The crew awoke at 2:03 a.m. CDT to the sounds of Lee Greenwood's "Proud To Be An American", which was played for Endeavour astronaut Chris Cassidy, who is a former Navy SEAL. They bade farewell to the ISS's eight-member Expedition 20 crew at 9:30 a.m.
Two astronauts switched place amid the goodbyes. Endeavour crewmember Tim Kopra will remain onboard the ISS to assume flight engineer duties. ISS resident Koichi Wakata, from the Japanese Aerospace Exploration Agency, will return to Earth aboard the shuttle after a four month stint at the station.
The ISS's next visitor will be the Progress 34 cargo ship, which is slated to arrive Wednesday.
On Monday, a pair of astronauts from Endeavour worked their way through a five hour spacewalk around the ISS. The jaunt saw them complete a range of maintenance and research tasks outside the station.
The effort marked the fifth and last spacewalk for the current shuttle mission, which is known as STS-127. It was also the 218th spacewalk in the history of the American space program.
Endeavour lifted off on July 15th from the Kennedy Space Center in Florida after a series of delays caused by faulty equipment and bad weather. It's set to return home on July 31st.
The mission hasn't been without some drama. Shuttle pilots were forced to maneuver the craft over the ISS so that the space station crew could check for possible damage from liftoff debris. NASA at this point does not believe the craft suffered any significant harm.
STS-127 is a 16-day roundtrip voyage that has seen the Endeavour crew work to complete construction of Japan's Kibo space laboratory. The astronauts added a porch-like platform to the lab's exterior that will allow experiments to be exposed to the vacuum of outer space.
NASA is expected to phase out the space shuttle program starting next year. Plans call for the development of an Apollo-style rocket and capsule system, dubbed Ares and Orion, to replace the orbiter. Obama administration officials, however, have recently raised questions about the plan's cost and practicality.
The Senate earlier this month confirmed former astronaut Maj. Gen. Charles Bolden as NASA administrator.
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