Halsell, Horowitz and Mission Specialists Mary Ellen Weber, Jeff Williams, Susan Helms, Jim Voss and Yury Usachev will spend their third day inside the station continuing the maintenance work and supply transfer activities that began Monday evening. During their first two days inside the station, the astronauts have moved more than a ton (2,049 pounds) of supplies and equipment inside the facility to be used by the first station crew. More than 3,000 pounds will be transferred to the station before Atlantis undocks on Friday evening.
Helms and Usachev already have completed the replacement of the fourth and final battery. The second battery replaced on Monday evening is fully recharged and working well as it supports station operations. The third battery, which was replaced last night, has begun its 20-hour charging process. All of the battery work is designed so that at least four of the station's six batteries are available to support station systems.
Other work on tap for this evening includes the replacement of a Zarya radio telemetry system which has reached the end of its design life. The radio telemetry system collects and stores station data when ground station communications are not available. The crew also will fill four large water bags and transfer the bags to the station to join seven similar bags left during the STS-96 mission last year. The water bags will be part of the potable water supply used by the first station crew when it arrives later this year.
Tonight also will see the second of three planned reboost maneuvers to raise the station's altitude. The one-hour procedure will involve 27 pulse firings of Atlantis's maneuvering thrusters. The three reboosts will raise the station to a new altitude about 237.5 x 227 statue miles and will place the station in the optimum altitude for the arrival of the Zvezda Service Module when it is launched in July.
Shuttle and station managers have decided to move the undocking time to one orbit later. The new undocking time is now 6:07 p.m. CDT on Friday, May 26th and will happen while the two spacecraft are over Russian ground stations. The later undocking will allow the crew to get a full eight-hour sleep period. Atlantis will make shortened fly around, one half revolution of the station, before leaving the vicinity of the station. The later undocking will have no impact to Atlantis' landing at Kennedy Space Center which still is planned for 1:18 a.m. CDT Monday, May 29th.
Later this evening at 10:11 p.m. CDT, Halsell, Horowitz and Helms will participate in a trio of interviews with the ABC Radio Network, KOIN-TV in Portland, Oregon, and a webcast education event for the Housing and Urban Development agency.
The Atlantis and station complex continues to operate well, completing one orbit of the Earth every 91 minutes.