Built in record time in just 12 months, the ocean-observing satellite was launched June 19, 1999, on a Titan II rocket from California's Vandenberg Air Force Base. It circles Earth at an altitude of 800 kilometers (500 miles) once every 101 minutes, passing close to Earth's north and south poles. The scatterometer instrument it carries is known as Seawinds.
Scatterometers operate by sending radar pulses to the ocean surface and measuring the "backscattered" or echoed radar pulses bounced back to the satellite. The instrument senses ripples caused by winds near the ocean's surface, from which scientists can compute the winds' speed and direction. The instruments can acquire hundreds of times more observations of surface wind velocity each day than can ships and buoys.
The mission is managed by JPL, which also built the Seawinds radar instrument. NASA's Goddard Space Flight Center managed development of the satellite, designed and built by Ball Aerospace & Technologies Corp.
Mass: 970 kilograms (2,140 pounds) total, consisting of 870-kilogram (1,914-pound) satellite (including radar instrument) and 76 kilograms (167 pounds) of thruster propellant
Science instruments: Scatterometer
Launch: June 19, 1999