SPOTÑSatellite pour l'
Observation de la TerreÑis a commercially successful series of French Earth-observation
satellites.
The first, SPOT 1, was launched aboard an Ariane rocket on Feb. 21, 1986. Orbiting 833 km (517 mi) above the Earth, SPOT
satellites utilize charge-coupled devices to achieve photographic resolution down to 10 m (33 ft). At this range individual buildings are clearly distinguishable. The circumpolar orbit of the satellites allows them to pass over every part of the Earth every 26 days. Because the orbit is also "Sun-synchronous," uniform lighting of the images is achieved. The current design lifetime of the satellites is about three years. A more advanced entry, SPOT 5, is planned for the late 1990s (see satellite, artificial).