A scatterometer is an instrument that measures near-surface ocean winds by sending a constant stream of radar pulses toward Earth from an orbiting satellite. When the radar pulse reflects back off the ocean surface, some of its energy is scattered by small, wind-driven waves rippling across the sea. By measuring these changes in the reflected radar signals, engineers can deduce the speed and direction of the winds that caused the ocean waves.
The NASA Scatterometer (NSCAT) instrument was designed and built by JPL and flown on Japan's Midori satellite (previously known as the Advanced Earth Observation Satellite (ADEOS)), the largest satellite ever developed by that country. Following launch from Japan's Tanegashima Space Center on August 17, 1996 (the evening of August 16 in U.S. Pacific Daylight Time or Eastern Daylight Time), the satellite circled Earth in an orbit that took it close to the planet's north and south poles. NSCAT yielded 268,000 measurements of ocean winds each day, covering more than 90 percent of Earth's ice-free seas.
Nine months after launch, the Midori satellite lost power, ending its and NSCAT's mission. NASA approved a rapid replacement mission called the Quick Scatterometer to take the place of NSCAT.
Mass: 280 kilograms (617 pounds)
Purpose: Radar instrument to monitor near-surface ocean winds
Launch: August 17, 1996
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