[9][10][11] Prior to the Space Shuttle Columbia disaster, the original crew manifest for STS-120 was: The STS-120 mission patch was designed by Michael Foreman before he was reassigned to STS-123.

[19] In light of the small gouge to the underside of Endeavour that occurred on STS-118, in August 2007, NASA managers announced that they expected to add a fifth spacewalk to the STS-120 mission, designed to test a heat-shield repair tool.

The mission marked:[4] Following STS-118 in August 2007, NASA managers decided to make modifications to the external tank to be used on STS-120, and modify the liquid oxygen feed-line brackets.

The week of September 17, 2007, NASA managers decided to delay Discovery's rollover to the Vehicle Assembly Building (VAB), due to a hydraulic fluid leak from the right main landing gear strut.

[25][26][27] On October 9, 2007, NASA's Engineering and Safety Center, an independent review group set up after the 2003 Columbia disaster, advised replacement of three of Discovery's reinforced carbon-carbon (RCC) panels on the leading wing edge, due to a loss of small amounts of the protective silicon-carbide coating.

[28][29] NASA reviewed the issue of oxidation of the panels for several months, using a variety of specialized testing methods, including thermography.

[28][29][30] On October 16, 2007, NASA Managers completed the Flight Readiness Review, and held a press conference to announce the mission plan.

[42] In a press briefing following launch, NASA managers noted a few "events" involving debris, but they occurred later in ascent, after the period of maximum aerodynamic velocity and speed, and were not concerning.

[46][47] Shannon said there were several items the team was waiting for higher resolution imagery to assess, including a possible protruding gap filler, and some external tank foam losses, but there was nothing to indicate any problems.

[50] Just before the two crews signed off to sleep, they were informed that after preliminary review of the RPM photography, focused inspection of the orbiter's heat shield would not be required.

[53] Wilson, Tani, and Anderson controlled the station's robotic arm, moving Harmony out of the bay and onto the port side of the Unity node.

[58] Until the air is fully exchanged, occupancy of the node is limited to only a few crew members at a time, and they are not to remain inside for extended periods.

Some of the work the crew has to do inside the node is to remove approximately 700 screws and bolts that are holding down equipment and panels, placed for security during launch, but not needed in space.

[58] After allowing the ventilation system work for several hours, the two crews participated in a press conference with CBS, Fox News, and WHAM-TV from inside Harmony.

This information allowed the managers on the ground to rule out some possibilities of the origin of the particles, such as the thermal covers, which are made of aluminized mylar.

[76] Nespoli and Melroy participated in a Public Affairs event (PAO), and received a call from the President of Italy, Giorgio Napolitano.

The entire crew took part in a second PAO event, fielding calls from news agencies from the United States, Europe, and Russia.

[77][78] Shortly after awakening in the morning, the crew was informed that the managers had chosen to take an extra day to evaluate and plan the fourth EVA.

[79][80] The crew took some time out to gather in the Harmony module to speak with former President George H. W. Bush and his wife, Barbara, who were visiting Johnson Space Center.

[82][83] The cufflink is made up of two wires, with two tabs at the end, that are threaded through existing reinforced aluminum holes in the solar array panels.

[85][86] The crew also positioned the station's mobile transporter and robotic arm on the end of the truss, to allow the apparatus to reach the solar array.

[85] After being awakened by the theme music from Star Wars, the station and shuttle crews got to work preparing for the mission's fourth EVA.

After translating out to the robotic arm, Parazynski attached himself to the adjustable portable foot restraint (APFR), and was taken to the solar array worksite.

[88][89] Working slowly, with direction from Wheelock and the ground team, Parazynski secured the five cufflinks to the array, and then backed away to observe the deploy action.

[99] At 10:32 UTC, the orbiter successfully backed away from the Pressurized Mating Adapter on the Destiny Laboratory, and pilot Zamka began the fly-around to allow the shuttle crew to photograph the new configuration of the station.

NASA managers officially cleared Discovery's heat shield for landing after reviewing the data sent down by the final inspection on Monday.

NASA did not activate either Edwards Air Force Base, or White Sands, as the weather looked favorable for both landing opportunities at Kennedy.

The weather forecast at the Shuttle Landing Facility called for good visibility, with mostly sunny skies, although the headwinds would be evaluated, as they had been peaking at 23 knots (43 km/h).

[106] Once the orbiter reached Florida, Melroy performed a 195-degree right overhead turn along the heading alignment cone (HAC) in order to line up for a landing on Runway 33.

[109] The deorbit burn is performed while the orbiter is facing opposite its direction of travel, which allows the engines to act as a braking system, slowing its speed by approximately 215 feet per second (66 m/s).