Space

July 8, 2013

Long-running NASA/CNES ocean satellite takes final bow

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 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.

 




All of this week's top headlines to your email every Friday.


 
 

 
LM-MUOS

U.S. Navy, Lockheed Martin ready to launch MUOS-4 Aug. 31

The U.S. Navy and Lockheed Martin are ready to launch the fourth Mobile User Objective System secure communications satellite, MUOS-4, from Cape Canaveral Air Force Station, Fla., Aug. 31 aboard a United Launch Alliance Atlas V...
 
 

NASA seeks proposals for extreme environment solar arrays

NASA’s space technology program is seeking proposals to develop solar array systems for space power in high radiation and low solar energy environments. In the near future, NASA will need solar cells and arrays for multiple applications in robotic and human space exploration missions. Because these systems were traditionally developed for operation near Earth, there...
 
 

NASA awards contract for construction of new mission launch command center

NASA has awarded a contract to Harkins Contracting Inc. of Salisbury, Maryland, for the construction of a new Mission Launch Command Center at the agency’s Wallops Flight Facility in Wallops Island, Va. The new 14,174 square-foot facility will serve as the hub for interfacing with and controlling rockets, their payloads and associated launch pad support...
 

 
NASA photograph

NASA concludes series of engine tests for next-gen rocket

NASA photograph The RS-25 engine fires up for a 535-second test Aug. 27, 2015 at NASA’s Stennis Space Center near Bay St. Louis, Miss. This is the final in a series of seven tests for the development engine, which will pr...
 
 
LM-satellite

Lockheed Martin makes tiny satellite cooling system

Lockheed Martin scientists are packing three times the power density into a key satellite cooling system whose previous design is already the lightest in its class. This project continues the company’s effort to reduce co...
 
 
Northrop Grumman photograph by Bob Brown

Northrop Grumman delivers telescope structure for James Webb Space Telescope

Northrop Grumman photograph by Bob Brown Northrop Grumman employees preparing the telescope structure, for NASA’s James Webb Space Telescope for shipment to Goddard Space Flight Center in Greenbelt, Md. REDONDO BEACH, Cal...
 




0 Comments


Be the first to comment!


Leave a Reply

Your email address will not be published. Required fields are marked *

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <s> <strike> <strong>