The Orbiter Processing Facility (OPF), in the case of Discovery, which is assigned OPF-3, is a hanger at the Kennedy Space Center, in Florida, where space shuttles are prepared for future flights and undergo maintenance after completing past flights. The orbiter vehicle is inspected, tested, and refurbished within the OPF, and any payloads removed (after completing a mission) or installed (in preparation for an upcoming mission). The tiles within the Thermal Protection System (TPS), so much of a concern lately for the safety of the crew, are also inspected inside the hanger.

Additional information about the three OPFs used by NASA to prepare the three space shuttles are found at NASA’s website: http://science.ksc.nasa.gov/facilities/opf.html.

The Vehicle Assembly Building (VAB), also located at the Kennedy Space Center, is the gigantic building where an orbiter is mated (or “stacked”) with its external fuel tank (ET) and twin solid rocket boosters (SRBs). The final assembly of orbiter, ET, and two SRBs is officially called a Space Transportation System (STS), or informally as a Space Shuttle. After the assembly process is complete, the space shuttle is moved on top of a mobile launcher platform and crawler-transporter to its launch pad.

Further information about the VAB is found at: http://science.ksc.nasa.gov/facilities/vab.html.

On Monday, Discovery will be mated to its external fuel tank (ET) and its two solid rocket boosters (SRBs) on top of the mobile launcher platform. Over the next week, work will be completed in preparation for its trip to Launch Pad 39A aboard the crawler-transporter. The trip is now scheduled to begin on Sunday, September 30.

The STS-120 mission to the International Space Station is now scheduled to liftoff on Tuesday, October 23, at about 11:38 a.m. EDT (1538 GMT).

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