The Planetary Society Blog
By Emily Lakdawalla
ANSMET Blogs: Finally in the field and bagging lots of meteorites
Dec. 29, 2008 | 14:57 PST | 22:57 UTC
Over the holidays I've been lax in posting the Antarctic Search for Meteorites blogs, so today I caught up on nearly two weeks' worth. My delay turned out to be beneficial, as there were still several days of waiting around McMurdo for most of the team until they and all their equipment finally arrived at their field campsite on December 23. It was a relief to finally see them reporting from the field! Their blogs from their first week of fieldwork show what seems to me to be a pretty productive meteorite hunt: they bag 20 to 30 or more meteorites a day, a few of them quite large. Unfortunately, the long delay meant that their fearless leader, Ralph Harvey, had to go home without ever making it to the field (but even that had a silver lining -- apparently his work on the ANSMET project has meant he's only been home for two of the last ten Christmases; if Qantas was nice to him he should have gotten home for this year's).
I needed to look up some definitions of meteorite types in order to understand the blogs from the field. These were taken from a glossary on the University of Arizona's website:
achondrite
A stony meteorite representing differentiated planetary material. Because differentiation is an igneous process, these are igneous rocks or breccias of igneous rocks. (Translation: achondrites are fragments that came from the catastrophic destruction of some large ancient asteroid, an asteroid that was large enough for its metallic and rocky components to separate by density into a metal-rich core and a rock-rich mantle. Achondrites are bits of the mantle part. )
carbonaceous chondrite
A type of primitive meteorite with evidence of nebular processes. (Translation: "nebular processes" means the processes that were happening in the primitive cloud of gas and dust that surrounded the Sun. Carbonaceous chondrites are sort of the opposite of chondrites in that they came from bodies that never coalesced into anything big enough to have internal geology -- they're relics of what was going on when solid stuff first started coming together in the solar system.)
ordinary chondrite
The most common type of meteorite to fall on Earth. Some are primitive specimens containing evidence of nebular processes, while others have been metamorphosed on a planetary body. (Translation: "metamorphosed" means "changed" -- in geology, it's heat or pressure, or both, that are usually the agents of change, turning one mineral into another.)
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