Antiadhesion elastomer seal coatings for UV and atomic oxygen protection

Abstract

Radiation blocking sunscreen coatings have been developed for the protection of elastomer seals used in low-Earth-orbit (LEO). The coatings protect the seals from ultraviolet (UV) radiation and atomic oxygen (AO) damage. The coatings were developed for use on NASA docking seals. Docking seal damage from the UV and AO present in LEO can constrain mission time-line, flight mode options, and increases risk. A low level of adhesion is also required for docking seals so undocking push-off forces can be low. The coatings presented also mitigate this unwanted adhesion. Greases with low collected volatile condensable materials (CVCM) and low total mass loss (TML) were mixed with slippery and/or UV blocking powders to create the protective coatings. Coatings were applied at rates up to 2 mg/cm 2 . Coated seals were exposed to AO and UV in the NUV (near-UV) and UV-C wavelength ranges (300 to 400 nm and 254 nm, respectively). Ground based ashers were used to simulate the AO of space. The Sun's UV energy was mimicked assuming a nose forward flight mode, resulting in an exposure rate of 2.

Coatings and Thin Films for Spacecraft Thermo‐Optical and Related Functional Applications

“…The latter are commonly used for space applications as they are stable in vacuum and they display low reactivity . For polymer coatings, a blocking compound can be mixed directly into the polymer part before curing …”

“…De Groh et al developed antiadhesion elastomer seal coatings for UV and ATOX protection, comprising grease and UV‐protection additives, for the use on NASA docking seals. These seals will be exposed to the space environment while the spacecraft is not docked.…”