Welcome to Antarctica!
On this web site you'll find text, visualizations, pictures, and links
relating an exciting research project studying Antarctica.
Images of the Entire Antarctica Continent Mapped with RADARSAT
For 18 days during the Southern Hemisphere spring of 1997, a
NASA-launched Canadian satellite called RADARSAT collected pieces of a
puzzle that will help scientists study the most remote and inaccessible
part of the Earth -- Antarctica. Scientists now have the puzzle pieces
put together, forming the first high-resolution radar map of the
mysterious frozen continent. With detail to the point of picking out a
research bungalow on an iceberg, the new map has both answered
scientists' questions about the icy continent, and left them scratching
their heads about what to make of strange and fascinating features never
seen before.
Read the official press release about the RADARSAT Mapping Mission
A NOTE ABOUT LIGHT AND
DARK...ACCORDING TO RADARSAT
Just like radar sweeping the sky looking for airplanes, RADARSAT
paints the Earth, reading the surface. But instead of a
momentary radar "ping", RADARSAT collects radar data from across a swath
it's observing. That data can then be used to construct
a map of a particular region, a map derived from readings of radar
reflectivity.
Unlike traditional photographs from space, a dark area does not
necessarily mean that less light is falling on the surface; as
translated by radar, dark does not mean shadow. Instead, light and dark
are relative measurements of radar reflectivity. Finely
powdered snow and smooth ice with few imperfections both tend not to
scatter radar projected against it; hence they look dark. Coarse material like old, pitted ice, rock slides, and crevasses scatter the radar beam and thus look bright--a strong radar signal. When the images are put together, they appear to form a map with shadows and hot spots, but in fact the light areas mean
there's a strong radar reflection while the dark areas mean there's
little to reflect the radar beam.
RADARSAT is the optimal instrument for high resolution imaging of
Antarctica for three important reasons. RADARSAT carries its own source
of illumination, in this case radar. Therefore it can operate day or
night, and at the poles night stretches on for months. Moreover, radar
can penetrate clouds, highly pervasive over much of Antarctica. RADARSAT
is also unusual in that it can rotate in orbit, changing its imaging
perspective in a way that's different from any other radar satellite.
This ability to be reoriented in space is what allowed researchers to
collect images of the continent at the bottom of the Earth.
CONTINENTAL
TOUR
Antarctica the coldest, windiest, driest, and on average highest
continent on Earth. It's huge, too-the size of the United States and
Mexico combined. While over 97 percent of the continent is ice covered,
its surface is remarkably diverse. Glaciers plow through 15,000 ft.
mountain ranges, rising above the land like citadel spires. Fields of
crazed ice stretch out as far as the eye can see. Icebergs the size of
New England States calve from walls of floating ice that are themselves
as big as Texas.
By stitching together the RADARSAT data, scientists at Ohio State
University's Byrd Polar Research Center and animators at NASA's Goddard
Space Flight Center have designed a virtual tour of the southernmost
continent. It begins and ends at McMurdo Station; in between are
thousands of miles of mystery and beauty.
Points of interest in this virtual tour include the following:
ROSS ISLAND/MCMURDO
STATION
Images and QuickTimes
Ross Island is home to McMurdo Station, the largest permanent facility
on the continent. Owned by the United States, McMurdo Station and its
attendant airport called Williams Field are primary gateways to the rest
of the frozen territory of Antarctica. Nearly 1200 researchers and
support staff live at McMurdo during the summer months; about 230 remain
year round.
The high point of Ross Island is Mt. Erebus, rising 3794 meters. It's
also the most active volcano on the continent and one of the active
volcanic vents that's responsible for the formation of the island. Many
days of the year a plume can be seen emanating from the mountain's
summit crater, which holds a unique lava lake. The mountain is
essentially active all the time, producing small explosions from the
lava lake several to many hundreds of times per day.
MCMURDO
DRY VALLEYS
Images and Quicktimes
These valleys found at the eastern edge of the Transantarctic Mountains are
essentially snow free. Melt water from alpine glaciers essentially run into
these valleys and feed a number of lakes and small ponds, but otherwise,
it gets very little moisture. It is a delicate environment. But its relative
protection from the harsher surrounding features of the mountains and East
Antarctic Ice Sheet also provides a unique opportunity for intense study.
The National Science Foundation maintains a long term ecological research
site in the McMurdo Dry Valleys to study the area and ecosystem.
The area is also something of a practice facility. The cold, arid
conditions provide a fairly good simulation of the surface of Mars. NASA
engineers have used the Dry Valleys to test equipment and operational
techniques in preparation for a chance to try their designs on the Red
Planet.
ALLEN HILLS
Images and QuickTimes
Along the edge of the Transantarctic Mountains lay the Allen Hills. Ice
pushes up against the slopes of the hills, nudging bits of
debris and surface material along. There against the slopes that ice
ablates rather quickly-it's worn away-by wind and solar
insolation. Left behind, however, are the geological artifacts that most
interest scientists, including fragments from 3 meteorites. It is
from the Allen Hills that several years ago scientists found several fragments
of something they believe is an actual piece of Earth's
second closest neighbor: Mars.
AMUNDSEN-SCOTT SOUTH POLE STATION
Images and QuickTimes
The U.S. National Science Foundation (NSF) operates the Amundsen-Scott
South Pole Station, but it's been a way station for
researchers from around the world. Seen from RADARSAT, the main geodesic
dome is visible along with several storage facilities.
Extending to the upper right from the research station is a long line.
It's a highway of sorts, heading to a now abandoned antenna
facility. The bright band below the main station is the airfield for the
facility 14,000 feet long.
South pole station is important to RADARSAT researchers in that it
provides a vital point of cartographic reference in every pass the
craft makes over the continent.
EAST ANTARCTIC ICE STREAMS / WEST ANTARCTIC ICE STREAMS
Images and QuickTimes
EAST ANTARCTIC ICE STREAMS
Prior to the RADARSAT mission, scientists knew little about these ice
streams which drain into the Filchner Ice Shelf. Now, for the first time
they've been mapped in their entirety. They're actually enormous
glaciers, stretching like conveyors of cracked ice and snow across vast
stretches of the continent. The Recovery Glacier, one of the principal
channels comprising the East Antarctic Ice Streams, reaches over 800
kilometers into the continent's interior. Several of the tributary
glaciers feeding into Recovery themselves extend for more than 250
kilometers.
WEST ANTARCTIC ICE STREAMS
The West Antarctic Ice Streams are to Antarctica what a fast eddy is to
an already dynamic river. Moving roughly 500 meters a
year--significantly faster than a typical glacier--the ice streams are
hundreds of kilometers long and up to fifty kilometers wide.
By comparison, the frozen material lining these remarkable rivers may
move only a couple of dozen meters a year.
RADARSAT is an excellent tool for scientists to study these fascinating
formations. If you were standing on the gently sloping ground
they'd be very hard to detect. From space, however, the West Antarctic
Ice Streams show up as clear as a river seen from a
plane. Experts are still not positive about why they move so quickly;
unlike water rushing down a trough there isn't much of a
slope to pull them. Theories include a lubricated stream bed of some
sort, helping the ice rush across the frozen continent like
waxed sled runners in a groove.
SNOWDUNES
Images and QuickTimes
RADARSAT provides a unique view of an unusual surface feature
striping the continent. Dunes of snow more than 10 kilometers
long stretch out across east and west Antarctica. Unlike their sand
analogues in more familiar deserts around the globe, these
dunes tend not to rise nearly as high. Their length and relative heights
raise interesting questions for researchers. One hypothesis
about their formation suggests that low intensity atmospheric waves
formed in the lee of small hills help cause the dunes, but so far
conclusive answers are elusive.
RADARSAT "sees" the ridges of the dunes not by traditional shadows,
but by the way the radar signal is reflected back to the
satellite. Because wind sorts flakes of snow according to size on the
up-wind and down-wind sides of hills, RADARSAT's view of the
area looks to be measuring height, when in fact it's measuring radar
reflectivity. That reflectivity helps scientists determine what
types of materials line the sides of the dunes, and thus help them
determine how they came to develop.
LAKE VOSTOK
Images and QuickTimes
More than two miles beneath the icy cloak shielding Antarctica from the
sky hides a massive fresh water lake. Seen from
RADARSAT, the lake appears as a flat plain surrounded by the sandpaper
of craggy ice. As the topographical ice sheet flows over
the subglacial lake, surface features smooth out. Researchers are
considering a drilling mission to the lake for exploration of this
remote environment. It remains in liquid state partially due to
geothermal heating and partially because of the insulating properties
of such a thick ice blanket above. Assuming financial issues can be resolved,
the
drilling project faces certain technological challenges, too. Major
mechanical work is always a challenge in the bitter cold. But from a
more research oriented perspective, there's the issue of how
to drill into the lake from above without contaminating a sample from
below with the drilling apparatus.
Lake Vostok is also a human foothold on the continent. Due to concerns
about continued funding, the future of the Russian
outpost located at the southern edge of the lake is in question. Note
the long, lonely road leading across the ice to the outpost at
Vostok. At the end of the road, the short, white dash in the ice marks
the station's airport runway.
LARSEN ICE SHELF
Images and QuickTimes
In 1978, scientists predicted that global warming would lead to a
disintegration of Antarctic Peninsula ice shelves. Spaceborne data
indicate that this prediction may be coming true. In these before and
after images, note the dramatic change in the apparent shoreline.
Scientists captured the first image in using the ERS-1 satellite in
1992. As seen in the second image, collected by RADARSAT in 1997, huge
changes have come to the coastline. In 1995, a 2000 sq. kilometer
section of the ice shelf collapsed into thousands of fragments that
eventually drifted out to sea. Researchers are still debating why the
ice shelf broke up so dramatically, and what significance the break up
has for interpreting local versus global changes to the environment.
Theories include a series of warmer than usual summers which may have
caused high levels of surface melting, or an overall climate warming
trend.
FIMBUL ICE SHELF
View related images and QuickTimes
Icebergs form when hunks of ice break away from glaciers pushing into
the ocean. Ice shelves are the edges of those glaciers,
extending out into the ocean faster than ice bergs can break off from
the edge. The Fimbul Ice Shelf has remained relatively
consistent in its appearance for the last thirty years, but researchers
are paying close attention to changes. Ice shelves are
considered to be particularly sensitive to climatic changes and
scientists have detected a marked retreat of several along the
Antarctic Peninsula.
Note the fascinating formations along the Fimbul, believed to be the
product of glacial ice flowing over rocky outcroppings and
islands.
LAMBERT GLACIER
Click here to view Images and QuickTimes
Covering more than a million square kilometers, Lambert Glacier is one
of the world's longest and largest. It's more than 400
kilometers long, emptying a significant portion of East Antarctica into
the Amery Ice Shelf. Much like a major river system,
Lambert Glacier is fed by a complex series of tributaries.
AMERY ICE SHELF
Click here to view Images and QuickTimes
At the mouth of the Lambert Glacier spreads the Amery Ice Shelf. For the
most part, ice shelves grow from glaciers pushing down into the sea. To a
lesser extent they also grow from precipitation. Ice Shelves respond to
climate change faster than sheets of ice on the ground or continental
glaciers. Continued study of ice shelves like Amery are intended to help
scientists better understand what sorts of changes are happening to the
world's climate in general. Of particular interest is whether observed
changes in various ice shelves are the result of natural processes or are
anthropogenic, that is, the result of actions taken by humans.
RONNE ICE SHELF
The Ronne Ice Shelf grows primarily due to a constant flow from inland
ice sheets. Where shearing stresses are greater than the
strength of the ice itself, cracks form. These cracks ultimately widen
and spread like varicose veins in the frozen skin of the coast,
only to break loose and become icebergs. Early in the 1990's a slab of
ice the size of Delaware broke free from this area. A
recent iceberg more than 40 miles wide now floating in the South
Atlantic originated from the Ronne Ice Shelf.
Interestingly, as ice shelves break up into ice bergs, the sea level
generally doesn't rise. That's because ice shelf are ostensibly
already floating in the water. That floating ice, connected to the shore
by ice sheets and glaciers, displaces a volume of water
equal to the volume of water contained in the shelf. When a berg breaks
off, or calves, there is no new water to displace. It simply
separates from shore...and goes on its way.
THE TALE OF THE BELGICA
Belgica QuickTimes
In 1899, the not yet famous polar explorer Roald Amundsen served aboard
the Belgian ship Belgica as it sailed around the edge
of the southernmost continent. Under the command of an ambitious 29 year
old Belgian Navy Lieutenant Adrien Victor Joseph de
Gerlache, the voyage that began as one of discovery and adventure became
a test of endurance and will.
Trapped for nearly 13 months in shifting pack ice seven feet thick,
most of the Belgica crew weathered isolation, limited food and
fuel, and endless, grinding cold before finding their way free to open
water. On the map note how the shifting ice dragged ship
around the edge of the continent while they were trapped.
RACE TO THE POLE
Race to the Pole QuickTimes RADARSAT
data Race to the Pole QuickTimes
In the winter of 1911 and 1912, two teams of explorers raced to reach
the South Pole. Of the two five-man teams, only one group
managed to return alive from the destination.
Norweigan explorer Roald Amundsen led his crew with teams of dog
pulling sleds across the bare ice. They planted a flag at the
bottom of the world on December 14th, 1911. On January 16th, 1912 a
British team led by Robert Falcon Scott, travelling under
their own power, reached the pole. Beset by frostbite, logistical
miscalculations, and several navigational mistakes, the team died
before they made it back to shore. Scott himself died a mere handful of
miles from his base camp. Months later another expedition
to Antarctica found Scott's detailed diary in his tent.
ADMIRAL BYRD FLIES OVER THE POLE
Images and QuickTimes
On November 29, 1929, Navy pilot and at that time Commander Richard
Evelyn Byrd and a crew of two made the first flight over
the south pole. He did it in a three engine Ford airplane called the
Floyd Bennett. Byrd used the trip to drop supplies to several
geological expeditions making their way across the ice below, but the
eighteen hour, forty-one minute journey's clear focus was
an over-flight of the South Pole. In fact, with Byrd acting as
navigator, the three men made several sweeping passes over the
general area around the pole, just to be sure they could actually claim
they had successfully reached their goal.
THE RADARSAT SATELLITE
NASA launched the RADARSAT satellite for the Canadian Space Agency in
exchange for certain operational executions. Unlike
mapping satellites that rely on reflected sunlight or infrared readings,
RADARSAT's Synthetic Aperture Radar (SAR) is able to
penetrate cloud cover or work in the dark of night.
RADARSAT Spacecraft Movie
LEARN MORE ABOUT ANTARCTICA AND THE RADARSAT MAPPING MISSION
This project is the collaborative result of many organizations,
agencies, corporations, and countless individuals. Below you'll find
links to many sites of groups that played a role in making this project
a reality.
Credit line for all images:
NASA/Goddard Space Flight Center - Scientific Visualization Studio
Canadian Space Agency
RADARSAT International Inc.
NOTE: All RADARSAT images presented on this website are for research and educational use only. All commercial use of RADARSAT data must be coordinated with the Canadian Space Agency.
Last Revised: July 7, 2006 at 01:07 PM EDT
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