LDEF (Postflight), S0014 : Advanced Photovoltaic Experiment, Tray E09

LDEF (Postflight), S0014 : Advanced Photovoltaic Experiment, Tray E09 The postflight photograph was taken in the SAEF II at KSC after the experiment was removed from the LDEF. The Advanced Photovoltiac Experiment (APEX) is an active experiment completely self contained in a 12 inch deep LDEF peripheral tray. The APEX includes 155 solar cells permanently mounted on 127 removable aluminum plates of 12 different sizes, an Eppley Type HF cavity radiometer, a Digital Solar Angle Sensor, a dichroic mirror assembly, a night or dark sensor, a row of 16 bandpass filters clamped over silicon solar cell sensors, two ultraviolet exposure monitors and two solar concentrator cells with deposited aluminum (on Kapton and Mylar foil) mirrors. An aluminum sub-structure provides a mounting surface for experiment components and controls the field of view of solar cells. Two separate electronic systems and power sources were included, one for the experiment and data acquisition and one, the Experiment Power and Data System (EPDS), for data processing and storage. The experiment structure was painted with Chemglaze Z-306 flat black paint over a Chemglaze 9924 wash primer and assembled with non-magnetic stainless steel fasteners. The tray flanges and tray clamp blocks appear as prelaunch but white paint dots on tray clamp blocks have a slight variation in color. The paint color on the upper-left clamp block is white, but paint on the right-center and lower-center clamp blocks is lightly discolored. The APEX has a number of physical changes that were observed in the flight photograph. The extent of degradation to the Chemglaze Z-306 black paint on exposed surfaces is clearer as evidenced by the amount of Chemglaze 9924 primer , a redish-brown color, visible. The difference in the amount of paint remaining may be a function of initial paint thickness, as the plate covering the tray's center section was painted at a different time than the other two plates. The small gold colored rectangular plate in the lower-right section of the tray, was fabricated from an aluminum alloy and coated with a clear anodize. A light brown discoloration can be seen on the solar cell mounting plates and on areas of the aluminum base structure. A solar concentrator cell, located at the lower end of the second slot from the right, appears to be damaged. The large piece of gold colored material lodged in the slot appears to be a segment of the aluminum deposited on Kapton mirror. Structural members of the experiment appear to be intact.

NASA Identifier: L91-10676 KSC-390C-1840.10