Polar Crisis: Satellite Tracks Arctic Meltdown
NEWSALERT: Tuesday, August 22, 2000
The latest news from Astronomy Now and Spaceflight Now
NASA Science News for August 22, 2000
An orbiting radar has cut through clouds and dark of night to monitor the ebb and flow of Arctic ice. Scientists say the data could reveal important trends in global climate change.
NASA Headquarters, Washington DC
Jet Propulsion Laboratory, Pasadena, CA
August 21, 2000
Using RADARSAT's special sensors to take images at night and to peer through clouds, NASA researchers can now see the complete ice cover of the Arctic. This allows tracking of any shifts and changes, in unprecedented detail, over the course of an entire winter. The radar-generated, high-resolution images are up to 100 times better than those taken by previous satellites.
Using this new information, scientists at NASA's Jet Propulsion Laboratory (JPL), Pasadena, CA, can generate comprehensive maps of Arctic sea ice thickness for the first time. "Before we knew only the extent of the ice cover," said Dr. Ronald Kwok, JPL principal investigator of a project called Sea Ice Thickness Derived From High Resolution Radar Imagery. "We also knew that the sea ice extent had decreased over the last 20 years, but we knew very little about ice thickness.'"
"Since sea ice is very thin, about 10 feet (3 meters) or less," Kwok explained, "it is very sensitive to climate change."
Until now, observations of polar sea ice thickness have been available for specific areas, but not for the entire polar region.
The new radar mapping technique has also given scientists a close look at how the sea ice cover grows and contorts over time. "Using this new data set, we have the first estimates of how much ice has been produced and where it formed during the winter. We have never been able to do this before," said Kwok. "Through our radar maps of the Arctic Ocean, we can actually see ice breaking apart and thin ice growth in the new openings."
RADARSAT gives researchers a piece of the overall puzzle every three days by creating a complete image of the Arctic. NASA scientists then put those puzzle pieces together to create a time-lapsed view of this remote and inhospitable region. So far, they have processed one season's worth of images.
"We can see large cracks in the ice cover, where most ice grows," said Kwok. "These cracks are much longer than previously thought, some as long as 1200 miles (2000 kilometers)." Kwok continued, "If the ice is thinning due to warming, we'll expect to see more of these long cracks over the Arctic Ocean."
Scientists believe this is one of the most significant breakthroughs in the last two decades of ice research. "We are now in a position to better understand the sea ice cover and the role of the Arctic Ocean in global climate change," said Kwok.
Radar can see through clouds and any kind of weather system, day or night, and as the Arctic regions are usually cloud-covered and subject to long, dark winters, radar is proving to be extremely useful. However, compiling these data into extremely detailed pictures of the Arctic is a challenging task.
"This is truly a major innovation in terms of the quantities of data being processed and the novelty of the methods being used," said Verne Kaupp, Director of the Alaska SAR Facility at the University of Alaska, Fairbanks.
The mission is a joint project between JPL, the Alaska SAR Facility, and the Canadian Space Agency. Launched by NASA in 1995, the RADARSAT satellite is operated by the Canadian Space Agency. JPL manages the Sea Ice Thickness Derived From High Resolution Radar Imagery project for NASA's Earth Science Enterprise, Washington, DC. The Earth Science Enterprise is dedicated to studying how natural and human-induced changes affect our global environment.
More information on this mission can be found on the Internet.
Canadian Space Agency
St. Hubert, Quebec
MDA's winning combination for this project is reflected in its state-of-the-art design for RADARSAT II, its Business Plan and vision for the future. MDA will implement an advanced system at half the cost of RADARSAT I, with a lighter, cheaper and more capable satellite. The new capabilities will increase data sales and assure the growth of the value-added Earth observation industry in Canada.
The objectives of the project are to continue Canada's RADARSAT program and to develop Earth observation satellite business through a private sector-led arrangement with the federal government. The project will result in the construction of an Earth observation satellite (RADARSAT II) that will provide data continuity to RADARSAT I users and offer data for new applications tailored to market needs. The Government of Canada and MDA will invest $225 million and $80 million respectively for the construction of this high-tech satellite system. MDA will be responsible for all ongoing operations and data commercialization. Space industry organizations from across the country will also benefit in the form of subcontracts to assist MDA. It is estimated that approximately 300 jobs will be created across Canada over the four-year construction phase of this project alone.
"Today's announcement will lead to the launch of the world's most advanced Earth observation satellite ever," said Minister Manley. "RADARSAT II will confirm Canada's world leadership in a technology which will prove critically important to environmental monitoring."
"This is a great day for British Columbia. RADARSAT II paves the road for extensive regional development, training and investment,"said Minister Anderson. "This program makes all Canadians winners as we will be able to focus on our achievements and placement in a knowledge-based world economy."
"This is a good deal for Canada and is the result of a fair competitive process," said Minister Gagliano. "RADARSAT II will offer Canada world-wide market opportunities led by industry and the users to usher our world class remote sensing capabilities into the next millennium."
The new satellite, scheduled for launch in 2001, will be the most advanced Synthetic Aperture Radar (SAR) satellite in the world and will contribute valuable data to commercial, government and scientific programs.
RADARSAT is unlike most remote sensing satellites in that it is able to collect its images through a powerful microwave Synthetic Apature Radar (SAR) satellite system which provides all-climate, day and night imagery to clients around the world. The data images, which RADARSAT collects, have proven to be an effective tool in the management and monitoring of the global environment in areas of ice navigation, cartography, geological exploration, maritime surveillance, disaster relief operations, agriculture and forestry surveillance.
Canadian Space Agency
St. Hubert, Quebec
Rolf Mamen, Director General of Space Operations at the CSA, said that "the results from this one satellite -- RADARSAT -- over a period of approximately four weeks have been remarkable. The last satellite map of Antarctica not only failed to provide an entire picture of the region but required images from thirteen different satellites over a six year period (1980-1987)."
For the scientific community, Dr. Robert Price, Director, Mission to Planet Earth Program Office at NASA Goddard Space Flight Center stated that "this milestone provides a significant amount of data that will help scientists determine what's happening to an important part of the Earth's cryosphere, namely the Antarctic, including understanding the impact of any Antarctic changes on our global climate change."
Scientists say that with Antarctica being the only continent on Earth not properly mapped they are not sure whether this massive ice sheet is growing larger or smaller. The newly acquired data from RADARSAT'S Antarctic Mapping Mission are already helping the scientific community answer this question.
"The invaluable radar image of Earth's geographic South Pole from RADARSAT shows an unexpectedly complex surface structure over what was previously believed to be the nearly featureless East Antarctic Ice Sheet," said Dr. Kenneth Jezek, Director of the Byrd Polar Research Center at Ohio State University. "The images reveal that large sections of the East Antarctic Ice Sheet are characterized by a heavily textured surface probably reflecting the bedrock topography over which the ice sheet is flowing. Of particular interest are what appear to be newly discovered flow features that extend for hundreds of kilometers upstream of the Recovery Glacier which drains into the Ronne Ice Shelf."
With the conclusion of the mapping portion of the mission, the next step in the process is for the science team members to process the collection of over 8,000 images at NASA's Alaska Synthetic Aperture Radar Facility at the University of Alaska. With the processing completed, scientists at the Byrd Polar Research Center must now "stitch" together the images and align the edges to make the complete Antarctic map -- a process that will take about one year to complete.
This near real time comprehensive snapshot view of the Antarctic continent was made possible by rotating the Canadian RADARSAT satellite 180 degrees from its normal orientation and by making use of its unique radar beam steering capability. Successfully completing its rotation on September 11, 1997, the satellite is scheduled to return to its standard configuration by November 3, 1997.
NASA's involvement in RADARSAT is part of the agency's Mission to Planet Earth enterprise, a long-term coordinated research program to study the Earth's land, oceans, air, ice and life as a total system.
Launched in November 1995, RADARSAT, Canada's first Earth observation satellite, is owned and operated by the CSA in Saint-Hubert, Quebec. Canada's remote sensing expertise is housed in the Canada Centre for Remote Sensing, of Natural Resources Canada, with RADARSAT imagery marketed and distributed by RADARSAT International, a Canadian company located in Richmond, British Columbia. The satellite was designed and built in Canada by a team of 30 companies from across the country, led by prime contractor Spar Aerospace.
Images from the Antarctic Mapping Mission are available on the CSA Web Site.
Canadian Space Agency
St. Hubert, Quebec
This unique image of the South Pole was obtained by rotating the RADARSAT satellite 180 degrees in yaw. This manoeuver was performed for the Antarctic Mapping Mission (AMM), between September 9 and 11. The manoeuver allowed the radar to image to the left of the satellite track instead of to the right and by steering the radar beam up to cover the South Pole. This coverage is not possible with other high resolution sensors because of a combination of their orbit inclination and field of view capability. Although other missions do regular ``yaw'' manoeuvers for sun data acquisition purposes, the AMM manoeuver is believed to be unique for an earth observation spacecraft like RADARSAT. The satellite will remain in this configuration until November 3 to allow the complete mapping of Antarctica at high resolution. This mapping of Antarctica, a largely uncharted region the size of Canada and Alaska combined will take 18 days to complete and will require the collection of over 5000 images.
The RADARSAT AMM has important significance for the scientific community; almost 70% of the Earth's fresh water is contained in the Antarctic region, and changes in this enormous reservoir directly influence world sea levels and climate. A high resolution digital image mosaic of the ice sheet and exposed portions of the continent will be prepared from images taken by RADARSAT. The new digital radar map will provide an unprecedented detailed portrayal of the surface form and features of the icesheet. This RADARSAT based map will help scientists to better understand the dynamic behaviour of the ice sheet and provide them a greater insight into the effects of human activity on the Southern Continent.
The RADARSAT AMM data will also serve as a benchmark for testing the predicted effects of global warming on the interior ice sheet and the bounding ice shelves, some of which have recently under gone rapid retreat especially in the Antarctic Peninsula.
Using the images taken by RADARSAT, scientists will be able to examine for the first time the effects of complex climatological, glaciological and geological processes on the Antarctic at high resolution and on a Continental wide scale. Furthermore, the availability of this unique data set will be welcomed by scientists from many of the nations interested in the governance and protection of Antarctica in accordance with the Antarctic Treaty System.
The AMM is a commitment that was negotiated and agreed to by the CSA in an International Memorandum of Understanding (IMOU) signed with the National Aeronautics and Space Administration (NASA) and the National Oceanographic and Atmospheric Administration (NOAA) on February 27, 1991. In exchange for the launch of the RADARSAT satellite by NASA, Canada agreed to provide the USA with access to a proportionate amount of RADARSAT's SAR on-time and to execute a yaw manoeuver of the spacecraft twice during the mission to allow the mapping of the Antarctic Continental Ice Sheet.
Partners in the AMM include the CSA and NASA. CSA support draws upon the Canada Centre for Remote Sensing (CCRS) and RADARSAT International (RSI). NASA support draws upon the Byrd Polar Research Centre of the Ohio State University (OSU), NASA's Alaska SAR Facility (ASF), NASA's Jet Propulsion Laboratory (JPL) and the Goddard Space Flight Center (GSFC), Vexcel Corporation, the Environmental Research Institute of Michigan and the National Imagery and Mapping Agency.
Launched in November 1995 and operated by the CSA from Saint- Hubert, Quebec, RADARSAT uses a sophisticated microwave radar system to produce images of extraordinary clarity through cloud cover, smog, haze, smoke, and even in darkness. The satellite can be programmed to capture images of an area as wide as 500 kilometres, and can detect objects as small as eight metres. Marketing and worldwide distribution of RADARSAT data have been licensed to the Canadian firm, RADARSAT International (RSI), of Richmond, British Columbia. With the AMM, RADARSAT will complete the detailed radar mapping of the entire planet Earth.
NASA Headquarters, Washington, DC
Goddard Space Flight Center, Greenbelt, MD
Jet Propulsion Laboratory, Pasadena, CA
Canadian Space Agency, St. Hubert, Quebec
October 1, 1997
"The quality of these first images is quite stunning," said Dr. Robert Thomas, program manager for polar research in NASA's Office of Mission to Planet Earth, Washington, DC. "Antarctica is the only continent on Earth that has not been properly mapped. Despite many years of research, we still do not know whether this massive ice sheet is growing larger or smaller. Radarsat's Antarctic Mapping Mission should help us answer this question, and many related questions about its potential for affecting global sea levels."
Nearly 70 percent of the Earth's fresh water is contained in the Antarctic region, and changes in this enormous reservoir directly influence world sea levels and climate. As a reference point, if fully melted, this ice would raise the global sea level by about 230 feet (70 meters).
Previous research has revealed that about 90 percent of Antarctic ice flows into the sea via large "ice streams." These rivers of ice are tens of miles wide and about a half-mile thick, and can flow rapidly within the predominantly slow-moving ice sheet. "We know little about why these ice streams form where they do, or what determines their speed," Thomas said. "Most Antarctic ice streams flow into 'ice shelves,' large, floating slabs of ice the size of Texas that rest on the ocean and occupy most of the Antarctic coastline. They move seaward at about a half-mile per year, occasionally 'calving' to form huge icebergs."
Where the seabed beneath an ice shelf becomes sufficiently shallow, the ice shelf runs aground, slows down and thickens to form an "ice rise" which tends to slow the seaward progress of the ice shelf, and ultimately to hinder ice discharge down the ice streams. However, if the ice shelf were to become sufficiently thin, for instance, by increased melting from beneath, the speed of ice discharge would increase, allowing more ice to flow into the ocean, and thus raising the sea level. "Just how quickly this could happen if climate were to change is not known, and would depend heavily on whether the ice sheet is already thinning or, as some evidence suggests, actually thickening," Thomas said. "These unknowns are the prime reasons for this research effort."
The first radar image of Earth's geographic South Pole from the Radarsat Antarctic campaign clearly shows the infrastructure of the Amunsden-Scott Station operated by the U.S. National Science Foundation. The image reveals the modern infrastructure that supports a host of international science programs, but also shows an abandoned aircraft runway and other remains of the old South Pole station, now buried under about 30 feet of snow and ice.
This image and several others, as well as further information on the Radarsat mission, are available on the Internet at the following URL, under the link to the Antarctic Mapping Mission.
The Antarctic Mapping Mission was made possible by rotating the satellite 180 degrees from its normal field of view, which was completed on Sept. 11. Full mapping will require the collection of over 5,000 images.
"Following the successful rotation, 30 percent of the mission's objectives have now been achieved," said Rolf Mamen, Director General of Space Operations at the Canadian Space Agency. "We are extremely pleased with the quality of the radar images being obtained of this unmapped region of our planet, and of the contribution we are making to the scientific community."
The high-resolution digital image mosaic of the ice sheet and exposed portions of the continent to be taken by the Antarctic Mapping Mission will serve as a benchmark for testing the predicted effects of global warming on the interior ice sheet and its bounding ice shelves. This unique data set also will support the development of policies to help preserve Antarctica in its relatively pristine state, through the goals subscribed under the international Antarctic Treaty System.
U.S. partners in the Antarctic portion of the Radarsat mission include the Byrd Polar Research Center of Ohio State University, Columbus, OH; NASA's Alaska Synthetic Aperture Radar Facility in Fairbanks; the Jet Propulsion Laboratory, Pasadena, CA, and the Goddard Space Flight Center, Greenbelt, MD.
"The job of mapping one of the last largely unexplored regions of the Earth is truly a mission of international cooperation, with collaboration that includes scientists from Great Britain, Germany, Japan, and Australia in addition to the United States and Canada," said Dr. Kenneth Jezek, a professor of geological science and director of the Byrd Polar Research Center at Ohio State University. "In that way, the Antarctic Mapping Mission is in keeping with the spirit and intent of the Antarctic treaty, which serves to preserve the continent for peaceful scientific research by any nation."
In exchange for the launch of the Radarsat satellite by NASA in November 1995, Canada agreed to provide access to a proportionate amount of its operational data and to execute the yaw maneuver of the spacecraft twice during the mission to allow the mapping of the Antarctic continental ice sheet.
Operated by the Canadian Space Agency from St. Hubert, Quebec, Radarsat utilizes a sophisticated microwave radar system able to produce images through cloud cover, smog, haze, smoke and darkness. The satellite can be programmed to capture images of an area as wide as 320 miles (500 kilometers), and can detect objects as small as 26 feet (eight meters.)
NASA's involvement in Radarsat is part of the agency's Mission to Planet Earth enterprise, a long-term coordinated research program to study the Earth's land, oceans, air, ice and life as a total system.
Canadian Space Agency
St. Hubert, Quebec
ST. HUBERT, Sept. 12, 1997 -- The Canadian Space Agency (CSA) announced today the successful 180 degree rotation of RADARSAT, the first time that such a manoeuver has been accomplished by an Earth observation satellite. As part of the Antarctic-1 Mapping Mission (AMM), the manoeuvre was executed to allow the satellite to begin taking radar images of the entire Antarctica, an uncharted region the size of the United States and Mexico combined that has never been fully mapped by high resolution radar remote sensing technology.
The rotation of the satellite began on September 9 from RADARSAT Mission Control in St. Hubert, Quebec, and took approximately 48 hours to complete. The manoeuver will permit imaging to the left of the satellite track instead of to the right. Following a 14-day commissioning stage, RADARSAT will begin imaging Antarctica for a period of 18 days. The CSA will then program the satellite to return to its original right-looking orientation to continue normal operations by November 4.
The mission has important significance for the scientific community; almost 70% of the Earth's fresh water is contained in the Antarctic region, and changes in that enormous reservoir directly influence world sea levels. The preparation of a high resolution digital mosaic of the ice sheet and exposed portions of the continent -- to be prepared by the Byrd Polar Research Centre of Ohio State University (OSU) -- will help us to better understand why changes in the ice sheet occur, providing more insight into the effects of human activity and global warming on the rapid retreat of large portions of the ice shelves in the Antarctic Peninsula. Using the images taken by RADARSAT, scientists will be able to examine for the first time history similar processes occuring across the entire continent.
The AMM is a commitment that was negotiated and agreed to by the CSA in an International Memorandum of Understanding (IMOU) signed with NASA on February 27, 1991. In exchange for the launch of the RADARSAT satellite by NASA, Canada agreed to provide the USA with access to RADARSAT's SAR on-time data and to execute a "yaw" manoeuvre of the spacecraft twice during the lifetime of RADARSAT operations to allow the mapping of the Antarctic Continent.
Partners in the mission include the CSA, National Aeronautics and Space Administration (NASA), National Oceanic and Atmospheric Administration (NOAA), Jet Propulsion Laboratory (JPL), Byrd Polar Research Centre of Ohio State University (OSU), Alaskan SAR Facility (ASF), Canada Centre for Remote Sensing (CCRS) and RADARSAT International (RSI).
Canada is responsible for the management of the AMM, calibration of the payload in each phase, executing the data acquisition plan and for ensuring the successful reception of the data to the specified receiving station (i.e. ASF being the main station followed by the Canadian Gatineau and Prince Albert (PASS) stations). McMurdo, an American USA Antarctica receiving station, will also be used to receive data directly and to retransmit them to ASF via the Tracking and Data Relay Satellite System (TDRSS). The data acquisition plan and strategy largely depends on the on-board tape recorders.
The preparation of a digital mosaic of Antarctica is being conducted under a NASA Pathfinder Project awarded to the Byrd Polar Research Centre of Ohio State University (OSU). The United States Jet Propulsion Laboratory, is responsible for the preparation of the data acquisition plan while the OSU is responsible for, producing a complete mosaic of the area within 1 1/2 years of the completion of the data acquisition.
Operated by the CSA from Saint-Hubert, Quebec, RADARSAT uses a sophisticated microwave radar system to produce images of extraordinary clarity through heavy cloud cover, smog, haze, smoke, and even in darkness. The satellite can be programmed to capture images of an area as big as 500 kilometres wide, and can detect objects as small as eight metres. Remote sensing expertise is provided by the Canada Centre for Remote Sensing, a department of Natural Resources Canada. Marketing and distribution of RADARSAT data has been licensed to the Canadian firm, RADARSAT International (RSI), of Richmond, B.C.
From the time of its launch in November 1995, RADARSAT has successfully imaged all regions of the Earth except for Antarctica. The Antarctic-1 Mapping Mission will complete the radar mapping of the entire world.
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