Loss of Landsat 6 handicaps research.
The Oct. 5 lunch from Vandenberg Air Force Base in California appeared to go smoothly at first, according to Michael Mignogno of the National Oceanic and Atmospheric Administration in Suitland, Md., which oversaw development of the satellite. Landsat 6 flew on a Titan 2 rocket -- a converted ICBM missile -- that carried the spacecraft altitude of 180 nautical miles before releasing it. What happened after that remains unknown.
The launch plan called for a built-in motor to propel the satellite to its final orbit at 438 nautical miles. However, Landsat 6 failed to communicate with ground stations and could not be located thereafter.
Landsat 6's primary sensor was designed to record images of Earth in seven discrete wavelength bands ranging from visible light to infrared radiation. The loss of Landsat 6 will hit hardest those who need up-to-date images, such as scientists assessing the pace of tropical deforestation or officials mapping and changes after hurricanes.
Landsat 5, launched in 1984 with an expected 3-year lifetime, continues to provide images but has lost part of its ability to transmit data. As a result, the satellite can only send information to Earth when it passes over one of the 17 existing ground stations, limiting the number of regions it can photograph, according to Carla Adam of EOSAT in Lanham, Md., the company that operates the Landsat satellites and distributes images. EOSAT could revive the recently shut down Landsat 4, launched in 1982, but it also suffers communication problems.
With Landsat 4 and 5 operating on borrowed time, it remains unclear whether they can last until Landsat 7 is ready for its planned launched in 1998. The French SPOT satellites also provide images of Earth, but these satellites collect information in only four spectral bands, making them less useful for distinguishing types of forest and rock. The higher-resolution SPOT images also cover a smaller swath of land, which drives up the cost of mapping broad regions.
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|Title Annotation:||researchers must depend on Lansat 4 and Landsat 5 satellites|
|Article Type:||Brief Article|
|Date:||Oct 23, 1993|
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