Using some of the same technology aboard spacecraft studying other planets, the experimental Seasat satellite launches to flight-test four instruments that use radar to study Earth and the seas. Its radar instruments measure the satellite's distance from the sea surface, measure near-surface ocean winds and take pictures using radar rather than light for illumination.

The mission lasts only 100 days but the satellite collects more ocean topography data than the previous 100 years of shipboard research. Many later Earth-orbiting instruments developed at JPL owe their legacy to this pioneering mission.

See also: Seasat