than 4 billion
years old, since these small rocky bodies quickly cooled after the
solar system's formation. Planets, on the other hand, were volcanically
active for much longer, and many of their rocks formed much later.
Black Beauty must have come from a planet, the team members concluded.
The meteorite had too much iron to have come from Mercury and it had
too many traces of water to have come from Venus. But when they analyzed
minerals called pyroxenes, they found that the ratio of iron to
manganese did match those of other Martian meteorites.
Further analysis showed that Black Beauty was rich in sodium and potassium, giving it a striking resemblance to
rocks on the Martian surface examined by Curiosity's laser-shooting ChemCam instrument, Agee said,
as well as those of Mars' Gusev crater, which was explored by the NASA rover Spirit before it broke down in 2010.
That makes NWA 7034 a one-of-a-kind sample from the Martian crust, Agee said.
"What Carl Agee did was actually very courageous," Humayun said.
"They looked beyond what most people would have fallen for ... [and]
recognized its Martian connection."
Additional analysis showed that Black Beauty contained about 10 times
more water than any other named Martian meteorite — about 6,000 parts
per million.
That's much more water than a rock its age should have. At 2.1
billion years old, it hails from the beginning of the Amazonian epoch,
which is thought to be a dry chapter in Martian history.
Perhaps Mars was wetter for longer than scientists have thought, Agee said.
There are even hints of organic carbon in the meteorite, Humayun
pointed out, although further study would need to be done to determine
whether that material is of Martian origin or was acquired since
arriving on Earth. The rock looks relatively fresh by Sahara standards,
Agee said, guessing that it could have landed within the last few
hundred years.
It's unclear why most Martian meteorites have come from the planet's
interior, he added, though it may be that crustal rock is more fragile
and less likely to survive a journey through space or entry into Earth's
atmosphere.
The find may inspire scientists to go back into their archives and
reconsider other oddball meteorites. Perhaps there are more Martian
specimens already in labs waiting to be identified, Humayun said.
amina.khan@latimes.com
end quote from:
Sahara rock appears to be first meteorite from Mars' crust
So then, when did it come to Earth and why? The most likely answer I think is it came with the Gulf of Mexico Asteroid around that time 65.5 million years ago when the larger dinosaurs went extinct. Imagine the planet out beyond Mars being blown up by a thermonuclear war like the Soviet Probe proved during the 1970s there. Let's call the Asteroid belt planet, Maldek, as many do. So when Maldek came apart from the nuclear war pieces of it went in all directions. Obviously, one or more hit Mars and blew a lot of it's atmosphere off and a lot of pieces of the planet itself too. So it couldn't easily be inhabited any more either. But, since the Earth had lost most of the larger land dinosaurs from the meteor asteroid from Maldek blowing up that hit and created the Gulf of Mexico, earth could then be colonized by the survivors of Maldek and Mars. This is one possible explanation of how this Happened. So maybe when the asteroid bounced off
of Mars that came from Maldek some of Mars stuck to it. And it eventually wound up in the Sahara desert after hitting Earth likely in the Gulf of Mexico and bouncing out back up into the atmosphere as pieces from the initial large impact and explosions on earth. Likely there are more like this around the world that will eventually or have been found and used by tool makers and tool users for thousands or more years already if they aren't buried too deep to be found by the initial impacts from space 65.5 million years ago in the Gulf of Mexico.
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