SM4: astronaut Andrew Feustel and WFC3

But for the absence of gravity, astronaut Andrew Feustel, perched on the end of the remote manipulator system arm, would be a bit top heavy as he helps to install the Wide Field Camera 3 (WFC3) during a May 14 spacewalk to perform work on the Hubble Space Telescope. Out of frame is veteran astronaut John Grunsfeld, his spacewalking crewmate. The pair kicked off five back to back days of extravehicular activity for the STS-125 crew. Feustel and Grunsfeld will participate in two of the remaining four spacewalks.