Shortly after the Earth observations with the VIIRS instrument launched onboard the Suomi NPP spacecraft have begun, it was observed that responsivity of some of the instrument’s spectral bands decreases with time faster than expected. It was determined that the VIIRS telescope mirror contamination with tungsten oxide is the root cause of the degradation, and that the rate of the degradation is controlled by exposure of the mirrors to ultraviolet radiation. We have monitored progress of the degradation using measurements of light reflected from the onboard calibrator’s solar diffuser and taking into account seasonal changes of the solar illumination of the diffuser. The measurements were then used to develop an empirical model of the degradation dynamics and predict future rate of the responsivity changes during the seven-year lifetime of the Suomi NPP mission.

Date Published: 21 May 2013
PDF: 7 pages
Proc. SPIE 8739, Sensors and Systems for Space Applications VI, 87390D (21 May 2013); doi: 10.1117/12.2016008

Published in SPIE Proceedings Vol. 8739:
Sensors and Systems for Space Applications VI
Khanh D. Pham; Joseph L. Cox; Richard T. Howard; Genshe Chen, Editor(s)