Optical engineer, Brendan McAndrew, installs radiometers inside the Ocean Color Instrument (OCI) thermal vacuum chamber in preparation for window calibration testing. The testing will help scientists and engineers know if the optical components of OCI are aligned correctly before it gets integrated to the PACE (Plankton, Aerosol, Cloud, ocean Ecosystem) spacecraft. OCI is a highly advanced optical spectrometer that will be used to measure properties of light over portions of the electromagnetic spectrum. It will enable continuous measurement of light at finer wavelength resolution than previous NASA satellite sensors, extending key system ocean color data records for climate studies. OCI is PACE's (Plankton, Aerosol, Cloud, ocean Ecosystem) primary sensor built at Goddard Space Flight Center in Greenbelt, MD.