Plant Gravity Sensing-2 (PGS-2) Photon Counting Unit (PCU) Checkout: Kelly attached PCUs to the CBEF Incubator Unit (IU) 1-Gravity (1-G) centrifuge. Japan Aerospace Exploration Agency (JAXA) ground controllers downlinked data from the Plant Experiment Unit (PEU) through the Image Processing Unit (IPU) and reviewed data from the installed PCU. The first run of PGS-2 is …