Despite the very slow progress of these surface vehicles, one of the major discoveries from the International Geophysical Year resulted from the recordings of these explosions. The scientists, bundled parkas, had to wait much longer than anticipated to record the echo from the ice sheet bottom. The reason: the ice was thicker than predicted. The East Antarctic Ice Sheet is up to 2.8 miles (4.5 kilometers) thick in places, enough ice to raise sea level globally 170 feet (52 meters) if it were to melt.
Driving over the ice sheet and setting off explosives every 50 miles is a slow process. Flying, even in a small airplane, is much faster. We will use two aircraft bristling with antennas and stuffed with instruments to collect new measurements of the ice sheet from the air, along with those taken from seismometers buried in the snow.
Mounted on the wings of the aircraft are eight antennas that transmit and receive 150 megahertz pulses to measure ice thickness. This radar system developed by the Center for Remote Sensing of Ice Sheets in Lawrence, Kan., has been developed specifically to image through the polar ice sheet. Similar to the seismic method, energy is transmitted through four of the antennas. The energy bounces back from the surface of the ice and the bottom of the ice sheet. We end up with thousands of measurements every second. This is a big improvement over 50 years ago when it took two to three days to measure ice thickness.
To get a better idea of the surface of the ice sheet, my colleague Michael Studinger has installed near-infrared laser mounted below the floor in the aircraft. Within the nitrogen- filled container, the laser fires at a revolving mirror. When the mirror spins, the laser is aimed first to one side of the aircraft then to the other, so that the laser measures the ice surface right below the aircraft and out to the side. When we accurately position the aircraft, the laser measures the distance to within 2 inches (5 centimeters)! Testing in the hall in our office, we can see people dashing in between rooms.
Along with the ice-thickness data, we want to understand the origin of the Gamburtsev Mountains. To do this, we need to decode the fundamental structure of the crust and lithosphere beneath. It will be years, maybe decades, before anyone drills into the Gamburtsev Mountains, so we will use gravity, magnetics and seismic velocities to remotely probe the subglacial terrains. The Earth's gravity field changes depending on the type of bedrock. A stronger gravity field means denser rock and a weaker gravity field means a less dense rock. An extremely accurate gravity meter will be mounted in the front of the aircraft. Measurements of variations in Earth's magnetic field will tell us about the nature of the underlying rocks. Some rocks are much more strongly magnetized than others. We will measure the changing magnetic field with cesium-based sensors mounted on the tip of the aircraft wings. Measurements of the magnetic field will tell us how magnetic the hidden rocks are.
The laser will measure the ice surface. The radar will measure the hidden topography. The gravity and magnetics will tell us about the makeup of the shallow part of the Earth—in general the crust. If we want to see deeper, we need a different method, A team lead by Doug Wiens from Washington University in St. Louis will install 26 seismometers spread hundreds of miles apart over the top of the Gamburtsev Mountains. Instead of shooting off explosives, the scientists will leave seismometers in place for months, recording distant earthquakes. These seismometers will be left in place for a year buried in the snow; they will be powered by the sun in the summer and by buried batteries through the long polar winter. The seismometers will record earthquakes from around the world to map the deeper structure beneath the mountain range. In the end, the seismic data will let us know how fast the energy from the global earthquakes travel and how warm or cold the Antarctic continent is at depths of hundreds of miles down.
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12 Comments
Add Comment"Two teams will build the camps, one on the north side and the other on the south side of the mountain range. The heavy equipment and fuel for the southern camp will be delivered by a surface traverse that will pass first through the South Pole."
Reply | Report Abuse | Link to thisIf one camp is across the south pole from the other camp, won't both of them be on the north side?
Our school will be following along! Some 8th grade students have decided to research your team's work in the Antarctic for their polar project. You have already inspired the next generation! Thank you!
Reply | Report Abuse | Link to thisHey! Where are all the liberals who think Space is a great waste of money? You know, the "We have to many problems here on Earth" people? The "if we only had that nickel NASA spends ..." Come on guys be consistent. This is a great waste of money. Government should NOT give welfare to 'science' unless it directly supports welfare programs to people OR unless it directly supports mismanagement of money and resources, to achieve an uncertain goal based on dubious politicized 'science' so the government can step in to 'offer' itself as the solution. Like Health Care and Global Warming ... uh ... Climate Change (can't have a changing climate can we!). The proper role of science is to support government expansion.
Reply | Report Abuse | Link to thisFor more information on the International Polar Year 2007-8, and ways that people all around the world can get involved, talk to scientists in the polar regions directly, and learn more about these critical regions, please visit www.ipy.org.
Reply | Report Abuse | Link to thisGreat Sheila if you want patches for your 8th graders let me know - e-mail me at mkt@ldeo.columbia.edu
Reply | Report Abuse | Link to thisThe reference to North and South camps is in relation to their placement relative to the subglacial mountain range - one is north and one is south of it.
Reply | Report Abuse | Link to thisI'm one of the ..uh. grunts / meteorology techs / mountaineers on this project. I've got a blog at http://patriotearth.blogspot.com where I'll be posting pics when I get back in January, in case you're interested in seeing some of the grittier sides of Antarctic field work. ;-)
Reply | Report Abuse | Link to thisA map sure would be helpful to understand the logistics and the scale of this project. As mentioned in the article, maps are often distorted or minimized, and missing mountains aren't likely to be noted even if one found a good map. So as a reference point, if you draw a line from the south camp to the north camp and continue it on, what is the first country the line would hit or what longitude would it fall on? And would you point readers to a good map with the 'missing mountains' on it?
Reply | Report Abuse | Link to thisHow much geologic mapping has occurred over the past several decades in Antartica? Is there a geologic map of the continet available for "public" viewing, showing the data that is currently available? Have different research teams from different countries shared information to produce a single map showing all of the information known to date? In the mapping of rock types, what is the standard that is used for designating different strata? Are there any exposed areas of limestone on the Antarctic continent?
Reply | Report Abuse | Link to thisGreat work, Robin, & thanks also for sharing your experience Ian. I've indulged in very romantic ideas of the noble few dedicating their lives to pure research and life on the ice, but after reading up on firsthand accounts, am now reconsidering these dreams...
Reply | Report Abuse | Link to thisPossible explanations as to the mountains .
Reply | Report Abuse | Link to thishttp://www.continuitystudios.net/guestvid.html
http://www.nealadams.com/nmu.html
For an interesting interview of Robin Bell on the subject of the Gamburtsev Mountains: http://www.sciencepoles.org/index.php?/articles_interviews/gamburtsev_dr_robin_bell_on_antarcticas_ghostly_mountains/&uid=1311
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