schedule for most of the day readying the ship for docking and preparing for the mission's three planned extra-vehicular activities (EVA). Mission specialists Joe Tanner and Heide Stefanyshyn-Piper checked out the spacesuits and tools that they, Burbank and MacLean used during spacewalks set for Days 4, 5, and 7. The spacewalks installed the girder-like P3/P4 truss, deploy new solar arrays, and prepare them for operation. On the space station, Expedition 13 Flight Engineer Jeffrey Williams prepared the orbiting laboratory for Atlantis arrival on Day 3. He readied the digital cameras that was used to take high-resolution photos of the shuttle's heat shield. With help from Commander Pavel Vinogradov, Williams pressurized the Pressurized Mating Adapter 2 at the end of the Destiny Laboratory Module, where Atlantis later docked. Vinogradov also prepacked equipment to be returned. September 11 (Flight day 3) [[File:STS-115 Truss Handoff.jpg|thumb|right|[[Space Shuttle Atlantis|Atlantiss]] Canadarm hands the P3/P4 Truss segment to the station's Canadarm2 on Day 3 (a frame of an animation)]] Day 3: Docking animation Prior to docking, Jett flew Atlantis through an orbital back flip while stationed about 180 meters (600 feet) below the space station. The maneuver allowed the Expedition 13 crew to take a series of high-resolution photographs of the orbiter's heat shield. At about 10:46 UTC Atlantis docked with the International Space Station, and almost two hours later the hatch between them was opened, and the crew was welcomed aboard the station at 12:35 UTC. Day 3: Handoff animation Following docking, Ferguson and Burbank attached the shuttle's robotic Canadarm to the 17.5-ton P3/P4 truss, lifted it from its berth in the payload bay, and maneuvered it for handover to the station's Canadarm2. After hatch opening, MacLean and Expedition 13 Flight Engineer Jeff Williams then used the Canadarm2 to take the truss from the shuttle's robotic arm. MacLean is the first Canadian to operate the Canadarm2 in space. Tanner and Stefanyshyn-Piper began the "camping out" preparations in the Quest Airlock to prepare for a Day 4 spacewalk. The preparations are new pre-breathing measures on the part of NASA, to avoid decompression sickness, or the bends, by getting rid of some nitrogen in their bloodstreams. The preparations involve wearing oxygen masks and sleeping overnight in the airlock with the airlock at under 69 kPa (10 psi), to acclimate their bodies the low pressures they will encounter when wearing their spacesuits. September 12 (Flight day 4) Day 4: