Astronauts Smith and Grunsfeld During Servicing Mission 3A

In this view, Steven L. Smith (bottom), STS-103 payload commander, and John M. Grunsfeld, mission specialist, are seen during an extravehicular activity (EVA) to replace the Hubble Space Telescope's (HST) Rate Sensor Units (RSUs or gyroscopes) on the third HST servicing mission, conducted in 1999. Grunsfeld was on a foot restraint connected to Discovery's Remote Manipulator System (RMS) robotic arm. Smith, making his second servicing visit to HST, was near the foot of the open aft shroud doors using handrails along the bottom of the telescope.