External Stowage Platform - ESP-2

ESP-2

ESP-2 was installed with the assistance of Space Shuttle Discovery's robotic arm and two spacewalkers during the STS-114 mission. It is much larger than ESP-1 with eight FRAM sites creating room for up to eight spare parts (ORUs). Like ESP-1, it is powered by the Unity Module. However unlike ESP-1, ESP-2 is attached to the Quest Joint Airlock using a specialized ESP Attachment Device (ESPAD). ESP-2 and ESP-3 are deployable versions of the integrated cargo carrier and have the same dimensions, approximately 8.5 feet long and 14 feet wide. The ORUs on ESP-2 are:

• FRAM-1 (top side) empty
• FRAM-2 (top side) Direct Current Switching Unit (DCSU) (added by STS-123 crew)
• FRAM-3 (top side) Direct Current Switching Unit (DCSU) (added by STS-123 crew)
• FRAM-4 (top side) Main Bus Switching Unit (MBSU) launched on ESP-2
• FRAM-5 (keel side) Pitch/Roll Joint (P/R-J) added by STS-123 crew
• FRAM-6 (keel side) Main Bus Switching Unit (MBSU) added by STS-120 crew
• FRAM-7 (keel side) Flex Hose Rotary Coupler (FHRC-3) launched on ESP-2
• FRAM-8 (keel side) Utility Transfer Assembly (UTA) launched on ESP-2

Notes:

• Video Stanchion Support Assembly (VSSA) launched on ESP-2 at FRAM-2 was jettisoned overboard on July 23, 2007 (the video stanchions were placed on the truss during EVAs).
• Pump Module (PM) (s/n 4), initially installed on FRAM-1 during STS-121, was removed on August 17, 2010 and installed on S1 Truss, replacing a failed PM. The failed unit had been temporarily stored on an ORU site on the MBS, then moved to ESP-2 by the STS-133 crew, then returned to earth by the STS-135 crew July 13, 2011.
• A failed Control Moment Gyroscope was installed on FRAM-5 from August 13, 2007 during STS-118 until February 13, 2008 when it was returned by STS-122.