One of the star specimens from 2012-2013, a large carbonaceous chondrite
Talk about poorly kept promises! The 2012-2013 field season has been over for more than 6 months and today, Long ago I said I’d post a summary of the results from that season, and finally, here it is.
We definitely had a successful season, but not quite what the pre-season plans would have suggested. Two parties went into the field as planned and on schedule, and you can read their day-to-day exploits in the previous posts. But to summarize, a 4-person reconnaissance party went to some promising sites in the most southerly reaches of the Transantarctic Mountains, while an 8-person systematic searching team went to the Larkman Nunataks and the icefields adjacent to Mts Cecily, Emily and Raymond in the Grosvenor Mountains. The recon team recovered meteorites from two previously visited icefields near the Klein Glacier landing site and a previously unvisited site in the Graves Nunatak region; but as they moved to sites along the upper Robison Glacier, the weather stopped cooperating. At one stage they endured the longest weather-related work-stoppage in ANSMET’s 37 year history, a full 14 days. It wasn’t all about snow and wind, either; warmer than usual weather in the McMurdo Sound region meant the Pegasus runway was too soft for use by wheeled aircraft, meaning the US Antarctic Program’s ski-equipped aircraft (LC-130’s and Twin Otters) had to do double duty, bringing cargo from the civilized world as well as supporting activities in the field and at remote stations. Together these factors led to a recon season where we managed to visit less than half of the sites we had hoped for, and the total number of meteorite recoveries was correspondingly low- only 63 specimens. In the end, success could be measured in the few new sites we knocked off our list of potential targets, but much work remains for us in that part of the Transantarctics.
The systematic team had much better luck with the weather. After a few days of acclimatization at the Mt. Bumstead icefields, the team traversed to Larkman Nunatak. The icefields in this area are relatively small, but there’s a challenge hiding at the foot of Larkman Nunatak- a moraine brimming with meteorites. Previous visits to the site emphasized the desire not only to complete searching of the icefields but also to finish a highly-controlled methodical foot search in that moraine. Neanderthals that we are, we even went so far as to try a few new things, like smaller wire-supported flags, battery powered drills for marking paths and finds, and the use of a metal-detector for double-checking. The payoff appears to have been substantial; about 331 specimens total for the season , including many that appear “unusual” and contrary to expectations, of significant size.
The meteorites from the 2012-2013 field season are being characterized right now. First descriptions of ANSMET meteorites are published in the Antarctic Meteorite Newsletter, a new edition of which should be out within the month (visit http://curator.jsc.nasa.gov/antmet/). As usual there is a backlog of meteorites from previous seasons that need descriptions, so we can expect that only the top dozen or two from the 2012-2013 field season will be described. But often those first few are the cream of the crop, one of which is shown above. So stay tuned……..
-Ralph Harvey, PI of ANSMET