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.