Mechanical technicians install the Flight Ocean Color Instrument (OCI) and Tilt Platform Assembly to the Plankton, Aerosol, Cloud, ocean Ecosystem (PACE) spacecraft. By installing the instrument, the spacecraft is now considered an observatory. 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 primary sensor built at Goddard Space Flight Center in Greenbelt, MD.