Changes in the Optical Properties of Simulated Shuttle Waste water Deposits: Urine Darkening

摘要

Manned spacecraft have historically dumped the crew-generated wastewater overboard, into the environment in which the spacecraft operates, sometimes depositing the wastewater on the external spacecraft surfaces. The change in optical properties of wastewater deposited on spacecraft external surfaces, from exposure to space environmental effects, is not well understood. Nonvolatile residue (NVR) from human urine is used to simulate wastewater deposits and document the changes in the optical properties of the NVR deposits after exposure to ultraviolet (UV) radiation. There are 20 NVR samples, from 0 to 1000 A/cm~2, and one sample contaminated with 1-2 mg/cm~2, exposed to UV radiation over the course of approximately 6151 equivalent sun hours. Random changes in sample mass, NVR, solar absorbance, and infrared emission were observed during the study. Significant changes in the UV transmittance were observed for the sample contaminated at the milligram per square centimeter level.