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Antarctica - Part 2b

Smithsonian Contributions to the Earth Sciences, Number 23

Catalog of Antarctic Meteorites, 1977-1978

Historical background (cont.):

The latter site was our next objective; therefore, I asked the
helicopter pilots to take us up there for a fast look around. As we
disembarked on the ice, Yanai almost immediately found a meteorite.
While we were examining it he was using his binoculars to good advantage
and spotted another one about 700 m away. Olsen, Yanai, and I started
across the ice toward it while the helicopter crew quickly returned to
their machine to follow us aloft. An observer would have been drawn into
the action irresistibly by the sight of three parka-clad pedestrians
crossing the ice, followed by a helicopter, all obviously headed for the
same place. We had found two meteorite specimens essentially in our
first twenty minutes in the field.
We were elated by this initial success, but made no additional
discoveries for about six weeks. We found no meteorites among the debris
at the bottom end of the Wright Upper Glacier, and when we set up our
next field camp at Mt. Baldr we found no more meteorites.
Subsequently we investigated a number of areas of bare ice located where
the ice plateau meets the Transantarctic Range, but found nothing.
During the closing days of the field season, acting at the suggestion of
Ken Craper, one of the helicopter pilots, we investigated a large patch
of ice adjacent to the Allan Hills. Almost immediately we found a stony
meteorite; then an iron one only 70 meters away. During that visit and
another, several days later, we recovered 45 specimens. Three were found
close together on the ice and fitted together along fracture surfaces to
form an almost complete fusion-crusted single specimen. Thirty-three
fragments of varying sizes were found scattered within a radius of 50
meters.
These also appear to be fragments of a single individual; their masses
summed to 407 kg. Accounts of these discoveries can also be found in
Cassidy (1977), Cassidy, et al. (1977), Yanai (1978), and Yanai, et al.
(1978).
All our discoveries at the Allan Hills site had been made using a
helicopter as a movable, low-level observing platform, from which we
could scan large areas in a short time. We found also that our
helicopter pilots quickly gained proficiency not only in spotting rocks
from about 10 meters above the ice surface but also in differentiating
between rocks and meteorites. Thus we owe many of these finds and many
subsequent discoveries to the excellent U.S. Navy flight personnel
assigned to support the U.S. research effort.
The 1976-77 discoveries demonstrated that the Yamato occurrence was not
unique; it seemed likely, therefore, that many more meteorite
concentration sites would be found on Antarctic ice. We suspected from
the beginning that Antarctic meteorites in general might have unique
characteristics not found in meteorites fallen in other regions. Among
these were long preservation times and low levels of terrestrial
contamination. Further, we felt there would be good chances of finding
rare or previously undescribed meteorite types and also, possibly, lunar
rocks that had reached the earth as products of impact on the moon's
surface. Such musings prompted concerns over the adequacy of our
collecting methods: it would be a shame to contaminate well-preserved
specimens by collecting them in a careless fashion. This concern
prompted me to mail a questionnaire to the membership of the
Meteoritical Society, seeking an expression of opinion on how Antarctic
meteorites should be handled. The response (Cassidy, 1979) included both
specific and general suggestions which, in sum, outlined a careful
curating process that begins at the moment of discovery and continues
through the transport and later subdivision of the specimen for
research. Based in large part on these recommendations, the National
Science Foundation accepted an offer, of help in the curating processing
from the National Aeronautics and Space Administration (NASA).
Currently, therefore, all the meteorite specimens are sent initially to
the NASA/Johnson Space Center Lunar Curator's Divison for processing.
The National Science Foundation also decided to eventually house the
majority of the U.S. portions of the collection at the Smithsonian
Institution.
During the following field season (1977-78), our collecting, storage,
and transport procedures became much more rigorous. Meteorites were
never touched by hand or gloves, but were picked up and sealed in teflon
bags and kept frozen throughout the journey from the ice cap to Houston.
My co-investigator for the 1977-78 field season was Billy Glass of the
Geology Department, University of Delaware, Keizo Yanai and Minoru
Funaki of the National Institute of Polar Research comprised the rest of
our four-man field party. We returned to Allan Hills and, collecting on
foot, recovered 309 specimens.


Best wishes,

Bernd

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