Geology Reference
In-Depth Information
Mountains and as the starting point for ANSMET expe-
ditions. During a typical season, a few experienced
ANSMET personnel will arrive in McMurdo in mid-
November to begin assembling and preparing expedition
gear. The remainder of the team typically arrives in
McMurdo in late November and immediately engages in
an intense 7
-
10 day preparation period. In addition to
assembling and testing the remaining field gear and
entering it into the cargo stream, the team spends several
days training both to meet the challenges of the Antarctic
environment and to introduce ANSMET procedures and
protocols.
The remote nature of ANSMET field sites requires
that the material needs of the field team be minimized,
allowing the team and all its gear to be efficiently moved
by aircraft in as few loads as possible. Aircraft use varies
considerably between field seasons, but most seasons
require the team to first move from McMurdo to an
intermediate site suitable for landings by large, ski-
equipped aircraft (usually the iconic LC-130 Hercules).
From there the team will move to the target site, either by
smaller aircraft (Twin Otter or helicopter) or by overland
traverse using snowmobiles and sleds to move our gear.
Travel to and from target sites can consume a significant
proportion of a field season and logistical resources.
Systematic field parties are typically larger and less
mobile than reconnaissance parties, with six to eight peo-
ple and one or two main targets for a given season. In
contrast, reconnaissance teams are smaller (two to four
people) and may move many times during a season, with
stays at target icefields as short as a few hours or as long
as a few weeks. Living in tents and conducting most
searches from aboard snowmobiles, the field team will
typically deploy with enough fuel, food, and other
expendables to cover a significant portion of an entire
six-week season; one or two resupply visits by light
aircraft make up the difference and provide the opportu-
nity for swapping out waste and damaged gear. When
distances between target icefields are low and aircraft are
available, ANSMET sometimes conducts a “flying
traverse,” with bulk cargo moving from one site to the
other via airplane while the field team transports itself
and survival gear overland by snowmobile.
ANSMET fieldwork is supported with rugged and
functional equipment that serves both survival and
scientific needs. USAP provides each participant with a
basic wardrobe of extreme cold weather (ECW) clothing,
including the infamous big red parka. Many ANSMET
participants supplement this clothing with more personal
or specialized gear for improved function and mobility
(notably eyewear, gloves, and underwear). USAP also
provides the four-sided, double-walled pyramidal Scott
tents that serve as shelter, each occupied by two field
party members and containing a propane stove for
warmth and cooking. Plywood and thick insulating pads
on the floors help keep the tents warm, while thick sleep-
ing bags provide overnight comfort. In recent years, each
tent has also been equipped with a 65W solar panel/field
power station that makes modest electrical power avail-
able for electronic devices such as computers, GPS, cam-
eras, and satellite phones. Expendables for the field camp
primarily include food and fuel (propane, gasoline, and
aviation fuel), with all solid waste recovered for recycling
and/or removal from the continent.
Snowmobiles are a key part of the ANSMET tool kit.
Not only do they serve as an individual mode of trans-
portation, they also dramatically increase the range
over which an ANSMET field party can conduct
searches. They also allow independent mobility and
constant team restructuring, serve as mobile storage
and measurement stations, and dramatically reduce the
fatigue associated with human-powered transport in
the Antarctic. Unquestionably, the logistical costs asso-
ciated with snowmobile use are high, due to the need for
aerial transport not only of the vehicles but also of up to
700 kg of fuel and spare parts for each in a typical
season, as well as off-season maintenance and storage.
However, the gains in terms of mobility and search efficiency
are equally large. Snowmobiles are to ANSMET field
party members what horses are to cowboys, serving a
multitude of needs and dramatically increasing the
effectiveness of each individual. ANSMET personnel
have tested the human-powered model, and while such
efforts are good for soul and body, they can dramatically
reduce the effectiveness of meteorite searches [
Haack
et al
., 2008].
2.3. SEARCHING FOR METEORITES
IN ANTARCTICA
The goal of ANSMET fieldwork is to recover a
complete and representative sample of the extraterres-
trial materials falling to Earth so that it can be made
available for research. While to some ANSMET's main
task may seem simple (only slightly elevated above an
Easter egg hunt), meeting these goals efficiently and with
high standards requires planning and a particularly meth-
odological approach. ANSMET has developed proce-
dures and protocols to systematically recover meteorite
specimens, ensuring few missed specimens, avoiding
preferential sorting by type or by size, and maximizing
scientific returns through contamination control and
detailed record keeping. These procedures and protocols
are a critical component of ANSMET success, helping
ensure that the U.S. collection is both representative of
the materials coming to Earth from space and contains
the maximum number of samples of the rarest types
of lithologies.
