KENNEDY SPACE CENTER, FLA. -- In the Orbiter Processing Facility, preparations are under way to close the payload bay doors of Discovery for the rollover of the orbiter to the Vehicle Assembly Building. Seen along the edges of the bay are the Canadian-built shuttle robotic arm and orbiter boom sensor system. The primary payload, the U.S. Node 2, which is named Harmony, will be installed in the payload bay at the pad prior to Discovery's liftoff on mission STS-120. The mission will be the 23rd flight for the assembly of the International Space Station. Space Shuttle Discovery is targeted for launch on Oct. 23. Photo credit: NASA/Jim Grossmann

KENNEDY SPACE CENTER, FLA. -- In the Orbiter Processing Facility, the right payload bay door of Discovery is nearly closed in preparation for the rollover of the orbiter to the Vehicle Assembly Building. The primary payload, the U.S. Node 2, which is named Harmony, will be installed in the payload bay at the pad prior to Discovery's liftoff on mission STS-120. The mission will be the 23rd flight for the assembly of the International Space Station. Space Shuttle Discovery is targeted for launch on Oct. 23. Photo credit: NASA/Jim Grossmann

KENNEDY SPACE CENTER, FLA. -- In the Orbiter Processing Facility, the left payload bay door of Discovery is being closed in preparation for the rollover of the orbiter to the Vehicle Assembly Building. Seen along the edges of the bay are the Canadian-built shuttle robotic arm and orbiter boom sensor system. The primary payload, the U.S. Node 2, which is named Harmony, will be installed in the payload bay at the pad prior to Discovery's liftoff on mission STS-120. The mission will be the 23rd flight for the assembly of the International Space Station. Space Shuttle Discovery is targeted for launch on Oct. 23. Photo credit: NASA/Jim Grossmann

KENNEDY SPACE CENTER, FLA. -- In the Orbiter Processing Facility, the Ku-band communications antenna is stowed in the payload bay of Discovery before the bay's doors are closed. The stowage is in preparation for the rollover of the orbiter to the Vehicle Assembly Building. The primary payload, the U.S. Node 2, which is named Harmony, will be installed in the payload bay at the pad prior to Discovery's liftoff on mission STS-120. The mission will be the 23rd flight for the assembly of the International Space Station. Space Shuttle Discovery is targeted for launch on Oct. 23. Photo credit: NASA/Jim Grossmann

KENNEDY SPACE CENTER, FLA. -- In the Orbiter Processing Facility, the right payload bay door of Discovery is being closed in preparation for the rollover of the orbiter to the Vehicle Assembly Building. The primary payload, the U.S. Node 2, which is named Harmony, will be installed in the payload bay at the pad prior to Discovery's liftoff on mission STS-120. The mission will be the 23rd flight for the assembly of the International Space Station. Space Shuttle Discovery is targeted for launch on Oct. 23. Photo credit: NASA/Jim Grossmann

KENNEDY SPACE CENTER, FLA. -- In the Orbiter Processing Facility, the payload bay doors of Discovery are being closed in preparation for the rollover of the orbiter to the Vehicle Assembly Building. The primary payload, the U.S. Node 2, which is named Harmony, will be installed in the payload bay at the pad prior to Discovery's liftoff on mission STS-120. The mission will be the 23rd flight for the assembly of the International Space Station. Space Shuttle Discovery is targeted for launch on Oct. 23. Photo credit: NASA/Jim Grossmann

KENNEDY SPACE CENTER, FLA. -- In the Orbiter Processing Facility, the Ku-band communications antenna is stowed in the payload bay of Discovery before the bay's doors are closed. The stowage is in preparation for the rollover of the orbiter to the Vehicle Assembly Building. The primary payload, the U.S. Node 2, which is named Harmony, will be installed in the payload bay at the pad prior to Discovery's liftoff on mission STS-120. The mission will be the 23rd flight for the assembly of the International Space Station. Space Shuttle Discovery is targeted for launch on Oct. 23. Photo credit: NASA/Jim Grossmann