Development of High Efficiency Optical Solar Reflectors for Improved Passive Thermal Control

The thermo-optical properties of optical solar reflectors (OSRs) for passive thermal control of spacecraft can be modified by using optical thin films.

Continuing development activity has reduced the solar absorptance to 0.033, enhanced the optical and environmental performance of the rear surface silver coating on standard OSRs and improved the conductivity of edge-coatings. This has resulted in a range of UV reflecting OSRs with improved ∝_s/ε_n ratios and OSRs with enhanced electrostatic discharge resistance. The improvements in the silver coating is expected to result in reduced handling losses during the laying down process. The paper will provide an update on work being carried out and available results from qualification programmes.