Overview of the ISS space product development experiment module

The Space Product Division Experiment Module (SPDEM) is a multi-sample furnace for processing materials in moderate temperature range below 1000° C in space. The furnace has flown on STS-52, STS-60, and STS-77 as the Crystals by Vapor Transport Experiment (CVTE) and Science Experiment Furnace (SEF). The SPDEM will be carried to the International Space Station (ISS) on Mission UF3 in September, 2004 as one of experiments in the First Materials Science Research Rack (MSRR-I). Modifications to the furnaces have been made to also perform additional experiments such as preform processing of ZBLAN glass. The SPDEM experiments will consist of four mercurous chloride vapor transport samples processed in a Transparent Furnace The vapor transport experiments will produce two mercurous chloride single crystals in two separate transparent furnaces during each experiment. Vapor transport of mercurous chloride is achieved at 340° C. The microgravity environment will provide a convection free environment for the production of single crystal Hg²C²I crystals to be used as acousto-optical devices for IR spectrometers. The Transparent Furnace allows visual observations of the crystal growth process using a gold coated heat reflecting quartz and viewing cameras to transmit captured images to the ground station. The third furnace will process up to sixteen ZBLAN preforms in a furnace in which the quartz shields are replaced by niobium heat reflectors in order to accommodate the safety requirement that no shatterable materials arc allowed in the ISS when change-out of samples is needed. The ZBLAN preforms will be processed in a platinum liner that is encased in stainless steel cartridges lined with electroless nickel. Each cartridge will be heated to 800° C, held for 15 minutes and quenched at 10° C per minute. The SPDEM facility is scheduled to be on-orbit approximately nine months, depending primarily on the number and types of experiments that it can accommodate. If more commercial materials development or scientific experiments are proposed, it may stay on ISS for a longer period of time.