[meteorite-list] Searching Antarctic Ice for Meteorites

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu Apr 22 10:02:16 2004
Message-ID: <200203010606.WAA24610_at_zagami.jpl.nasa.gov>

http://www.psrd.hawaii.edu/Feb02/meteoriteSearch.html

Searching Antarctic Ice for Meteorites
Planetary Science Research Discoveries
February 28, 2002

     --- Silver anniversary season:
     The vigorous life and times of
     the ANSMET team at Meteorite
     Hills resulted in a new set of
     336 meteorites collected off the
     ice.

Written by Linda M.V. Martel
Hawaii Institute of Geophysics and Planetology

For a twenty-fifth austral summer, the Antarctic Search for Meteorites
(ANSMET) program sent a team of people from far-flung homes to the ice to
search for meteorites. From Dec. 7, 2001 to Jan. 23, 2002 we camped at
Meteorite Hills and traversed by snowmobiles to the surrounding ice fields
where we searched, sometimes on foot, in systematic parallel sweeps. Led by
Principal Investigator, Ralph Harvey of Case Western Reserve University
(CWRU, Cleveland), the team members were: John Schutt (Co-I and mountaineer
from Washington state), Jamie Pierce (Summit Expeditions mountaineer,
Seattle), Nancy Chabot (ANSMET post-doc at CWRU), Cari Corrigan (CWRU),
Matthew Genge (Natural History Museum, London), Duck Mittlefehldt (NASA
Johnson Space Center, Houston), Juanita Ryan (NSF's Teachers Experience
Antarctica program, San Jose), Maggie Taylor (NASA Jet Propulsion
Laboratory, Pasadena) and me. Our efforts added 336 meteorites (from as
small as 1-centimeter long to almost 30-centimeters long) to the world's
collection of extraterrestrial bits and pieces. Whether these meteorites are
collisional debris from asteroids or from high-energy impacts on the Moon or
Mars awaits to be seen.

Reference:

U. S. Antarctic Search for Meteorites program.

 --------------------------------------------------

Support

ANSMET meteorites represent the materials making up the solar system. The
unbiased and uncontaminated sampling of meteorites recovered from the
Antarctic ice sheet provides researchers with "ground truth" about the
materials and formation conditions of the solar nebula, asteroids, moons,
and planets. Taking these rocks from space off the ice and into the
laboratory is crucial to our quest to understand the history and composition
of the solar system we live in. ANSMET makes annual expeditions to
Antarctica to provide this much-needed continuous and readily available
supply of extraterrestrial materials.

ANSMET is funded through a partnership among the National Science
Foundation, NASA, and the Smithsonian Institution. For the 2001-2002 season,
ANSMET was one of twenty-six Antarctic activities supported by the Geology
and Geophysics program of the Office of Polar Programs at the National
Science Foundation. Our NSF program manager, Scott Borg, was in McMurdo when
I arrived. Increased NASA funding this season, through program manager Joe
Boyce, enabled our team to have ten members rather than the usual eight.

 --------------------------------------------------

Logistics for a season in the sun

After leaving home, our expedition team members converged in Christchurch,
New Zealand home to the New Zealand, Italian, and U. S. Antractic programs.
Officials at the Clothing Distribution Center briefed us on Extreme Cold
Weather (ECW) clothing and issued about 40 pounds of it to each of us. We
were outfitted with layers of long underwear, fleece shirt and pants, heavy
wind pants, down-filled parka, double-insulated boots, goggles, neck
warmers, hats, and more mittens and gloves than you could count.

Flights south to McMurdo Station (77o 51' S, 166o 40' E) are handled by the
U.S. Air National Guard or Royal New Zealand Air Force with LC130 Hercules
cargo planes. The canvas-webbing seats, noise, and dark spaces of the plane
were new experiences for me. It was all in stark contrast to the nearly
blinding white snow and ice of the landing field at McMurdo.

The season began with a planned staggered start allowing the two
mountaineers, John Schutt and Jamie Pierce, to arrive first at McMurdo in
mid-November. McMurdo is one of three U. S. year-round stations on the
Antarctic continent. The other two stations are Amundsen-Scott South Pole
and Palmer. All together, NSF's U. S. Antarctic Program (USAP) supported 800
researchers in Antarctica this year participating in approximately 148
different research projects. Over 2,000 civilian contract employees and U.S.
military personnel supported these projects on the continent. It can't be
over emphasized how crucial their support is for the transport and ultimate
well being of each and every soul and piece of equipment out on the ice. Our
team relied on the expertise of Steve Dunbar, Alana Jones, and Robbie Score
from NSF's polar contractor, Raytheon Polar Services.

In McMurdo, John Schutt and Jamie Pierce began the lengthy preparation,
loading, and unloading of gear and supplies for the team's entire seven-week
field season. Four meteorite collection kits, 1900 pounds of food, eight
snowmobiles, over 5000 gallons of fuel, four Scott polar tents for
dwellings, one old polar tent for the outhouse, one group tent, stoves, cook
kits, sleep kits, radios, GPS units, a satellite phone, laptops, cameras,
batteries, solar panels, wind turbine, sleds, maps, satellite images, ice
chippers and axes, rock hammers, ropes, bungee cords, knee pads, bamboo
poles, buckets, boxes and bags, survival gear, and personal gear comprised
the necessities for five men and five women in the deep field of Antarctica.
All the other team members except for me arrived in McMurdo on Nov. 30, 2001
for training and preparations. They deployed to the remote field camp by
Twin Otter airplane on Dec. 7. Jamie stayed longer in McMurdo in order to
meet my arrival from Christchurch and prepare me for Meteorite Hills.

Our tent camp at Meteorite Hills (79o 38' S, 155o 41' E) was organized for
eight people at a time, so Jamie and I were geared up to swap places with
Ralph Harvey and Juanita Ryan. The same Twin Otter plane that brought Jamie
and me into camp on Dec. 21 also took out John Schutt and Duck Middlefehldt
to the Finger Ridges ice fields about 55 kilometers away for a short
reconnaissance mission. They returned to camp on Dec. 26, the same day that
Ralph and Juanita left for home. This shifting of teammates allowed me to be
in camp for 34 days. Six intrepid members, Cari Corrigan, Duck Middlefehldt,
John Schutt, Maggie Taylor, Matt Genge, and Nancy Chabot, were in camp for
the entire 48 days.

 --------------------------------------------------

Special aspects of life on the polar plateau

ANSMET camps are self-sufficient with equipment, gear, fuel, and food. Boxes
of frozen food (meats, seafood, vegetables, fruit, cheese, rice, breads,
chocolate bars, soups, etc.) sat outside each tent, some items needing only
a quick thaw at the top of the stove-heated tent before cooking. A bucket of
ice chips in each tent was not an option as thermoses and water bottles
needed constant refilling. We required no permanent or semi-permanent
structures, but two special tents added for the first time stand out in my
mind: a group tent, which housed a laptop and Iridium satellite phone, and
an outhouse tent. The Iridium's mobile phone system worked very well from
our remote location. Voice and data from Meteorite Hills were relayed by one
of 66 orbiting Iridium satellites to ground stations which then relayed to
public telephone networks. In addition to the phone, we had the usual HF
radios issued to remote field parties. The HF radios, which operate by
bouncing high frequency signals off the ionosphere from transmitter to
receiver, were affected more than once by solar flare activity during the
field season. When the HF radios were inoperable, our communications with
McMurdo were made with the satellite phone.

The weather and snowmobiles seemed to dictate our every move. Bright and
cloudless calm-wind days were interrupted by unprecedented high winds and
overcast snowy days. Winds howled at 80 kilometers per hour and blasted up
to 160 kilometers per hour for days at a time. I will never forget sitting
in the tent with Nancy listening to the noisy pandemonium of those winds. We
spent roughly 50 percent of the field season tent bound due to bad weather
or in camp waiting for the arrival of a Twin Otter plane. And 50 percent of
our snowmobiles (four of eight) became disabled during the last day of
fieldwork after a season of repairs and replacements of bogie wheels, spark
plugs, and skis.

 --------------------------------------------------

Collection procedures

During the systematic searches and sweeps we used only our eyes to scan the
blue ice, sometimes with the aid of binoculars. Forming a line either on
snowmobile or on foot we worked by moving in parallel transects spaced apart
according to the terrain and concentration of meteorites. We searched back
and forth for hours and hours with backs to the wind and faces in the wind
to find dark objects on the ice. They turned out to be, more often than we
liked, shadows or terrestrial rocks dumped by glaciers. The fun began when
someone spotted a meteorite and waved his or her arms to signal the rest of
the team to converge at the find. It had to be a big physical movement
because we were usually too far away from each other astride noisy
snowmobiles, buffeted by winds, to hear any voices.

A snowmobile with a GPS receiver parked next to the meteorite to record
about five minutes of location data and a collection bag was brought out. It
held sterile Teflon bags, Teflon tape, stainless-steel tongs, number
counter, and aluminum number tags. Each meteorite was given a unique field
number that was logged in the notebook along with the rock's size and
estimate of fusion crust and preliminary classification. Any outstanding
characteristics of the meteorite or unusual collection details were also
noted (for example, if the rock had an unusual color or was inadvertently
touched.)

Next came an official digital photograph of each meteorite with the counter
held behind it showing the field number. Data logging during our field
season was handled by John, Ralph, Nancy, and Jamie. We all used the sterile
tongs to pick up the meteorites and placed them into sterile Teflon bags.
Each bag was taped securely. A bamboo flag pole marked with the field number
was positioned at each meteorite's location as a backup in case something
went wrong before or during the transfer of GPS data to John's laptop back
in camp. Workdays typically ran eight to nine hours long--painstaking work
by motivated and persistent seekers with good senses of humor. On the best
days, the team found 20 or more meteorites, but some days we only netted
three or a half dozen. The finally tally of 336 meteorites came from ice
fields around Meteorite Hills (326 specimens), Finger Ridges (6), from a
science group at Mt. Crean (1), and from another group at Odell Glacier (3).

 --------------------------------------------------

Clean, cold storage

With superb clothing, shelter, gear, knowledgeable and experienced leaders,
and dedicated teammates, it was almost easy for me to forget I was living in
an extreme environment. We had ready access to calorie-packed food that was
easy to prepare, we had email, and a phone! Then reality would hit: icy
winds whipped up, the wind turbine roared, I had to go, I couldn't take a
shower or it was time to drive the snowmobile over sastrugi--those dreaded
wind-sculpted crusted snow dunes. There was no doubt I was out of my normal
habitat. I was living in a windy freezer.

It is this very environment that helps make Antarctica an ideal place to
recover rocks from space. They are in clean, cold storage. Meteorites that
have been falling on the surface through the millennia become buried in the
ice moving slowly seaward. At mountains or subsurface obstructions, the
forward movement of the ice is blocked. Old deep ice, laden with meteorites,
is pushed up to the surface against the barriers. Dry (sometimes brutal)
katabatic winds (winds blowing down the slopes) clear the surface of snow
and aid sublimation and mechanical erosion which expose the meteorites on
what we call stranding surfaces. The desert conditions of Antarctica help to
preserve meteorites that would otherwise weather away under more humid
settings. The blue and white background and relative lack of terrestrial
sediments make it easier to spot dark meteorites on the stranding surfaces
than in a forest or farmer's field.

We made genuine efforts to keep every meteorite clean, by doing our best to
collect them without touching them with hands, gloves or tools. We mostly
towed the line, though there were a few mistakes, like the time I
accidentally drove over one (which was duly noted in the notebook.) As for
cold storage, the meteorites were collected frozen, stored and shipped
frozen, and will finally be thawed under clean room conditions at the
Antarctic Meteorite Curation labs at NASA's Johnson Space Center.

The removal of rock specimens is strictly
controlled by the Antarctic Treaty (signed by 44
nations representing about two-thirds of the
world's population) which says that specimens of
any kind can only be removed for scientific
research. The recovered ANSMET meteorites fall
under this category and are the responsibility of
the National Science Foundation. Under a
three-agency agreement, NASA supports initial
characterization, curation, and the distribution
and notification of samples. The Smithsonian
Institution assists in sample characterization
and provides for long-term curation. Image
courtesy of the National Science Foundation.

After thawing, each meteorite will be examined, cracked open, and small
pieces will be broken off for study as thin sections under a microscope.
>From these initial characterizations, short descriptions will be written up
and distributed in the bi-annual publication called the Antarctic Meteorite
Newsletter. Descriptions of the 2001-2002 Meteorite Hills meteorites will
begin appearing in the Newsletter in late summer 2002, with names beginning
with MET01xxx. The worldwide distribution of these samples to interested
researchers is guided by the Meteorite Working Group, a peer group of
meteorite experts.

 --------------------------------------------------

Post-season reflections

Our collection of 336 meteorites is near the season average
number of 350. According to ANSMET records, individual season
totals have varied from 30 (in 1976-77) to more than 1000
meteorites (in 1987-88, 1997-98, and 1999-2000). In all,
roughly 11,000 Antarctic meteorites have been found by ANSMET
teams during the past 25 years. The total reaches nearly 25,000
when Japanese and European collections are included.

The February 2002 Antarctic Meteorite Newsletter contains a
brief description of our season written by Ralph Harvey. Of the
336 meteorites collected from all sites this season, he reports
from his notes that 308 are ordinary chondrites, 10 are
achondrites, 11 are carbonaceous chondrites, 2 are irons, and 5
are as yet unclassified. David Kring (University of Arizona)
provides a nice on-line overview of meteorites and their
properties.

The launch of the ANSMET expedition website was a huge success
thanks to webmaster Tim Harincar, creator of WebExpeditions.
Our daily journal entries and photos from the field reached
about 25,000 website visitors. Tim reports that one hundred and
twenty-four subscribers received our journal updates via email.
And that doesn't even count all the classrooms and offices full
of people back home who we knew were asking, "How many did they
find today?" Our communication links in the field were more
than technological wonders, they were lifelines.

Since returning to Honolulu, I am adding the Antarctic meteorites story to
my usual education and public outreach activities. It is a vital
responsibility of the scientific community to share the fascinating
discoveries being made by planetary exploration and the research being done
on extraterrestrial materials. Talking with students, teachers, and the
public also lets me relive the experience of working with a group of
wonderful people in an incredible place, one of Earth's last frontiers. I
speak about the search and recovery of meteorites and the role these
specimens play in shaping what we understand about the formation of our
solar system. My stories are also about cool science careers, great
teamwork, and how the most extraordinary dreams can come true for ordinary
people. When the School of Ocean and Earth Science and Technology at the
University of Hawaii has its Open House in April one thousand school kids
will be on campus and will see our popular meteorite activities. I'll be
there in a Scott tent mock-up with genuine Extreme Cold Weather clothes (on
loan from Raytheon... nope, I won't be actually wearing them in this heat)
ready to share the experience of searching for meteorites in Antarctica.
Can't wait to see their wide eyes twinkle.
Received on Fri 01 Mar 2002 01:06:20 AM PST