July 3, 2013
Steve Cole
Headquarters, Washington
202-358-0918
Alan Buis
Jet Propulsion Laboratory, Pasadena, Calif.
818-354-0474
Julien Watelet
Centre National d'Etudes Spatiales, Paris, France
Centre National d'Etudes Spatiales, Paris, France
011-33-6-88061148
Long-Running NASA/CNES Ocean Satellite Takes Final Bow
WASHINGTON -- The curtain has come down on a superstar of the satellite oceanography world that played the "Great Blue Way" of the world's ocean for 11 1/2 years. The successful joint NASA and Centre National d'Etudes Spatiales (CNES) Jason-1 ocean altimetry satellite was decommissioned this week following the loss of its last remaining transmitter.
Launched Dec. 7, 2001, and designed to last three to five years, Jason-1 helped create a revolutionary 20-plus-year climate data record of global ocean surface topography that began in 1992 with the launch of the NASA/CNES TOPEX/Poseidon satellite. For more than 53,500 orbits of our planet, Jason-1 precisely mapped sea level, wind speed and wave height for more than 95 percent of Earth's ice-free ocean every 10 days. The mission provided new insights into ocean circulation, tracked our rising seas and enabled more accurate weather, ocean and climate forecasts. "Jason-1 has been a resounding scientific, technical, and international success," said John Grunsfeld, associate administrator NASA's Science Mission Directorate in Washington. "The mission met all of its requirements, performed an extended mission and demonstrated how a long-term climate data record should be established from successively launched satellites. Since launch, it has charted nearly 1.6 inches (4 centimeters) of rise in global sea levels, a critical measure of climate change and a direct result of global warming. The Jason satellite series provides the most accurate measure of this impact, which is felt all over the globe."
During parts of its mission, Jason-1 flew in carefully coordinated orbits with both its predecessor TOPEX/Poseidon and its successor, the Ocean Surface Topography Mission/Jason-2, launched in 2008. These coordinated orbit periods, which lasted about three years each, cross-calibrated the satellites, making possible a 20-plus-year unbroken climate record of sea level change. These coordination periods also doubled data coverage.
Combined with data from the European Space Agency's Envisat mission, which also measured sea level from space, these data allow scientists to study smaller-scale ocean circulation phenomena, such as coastal tides, ocean eddies, currents and fronts. These small-scale features are thought to be responsible for transporting and mixing heat and other properties, such as nutrients and dissolved carbon dioxide, within the ocean. "Jason-1 was an exemplary and multi-faceted altimeter mission and contributed so much to so many scientific disciplines," said Jean-Yves Le Gall, CNES president in Paris. "Not only did Jason-1 extend the precise climate record established by TOPEX/Poseidon, it made invaluable observations for mesoscale ocean studies on its second, interleaved orbit. Even from its 'graveyard' orbit, Jason-1 continued to make unprecedented new observations of the Earth's gravity field, with precise measurements right till the end."
The in orbit Jason-2 mission, operated by the meteorological agencies of the United States and Europe (the National Oceanic and Atmospheric Administration and EUMETSAT) in collaboration with NASA and CNES, is in good health and continues to collect science and operational data. This same U.S./European team is preparing to launch the next satellite in the series, Jason-3, in March 2015.
Contact was lost with the Jason-1 satellite on June 21 when it was out of visibility of ground stations. At the time of the last contact, Jason-1 and its instruments were healthy with no indications of any alarms or anomalies. Subsequent attempts to re-establish spacecraft communications from U.S. and French ground stations were unsuccessful. Extensive engineering operations undertaken to recover downlink communications also were unsuccessful.
After consultation with the spacecraft and transmitter manufacturers, it was determined a non-recoverable failure with the last remaining transmitter on Jason-1 was the cause of the loss of contact. The spacecraft's other transmitter experienced a permanent failure in September 2005. There now is no remaining capability to retrieve data from the Jason-1 spacecraft.
On July 1, mission controllers commanded Jason-1 into a safe hold state that reinitialized the satellite. After making several more unsuccessful attempts to locate a signal, mission managers at CNES and NASA decided to proceed with decommissioning Jason-1. The satellite was then commanded to turn off its magnetometer and reaction wheels. Without these attitude control systems, Jason-1 and its solar panels will slowly drift away from pointing at the sun and its batteries will discharge, leaving it totally inert within the next 90 days. The spacecraft will not reenter Earth's atmosphere for at least 1,000 years. "Like its predecessor TOPEX/Poseidon, Jason-1 provided one of the most comprehensive pictures of changes in the tropical Pacific Ocean, including the comings and goings of El Nino and La Nina events," said Lee-Lueng Fu, Jason-1 project scientist at NASA's Jet Propulsion Laboratory (JPL) in Pasadena, Calif. "These Pacific Ocean climate cycles are responsible for major shifts in sea level, ocean temperatures and rainfall every two to five years and can sometimes be so large that worldwide weather patterns are affected. Jason-1 data have been instrumental in monitoring and predicting these ever-changing cycles."
In the spring of 2012, based on concern over the limited redundancy of Jason-1's aging control systems, NASA and CNES moved the satellite into its planned final "graveyard" orbit, depleted its extra fuel and reconfigured the mission to make observations that will improve our knowledge of Earth's gravity field over the ocean, in addition to delivering its oceanographic data products.
The first full 406-day marine gravity mission was completed on June 17. The resulting data have already led to the discovery of numerous small seamounts, which are underwater mountains that rise above the deep-sea floor. The data also have significantly increased the resolution of Earth's gravity field over the ocean, while increasing our knowledge of ocean bathymetry, which is the underwater depth of the ocean floor.
JPL manages the U.S. portion of the Jason-1 mission for NASA's Science Mission Directorate. CNES manages the French portion of the mission.
For more information on Jason-1, visit:
http://www.aviso.oceanobs.com
Scientists have studied the rates of basal melt, or the melting of the ice shelves from underneath, of individual ice shelves, the floating extensions of glaciers that empty into the sea. But this is the first comprehensive survey of all Antarctic ice shelves. The study found basal melt accounted for 55 percent of all Antarctic ice shelf mass loss from 2003 to 2008, an amount much higher than previously thought.
Antarctica holds about 60 percent of the planet's fresh water locked into its massive ice sheet. Ice shelves buttress the glaciers behind them, modulating the speed at which these rivers of ice flow into the ocean. Determining how ice shelves melt will help scientists improve projections of how the Antarctic ice sheet will respond to a warming ocean and contribute to sea level rise. It also will improve global models of ocean circulation by providing a better estimate of the amount of fresh water ice shelf melting adds to Antarctic coastal waters.
The study uses reconstructions of ice accumulation, Satellite and aircraft readings of ice thickness, and changes in elevation and ice velocity to determine how fast ice shelves melt and compare the mass lost with the amount released by the calving, or splitting, of icebergs.
"The traditional view on Antarctic mass loss is it is almost entirely controlled by iceberg calving," said Eric Rignot of NASA's Jet Propulsion Laboratory in Pasadena, Calif., and the University of California, Irvine. Rignot is lead author of the study to be published in the June 14 issue of the journal Science. "Our study shows melting from below by the ocean waters is larger, and this should change our perspective on the evolution of the ice sheet in a warming climate."
Ice shelves grow through a combination of land ice flowing to the sea and snow accumulating on their surface. To determine how much ice and snowfall enters a specific ice shelf and how much makes it to an iceberg, where it may split off, the research team used a regional climate model for snow accumulation and combined the results with ice velocity data from satellites, ice shelf thickness measurements from NASA's Operation IceBridge - an continuing aerial survey of Earth's poles - and a new map of Antarctica's bedrock.
Using this information, Rignot and colleagues were able to deduce whether the ice shelf was losing mass through basal melting or gaining it through the basal freezing of seawater.
In some places, basal melt exceeds iceberg calving. In other places, the opposite is true. But in total, Antarctic ice shelves lost 2,921 trillion pounds (1,325 trillion kilograms) of ice per year in 2003-2008 through basal melt, while iceberg formation accounted for 2,400 trillion pounds (1,089 trillion kilograms) of mass loss each year.
Basal melt can have a greater impact on ocean circulation than glacier calving. Icebergs slowly release melt water as they drift away from the continent. But strong melting near deep grounding lines, where glaciers lose their grip on the seafloor and start floating as ice shelves, discharges large quantities of fresher, lighter water near the Antarctic coast line. This lower-density water does not mix and sink as readily as colder, saltier water, and may be changing the rate of bottom water renewal.
"Changes in basal melting are helping to change the properties of Antarctic bottom water, which is one component of the ocean's overturning circulation," said author Stan Jacobs, an oceanographer at Columbia University's Lamont-Doherty Earth Observatory in Palisades, N.Y. "In some areas it also impacts ecosystems by driving coastal upwelling, which brings up micronutrients like iron that fuel persistent plankton blooms in the summer."
The study found basal melting is distributed unevenly around the continent. The three giant ice shelves of Ross, Filchner and Ronne, which make up two-thirds of the total Antarctic ice shelf area, accounted for only 15 percent of basal melting. Meanwhile, fewer than a dozen small ice shelves floating on "warm" waters (seawater only a few degrees above the freezing point) produced half of the total melt water during the same period. The scientists detected a similar high rate of basal melting under six small ice shelves along East Antarctica, a region not as well known because of a scarcity of measurements.
The researchers also compared the rates at which the ice shelves are shedding ice to the speed at which the continent itself is losing mass and found that, on average, ice shelves lost mass twice as fast as the Antarctic ice sheet did during the study period.
"Ice shelf melt doesn't necessarily mean an ice shelf is decaying; it can be compensated by the ice flow from the continent," Rignot said. "But in a number of places around Antarctica, ice shelves are melting too fast, and a consequence of that is glaciers and the entire continent are changing as well."
For images related to this release, please visit:
June 13, 2013
J.D. Harrington
Headquarters, Washington
202-358-5241
j.d.harrington@nasa.gov
Maria-Jose Vinas Garcia
Headquarters, Washington
202-358-5241
j.d.harrington@nasa.gov
Maria-Jose Vinas Garcia
RELEASE 13-183
Warm Ocean, Not Icebergs, Causing Most of Antarctic Ice Shelves' Mass Loss
PASADENA, Calif. - Ocean waters melting the undersides of Antarctic ice shelves are responsible for most of the continent's ice shelf mass loss, a new study by NASA and university researchers has found.
Scientists have studied the rates of basal melt, or the melting of the ice shelves from underneath, of individual ice shelves, the floating extensions of glaciers that empty into the sea. But this is the first comprehensive survey of all Antarctic ice shelves. The study found basal melt accounted for 55 percent of all Antarctic ice shelf mass loss from 2003 to 2008, an amount much higher than previously thought.
Antarctica holds about 60 percent of the planet's fresh water locked into its massive ice sheet. Ice shelves buttress the glaciers behind them, modulating the speed at which these rivers of ice flow into the ocean. Determining how ice shelves melt will help scientists improve projections of how the Antarctic ice sheet will respond to a warming ocean and contribute to sea level rise. It also will improve global models of ocean circulation by providing a better estimate of the amount of fresh water ice shelf melting adds to Antarctic coastal waters.
The study uses reconstructions of ice accumulation, Satellite and aircraft readings of ice thickness, and changes in elevation and ice velocity to determine how fast ice shelves melt and compare the mass lost with the amount released by the calving, or splitting, of icebergs.
"The traditional view on Antarctic mass loss is it is almost entirely controlled by iceberg calving," said Eric Rignot of NASA's Jet Propulsion Laboratory in Pasadena, Calif., and the University of California, Irvine. Rignot is lead author of the study to be published in the June 14 issue of the journal Science. "Our study shows melting from below by the ocean waters is larger, and this should change our perspective on the evolution of the ice sheet in a warming climate."
Ice shelves grow through a combination of land ice flowing to the sea and snow accumulating on their surface. To determine how much ice and snowfall enters a specific ice shelf and how much makes it to an iceberg, where it may split off, the research team used a regional climate model for snow accumulation and combined the results with ice velocity data from satellites, ice shelf thickness measurements from NASA's Operation IceBridge - an continuing aerial survey of Earth's poles - and a new map of Antarctica's bedrock.
Using this information, Rignot and colleagues were able to deduce whether the ice shelf was losing mass through basal melting or gaining it through the basal freezing of seawater.
In some places, basal melt exceeds iceberg calving. In other places, the opposite is true. But in total, Antarctic ice shelves lost 2,921 trillion pounds (1,325 trillion kilograms) of ice per year in 2003-2008 through basal melt, while iceberg formation accounted for 2,400 trillion pounds (1,089 trillion kilograms) of mass loss each year.
Basal melt can have a greater impact on ocean circulation than glacier calving. Icebergs slowly release melt water as they drift away from the continent. But strong melting near deep grounding lines, where glaciers lose their grip on the seafloor and start floating as ice shelves, discharges large quantities of fresher, lighter water near the Antarctic coast line. This lower-density water does not mix and sink as readily as colder, saltier water, and may be changing the rate of bottom water renewal.
"Changes in basal melting are helping to change the properties of Antarctic bottom water, which is one component of the ocean's overturning circulation," said author Stan Jacobs, an oceanographer at Columbia University's Lamont-Doherty Earth Observatory in Palisades, N.Y. "In some areas it also impacts ecosystems by driving coastal upwelling, which brings up micronutrients like iron that fuel persistent plankton blooms in the summer."
The study found basal melting is distributed unevenly around the continent. The three giant ice shelves of Ross, Filchner and Ronne, which make up two-thirds of the total Antarctic ice shelf area, accounted for only 15 percent of basal melting. Meanwhile, fewer than a dozen small ice shelves floating on "warm" waters (seawater only a few degrees above the freezing point) produced half of the total melt water during the same period. The scientists detected a similar high rate of basal melting under six small ice shelves along East Antarctica, a region not as well known because of a scarcity of measurements.
The researchers also compared the rates at which the ice shelves are shedding ice to the speed at which the continent itself is losing mass and found that, on average, ice shelves lost mass twice as fast as the Antarctic ice sheet did during the study period.
"Ice shelf melt doesn't necessarily mean an ice shelf is decaying; it can be compensated by the ice flow from the continent," Rignot said. "But in a number of places around Antarctica, ice shelves are melting too fast, and a consequence of that is glaciers and the entire continent are changing as well."
For images related to this release, please visit:
http://go.nasa.gov/175OAkF
May 30, 2013
Bert Ulrich/Steve Cole
Headquarters, Washington
202-358-1713/ 202-358-0918
RELEASE M13-088
Actor Jaden Smith Focuses on Earth Science in a New NASA PSA
WASHINGTON - Jaden Smith, star of Columbia Pictures' movie "After Earth," is featured in a new NASA public service announcement that describes the contributions of the agency's Earth science program to environmental awareness and exploration of our home planet.
The public service announcement features imagery from "After Earth" as well as animations of Earth data from 17 orbiting NASA satellites. The satellites are making cutting-edge observations of the entire Earth system, including the atmosphere, oceans, land surface, and snow and ice. The observations are used by scientists worldwide to improve our understanding of our complex planet, better predict the future of our changing climate, and enhance life on Earth today.
"NASA has a fleet of satellites around the planet that keeps track of climate change and studies how humans are affecting the planet," Smith says in the public service announcement. "At NASA right now, scientists and engineers are working every day to help humans learn how to better care for their home so that we never have to leave."
NASA Television will broadcast the announcement beginning Thursday, May 30. It is available to television and radio stations and other interested media outlets. To download and view the announcement, visit:
"NASA has a fleet of satellites around the planet that keeps track of climate change and studies how humans are affecting the planet," Smith says in the public service announcement. "At NASA right now, scientists and engineers are working every day to help humans learn how to better care for their home so that we never have to leave."
NASA Television will broadcast the announcement beginning Thursday, May 30. It is available to television and radio stations and other interested media outlets. To download and view the announcement, visit:
For more information about NASA's Earth science program, visit: http://www.nasa.gov/earth
Feb. 11, 2013
NASA Launches New Earth Observation Satellite to Continue 40-Year Legacy
WASHINGTON - NASA's Landsat Data Continuity Mission (LDCM) roared into space at 1:02 p.m. EST (10:02 a.m. PST) Monday aboard an Atlas V rocket from Vandenberg Air Force Base in California.
The LDCM spacecraft separated from the rocket 79 minutes after launch and the first signal was received three minutes later at a ground station in Svalbard, Norway. The solar arrays deployed 86 minutes after launch, and the spacecraft is generating power from them. LDCM is on course to reach its operational, sun-synchronous, polar orbit 438 miles (705 kilometers) above Earth within two months.
"Landsat is a centerpiece of NASA's Earth Science program, and today's successful launch will extend the longest continuous data record of Earth's surface as seen from space," NASA Administrator Charles Bolden said. "This data is a key tool for monitoring climate change and has led to the improvement of human and biodiversity health, energy and water management, urban planning, disaster recovery and agriculture monitoring - all resulting in incalculable benefits to the U.S. and world economy."
LDCM will go through a check-out phase for the next three months. Afterward, operational control will be transferred to NASA's mission partner, the Department of the Interior's U.S. Geological Survey (USGS), and the satellite will be renamed Landsat 8. Data will be archived and distributed free over the Internet from the Earth Resources and Science (EROS) center in Sioux Falls, S.D. Distribution of Landsat 8 data from the USGS archive is expected to begin within 100 days of launch.
LDCM is the eighth in the Landsat series of satellites that have been continuously observing Earth's land surfaces since 1972.
"Landsat has been delivering invaluable scientific information about our planet for more than forty years," Interior Secretary Ken Salazar said. "It's an honor to be a part of today's launch to ensure this critical data will continue to help us better understand our natural resources and help people like water managers, farmers, and resource managers make informed decisions."
The use of Landsat data been transformed in recent years by advancements in computing power and the decision by USGS to allow free online access to the information. This revolution has allowed scientists to detect changes over time to our planet and has enabled a host of applications based on Landsat measurements to be developed by researchers, the private sector, and state, local, and tribal governments.
LDCM continues that legacy with more and better observations. The spacecraft carries two instruments, the Operational Land Imager (OLI) and Thermal Infrared Sensor (TIRS). The measurements will be compatible with data from past Landsat satellites, but the LDCM instruments use advanced technology to improve reliability, sensitivity, and data quality.
"LDCM is the best Landsat satellite ever built," said Jim Irons, a LDCM project scientist at NASA's Goddard Space Flight Center in Greenbelt, Md. "The technology will advance and improve the array of scientific investigations and resource management applications supported by Landsat images. I anticipate new knowledge and applications to emerge with an increasing demand for the data."
OLI will continue observations currently made by Landsat 7 in the visible, near infrared, and shortwave infrared portions of the electromagnetic spectrum. It also will take measurements in two new bands, one to observe high-altitude cirrus clouds and another to observe atmospheric aerosols, as well as water quality in lakes and shallow coastal waters. OLI's new design has fewer moving parts than instruments on previous Landsat satellites.
TIRS will collect data on heat emitted from Earth's surface in two thermal bands, as compared with a single thermal band on previous Landsat satellites. These thermal band observations are becoming increasingly vital to monitoring water consumption, especially in the arid western United States.
On Monday afternoon, Bolden will tour Vandenberg's Space Launch Complex 4, which is home to a new Space Exploration Technologies (SpaceX) launch pad. The pad is nearing completion to support SpaceX launches beginning in 2013. NASA's first use will be in 2015 with the launch of the Jason-3 mission, which will precisely measure sea surface height on Earth to monitor ocean circulation and sea level. SpaceX is the newest American company to demonstrate the capability to launch science missions for NASA and other government agencies. Jason-3 will be developed and operated as part of an international effort led by the National Oceanic and Atmospheric Administration. Bolden also will see the Orbital Sciences Pegasus rocket, being readied at Vandenberg, for the launch this April of NASA's Interface Region Imaging Spectrograph (IRIS) heliophysics mission.
Ball Aerospace & Technologies Corp. built the OLI instrument in Boulder, Colo. NASA's Goddard Space Flight Center built the TIRS instrument. Orbital Sciences Corp. built, integrated, and tested the spacecraft in Gilbert, Ariz. USGS provided the LDCM ground system. The launch was managed by NASA's Launch Services Program based at the agency's Kennedy Space Center in Florida. United Launch Alliance provided the Atlas V launch vehicle.
For more information about LDCM, visit:
The LDCM spacecraft separated from the rocket 79 minutes after launch and the first signal was received three minutes later at a ground station in Svalbard, Norway. The solar arrays deployed 86 minutes after launch, and the spacecraft is generating power from them. LDCM is on course to reach its operational, sun-synchronous, polar orbit 438 miles (705 kilometers) above Earth within two months.
"Landsat is a centerpiece of NASA's Earth Science program, and today's successful launch will extend the longest continuous data record of Earth's surface as seen from space," NASA Administrator Charles Bolden said. "This data is a key tool for monitoring climate change and has led to the improvement of human and biodiversity health, energy and water management, urban planning, disaster recovery and agriculture monitoring - all resulting in incalculable benefits to the U.S. and world economy."
LDCM will go through a check-out phase for the next three months. Afterward, operational control will be transferred to NASA's mission partner, the Department of the Interior's U.S. Geological Survey (USGS), and the satellite will be renamed Landsat 8. Data will be archived and distributed free over the Internet from the Earth Resources and Science (EROS) center in Sioux Falls, S.D. Distribution of Landsat 8 data from the USGS archive is expected to begin within 100 days of launch.
LDCM is the eighth in the Landsat series of satellites that have been continuously observing Earth's land surfaces since 1972.
"Landsat has been delivering invaluable scientific information about our planet for more than forty years," Interior Secretary Ken Salazar said. "It's an honor to be a part of today's launch to ensure this critical data will continue to help us better understand our natural resources and help people like water managers, farmers, and resource managers make informed decisions."
The use of Landsat data been transformed in recent years by advancements in computing power and the decision by USGS to allow free online access to the information. This revolution has allowed scientists to detect changes over time to our planet and has enabled a host of applications based on Landsat measurements to be developed by researchers, the private sector, and state, local, and tribal governments.
LDCM continues that legacy with more and better observations. The spacecraft carries two instruments, the Operational Land Imager (OLI) and Thermal Infrared Sensor (TIRS). The measurements will be compatible with data from past Landsat satellites, but the LDCM instruments use advanced technology to improve reliability, sensitivity, and data quality.
"LDCM is the best Landsat satellite ever built," said Jim Irons, a LDCM project scientist at NASA's Goddard Space Flight Center in Greenbelt, Md. "The technology will advance and improve the array of scientific investigations and resource management applications supported by Landsat images. I anticipate new knowledge and applications to emerge with an increasing demand for the data."
OLI will continue observations currently made by Landsat 7 in the visible, near infrared, and shortwave infrared portions of the electromagnetic spectrum. It also will take measurements in two new bands, one to observe high-altitude cirrus clouds and another to observe atmospheric aerosols, as well as water quality in lakes and shallow coastal waters. OLI's new design has fewer moving parts than instruments on previous Landsat satellites.
TIRS will collect data on heat emitted from Earth's surface in two thermal bands, as compared with a single thermal band on previous Landsat satellites. These thermal band observations are becoming increasingly vital to monitoring water consumption, especially in the arid western United States.
On Monday afternoon, Bolden will tour Vandenberg's Space Launch Complex 4, which is home to a new Space Exploration Technologies (SpaceX) launch pad. The pad is nearing completion to support SpaceX launches beginning in 2013. NASA's first use will be in 2015 with the launch of the Jason-3 mission, which will precisely measure sea surface height on Earth to monitor ocean circulation and sea level. SpaceX is the newest American company to demonstrate the capability to launch science missions for NASA and other government agencies. Jason-3 will be developed and operated as part of an international effort led by the National Oceanic and Atmospheric Administration. Bolden also will see the Orbital Sciences Pegasus rocket, being readied at Vandenberg, for the launch this April of NASA's Interface Region Imaging Spectrograph (IRIS) heliophysics mission.
Ball Aerospace & Technologies Corp. built the OLI instrument in Boulder, Colo. NASA's Goddard Space Flight Center built the TIRS instrument. Orbital Sciences Corp. built, integrated, and tested the spacecraft in Gilbert, Ariz. USGS provided the LDCM ground system. The launch was managed by NASA's Launch Services Program based at the agency's Kennedy Space Center in Florida. United Launch Alliance provided the Atlas V launch vehicle.
For more information about LDCM, visit:
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