[11] Several items were returned with Atlantis: A malfunctioning Control Moment Gyroscope (CMG) that was swapped out with a new one during STS-118, and the empty Nitrogen Tank Assembly was placed in the orbiter's payload bay, along with a trundle bearing from the Starboard SARJ that was removed during an EVA performed by Expedition 16.

[11][12] Stowed within the Official Flight Kit (OFK), Atlantis carried three green starting flags provided by NASCAR in recognition of the 50th running of the Daytona 500 on February 17, 2008, and the 50th anniversary of NASA on October 1, 2008.

[13] The mission marks:[4][15][16] The external tank (ET-125) arrived at the Kennedy Space Center on September 14, 2007, after traveling by barge from the Michoud Assembly Facility in Louisiana.

The external tank was then transferred to the Vehicle Assembly Building (VAB) to be inspected, and have the liquid oxygen feedline bracket modified, before being mated to the solid rocket boosters on October 17, 2007.

Managers evaluated if the Launch Commit Criteria could be removed, allowing Atlantis to fly with two of four sensors, and augment the LCO system with on-ground monitoring of propellant use by the Flight Control staff.

The other option would involve repair or replacement of the sensors, which would most likely require the orbiter be moved back into the Vehicle Assembly Building, and would rule out a December launch.

[26][27] The Launch Commit Criteria would be changed, and Flight Controller procedures would be finalized to allow for additional monitoring of the ECO system during ascent.

Following STS-122, Space Shuttle Program Director Wayne Hale and Mission Management Team Chairman LeRoy Cain explained that there would be a variety of activities and procedures put into effect to address the ECO issues.

[31] During the post-scrub news conference, Launch Director Doug Lyons said that a rollback to the Vehicle Assembly Building was not a situation managers were considering currently, and explained that the pad offers extensive access to the systems for troubleshooting and investigation.

Engineer Peter Johnson and Dr. Carlos T. Mata operated two TDRs to gather data about the characteristics of the behaviour of the sensor circuitry before, during, and after tanking.

During launch preparations at Kennedy, technicians noticed a small section of the aft radiator retract hose that was bent in a shape similar to the Greek letter Omega.

[33][34] The hose is part of the shuttle's cooling system that carries Freon, and is designed to flex when the payload bay doors are opened and closed.

[35] Making sure they were not overlooking potential problems, NASA engineers designed a tool to guide the hose back into the storage box, and performed the procedure on February 3, 2008.

[41] The crew opened the payload bay doors, deployed the Ku antenna, checked out and activated the shuttle's robotic arm, and downlinked the video footage taken during external tank separation to NASA managers.

[44][45] During interviews with CBS and NBC in the morning, Expedition 16 Commander Peggy Whitson told reporters that since her birthday was Saturday, "My present is a new module that we're going to install on the station, I'm really looking forward to it.

Shannon noted that the initial imagery given to the engineering team showed "absolutely nothing of concern", with only one foam piece appearing to possibly impact the vehicle, 440 seconds into ascent.

[45][46] Shannon said the team would evaluate the data obtained during Saturday's Rendezvous Pitch Maneuver, performed prior to docking, as well as the imagery from the OBSS survey, and during flight day 3's MMT meeting a decision would be made whether a focused inspection of the orbiter's thermal protection system would be needed.

[46] The shuttle crew worked through the rendezvous timeline in the morning, including several adjustment burns of the orbiter's engines to refine the path towards the station.

Between 16:24 and 16:31 UTC, Atlantis performed the Rendezvous Pitch Maneuver to allow the station crew to use high resolution cameras and document the thermal protection system.

After working through a variety of leak check procedures, the hatches were opened between the shuttle and station at 18:40 UTC, and the two crews exchanged greetings and conducted a mandatory safety briefing.

[47][49] At 20:14 UTC, the ground team radioed the crew to alert them that the managers had decided to make a 24-hour delay to EVA-1, originally scheduled for Flight Day 4, and that Stanley Love would replace Hans Schlegel for EVA-1 on Monday.

[50][52] Unconfirmed news reports claim that Schlegel had "lost his voice", and since communication is a critical function of an EVA, the decision to swap crewmembers was made.

[48] The two crews spent their first joint mission day working through a focused inspection of the OMS pod blanket, reviewing the upcoming EVA procedures, and beginning the transfer of items from the shuttle to the station.

During the afternoon's mission status briefing, ISS Orbit One Flight Director Bob Dempsey noted that the two crews were far ahead of the timeline for activation, and excited about the station's new addition.

[60][61] The crew of Atlantis also took some time out to talk to reporters on the ground, one session in the morning, and another in the afternoon with CBS News, and Pittsburgh television stations.

[64] During the mission status briefing, Lead ISS Flight Director Sally Davis announced that the managers had officially approved an additional docked day extension, and the team had also cleared the orbiter's entire thermal protection system for re-entry, pending late inspection results.

[65] The right OMS pod blanket was determined to be of no issue for re-entry the day before, and the areas around the orbiter's windows that appeared damaged were fully cleared.

[69] Both crews participated in an EVA review in the late afternoon, and Walheim and Love spent the night in the station's airlock in preparation for the mission's final spacewalk.

[73] While the ongoing task of outfitting the Columbus module continued, Atlantis' propulsion system was fired for 36 minutes to reboost the station's altitude by 1.4 miles (2.2 kilometers) in preparation for the arrival of Space Shuttle Endeavour during STS-123.

Atlantis touched down on Runway 15 of the Shuttle Landing Facility at 9:07 am EST (14:07:10 UTC),[1] approximately 12 days, 18 hours, 21 minutes and 40 seconds into the mission.