Hubble Space Telescope Protective Cover System

Abstract

The Hubble Space Telescope (HST) will be the first permanent National Astronomical Observatory in space 310 miles above the earth. To meet the scientific objectives of its mission the Ritchey-Chretien optical system must meet stringent contamination control criteria to prevent obscuration and scattering losses. The HST was assembled, tested and prepared in the 10K laminar flow clean room to meet these contamination control concerns. Once testing and preparations for shipment are complete the HST will be ready for its momentous 5,000 mile trip from Lockheed Missiles and Space Co., California to the Kennedy Space Center for launch. Measuring 43 feet in length and 14 feet in diameter, the HST will weigh in at 25,000 pounds (see Figure 1). Due to the size of the HST it cannot be transported by air but must be shipped by sea to the launch site. During this trip the HST will be in six different containers/locations for a minimum of six months. Environments vary from the Vehicle Assembly and Test Area clean room at Lockheed ( a horizontal laminar flow Class 10K clean room) to the Vertical Processing Facility (a nonlaminar flow 100K clean work area), see Figure 2. The HST contamination control budget for degradation of the primary and secondary optics only permits 0.1% for reflectance loss at 1216 angstroms and 0.1% due to particulate obscuration due to transportation and launch activities. The key to protecting the HST optics is the protective cover system and the internal gas purge.