Contamination Control Assessment of the World's Largest Space Environmental Simulation Chamber

Abstract The Space Power Facility’s thermal vacuum test chamber is the largest chamber in the world capable of providing an environment for space simulation. To improve performance and meet stringent requirements of a wide customer base, significant modifications were made to the vacuum chamber. These include major changes to the vacuum system and numerous enhancements to the chamber’s unique polar crane, with a goal of providing high cleanliness levels. The significance of these changes and modifications are discussed in this paper. In addition, the composition and arrangement of the pumping system and its impact on molecular back-streaming are discussed in detail. Molecular contamination measurements obtained with a TQCM and witness wafers during two recent integrated system tests of the chamber are presented and discussed. Finally, a concluding remarks section is presented. Introduction This paper presents aspects of contamination control in the Space Power Facility (SPF) thermal vacuum test chamber. This test chamber is the largest chamber in the world capable of providing an environment for space simulation. SPF is located at the NASA Glenn Research Center’s Plum Brook Station near Sandusky, Ohio. The thermal vacuum chamber has a rich heritage, in large part by being able to accommodate a wide range of testing environments, ranging from ambient pressures and temperatures of launch, through ascent, to the extreme low pressures and widely fluctuating temperatures occurring in space. The facility was designed and constructed to test both nuclear and non-nuclear space hardware in a simulated low-Earth-orbit environment. Although the facility was designed for testing nuclear hardware, only non-nuclear tests have been performed throughout its history. Some of the test programs that have been performed at the facility include high-energy experiments, rocket- fairing separation tests, Mars Lander system tests, deployable Solar Sail tests and International Space Station hardware tests. The large chamber size accommodates both small and bulky test article configurations. With the additions of two new testing facilities within SPF, adding world- class vibration and acoustic capability, the thermal vacuum chamber is the cornerstone of a comprehensive facility for conducting a variety of ground- based tests. The SPF Facility layout, shown in Figure 1, is ideal for performing multiple test programs. The facility has two large high bay areas adjacent to either side of the vacuum chamber. The advantage of having both areas available is that it accommodates the undertaking of two complex test programs. For example, one test can be prepared in a high bay while another test is being conducted in the vacuum test chamber. Large chamber doors provide access to the test chamber from either high bay. The test chamber is enclosed inside a larger concrete vacuum chamber.