From: NASA-JPL
Published June 30, 2017 05:00 PM

Veteran Ocean Satellite to Assume Added Role

A venerable U.S./European oceanography satellite mission with NASA participation that has expanded our knowledge of global sea level change, ocean currents and climate phenomena like El Niño and La Niña will take on an additional role next month: improving maps of Earth's sea floor.

The Ocean Surface Topography Mission (OSTM)/Jason-2 satellite, a partnership among NASA, the National Oceanic and Atmospheric Administration (NOAA), the French Space Agency Centre National d'Etudes Spatiales (CNES) and the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT), marked its ninth year in orbit on June 20. Designed to fly three to five years, OSTM/Jason-2 has now completed more than 42,000 trips around our planet, contributing to a database of satellite altimetry that dates back to the launch of the U.S./French Topex/Poseidon satellite in 1992.

Over the past nine years, OSTM/Jason-2 has precisely measured the height of 95 percent of the world's ice-free ocean every 10 days. Since its launch in June 2008, it has measured a 1.6-inch (4-centimeter) increase in global mean sea level, which has been rising at a rate of about 0.12 inches (3 millimeters) a year since satellite altimetry records began in 1993. It has also tracked changes in regional sea level; monitored the speed and direction of ocean surface currents; enabled more accurate weather, ocean and climate forecasts; and observed multiple El Niño and La Niña events. Since October 2016, it has operated in a tandem mission with its successor, Jason-3, launched in January 2016, doubling coverage of the global ocean and improving data resolution for both missions.

But as OSTM/Jason-2's onboard systems age and key components begin to show signs of cumulative space radiation damage, it has become prudent to move the older satellite out of its current shared orbit with Jason-3. On June 20, Jason-2's four mission partner agencies agreed to lower Jason-2's orbit by 17 miles (27 kilometers) in early July, from 830 to 813 miles (1,336 to 1,309 kilometers), placing it in a new orbit with a long repeat period of just more than one year. The move is designed to safeguard the orbit for Jason-3 and its planned successor, Jason-CS/Sentinel-6, planned for launch in 2020.

Continue reading at NASA-JPL

Illustration: Illustration of the U.S./European Ocean Surface Topography Mission (OSTM)/Jason-2 satellite in orbit. OSTM/Jason-2 will soon take on an additional role to help improve maps of Earth's sea floor. Credit: NASA-JPL/Caltech

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