Wake Shield safely home after latest mission

by James V. Geluso

Daily Cougar Staff

After a flight fraught with problems, the Wake Shield Facility is safe and on the ground.

The space shuttle Endeavour, ending mission STS-69, touched down at 7:37 a.m. Monday at Cape Canaveral, Fla. The Wake Shield Facility is scheduled to be removed from the shuttle on Saturday.

Despite several problems, the flight is considered a success. Four of a possible seven growth runs were made. Each growth run is an attempt to grow one of the ultra-pure semiconductor wafers for which the WSF is designed.

The WSF was deployed 250 miles over western Africa at 6:25 a.m. CDT Sept. 11. The flight plan called for 50 hours of free flight and seven growth runs.

After three successful runs, the orbiter was forced to go into "safe" mode, in which most of the systems are shut down, in order to cool the attitude control system, which was malfunctioning slightly. In order to allow the WSF to complete as much of its mission as possible, its free-flight time was extended by 24 hours.

After 20 hours of cooling, the fourth growth cycle was started but quickly delayed when a problem developed with the source cells that feed arsenic onto the substrate platform where the films are grown.

Once that problem was resolved, a fourth film was produced. An attempt to grow a fifth film was aborted when a low reading was detected on one of the four power cells.

The WSF was intercepted by the shuttle at 8:59 a.m. Friday and berthed in the shuttle at 10:18 a.m. It was lifted out of the cargo bay once more early Saturday for an experiment and flew through the extreme upper reaches of the atmosphere at five miles a second. The results of that experiment will be used to discover how ionized particles around a spacecraft may interfere with communications and operations.

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