The Plankton, Aerosol, Cloud, ocean Ecosystem (PACE) spacecraft bus with mass mockups installed is lifted before structural proof testing at NASA's Goddard Space Flight Center in Greenbelt, Maryland on May 26th, 2021. PACE's unprecedented spectral coverage will provide the first-ever global measurements designed to identify phytoplankton community composition. The mission will make global ocean color measurements, using the Ocean Color Instrument (OCI), to provide extended data records on ocean ecology and global biogeochemistry along with polarimetry measurements, using the Spectro-polarimeter for Planetary Exploration (SPEXone) and the Hyper Angular Research Polarimeter (HARP2) to provide extended data records on clouds and aerosols. The Earth-observing satellite mission, built at Goddard Space Flight Center in Greenbelt, MD, will continue and advance observations of global ocean color, biogeochemistry, and ecology, as well as the carbon cycle, aerosols and clouds.