During past years, there have been a substantial number of Contamination Control Plans (CCPs), which have been developed for a wide variety of space missions. These plans contain useful and generally applicable information for many current and future instrument and spacecraft missions. Often, the information contained within these CCPs is essentially lost after the mission and contamination control engineers are left to develop entirely new CCPs for each new spacecraft or instrument project. A new CCP database system, sponsored by NASA Goddard Space Flight Center (GSFC) and Swales Aerospace, is under development and is designed to encapsulate and categorize past Contamination Control Plans, in an extensive, methodically-searchable, database tool. Users will be able to compare and contrast various past CCPs, extract pertinent information, then apply this data to any new mission or project. This tool is not only useful as a baseline database for quicker development of new CCPs, but can also be used as a teaching tool for new contamination control engineers.
The Hubble Space Telescope (HST) has been designed to accommodate changeout and/or repair of many of the primary instruments and subsystem components, in an effort to prolong the useful life of this orbiting observatory. In order to achieve the science goals established for this observatory, many HST instruments must operate in regimes that are greatly influenced by the presence of on-orbit propagated contaminants. To insure that the required performance of each instrument is not compromised due to these contaminant effects, great efforts have been made to minimize the level of on-orbit contamination. These efforts include careful material selection, performing extensive pre-flight vacuum bakeouts of parts and assemblies, assuring instrument assembly is carried out in strict cleanroom environments, performing precision cleaning of various parts, and most recently, the incorporation of a relatively new technology -- molecular adsorbers -- into the basic design of future replacement instruments. Molecular adsorbers were included as part of the wide field/planetary camera 2 (WFPC-2) instrument, which was integrated into the HST during the servicing mission 1 (SM1) in 1993. It is generally recognized that these adsorbers aided in the reductio of on-orbit contamination levels for the WFPC-2 instrument. This technology is now being implemented as part of the basic design for several new instruments being readied for the servicing mission 2 (SM2), scheduled for early 1997. An overview of the concept, design, applications, and to-date testing and predicted benefits associated with the molecular adsorbers within these new HST instruments are presented and discussed in this paper.
The Cosmic Background Explorer (COBE) was recently launched and is now acquiring spectacular science data on the cosmic structure of the universe. The instruments developed to obtain this science data are extremely sensitive to contamination. The task of the project scientists and the contamination engineers was to develop specific contamination requirements which were linked to the mission science objectives. A description of the mission the instruments the science goals the derivation of the subsequent contamination requirements an overview of the contamination control program and a brief summary of contamination program results will be presented. The COBE Project was initiated to answer basic questions concerning the formation of the universe: What was the primeval explosion that started the expanding universe? What made it uniform on such a gigantic scale? What started the formation of galaxies? What caused them to be arranged in giant clusters of galaxies? Is there a center or an edge of the universe?'' The answers to many of these ambitious questions are now being obtained by the scientific instruments on board COBE: the Diffuse Infrared Background Experiment (DIRBE) the Far Infrared Absolute Spectrophotometer (FIRAS) and the Differential Microwave Radiometers (DMRs). The DIRBE is a cryogenically cooled instrument with a primary mirror highly sensitive to particulate scattering. The FIRAS is a cryogenically cooled spectrophotometer with a sky horn also intolerant of particulate scattering. The DMRs are radiometers that have antennae with narrow throats which can become obscured due to the presence of particles. The cryogenic cooling of the DIRBE and FIRAS led to the need for relatively strict molecular requirements and the scattering and obscuration issues led to the need for extremely rigid particulate requirements. Analytical studies and testing results were used to quantify cleanliness levels that would allow for the achievement of the mission objectives. 1. THE MISSION The COBE shown in Figure 1 is a 19 foot long 13 foot diameter spacecraft weighing 5000 pounds. The spacecraft was launched in November 1989 into a near polar circular orbit 559miles above the Earth''s surface. To achieve this orbit COBE was launched on a Delta rocket from the Vandenburg Air Force Base. The COBE''s spin axis was oriented 94 away from the sun and was directed outward from Earth. To shield the instruments from the earth sun and moon''s light COBE carried a sunshade. Each instrument in the three instrument complement works in unison as will be briefly described in the following sections. 16 / SPIE Vol. 1329 Optical System Contamination: Effects Measurement Control 11(1990)
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