Control of molecular contamination and outgassing of the SOFIE instrument

The Solar Occultation for Ice Experiment (SOFIE) instrument is one of three science instruments for the Aeronomy of Ice in the Mesosphere (AIM) mission. SOFIE is used to measure solar attenuation by mesospheric ice aerosols during each observatory sunrise and sunset using an 8-channel (16-detector) differential absorption radiometer. It directly views the sun and compares the near UV to the mid-IR spectral response during exo-atmospheric and endo-atmospheric measurements. Deposition of molecular films can degrade the reflectance and transmittance of SOFIE's optics. During on-orbit performance, it may be possible for the extended solar exposure to promote photochemical deposition and darkening effects in the UV. This paper will review the methods used to derive and verify contamination control budgets for particulate and molecular contamination during the fabrication and testing of the SOFIE instrument. Reported results include the molecular surface cleanliness throughout integration and test as well as outgassing measurements using internal and external quartz crystal microbalances. This information provides important baseline data for future correlation of instrument outgassing and potential photo-deposited contamination effects should they occur during on-orbit solar exposure.