Montage of our solar system

The crew of the space shuttle Discovery was unable to deploy the Wake Shield Facility into free-flying orbit this week, but an experiment on the facility sponsored by the U.S. Ballistic Missile Defense Organization and NASA's Jet Propulsion Laboratory was successfully completed, it was announced.

The primary experiment of the Wake Shield Facility (WSF) was to grow a thin film of compounds such as gallium arsenide in low Earth orbit through a process called molecular beam epitaxy. The large, disk-shaped WFS was expected to generate what scientists called an "ultra-vacuum" in its wake to create conditions for the film growth process.

The BMDO- and JPL-sponsored experiment, called Materials Laboratory-1 (MatLab-1), was on the leading, or ram, surface of the WSF facing the direction the shuttle was orbiting.

MatLab-1, developed and integrated by Case Western Reserve University in Cleveland, Ohio, was to evaluate effects caused by atomic oxygen bombardment in low-Earth orbit. It was the third in a series of small, fast, low-cost flight experiments funded by the BMDO Materials and Structure Program Office. It was implemented by the BMDO Space Environment and Effects program managed by Dr. Ranty Liang at JPL.

An attitude control system problem prevented the WSF being deployed into an orbit 75 kilometers (40 nautical miles) behind the shuttle. WSF, however, remained attached to the shuttle's remote manipulator arm, allowing the MatLab-1 experiment to receive the exposure to space and the experiment to be completed.

Most of the 29 materials onboard MatLab-1 were candidates provided by BMDO contractors. Among them were atomic oxygen protective coatings and advanced composites. Several active atomic oxygen sensors, called actinometers, were calibrated and qualified for subsequent BMDO flight experiments on the Space Test Experiments Platform (STEP-3) mission to be launched later this year, said James Kenny of JPL, deputy program manager.

He said that approximately 60 hours of data, some received in real time, were gathered and will be analyzed over the next few weeks by the principal investigator, Dr. David Brinza of JPL. The results will help determine which materials to use in the space environment -- for instance, rockets, satellites, and the Space Station -- based on weight and durability.

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