Photograph courtesy Daniel Costa
Call it a polar ice cap of a different sort—a Weddell seal sports an oceanographic sensor in McMurdo Sound, Antarctica, in 2010.
When seals dive under the ice in search of food, the sensors attached to their heads collect data on the surrounding water's conductivity, temperature, and depth. This information is transmitted via satellite to scientists researching the physical processes of Antarctica's oceans.
What's more, the technology gives scientists a peek into the lives of the world's southernmost seals, including how they locate and capture prey. Since 1968, more than 15,000 animals have been tagged—one of the longest running field experiments of long-lived mammals, according to the U.S. National Science Foundation's Office of Polar Programs.
Sensor-toting seals are only one of several experiments that scientists have set up on Earth's chilliest outpost since the early 20th century, when pioneering expeditions first probed the Antarctic interior. (See "South Pole Travel Heats Up on 100th Anniversary of 'Discovery.'")
"It's only a hundred years ago when the first expeditions went there, [and we've] only had bases there for about 50 years now, [but] the [scientific] advances made are huge," said John Turner, a climate scientist at the British Antarctic Survey.
In 2010, Antarctica housed 111 scientific research stations representing dozens of countries, none of which can lay claim to the continent, according to the Council of Managers of National Antarctic Programs.
"It's still an extremely harsh environment; you have to be very careful. One of the big challenges is to keep it pristine," added Turner, who also works with the nonprofit the Scientific Committee on Antarctic Research.
"This is a continent for science."
South Pole Galaxy Detector
Photograph courtesy Keith Vanderlinde, NSF
Northern lights brighten the sky over the 10-Meter South Pole Telescope in 2008.
The largest telescope ever built at the Pole, the instrument measures cosmic microwave background radiation, which is heat left over from the big bang that now permeates the universe.
Patches of hot, electrically charged gas from big galaxy clusters can cause distortions in this radiation. By detecting these disturbances, the telescope can identify previously unseen galaxy clusters that exist in the deep universe. (See "Unknown 'Structures' Tugging at Universe, Study Says.")
The telescope has already found more than 200 galaxy clusters, including the biggest galaxy cluster ever discovered, according to the National Science Foundation.
Ice Core With Visible Volcanic Ash Layer
Photograph courtesy Heidi Roop
Volcanic ash from an ancient eruption is seen in a 3.3-foot-long section of ice core, taken from the West Antarctic ice sheet in 2010.
Deposited as snow over the millennia, the ice gives scientists physical evidence of what floated through the atmosphere up to a million years ago, including greenhouse gases such as carbon dioxide, according to the National Science Foundation.
Antarctic ice cores make up "the most detailed, long-term record of climate change we've got on Earth," Turner said. (See "New Ice Core Reveals 800,000 Years of Climate History.")
As part of the ongoing West Antarctic Ice Sheet (WAIS) Divide Ice Core Drilling Project, scientists are drilling deep into the ice, hoping to eventually reach 2.2 miles.
The project has several aims, including tracing the history of greenhouse gas concentrations in the atmosphere over the past hundred thousand years, investigating the stability of the West Antarctic ice sheet, and examining the biology of deep ice.
Photograph courtesy Donnie Reid
Slicing the waters like a World War II torpedo, an autonomous underwater vehicle (AUV) travels under the ice of McMurdo Sound in 2010.
The "intelligent robot" is preprogrammed to dive under the ice of the Erebus Glacier Tongue and collect oceanographic data without the need for instruction from people on the surface, according to the Glacier Tongues and Ocean Mixing Research Project.
Project scientists are studying glacier tongues—floating platforms of ice that extend into the sea—because the physical oceanographic processes around them represent in miniature what occurs on a wider scale on Antarctic ice shelves.
Such research is "critical," considering Antarctic sea ice may shrink by 33 percent by 2100—possibly leading to a collapse of the ice shelves, according to the project website. (See pictures: "Jamaica-Size Ice Shelf Breaks Free.")
The AUVs are "unbelievable technology" that "really helps us understand how the ice is changing in these vulnerable areas," Turner said.
Photograph courtesy B. Stock, NSF
A person tests a particle-detecting sensor (left, partially shown) while another attaches a separate sensor to the cable (center, seen descending into the ice) in a December 2010 picture taken in the IceCube Neutrino Observatory.
Situated at the geographic South Pole, the $279 million observatory—the largest of its kind—will search for neutrinos, mysterious subatomic particles that can travel through almost any type of matter.
Echoing some undersea neutrino observatories, IceCube is made up of 86 sensor-equipped cables that snake down ice holes as deep as 1.5 miles. The South Pole, according to the IceCube website, is "the only place to find a chunk of ice big enough!"
"We're hoping that the most exciting things that we find are about the nature of the universe, the big bang, how the universe has evolved, and why we're here," Greg Sullivan, a physicist at University of Maryland, College Park, told National Geographic News from the South Pole in January 2011.
Demystifying Mount Erebus
Photograph by George Steinmetz, National Geographic
Since the 1970s, scientists have been studying the world's southernmost active volcano, the 12,447-foot Mount Erebus (pictured), which is situated on Ross Island.
Each summer, a group of scientists and students climb to the Mount Erebus Volcano Observatory, which sits at about 11,000 feet—a short snowmobile ride or hike from the crater's rim.
For a few weeks, amid an average temperature of minus 20°C (-4°F), the team researches the geophysics of the volcano, its ongoing activity, and the carbon dioxide emissions from its lava lake, among other things. Mount Erebus is one of the few volcanoes on Earth that has a long-lived lava lake.
Measuring Cosmic Rays
Photograph courtesy U. Maryland CRPL/NASA
Scientists with the Cosmic Ray Energetics and Mass (CREAM) experiment prepare to release a high-altitude balloon in 2008.
The team, which works with NASA, is using so-called ultralong-duration balloons to measure chemical elements in cosmic rays, or high-energy radiation hitting Earth from space.
In 2005, a CREAM balloon soared for nearly 42 days, making three orbits around the South Pole and reaching a height of 23 miles into Earth's stratosphere. The trip broke the record for duration and distance for high-altitude balloons, according to NASA. (Learn about the layers of Earth's atmosphere.)
Antarctica's summer weather gives a "stable ride" for these balloons and a relatively inexpensive way to get experiments into near-space, according to the National Science Foundation.
Tracking Ice Flow
Image courtesy Landsat 7/NASA
Shattered icebergs drift near the edge of the Larsen Ice Shelf on the eastern coast of the Antarctic Peninsula in a 2000 satellite picture.
In 2010 team members with a multidisciplinary project called the Larsen Ice Shelf System Antarctica (LARISSA) placed high-precision GPS stations in the bedrock of the western side of the peninsula, which will measure even minute changes in ice flow.
Tracking the ice flow will fill in gaps in existing satellite data of Antarctic ice loss, which scientists use to estimate sea level rise.
About 90 percent of the world's freshwater ice is tied up in Antarctic ice sheets—enough to raise global sea level by about 200 feet, Turner noted.
Even "if a very small fraction of that melts," he said, "it would have severe implications."
"Crazy Green" Ice Pools
Photograph courtesy David Munroe, USAP
"Crazy green" pools teeming with life (pictured) were found during a 2010-2011 expedition to the little-studied Amundsen Sea (see map).
For the first time, two research icebreakers plied the algae-filled waters of the Amundsen Sea's polynya, a region of seasonally open water surrounded by sea ice, National Geographic News reported in February 2011.
The scientists aboard the ships took samples of the polynya's surface waters, which revealed that the pools held as much as 45 micrograms of chlorophyll per liter, according to Patricia Yager, chief scientist for the Amundsen Sea Polynya International Research Expedition (ASPIRE), which is funded by the U.S. National Science Foundation and theSwedish Polar Research Secretariat.
That's five times greener than parts of the Amazon River plume, the nutrient-rich region where the Amazon empties into the Atlantic.
It's "the greenest water I've seen in the world," Yager said in February 2011.
(Related: "Antarctica May Contain 'Oasis of Life.'")
Peering Under the Ice
Photograph by Maria Stenzel, National Geographic
A person holds a three-inch-thick (eight-centimeter-thick) piece of ice taken from Lake Vida, an ice-covered lake in the McMurdo Dry Valleys of East Antarctica, in an undated photograph.
Lake Vida was thought to be frozen solid until the 1990s, when ground-penetrating radar revealed a highly salty liquid layer at its bottom, according to Lake Vida Project.
At least 70 lakes have been discovered under the Antarctic ice sheet, some of which may even contain life.
For instance, scientists have found microbes living in Antarctica's Lake Vostok that derive energy from minerals—or, as Montana State ecologist John Priscu put it in 2007, "eating rocks."
A century after British explorer Robert Scott reached the South Pole, "incredibly rich," rarely seen pictures give an inside look at the ill-fated expedition.
You too can visit the South Pole, a hundred years after explorers first reached the southernmost point on Earth.
See photos of Arctic and Antarctica landscapes and wildlife, such as polar bears, gentoo penguins, and leopard seals, by photographer Paul Nicklen.
He's trekked across Antarctica via the South Pole, set a speed record crossing the Greenland ice cap, and reached the North Pole with hungry polar bears at his heels. But now David de Rothschild navigates a new landscape: cyberspace.
Since 1986, when fewer than a thousand tourists journeyed to Antarctica, the numbers have grown dramatically. Is tourism too big a gamble?
NG News writer/editor Christine Dell'Amore explores galaxy clusters and neutrinos from facilities near the geographic South Pole.
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