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Shuttle team gears up for heat shield inspection BY WILLIAM HARWOOD STORY WRITTEN FOR CBS NEWS "SPACE PLACE" & USED WITH PERMISSION Posted: August 12, 2007 Amid planning for an afternoon inspection to assess the extent of shuttle heat shield damage, space station controllers successfully restarted a command-and-control computer that locked up Saturday because of an apparent software glitch. "Last night we did power cycle it and reconfigured all the computers so they are in a good state for today's operations and everything's back to nominal," said station flight director Heather Rarick. "The main focus (today), especially for the shuttle team, will be to perform the focused inspection of the bottom of the shuttle to review some potential tile damage and see what the extent of that is." Space station commander Fyodor Yurchikhin and flight engineer Oleg Kotov, meanwhile, plan to continue preparations for replacing critical computer cabling and a command processor known by its Russian acronym BOK-3 on Tuesday. Corroded cables connectors at the BOK-3 unit may have played a role in crippling Russian computer crashes during the last shuttle visit in June. The computers have been running normally since Yurchikhin and Kotov installed jumpers to bypass suspect secondary power supply surge protectors and those jumpers will remain in place during the BOK-3 replacement work later in the week. The main focus today, however, is an up-close inspection of heat shield tile damage spotted after Endeavour's launch on Wednesday. John Shannon, chairman of NASA's Mission Management Team, told reporters late Saturday engineers believe the damage in question was caused by a chunk of foam insulation that popped off a propellant line support bracket on the shuttle's external fuel tank 58 seconds after liftoff. The debris slammed into an aft strut that helps hold the shuttle's back end to the tank and shattered into multiple fragments. One of those ricocheted off the strut and into the shuttle's belly, hitting between the right main landing gear door and an aft door covering the ship's liquid oxygen feedline inlet. The damage, visible in photographs taken by the station crew during Endeavour's approach on Friday, measures 3.48 by 2.31 inches. The tiles in that area are about 1.12 inches thick. The photos do not show how deep the gouge might be and the depth of the damage is critical for the thermal analysis of its impact during re-entry. As luck would have it, the damage site is right above an internal rib in the right wing called a stringer. Even if the tile was gouged out all the way to its base, Shannon said, any unusual heat during re-entry that made it to the underlying aluminum skin would spread out in the structure and not result in a localized hot spot. Engineers concluded that in an emergency, Endeavour could safely return to Earth as is. But the crew's flight plan has always included time for a so-called focused inspection on the day between the first two spacewalks of the mission. When engineers spotted the tile damage, mission managers immediately told the flight control team to carry out the inspection today, as protectively planned, to fully assess the impact. While engineers do not appear overly concerned, Shannon emphasized they do not yet know how deep the gouge is, a critical part of the thermal analysis. Starting the day with a bit of humor, the Endeavour astronauts were awakened at 7:06 a.m. by a recording of Shania Twain's "Up" played by mission control in Houston. The song began: It's 'bout as bad as it could be The chorus concludes "There's no way but up from here." "Good morning Endeavour, and a special good morning to you today, Dave," called astronaut Shannon Lucid from Houston. "Good morning from the Spacehab," Canadian flier Dave Williams replied. "Really enjoyed the wakeup music this morning." "Well, we aim to please." The astronauts will first attach a 50-foot extension to the shuttle's robot arm, called the orbiter boom sensor system. The OBSS features a high-resolution camera and a laser scanner that will help engineers map out the damage in three dimensions. Because of clearance issues when the shuttle is docked at the space station, the OBSS must be picked up from its perch in the orbiter's cargo bay by the space station's robot arm, operated by pilot Charles Hobaugh. He will pick up the OBSS around 9:50 a.m. and hand it off to Caldwell shortly after 11 a.m. Assisted by teacher-turned-astronaut Barbara Morgan, Caldwell plans to begin the actual inspection work a few minutes past noon. "The shuttle arm cannot reach over and grab the end of the orbiter boom sensor system, the OBSS," Shannon said Saturday. "So there's a grapple fixture about a third of the way down. We will use the station arm to pick it up with that grapple fixture and then hand it off to the shuttle arm. We'll go underneath the vehicle, do all of our laser work, it will take about three hours, about two hours underneath the belly of the vehicle, it'll come back up and then the reverse will happen. We'll hand it back to the SSRMS (station arm), the SSRMS will put it down into the holder in the shuttle payload bay." Here is an updated timeline of today's activity (in EDT and mission elapsed time):
EDT........DD...HH...MM...EVENT
08/12/07
07:07 AM...03...12...30...STS/ISS crew wakeup
09:22 AM...03...14...45...ISS: Russian BOK-3 computer
repair work (5 hours)
09:37 AM...03...15...00...Shuttle arm (SRMS) moves to
inspection boom (OBSS) pre-grapple position
09:47 AM...03...15...10...Station arm (SSRMS) grapples/unberths OBSS
10:32 AM...03...15...55...SSRMS moves OBSS to handoff position
11:12 AM...03...16...35...SRMS grapples OBSS
11:22 AM...03...16...45...SSRMS ungrapples OBSS
11:32 AM...03...16...55...Spacewalk tools configured
12:07 PM...03...17...30...Heat shield inspection begins
12:07 PM...03...17...30...Logistics transfer operations
12:42 PM...03...18...05...Spacesuit battery charging
02:37 PM...03...20...00...Shuttle crew meals begin
03:37 PM...03...21...00...SSRMS grapples OBSS
03:37 PM...03...21...00...Equipment airlock preps for Monday spacewalk
04:07 PM...03...21...30...SRMS ungrapples OBSS
04:07 PM...03...21...30...SAFER emergency jetpack checkout
04:22 PM...03...21...45...SSRMS berths OBSS
04:52 PM...03...22...15...Spacewalk tools configured
05:00 PM...03...22...24...Mission status briefing on NASA TV
05:07 PM...03...22...30...SSRMS releases OBSS
05:27 PM...03...22...50...Educational experiment transfer and video
06:32 PM...03...23...55...Logistics transfer tagup
06:47 PM...04...00...10...Spacewalk procedures review
07:47 PM...04...01...10...Station arm walkoff to lab
09:02 PM...04...02...25...EVA-2: Mask pre-breathe
09:47 PM...04...03...10...EVA-2: Airlock depress to 10.2 psi
10:07 PM...04...03...30...ISS crew sleep begins
10:37 PM...04...04...00...STS crew sleep begins
12:00 AM...03...05...24...Daily video highlights reel on NASA TV
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MISSION INDEX |
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VIDEO:
PREVIEW OF SPACEWALK NO. 1 