Artist's concept of Topex/Poseidon. Photo: NASA/JSC

Like "The Little Engine That Could," Topex/Poseidon just keeps chugging along in orbit taking the pulse of our oceans. August 10 marked the 9th anniversary of the launch of this remarkable satellite, which has revolutionized our understanding of the oceans. Circling Earth every 112 minutes, the satellite has run it's familiar course over 42,000 times in the 9 years it's been flying.

This joint U.S./French satellite mission continues to provide ocean scientists with a unique, revolutionary view of our ocean waters that are so vital to all life. Covering more than 70 percent of Earth's surface, stirred and mixed by mighty currents, the oceans distribute heat across the globe and regulate our climate.

The mission helped track 1997's El Nino, marked by the red swath.Launched on August 10, 1992, the U.S and France celebrated the International Space Year with the launch of Topex/Poseidon, the most advanced space mission ever designed to study ocean currents. For nine years the mission, a joint effort by NASA and the French space agency Centre National d'Etudes Spatiales (CNES), has been providing essential data for quantitative studies of ocean circulation that are crucial to an understanding of climate change.

Topex/Poseidon has proven so successful that a follow-on mission, Jason-1, is being readied for launch to extend sea- surface height measurements into the next decade.

Topex/Poseidon uses a radar altimeter to measure sea-surface topography over 90 percent of the Earth's ice-free oceans. Among the invaluable achievements of the mission are:

• Continuous global coverage of the ocean surface topography, which has led to a fundamental new understanding of the dynamics of ocean circulation that affects climate change.
  
  
• Providing an effective way to monitor changes such as El Nino and La Nina.
  
  
• A dramatic improvement of the determination of deep ocean tides and their effects on ocean general circulation.
  
  
• The capability to monitor the changes of the global mean sea level, an effective indicator of the consequence of global temperature change. In the 9 years of mission life we have been able to establish the rate of change that used to take 30 years of sparse tide gauge observations.

The American/French team has worked diligently to maximize satellite performance and data return throughout the mission. Their efforts have contributed directly to the outstanding results and success obtained thus far, and continue to be reflected in the excellent prospects for future satellite longevity.

Topex/Poseidon has become the longest running earth-orbiting radar mission. It continues returning first-rate data for applications on a wide range of topics, including ocean circulation, sea level rise, oceanic nutrient production, offshore operations and ship routing, and more. Continuous global coverage of ocean topography has now been taken for granted as a way of life by young oceanographers. The behind-the-scene effort and creativity of the dedicated project staff deserves an all-around applause for their far-reaching impact.

Dr. Bill Patzert, JPL oceanographer, said, "I'm amazed by the durability of the spacecraft. Let's give all the women and men, both American and French, that built and operated this amazing space robot a big hand. Scientists from all over the world cherish these data; our view of the oceans role in climate change has been revolutionized!"