Optical material problems of interplanetary space.

The successful flights of Mariners II and IV demonstrated that optical systems can survive and operate after months of exposure to interplanetary space. Special considerations must be taken in designing for deep space. The phenomena of sublimation and deterioration of solid materials in deep-space vacuum influence the selection of all materials used in the optical system including metals and organic compounds. Three basically different approaches of thermal design are available to the designer. Each method is capable of maintaining focus throughout large temperature excursions. Micrometeoroid and radiation damage are not major problems. The material selection for and thermal design of the Mariner IV television camera optical system is described.