Otto Berg's flight spare of a cosmic dust detector experiment built for the Interplanetary Monitoring Platforms (IMP-D and IMP-E) carried on Explorer 33 and Explorer 35. The unit measures 8″ x 10″ x 6.5″ and features a sensor system in four different axes, with electrical ports on one side of the housing. The device is labeled: "Marshall Laboratories, Torrance, California, Model ML195-1, 6A18-1-J1, Serial No. 3, Part No. 50711-101, Weight 1279 GMS." In fine condition.
Explorer 33, launched on July 1, 1966, and Explorer 35, launched on July 19, 1967, were similar in design, and both intended to study the environment around Earth at lunar distances, aiding the Apollo program. They were outfitted with instruments for studies of interplanetary plasma, energetic charged particles (electrons, protons, and alphas), cosmic dust, magnetic fields, and solar X-rays.
From the collection of Dr. Otto Berg.