EVA 1 - Grunsfeld and Smith during RSU changeout

STS-103 mission specialist John M. Grunsfeld (attached to a workstation on the RMS arm) and payload commander Steven L. Smith (free-floating) perform a changeout of the Rate Sensor Units (RSU) in one of the bays of -V3 plane of the Hubble Space Telescope (HST). This repair was performed during the first of three extravehicular activities (EVAs) of the mission. Grunsfeld is distinguished by having no marks on his EMU and Smith is distinguished by the red strip on the pants of his EMU.