Astronaut Michael L. Gernhardt, STS-104 mission specialist, participates in one of three STS-104 space walks while holding on to the end effector of the Canadarm on the Space Shuttle Atlantis. Gernhardt was joined on the extravehicular activity (EVA) by astronaut James F. Reilly (out of frame). The major objective of the mission was to install and activate the Joint Airlock, which completed the second phase of construction on the International Space Station (ISS). The airlock accommodates both United States and Russian space suits and was designed and built at the Marshall Space Flight Center by the Boeing Company.