Artist's concept shows the international Ocean Surface Topography Mission/Jason-2 spacecraft in orbit. (NASA/JPL-Caltech)

NASA - OSTM

22 May 2008

(Partners are NASA, French space agency, European satellite organization)

Washington -- A satellite that will help scientists better monitor and understand rises in global sea level, study ocean circulation and its links to climate and improve weather and climate forecasts will launch June 15 from Vandenberg Air Force Base in California.

The Ocean Surface Topography Mission (OSTM), also called Jason 2, is a joint effort of 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).

The mission will extend into the next decade the continuous recording of sea-surface height measurements begun in 1992 by the NASA-French space agency TOPEX/Poseidon mission and extended by the NASA-French space agency Jason 1 mission in 2001.

"OSTM/Jason 2 will help create the first multidecadal global record for understanding the vital roles of the ocean in climate change," project scientist Lee-Lueng Fu of NASA's Jet Propulsion Laboratory (JPL) in California said during a May 20 briefing.

The satellite will continue monitoring trends in sea-level rise, one of the most important consequences and indicators of global climate change. TOPEX/Poseidon and Jason 1 measurements show that mean sea level has risen by about 3 millimeters a year since 1993, twice the rate estimated from tide gauges in the past century. But 15 years of data are not enough to determine long-term trends.

"Data from the new mission,” Fu added, “will allow us to continue monitoring global sea-level change, a field of study where current predictive models have a large degree of uncertainty.”

DATA WILL ADVANCE UNDERSTANDING OF GLOBAL CLIMATE CHANGE

High-precision ocean altimetry, developed through NASA and the French space agency, measures the height of the sea surface relative to Earth's center to within about 3.3 centimeters. These measurements, called ocean-surface topography, give scientists information about ocean current speed and direction.

Because the amount of heat in the ocean strongly influences sea-surface height, height also can indicate where ocean heat is stored. Combining ocean current and heat storage data is key to understanding global climate variation.

OSTM/Jason 2 will ride to space aboard a NASA-provided United Launch Alliance Delta II rocket, entering orbit 10-15 kilometers below the 1,336-kilometer-high orbit of Jason 1. OSTM/Jason 2 will use thrusters to raise itself into the same orbital altitude as Jason 1 and move in close behind its predecessor. The two spacecraft will fly in formation, making nearly simultaneous measurements.

The tandem mission will double the amount of data collected, improving tide models in coastal and shallow seas and helping researchers better understand ocean currents and eddies. The OSTM/Jason 2 mission is designed to last at least three years.

JPL manages the work for NASA's Science Mission Directorate. After the spacecraft has been checked out on orbit, CNES will hand over operations and control to NOAA. NOAA and EUMETSAT will generate, archive and distribute data products.

More information about OSTM/Jason 2 is available on the NASA Web site.