French Advances in Science & Technology: Issue #336 "A SPOT in the Sky"

Status Report From: French Advances in Science and Technology
Posted: Saturday, May 18, 2002

The earth is increasingly ringed with spots as the CNES's (National Space Agency) latest earth photographing satellite, SPOT 5, was successfully launched last week and placed in sun-synchronous orbit along with the three of its predecessors still active (Spot 3 ceased activity in 1996 after three years of service). But instead of seeing spots, earthlings will be seen by them, as Number Five is the latest step in the ESA's commitment to keeping the planet under observation.

Although the equipment on board Spot 5 permits greatly increased performance and resolution--it's High Resolution Stereoscopic (HRS) camera will permit 3D images of a swathe of the globe's surface 80x100 miles with a resolution of 2.5 meters in black-and-white and 10m in color-signals from predecessor Spots (particularly 2 and 4) will continue to be treated by Spot project tracking systems. Even at lower resolutions, the Spot network taken all together can now provide photographic coverage of any place on the earth within 24 hours instead of having to wait typically several weeks before an observation satellite covers the same ground twice.

Spot 5 plays a large part in this new and useful capacity (e.g. tracking the development of floods or volcanic eruptions) because of its wide peripheral vision; although only repeating its orbit every 26 days, it will be able to photograph any point on earth every 4 or 5 days. While Spot 5's resolution is still not as sharp as the best US effort, the satellite Ikonos, the sterescopic capacity of recording topographical information as well as information from the other three instruments on board ensure a leading role to the Spot project in the competitive market for satellite photographs, such as its specialized eye trained to analyze vegetation coverage. Also, geographic institutes around the world, most of whom find Ikonos images too expensive, may well be able to use Spot's topographical views which cover 100 times more area. (China has already signed with Spot Images to help it produce for the first time cartographic coverage of its entire territory at a scale of 1/50,000.)

The next step for the CNES will be its Pleiades series of radar-equipped satellites able to see through clouds. Meanwhile early transmissions from Spot 5 are up to expectations, as the first image beamed back last week was a view of the city of Athens. (Le Figaro, May 3, p12, Fabrice Nodé-Langlois; France in Space #'s 205,6)

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