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Endeavour astronauts prepare for first spacewalk BY WILLIAM HARWOOD STORY WRITTEN FOR CBS NEWS "SPACE PLACE" & USED WITH PERMISSION Posted: August 11, 2007 Amid ongoing work to assess the health of the shuttle Endeavour's heat shield, astronauts Rick Mastracchio and Dave Williams are gearing up for a six-and-a-half-hour spacewalk today to attach a 5,000 pound spacer segment to the space station's main solar array truss. The two astronauts spent the night in the station's Quest airlock module at a pressure of 10.2 pounds per square inch, part of a normal "camp out" procedure to help acclimate their bodies for working in NASA's 5-psi spacesuits. Before the spacewalk begins, the right-side S4 solar array wings, which normally rotate to track the sun, will be stopped and locked in place in preparation for the attachment of the S5 segment. S5 fits on the end of S4, serving as a spacer to provide the clearance needed by a final set of solar arrays - S6 - that will be attached next year. "S5 is a very small piece of the space station truss segments," Mastracchio said in a NASA interview. "S4 has a large set of solar arrays on it; S6 will have another large set of solar arrays. In between S4 and S6 is obviously S5. It's a very small piece. It's basically an interface or an adaptor so that you could attach S6 to the first set of solar arrays." The shuttle astronauts were awakened today at 7:39 a.m. by a recording of John Mayer's "Gravity" beamed up from mission control in Houston. "Good morning, Endeavour," called astronaut Shannon Lucid from Houston. "And a special good morning today to you, Scorch." "Thanks, Shannon," replied shuttle pilot Charles "Scorch" Hobaugh. "Why'd you turn the music off so quick? I'd like to thank my family for that nice selection of a song. Seems kind of appropriate and we're excited to get off to a great day with our EVA team, getting outside." Mastracchio and Williams plan to begin their first spacewalk just after 12:30 p.m. when they switch their spacesuits to battery power a few minutes before floating out of the airlock hatch. "It's going to be a really exciting spacewalk for us," Williams said in a NASA interview. "We're both highly trained spacewalkers, and we've both been to space, but neither one of us has actually done a spacewalk before. So, you can imagine opening the hatch of the airlock, sticking your head out, looking down at the Earth below you, traveling 25 times the speed of sound, reaching out and, handrail by handrail, moving out to the extreme limit on the starboard side of the space station. "Once we get out there, we'll be looking out into free space as the robotic arm comes around with S5, brings it towards us, and we attach S5, driving a number of bolts with an electric power drill and doing a number of electrical connections and things. Then, once we get S5 in place, the grapple fixture that the robotic arm used to move S5 has to be moved (to permit S4 to rotate). So, we will go out right on the end of S5, the structure we just attached to the station, and we're going to grab on to this grapple fixture. I'm going to be standing in a foot restraint and Rick is going to push me around the corner of S5 and I'm going to hand off the grapple fixture to Rick. "When I get out of that foot restraint, I no longer have handrails beside me to grab on to," Williams said. "So, I will use a tether attached to the foot restraint, reach down, pull myself out, and float freely in space tethered to this foot restraint, and pull myself back towards the space station. You can imagine what that's going to be like. We're really looking forward to it." Here is an updated timeline of today's activity, based on the crew's revised flight day four timeline and revision D of the NASA television schedule (in EDT and mission elapsed time):
EDT............DD...HH...MM...EVENT
08/11/07
07:37 AM...02...13...00...STS/ISS crew wakeup
08:17 AM...02...13...40...EVA-1: 14.7 psi repress
08:37 AM...02...14...00...EVA-1: Hygiene break
09:02 AM...02...14...25...EVA-1: Crew lock depress to 10.2 psi
09:27 AM...02...14...50...EVA-1: Campout EVA preps
10:27 AM...02...15...50...Logistics transfers resume
10:57 AM...02...16...20...EVA-1: Spacesuit purge
10:57 AM...02...16...20...Station-to-shuttle power transfer system
shut down for EVA-1
11:12 AM...02...16...35...EVA-1: Spacesuit prebreathe
12:02 PM...02...17...25...EVA-1: Crew lock depressurization
12:07 PM...02...17...30...Station arm (SSRMS) to pre-install position
12:37 PM...02...18...00...EVA-1: Airlock egress
12:52 PM...02...18...15...SSRMS support
12:52 PM...02...18...15...EVA-1: Sortie setup
01:22 PM...02...18...45...EVA-1: S4/S5 launch lock removal
01:37 PM...02...19...00...ISS: BOK-3 computer unit repair review
01:57 PM...02...19...20...SVA-1: S5 truss installation
03:07 PM...02...20...30...SSRMS ungrapples S5
03:27 PM...02...20...50...EVA-1: PVR grapple fixture relocation
03:37 PM...02...21...00...ISS: BOK-3 study
04:07 PM...02...21...30...ISS: BOK-3 preparation for repair
04:27 PM...02...21...50...EVA-1: Get ahead tasks
04:42 PM...02...22...05...EVA-1: S5 cleanup
05:17 PM...02...22...40...EVA-1: P6 forward radiator retraction
06:27 PM...02...23...50...EVA-1: Payload bay cleanup
06:42 PM...03...00...05...EVA-1: Airlock ingress
07:02 PM...03...00...25...EVA-1: Airlock repressurization
07:17 PM...03...00...40...Spacesuit servicing
08:30 PM...03...01...54...Mission status briefing on NTV
08:32 PM...03...01...55...Transfer tagup
08:52 PM...03...02...15...SSPTS re-activated
10:37 PM...03...04...00...ISS crew sleep begins
11:07 PM...03...04...30...STS crew sleep begins
08/12/07
12:00 AM...03...05...54...Daily video highlights reel on NTV
05:30 AM...03...10...54...Flight director update on NTV
07:06 AM...03...12...30...Crew wakeup
After S5 is attached, Williams and Mastracchio will move to Z1 truss, make their way up to the P6 solar array segment, monitor the retraction of a cooling radiator and then lock it in place for the move later this fall to the left end of the power truss.
"After we're done with the S5 work, we'll go up to P6, which is the solar array pointing zenith on the space station, and we will retract the forward radiator and cinch it down and stow it and get it ready to be moved, because P6 is going to be moved from the zenith to the port side of the space station on a future mission," Mastracchio said. "So by us retracting that radiator, it gets it ready, it's one step closer to being ready for a move." While the spacewalk is in progress, station Commander Fyodor Yurchikhin and flight engineer Oleg Kotov plan to begin a long, complex repair job to replace a critical component in the Russian computer system. The unit is mounted near an air conditioner in the Zvezda command module and engineers believe corrosion found on cables leading to and from the box, known as BOK-3, may have played a role in widespread computer failures during a June shuttle visit. The new hardware was delivered to the station Aug. 5 aboard an unmanned Russian Progress supply ship. It will take the station crew four days to complete the computer overhaul and test the wiring. NASA planners, meanwhile, are making plans for a focused inspection of the shuttle's heat shield Sunday to gather additional data on a tile that was damaged during launch, possibly by the impact of a chunk of ice. The inspection is expected to begin just after noon and an updated flight plan will be posted here as soon as it becomes available. Flight controllers say the shuttle's new station-to-shuttle power transfer system, or SSPTS, continues to work normally, delivering some 6.5 kilowatts of electricity to the orbiter from the space station's solar power grid. The system is designed to let the shuttle reduce its use of hydrogen and oxygen for its fuel cells to remain docked at the station longer than otherwise possible. Because power to SSPTS comes in part from the S4 solar arrays, which must be locked in place for today's spacewalk, the power transfer system will be deactivated just before 11 a.m. and restarted about a half hour after the spacewalk ends. Assuming the system continues to work normally, mission managers are expected to extend Endeavour's mission by three days and add a fourth spacewalk.
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MISSION INDEX |
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VIDEO:
PREVIEW OF SPACEWALK NO. 1 