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NASA
SUCCESSFULLY LAUNCHES THE ICESAT/CHIPSAT SATELLITES NASA’s
Ice, Cloud and Land Elevation satellite (ICESat) and Cosmic Hot Interstellar Spectrometer
(CHIPS) satellite lifted off from Vandenberg Air Force Base, Calif., at 4:45 p.m.
PST aboard Boeing’s Delta II rocket.
Separation of the ICESat spacecraft
occurred 64 minutes after launch at 5:49 p.m. PST. Initial contact with ICESat
was made 75 minutes after launch at 6 p.m. PST as the spacecraft passed over the
Svalbard Ground Station in Norway.
The
CHIPS spacecraft separated from the launch vehicle 83 minutes after launch at
6:08 p.m. PST. Initial contact with CHIPS was made 98 minutes after launch at
6:23 p.m. PST as the spacecraft passed over the University of California, Berkeley.
“The
Delta vehicle gave us a great ride! The ICESat spacecraft was right where we expected
and is performing great. The whole team is thrilled to be having such a wonderful
start to our mission” said Jim Watzin, the ICESat Project Manager at NASA’s
Goddard Space Flight Center in Greenbelt, Md. Over
the next few days the ICESat spacecraft will gradually be despun and placed into
a safe stable attitude. Within two weeks the onboard propulsion system will gradually
tune the orbit. Once in its final orbital position, ICESat will be approximately
373 miles (600 kilometers) above the Earth. ICESat
is the latest in a series of Earth Observing System spacecraft, following the
Terra satellite launched in December 1999, and the Aqua satellite launched earlier
in May of this year. The primary role of ICESat is to quantify ice sheet growth
or retreat and to thereby answer questions concerning many related aspects of
the Earth’s climate system, including global climate change and changes in
sea level. Ball
Aerospace and Technologies Corporation (Ball) in Boulder, Colorado built the ICESat
spacecraft. The Earth Science Data and Information System at NASA Goddard will
provide space and ground network support and the University of Colorado’s
Laboratory for Atmospheric and Space Physics will team with Ball to provide mission
operations and flight dynamics support. The GLAS and ICESat data will be initially
processed at the ICESat Investigator-led Processing System with support from the
University of Texas, Center for Space Research. The mission data will be distributed
and archived by the National Snow and Ice Data Center. Goddard
manages the Earth Observing System for NASA’s Earth Science Enterprise in
Washington, D.C. More information about the ICESat program is available at: http://ICESat.nasa.gov More
about NASA’s Earth Science Enterprise can be found at:
http://www.earth.nasa.gov CHIPS
will study the gas and dust in space, which are believed to be the basic building
blocks of stars and planets. The CHIPS satellite, the first NASA University-Class
Explorer (UNEX) mission, weighs 131 pounds (60 kilograms) and is the size of a
large suitcase. It will orbit above the Earth at about 350 miles (590 kilometers)
altitude and is expected to operate for one year. CHIPS
is sponsored by the Office of Space Science, NASA Headquarters, Washington, D.C.
The project is managed at the Wallops Flight Facility, Wallops Island, Va., and
Goddard through the NASA Explorers Program. The CHIPS instrument was built at
the Space Science Laboratory of the University of California, Berkeley, and SpaceDev,
Inc. of Poway, Calif., built the spacecraft bus. For detailed information about
CHIPS and its mission, go to: http://chips.ssl.berkeley.edu http://www.gsfc.nasa.gov/topstory/2002/1217chips.html
LASERS
ON ICE: ICESat BEGINS ITS MISSION (Click
on image or link beneath image to view animations.)
Frozen
does not mean immobile. To scientists who study the nature of our home planet's
climate, the frozen poles of Earth are dynamic and dramatic places. That's why
NASA is sending a specialized spacecraft into orbit, specifically tailored to
study changes in global ice cover. Called ICESat, for the Ice, Cloud and land
Elevation Satellite, it will use a technology called "lidar" to map
the Earth. It's a high tech, yet proven system that's been used with great success
in mapping Mars. By using lasers to literally measure changes in planetary features,
the space agency will collect critical data about our home.
Although principally designed to measure changes in global ice cover, ICESat will
also make important readings about clouds, atmospheric aerosols, vegetation, land
topography, and the oceans.
HOT TOPIC: SCIENTISTS EAGER TO STUDY ICE
Click
here for audio text of this animation
LOOKING DOWN WITH LASERS
Click
here for audio text of this animation ICESat:
LASER LIGHT MEASURES EARTH'S ICE
The
newest addition to NASA's fleet of Earth observing satellites has only one scientific
instrument. The satellite is called ICESat; the scientific instrument it carries
is called GLAS, the Geoscience Laser Altimeter System.
ICESat has been
developed to answer some important questions about our changing planet. Experts
designed the GLAS instrument principally to measure changes in the overall surface
elevation of the polar ice sheets through time. This kind of research is vital
to understanding how sea levels might change around the world as well as other
fundamental aspects of worldwide climate conditions.
But ICESat's mission
only begins with measurements of ice. The system will also make important measurements
about clouds, from cloud height to cloud structure. It will also help researchers
measure land surface topography, as well as make determinations about surface
feature characteristics, including reflectivity, vegetation heights, as well as
snow and sea-ice surfaces.
NEAR-POLAR ORBIT, WORLDWIDE MEASUREMENTS
The
ICESat satellite left Earth from the Vandenburg Air Force Base in California.
It rode into orbit onboard a Boeing Delta II rocket, model 7320.
Manufactured by Ball Aerospace, the ICESat spacecraft will initially fly
at 367 miles (590 km) above the Earth. It's designed to operate for a minimum
of three years, delivering data to Earth-bound scientists every day.
Satellites move fast-more than 16,000 miles per hour-and precise navigation while
on orbit isn't a simple matter. That's why the ICESat vehicle has state of the
art navigation systems to keep it pointed in the right direction. Star trackers
are major parts of a system that will tell us where the GLAS lasers are pointed.
Additionally, the satellite incorporates two highly advanced "Blackjack"
GPS receivers, allowing mission engineers to keep track of ultra-precise locations
of the spacecraft while on orbit. NASA's Jet Propulsion Laboratory developed the
Blackjack GPS system to provide highly precise global positioning information.
ICESat will collect data about the Earth using the lasers on the GLAS instrument.
The orbit of the satellite is such that the ground track, of the vehicle-- that
is, where the laser pulses hit the Earth--will move westward as the Earth turns.
Because of its near-polar orbit around the globe, the greatest number of data
points collected by ICESat will naturally be collected near the poles. But its
mission isn't just a polar one. Because GLAS operates continuously, the satellite
will also collect important information around the rest of the world, too, with
important measurements of clouds, vegetation, land surface reflectivity, land
surface elevation, and more. THROUGH
THE LOOKING GLAS
GLAS-the
Geoscience Laser Altimeter System-is the only scientific instrument aboard Ice,
Cloud and land Elevation Satellite. The large cylindrical side of the satellite
comprises the biggest part of the GLAS instrument. It's the one-meter observatory
mirror, the part of the instrument that detects reflected pulses of laser light
from the Earth below. Beside that large mirror is a small "tunnel":
that's the laser emitter. The onboard laser will emit short pulses of light forty
times a second in two different wavelengths towards the Earth By the time the
laser pulses reach the surface of the planet, they will have spread out to "footprints"
roughly 70 meters in diameter, with roughly 170 meters of space between each subsequent
pulse along the ground track.
As the scientific portion of the ICESat
spacecraft, GLAS has been designed specifically for its abilities to precisely
and repeatedly measure surface topography. Of particular interest are the surface
characteristics of the Earth's ice sheets, particularly as they change over time.
GLAS will also make regular measurements of aerosols found in the atmosphere as
well as complex cloud structures, useful for short-term climate and weather predictions.
ICESat is only the latest in a series of remote sensing missions designed to collect
information about the Earth. NASA's Earth Science Enterprise (ESE) includes a
series of satellites that began to take their places on orbit in the late 1990s.
By utilizing data from the various instruments flying around the Earth, scientists
who work with the ESE fleet can study our home planet in systemic terms. ACCUMULATING
DATA:
GLAS BUILDS ITS FACTS ONE POINT AT A TIME
GLAS
is the first laser altimeter system tasked to map the whole Earth from space.
But it's not the first time an instrument of this kind has ever been used. The
technology behind GLAS is called lidar. Lidar is a distance measuring system similar
to radar, except that instead of radio waves it uses pulses of laser light for
range finding. The name is a contraction based on the words light and radar: LIght
Detection And Ranging. A lidar system determines precise distances by measuring
the amount of time necessary for a pulse of light to leave an emitter, hit a target,
and return. In this case, distance measurements helped researchers determine changes
in ice thickness, vegetation, cloud thickness, and much more.
Lidar
offers diverse scientific disciplines powerful tools for
exploration. Besides
being used on aircraft to study Greenland's ice cap, lidar systems have been used
to study coastal erosion on both the east and west coast. Additionally, a lidar
system managed by the Goddard Space Flight Center proved to be one of the star
performing instruments on the Mars Global Surveyor spacecraft, successfully undertaking
a detailed mapping project of the red planet. LIGHT
THROUGH THE CLOUDS
Laser
light emitted by the GLAS instrument will do more than provide measurements about
the surface of the planet. One of the other important topics of investigation
will be cloud cover. Clouds are highly influential to the Earth's climate, but
the two main ways they affect the planet's temperature tend to be opposites. Clouds
cool the atmosphere and the Earth by reflecting energy from the sun back into
space; they shield the Earth, in other words. But clouds also trap heat by absorbing
infrared energy emitted by the surface of the Earth, acting like an insulating
blanket. In terms of understanding the overall effect, experts say that the net
effect depends on how clouds are vertically distributed, how they're composed,
and how thick they are. By passing GLAS's laser light through clouds, scientists
will be able to make precise and vital measurements about cloud heights and structures-important
details for determining important trends in the planet's overall climate system.
GREEN MANSIONS:
ICESat AND THE VEGETATION CANOPY
The
name of the satellite certainly implies a primary mission to study the world's
ice, but ICESat is actually a vehicle with broader goals. Using the GLAS instrument,
ICESat will also be used to study changes in the height of vegetation around the
world. The process for doing this is clever. The instrument laser fires in pulses.
By separating the partial reflection of the vegetation canopy from the basic structure
of the surrounding plant life and ground surface, vegetation height can be determined.
Further, by comparing the relative reflectivity of the two wavelengths emitted
by the laser, experts can develop a vegetation index that's independent of other
measurements based on observations of reflected sunlight.
Plant growth
is a significant indicator of the overall health of the planet, providing evidence
about temperature changes, atmospheric changes, and differences in the length
of growing seasons. Accurate vegetation and topographical maps will also be valuable
for a variety of commercial, land use, navigation, and other commercial applications.
CHANGING
SEASONS, CHANGES IN THE ICE Research
and data collection of Arctic Ocean ice isn't easy. But using data collected by
a number of different satellites from 1990 to 1999, scientists have been able
to stitch together a quality-controlled record of sea ice in that part of the
world. In this sequence we can see how ice around the poles oscillates seasonally.
The data used to create these images come from different instruments onboard a
group of satellites: the scanning multi-channel microwave radiometer attached
to the Nimbus 7 satellite, and the special sensor microwave imagers attached to
the Defense Meteorological Satellite Program's F8, F11, and F13 satellites.
Part of the challenge for researchers was in the elimination of "bad
data", from atmospheric interference to instrument calibration issues and
more. The visualization present average annual polar ice concentrations for the
nineteen-year period studied. As part of their research into polar ice trends,
scientists collected data on the annual spread and recession of ice around the
North and South Pole. One of the features made most clear by their efforts is
how the ice packs are dynamic and complex environments, showing seasons much like
the rest of the world. In spring and summer, the ice shrinks, and in autumn and
winter it grows. Scientists use observations of seasonal changes in the ice to
determine if biannual averages are changing over time.
GREENLAND'S THINNING ICE Based
on recent research using NASA's airborne laser altimeter, scientists have identified
pronounced thinning of Greenland's ice cap. In the following animation, blues
indicate areas where the loss of ice is greatest, and yellows indicate regions
that are apparently thickening. Gray areas indicate no significant change in ice
thickness there. Notice how the thinning is most severe at the coasts. As ice
melts near the edges, it gives up moisture to the slightly warmer air around it.
That air rises to higher altitudes inland and the moisture precipitates out as
snow, increasing inland elevations. Thus, a slight thickening in the interior
supports observations of a greater net loss to the overall sum of Greenland's
ice cap.
LIDAR: USING LIGHT TO MEASURE HEIGHT Lidar
is a distance measuring system similar to radar, except that instead of radio
waves it uses pulses of laser light for range finding. Lidar derives from the
words light and radar. The instrument determines precise distances by measuring
the amount of time necessary for a pulse of light to leave an emitter, hit a target,
and return. In this case, distance measurements helped researchers determine changes
in ice thickness. CRISSCROSSING
GREENLAND BY PLANE Initial
research into Greenland's ice cap using lidar began in 1993 when a team from NASA's
Wallops Island Flight Facility surveyed the area. Flying an aging but sturdy aircraft
called a P-3B, altitude measurements were taken again in 1998 and 1999 for comparison.
Researchers could essentially duplicate airplane flight paths due to a highly
precise Global Positioning System (GPS) flown onboard. LIDAR:
MEASURING TERRAIN ON EARTH AND ELSEWHERE Lidar
offers diverse scientific disciplines powerful tools for
exploration. Besides
being used to study Greenland's ice cap, lidar has been used to study coastal
erosion on both the east and west coast. Additionally, a lidar system managed
by the Goddard Space Flight Center is currently orbiting Mars as part of the Mars
Global Surveyor spacecraft, engaged in a detailed mapping project of the red planet. ICE:
THE PLANET'S THERMOSTAT
Here
we begin with a view of Greenland as it may have looked 100,000 years ago. Moving
in, notice what happens as the climate begins to warm. Glaciers surrounding the
edge of Greenland begin to slump, then melt, adding billions of gallons to the
oceans. The humid air from the coasts rises to the interior, where it cools and
dumps snow. When the camera pulls back, we see Greenland's ice cap much reduced
in size, resulting in measurable and significant changes to the world's climate.
STREAMS OF ICE Recent
observations by a NASA-launched Canadian spacecraft called Radarsat are giving
scientists a remarkable view of two fascinating features of Antarctica's landscape.
Over a twenty-four day span, scientists used two images over identical regions
of Antarctica in a technique called interferometry. Their comparative analysis
of the images helped develop the following ice stream animations on the west side
of the continent, showing flow rate and direction to an extent never before possible. VECTOR
ANALYSIS OF FLOW In
this visualization, longer black lines indicate a faster rate of flow than shorter
lines. The fastest ice streams can move 400 to 500 meters a year, a blazing speed
compared to tributary speeds of little more than 10 meters a year.
Experts
say the new information can help describe large scale changes to the Antarctic
environment, as well as historical models about geological change.
HOW THEY WORK: A VIRTUAL MODEL OF ICE STREAMS
Experts
still aren't positive how ice streams actually work. The current theory says that
tributaries of slower ice come together to create larger streams, often at points
where elevation and terrain
merge and act like a sluice. At these convergences,
ice then literally slides across a lubricated bed of oceanic muck covered by a
millimeter thin layer of water, gaining strength as it drives toward the ocean.
BRIGHT WHITE REFLECTS LIGHT
The
polar caps not only hold much of the planet's total fresh water, but also play
an important role in regulating the Earth's temperature. The relevant characteristic
is called albedo. It's a measure of how much radiation, or light, is reflected
from a body. Similar to how a white shirt helps keep a person cooler in the summer
than a black shirt, the vast stretches of polar ice covering much of the planet's
top and bottom reflect large amounts of solar radiation falling on the planet's
surface. Were the ice caps to appreciably recede, sunlight that otherwise would
have been reflected back into space would get absorbed by the darker, denser mass
of ocean and land beneath. As light is absorbed, the environment is heated, thus
intensifying a feedback loop: a warmer planet yields more ice melting thus an
even warmer planet.
IS THE OCEAN RISING?
This
animation provides a more close-up perspective of the relationship between ice
and solar reflectivity. As glaciers, the polar caps, and in this case, icebergs
melt, less sunlight gets reflected into space. It is instead absorbed into the
oceans and land, thus raising the overall temperature, and adding energy to a
vicious circle. Of the many concerns voiced by scientists who study global warming
trends, rising ocean levels is one of the most dramatic. An average rise in global
ocean levels of just a few inches could have devastating effects on coastal towns,
cities, and ecosystems. Why then is even the slightest risk of a shrinking polar
cap not sounding alarms all across the world's lowland regions?
It comes
down to a simple principal proved thousands of years ago by the Greek philosopher
and scientist Archimedes. He showed that a body, in this case the floating ice
of the North Pole, immersed in a fluid is buoyed up by a force equal to the weight
of the displaced fluid. In other words, since the northern pack ice is already
floating its melting would not independently cause ocean levels to rise. However,
the attending planetary conditions necessary to facilitate polar melting would
likely have other enormous effects on the environment, including the likely melting
of the southern polar cap. As the ice over Antarctica is NOT floating, a corresponding
rise in the world's sea level would almost certainly result if it melted. RADARSAT:
INTERNATIONAL COLLABORATION REVEALS A CONTINENT
In
the following collection of images, we look at various regions of Antarctica,
the southernmost continent. The satellite that collected the data for each of
these scenes is called Radarsat, a Canadian spacecraft placed on orbit by NASA. ANTARCTICA
TOUR: ROSS ISLAND/McMURDO STATION
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 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's 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
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 of meteorites. It is from the Allen Hills
that several years ago scientists found a fragment of something they believe is
an actual piece of Earth's second closest neighbor: Mars. AMUNDSEN-SCOTT
SOUTH POLE STATION
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
Prior
to the Radarsat mission, scientists knew little about the East Antarctic Ice Streams,
draining 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 and the large Slessor Glacier extend for more than 250 kilometers.
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
RIPPLE THE ANTARCTICA'S SURFACE Radarsat
also enabled researchers to gain a better understanding about a surface feature
found only at the bottom of the world. These snow dunes are believed to be highly
stable surface features. They're made of ice particles, or grains, of different
sizes. Individually each dune is nearly impossible to see without the aid of satellite
remote sensing systems, but the range of the snowdunes is larger in total area
than the state of California. Unlike their sand analogues in more familiar deserts
around the globe, these dunes tend not to rise nearly as high. Stretching for
hundreds of kilometers, these dunes rise only 2 to 3 meters but often have a periodicity
of more than 2 kilometers; that means there may be as much as 2 kilometers between
each dune. 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 grains 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. LATE
VOSTOK
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. The drilling project
faces certain technological challenges. Major mechanical work is always difficult
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. It was at Vostok Station, located at the southern end
of the lake, that Russian scientists recorded the coldest temperatures on Earth.
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
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 that
may have caused high levels of surface melting, or an overall climate warming
trend. FIMBUL
ICE SHELF
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
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
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. Interestingly, as
ice shelves break up into icebergs, overall sea level generally doesn't rise.
That's because ice shelf are ostensibly already floating in the water. Floating
ice shelves, 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.
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SPACECRAFT
MANUFACTURE - B-ROLL
Written
and Produced for Television and The Web by:
Michael
Starobin Executive
Producer: Wade
Sisler
Scientific
Consultants:
Dr.
Chris Shuman
Dr.
Claire Parkinson
Dr.
Robert Bindschadler Back
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