Posted: Sat, Jun 28, 2003, 1:40 PM ET (1740 GMT)
A problem with the Landsat 7 remote sensing spacecraft has rendered the spacecraft essentially useless for nearly a month, with no solution to the problem on the immediate horizon. Spacecraft controllers first noticed the problem on May 31, and traced it to the failure of the spacecraft's Scan Line Corrector (SLC), a device that allows the spacecraft's imager to compensate for the motion of the spacecraft. The US Geological Survey has removed all Landsat 7 data collected since May 31 and has limited the spacecraft to housekeeping operations and efforts to correct the problem. As of Friday the SLC remained offline, meaning that most of the data returned by the spacecraft's Enhanced Thematic Mapper plus instrument contains gaps and duplicated data. Engineers have identified over 150 fault scenarios, generally involving electrical and mechanical problems, and are looking into each to find those most likely to explain the SLC problem. Scientists are also developing techniques to interpolate across images to fill in the missing data, but caution that the validity of those techniques have not been fully investigated.

Related Links:

•  Landsat 7 anomaly investigation updates