LDEF (Flight), S1001 : Low-Temperature Heat Pipe Experiment Package (HEPP) for LDEF, Tray F12 EL-1994-00008 The flight photograph of the Low Temperature Heat Pipe Package (HEPP) experimentwas taken while the LDEF was attached to the Orbiter's RMS arm prior to berthing in the Orbiter's cargo bay. The white paint dots on the center clamp blocks of the experiment trays left flange and lower flange appear to be slightly discolored. The Low Temperature Heat Pipe Package (HEPP) experiment occupies two 12 inch deep LDEF experiment trays connected with an inter-tray wiring harness. The HEPP Experiment tray, a peripheral tray modified to accommodate radiator location and field of view requirements, is located in the LDEF tray location F12. The HEPP Power tray, an end corner tray, is located on the space end of the LDEF in tray location H01. The experiment tray (F12) contains a Constant ConductanceHeat Pipe, a Thermal Diode Low Temperature Heat Pipe, a radiator coupled with a phase change material canister, the data acquisition and control systems and the LDEF experiment power and data system (EPDS) for processing, recording and storing experiment data. The HEPP EPDS is also used to record and store thermal data from the CVCHPE (AO076) and the THERM (P0003) experiments. Fiberglass standoffs and internal multilayer insulation (MLI) blankets ther- mally isolated the experiment from the experiment tray and the LDEF interior. The radiator and radiator shield panels located in the left half of the tray were covered with silvered TEFLONﾮ tape to provide the desired optical properties. The outside of the HEPP, except the radiator shield panels and the radiator, was covered with an aluminized Kapton multilayer insulation (MLI) blanket with the outer Kapton layer coated with vapor deposited aluminum on one side only. The two patches of thin film materials, part of an atomic oxygen experiment by NASA GSFC that consist of five patches of thirteen samples each and located at three different places on the LDEF (F09, F12 and H01), were attached to the cover of the external thermal blanket with Kapton tape. The experiment was assembled and mounted in the experiment tray with non-magnetic stainless steel fasteners. The radiator and the radiator shields appear deep blue apparently due to the lighting and the reflecting surface. The upper and lower radiator side shields appear to be discolored by a brown stain that can be seen through the deep blue color. The TEFLONﾮ tape used to provide continuity between the side shield and end shield surfaces appears to be loose and only secured at the outer edges. The tape and the areas initially covered by the tape appear discolored. The external thermal control blanket appears to be in good condition, however, the lower patch of atomic oxygen experiment materials has many severely degraded samples. Several of the materials have sections eroded away and remain attached at only one end, others appear to be completely gone. The materials in the upper patch appear to have a better survival rate but are wrinkled and have distorted shapes.
