Thec. ry has been developed for predicting the loss of response of a QeM to a liquid deposit due to viscous effects in the deposit. The lO~5 of response is expressed by a response factor, equal to the response of the OeM to a liquid film divided by its re::;ponsp. to a solid film of the same mass per unit area. The theory assumes a droplet-type deposit morphology. and considers the influence oC droplet distribution parameters. Experiments have heen conducted to examine the validity of the theory, using DC 704 silicone oil. as the subject deposit material. Experiments were made in two series -one with constant deposit mass and variable temperature. the other with variable deposit mass and constant temperature. Satisfactory agreement with the theory was found. Interpretation of the data using the theory has enabled information on droplet area coverage and number density to be deduced.
The predominant species in the plume residue resulting from the incomplete combustion of MMH and N 2 O 4 during the pulse mode operation of the bipropellant motors has been found to be monomethylhydrazine nitrate (MMH-HNO 3 ). At orbital altitude, it is also the most detrimental condensible matter as other species in the plume product or unburned propellant droplets have vapor pressures too high to be of concern. Quantitative data on contamination effects from the MMH/N 2 O 4 thrusters in pulse mode operations are limited. This paper reports experiments in which several types of thermal control surfaces were systematically contaminated with a range of amounts of synthesized MMH-HNO 3 , after which the resulting change in solar absorptance was measured. Limited experiments were also made to measure the change of solar transmittance of fused silica disks.
The ambient temperature outgassing rate of several multilayer insulation materials has been measured for evacuation times of about six days. The material tested included Mylar radiation shields, double and single metallized with aluminum and gold; double and single aluminized Kapton radiation shields of different thicknesses; and three net and two glass fiber-cloth spacer materials. Experimental measurements were made by collecting outgassing flux from an effusion cell-type sample holder on a liquid-nitrogen-cooled quartz crystal microbalance. The absolute accuracy, measurement range, degree of resolution, and other features of this technique are discussed in detail. The physical phenomena controlling outgassing rate are discussed. It is concluded that long-term outgassing of the metallized shields is probably controlled by degassing of the metallized surfaces. On this assumption empirical equations are proposed for estimating long-term outgassing rates. Data from previous measurement programs are evaluated and compared with the new data as a standard.
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