Following standard post-Columbia procedure, NASA will monitor Endeavour's launching with scores of cameras, radars and other sensors to look for any signs of foam insulation falling from the ship's external tank that might threaten impact damage to the shuttle's fragile heat shield.

Based on the performance of the shuttle Atlantis' external tank during the most recent flight in June, NASA appears to have turned the corner in its work to minimize foam shedding in the wake of the Columbia disaster. Atlantis' tank was one of the most debris free to date and NASA managers are optimistic Endeavour's tank and subsequent models will perform well.

But that doesn't mean leaving anything to chance. As with all post-Columbia crews, the Endeavour astronauts will unlimber the shuttle's robot arm the day after launch, attach a 50-foot instrument boom and inspect the shuttle's critical reinforced carbon carbon nose cap and wing leading edge panels with a laser scanner and a high-resolution camera.

The shuttle's heat shield tiles will receive their closest scrutiny on flight day three during final approach to the space station. Passing 600 feet directly below the outpost, Kelly will guide Endeavour through a slow 360-degree back flip known as a rendezvous pitch maneuver, or RPM, exposing the ship's belly to powerful digital cameras wielded by the station crew.

With the RPM maneuver complete, Kelly will guide Endeavour to a point about 400 feet directly in front of the station. From there, with the orbiter's nose pointing toward deep space and its open payload bay toward the station, Kelly will guide the shuttle to a docking with pressurized mating adapter No. 2 on the forward end of the Destiny laboratory module.

"We'll come up from beneath the space station," Kelly explained in a NASA interview. "And inside of 1,000 feet, we'll do this rendezvous pitch maneuver where the shuttle flips around. And then once that's complete, we'll get the vehicle stabilized below the space station, close in a little bit further and then start a fly-around where I'll fly the shuttle 90 degrees to what's called the V-bar. It's really the velocity vector."

"So, I'm flying in front of the space station as we both kind of head around the same orbit and then close in from there. And basically you fly the vehicle manually using these camera views and out-the-window views until you get about two inches away, and then you push a button and the autopilot fires a series of firings to kind of complete the last part of the contact to make sure that you have the right contact parameters where you're actually connecting the two docking systems."

When the docking systems engage, the new station-to-shuttle power transfer system, or SSPTS, will automatically plug into the lab's solar power system. But the power converters in the orbiter will not be activated until later in the day. First up for the shuttle crew is a brief "meet and greet" with their station colleagues in the Destiny module and work to pull the S5 solar array spacer truss out of Endeavour's cargo bay.

Caldwell, operating the shuttle's robot arm, will begin that process about two hours after hatch opening, pulling the S5 truss out of the cargo bay and positioning it for handoff to the station arm. Hobaugh, operating the lab's Canadarm2, will then grapple the truss and move it to an overnight storage location.

Mastracchio and Williams, meanwhile, plan to get the station's Quest airlock module ready for their first spacewalk the next day to attach S5 to the S4 solar array segment on the right end of the lab's main power truss. Both astronauts will spend the night in the airlock at a reduced pressure of 10.2 pounds per square inch to help purge nitrogen from their bloodstreams and prevent the bends after working in their 5-psi spacesuits.

Before the spacewalk begins the following day, the S4 solar array's SARJ will be stopped and the array locked in place in preparation for the attachment of S5. Mastracchio and Williams plan to begin their first spacewalk around 1:07 p.m. on Aug. 11.

"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."

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.

DATE/EDT.......HH...MM...SS...EVENT

08/11/07
Sat 12:07 AM...02...05...30...STS crew sleep begin
Sat 08:07 AM...02...13...30...STS/ISS crew wakeup
Sat 08:47 AM...02...14...10...EVA-1: 14.7 psi repress
Sat 09:07 AM...02...14...30...EVA-1: Hygiene break
Sat 09:32 AM...02...14...55...EVA-1: Crew lock depress to 10.2 psi
Sat 09:57 AM...02...15...20...EVA-1: Campout EVA preps
Sat 11:27 AM...02...16...50...EVA-1: Spacesuit purge
Sat 11:27 AM...02...16...50...SSPTS shut down for EVA-1
Sat 11:42 AM...02...17...05...EVA-1: Spacesuit prebreathe
Sat 12:32 PM...02...17...55...EVA-1: Crew lock depressurization
Sat 12:37 PM...02...18...00...SSRMS to pre-install position
Sat 01:07 PM...02...18...30...EVA-1: Airlock egress
Sat 01:22 PM...02...18...45...SSRMS support
Sat 01:22 PM...02...18...45...EVA-1: Sortie setup
Sat 01:52 PM...02...19...15...EVA-1: S4/S5 launch lock removal
Sat 02:27 PM...02...19...50...SVA-1: S5 installation
Sat 03:37 PM...02...21...00...SSRMS ungrapples S5
Sat 03:57 PM...02...21...20...EVA-1: PVR grapple fixture relocation
Sat 04:57 PM...02...22...20...EVA-1: Get ahead tasks
Sat 05:12 PM...02...22...35...EVA-1: S5 cleanup
Sat 05:47 PM...02...23...10...EVA-1: P6 forward radiator retraction
Sat 06:57 PM...03...00...20...EVA-1: Payload bay cleanup
Sat 07:12 PM...03...00...35...EVA-1: Airlock ingress
Sat 07:32 PM...03...00...55...EVA-1: Airlock repressurization
Sat 07:47 PM...03...01...10...Spacesuit servicing
Sat 09:02 PM...03...02...25...Transfer tagup
Sat 09:22 PM...03...02...45...SSPTS re-activated
Sat 11:07 PM...03...04...30...ISS crew sleep begins
Sat 11:37 PM...03...05...00...STS crew sleep begins

Once again, Mastracchio and Williams plan to camp out in the Quest airlock to purge nitrogen from their blood in preparation for EVA-2. The goal of the second excursion is to remove and replace one of the station's four control moment gyroscopes, or CMGs.

The station uses four massive CMGs to control the lab's orientation without burning hard-to-replace rocket fuel. One of them, CMG No. 3, acted up last year and was taken off line on Oct. 10, 2006. The refurbished unit being installed during Endeavour's mission will restore full redundancy to the critical orientation system. For readers interested in technical detail, here is a description from an earlier NASA press kit:

The motion control subsystem (MCS) hardware launched as part of the Z1 element includes the CMGs and the CMG assemblies.

The CMG assembly consists of four CMGs and a micrometeorite/orbital debris shield. The four CMGs, which will control the attitude of the ISS, have a spherical momentum storage capability of 14,000 ft-lb/sec, the scalar sum of the individual CMG wheel moments. The momentum stored in the CMG system at any given time equals the vector sum of the individual CMG momentum vectors.

To maintain the ISS in the desired attitude, the CMG system must cancel, or absorb, the momentum generated by the disturbance torques acting on the station. If the average disturbance torque is nonzero, the resulting CMG output torque is also nonzero, and momentum builds up in the CMG system. When the CMG system saturates, it is unable to generate the torque required to cancel the disturbance torque, which results in the loss of attitude control.

The CMG system saturates when momentum vectors have become parallel and only momentum vectors change. When this happens, control torques perpendicular to this parallel line are possible, and controllability about the parallel line is lost.

Russian segment thrusters are used to desaturate the CMGs.

An ISS CMG consists of a large flat wheel that rotates at a constant speed (6,600 rpm) and develops an angular momentum of 3,500 ft-lb/sec about its spin axis. This rotating wheel is mounted in a two-degree-of-freedom gimbal system that can point the spin axis (momentum vector) of the wheel in any direction.

At least two CMGs are needed to provide attitude control. The CMG generates an output reaction torque that is applied to the ISS by inertially changing the direction of its wheel momentum. The CMG's output torque has two components, one proportional to the rate of change of the CMG gimbals and a second proportional to the inertial body rate of the ISS as sensed at the CMG base. Because the momentum along the direction of the spin axis is fixed, the output torque is constrained to lie in the plane of the wheel. That is why one CMG cannot provide the three-axis torque needed to control the attitude of the ISS.

Each CMG has a thermostatically controlled survival heater to keep it within thermal limits before the CMGs are activated on Mission 5A. The heaters are rated at 120 watts and have an operating temperature range of -42 to -35 F.

"Our second spacewalk, I think, is almost going to be as exciting as the first," Williams said. "Our job is to replace one of the gyros that we use to stabilize the position of the space station. There are four gyros that we currently have on board the space station. The gyro essentially is a spinning disk that conserves momentum. It's used to stabilize the station. One of them isn't functioning properly, so we have to replace it.

"To do that, Rick and I will go up to the Z1 area, take out the old gyro that's not working properly, temporarily stow it, then Rick is going to go down to the payload bay of the space shuttle, I'm going to get onto the robotic arm and I will go down to the payload bay of the space shuttle on the robotic arm. We're going to remove the new CMG, the new gyro, from the payload bay of the shuttle. It weighs 1,200 pounds. I'm going to be holding on to it on each side, with my heels turned outward holding me in place in the foot restraint on the end of the robotic arm.

"And then we're going to come back up to the stowage platform, ESP-2, right by the airlock, install the stowage assembly for the new gyro, then take the new gyro off, bring it back to the work site where we had the old gyro, swap the two and bring the old one back to the stowage platform. A lot of choreography there. It gets kind of confusing about which is going where and things. So we've worked very hard on the choreography."

DATE/EDT.......HH...MM...SS...EVENT

08/13/07
Mon 07:07 AM...04...12...30...STS/ISS crew wakeup
Mon 07:47 AM...04...13...10...EVA-2: Airlock repress to 14.7 psi
Mon 08:07 AM...04...13...30...EVA-2: Hygiene break
Mon 08:37 AM...04...14...00...EVA-2: Airlock depress to 10.2 psi
Mon 08:57 AM...04...14...20...EVA-2: Campout EVA prep
Mon 10:07 AM...04...15...30...Logistics transfers resume
Mon 10:27 AM...04...15...50...EVA-2: Spacesuit purge
Mon 11:32 AM...04...16...55...EVA-2: Crew lock depressurization
Mon 12:07 PM...04...17...30...EVA-2: Airlock egress
Mon 12:22 PM...04...17...45...EVA-2: Setup
Mon 12:52 PM...04...18...15...EVA-2: Remove, temp stow failed CMG
Mon 01:22 PM...04...18...45...EVA-2: Transfer new CMG to ESP-2
Mon 02:07 PM...04...19...30...Crew meals begin
Mon 02:52 PM...04...20...15...EVA-2: Remove new CMG from ESP-2
Mon 03:42 PM...04...21...05...EVA-2: Install new CMG on Z1
Mon 04:37 PM...04...22...00...EVA-2: Install failed CMG on ESP-2
Mon 05:47 PM...04...23...10...EVA-2: Payload bay cleanup
Mon 06:12 PM...04...23...35...EVA-2: Airlock ingress
Mon 06:32 PM...04...23...55...EVA-2: Airlock repressurization
Mon 06:47 PM...05...00...10...Spacesuit servicing
Mon 08:07 PM...05...01...30...Transfer tagup
Mon 10:07 PM...05...03...30...ISS crew sleep begins
Mon 10:37 PM...05...04...00...STS crew sleep begins

That night, Mastracchio and station astronaut Clay Anderson will sleep in the Quest airlock module to prepare for spacewalk No. 3.

Anderson originally was scheduled to take off aboard Endeavour to replace long-duration station astronaut Sunita Williams. But after the shuttle Atlantis was delayed three months, from March to June, because of hail damage to the ship's external tank, NASA managers decided to launch Anderson aboard Atlantis and to bring Williams home in June as originally planned. Anderson's place in Endeavour's crew was given to Drew.

"Once those guys arrive, I'll pretty much do the same jobs with them that I was planning on doing had I launched with that crew, and that includes EVAs No. 3 and 4, one with Rick Mastracchio and one with Dave Williams, and then I'll also be helping Charlie Hobaugh when he manipulates the arm to install the S5 truss," Anderson said in an interview.

The goals of the third spacewalk are to upgrade the station's S-band communications system; to relocate two logistics carts attached to the mobile transporter on the front side of the main solar array truss; and to retrieve two experiment packages.

"We're going to move the SASA antenna off of P6," Mastracchio said in a NASA interview. "Again, P6 is going to eventually be moved from the zenith part of station to the port side. So, we have to kind of clean up P6. And part of it is to move this large antenna off of P6 and install it on P1. While I'm doing that, Clay Anderson, who will be living on space station when we get there, will be installing two electronics boxes to support that antenna. That will give the space station its second set of antennas, I should say, communication antenna capability.

"The second part of that EVA is we've got two large CETA carts that run along the rail, the tracks on the truss. We'll be moving those CETA carts from the one side to the other side in preparation for a future mission. And then, there's some other clean-up work after that."

DATE/EDT.......HH...MM...SS...EVENT

08/15/07
Wed 06:37 AM...06...12...00...STS/ISS crew wakeup
Wed 07:17 AM...06...12...40...EVA-3: Airlock repress to 14.7 psi
Wed 07:37 AM...06...13...00...EVA-3: Hygiene break
Wed 07:57 AM...06...13...20...EVA-3: Airlock depress to 10.2 psi
Wed 08:27 AM...06...13...50...EVA-3; Campout EVA prep
Wed 09:57 AM...06...15...20...EVA-3: Spacesuit purge
Wed 10:12 AM...06...15...35...EVA-3: Spacesuit pre-breathe
Wed 11:02 AM...06...16...25...EVA-3: Airlock depressurization
Wed 11:37 AM...06...17...00...EVA-3: Airlock egress
Wed 11:52 AM...06...17...15...EVA-3: Setup
Wed 12:32 PM...06...17...55...EVA-3: EV1: P6 SASA relocation
Wed 12:32 PM...06...17...55...EVA-3: EV3: P1 BSP and transponder installation
Wed 02:27 PM...06...19...50...EVA-3: CETA 1 move starboard
Wed 03:07 PM...06...20...30...Crew meals
Wed 03:27 PM...06...20...50...EVA-3: CETA 2 move starboard
Wed 04:27 PM...06...21...50...EVA-3: EV1: SASA gimbal locks
Wed 04:27 PM...06...21...50...EVA-3: EV3: P6 transponder retrieval
Wed 04:57 PM...06...22...20...EVA-3: EV1: MISSE 3 and 4 removal
Wed 05:07 PM...06...22...30...Spacehab debris shields
Wed 05:42 PM...06...23...05...EVA-3: Airlock ingress
Wed 06:02 PM...06...23...25...EVA-3: Airlock repressurization
Wed 06:12 PM...06...23...35...SRMS powerdown
Wed 06:27 PM...06...23...50...MISSE-3 transfer
Wed 06:47 PM...07...00...10...MISSE-4 transfer
Wed 07:42 PM...07...01...05...Transfer tagup
Wed 09:37 PM...07...03...00...ISS crew sleep begins
Wed 10:07 PM...07...03...30...STS crew sleep begins

If the mission extension isn't possible for some reason, Kelly and company will wrap up their transfer work on flight day nine, enjoy a final joint meal and seal hatches between the shuttle and the space station in preparation for undocking on flight day 10. Under that scenario, Endeavour would undock on Aug. 17 and land around 2:10 p.m. on Aug. 19.

But NASA managers are optimistic the SSPTS will work normally, allowing the mission extension and the fourth spacewalk. The tasks planned for EVA-4 are not critical, but they will save time during upcoming assembly missions and NASA managers would like to get the work done now if possible.

Assuming the mission is extended, flight day nine will be devoted to logistics transfer work.

"We have about 110 hours of transfer activity scheduled for the mission, that includes the hardware in the Spacehab as well as the hardware in the middeck," said station flight director Joel Montalbano. "If we don't get a good jump on this during the flight day five, flight day nine is our big day.

"Why are we waiting until flight day nine? One of the things we try and do is during robotics operations you don't want people doing transfer operations. And the reason is, for robotics operations you're basically in the U.S. laboratory trying to do critical movements with the robotic arm and you don't want anybody running by you or floating by you with a bag and bumping your arm or anything. So we basically baseline no transfer activities during robotics."

For spacewalk No. 4, Anderson and Williams will spend a final night in the Quest airlock before venturing outside again on flight day 10 to install wireless instrumentation equipment on the station's solar array truss; to tie down micrometeoroid debris shields on the Destiny module; and to install clamps on the power truss that will permit a future crew to temporarily store a heat shield inspection boom on the station.

DATE/EDT.......HH...MM...SS...EVENT

08/17/07
Fri 05:37 AM...08...11...00...STS/ISS crew wakeup
Fri 06:17 AM...08...11...40...EVA-4: Airlock repress to 14.7 psi
Fri 06:37 AM...08...12...00...EVA-4: Hygiene break
Fri 06:57 AM...08...12...20...EVA-4: Airlock depress to 10.2 psi
Fri 07:27 AM...08...12...50...EVA-4: Campout EVA prep
Fri 08:37 AM...08...14...00...Logistics transfers resume
Fri 08:57 AM...08...14...20...EVA-4: Spacesuit purge
Fri 09:12 AM...08...14...35...EVA-4: Spacesuit pre-breathe
Fri 10:02 AM...08...15...25...EVA-4: Crew lock depress
Fri 10:37 AM...08...16...00...EVA-4: Airlock egress and setup
Fri 10:52 AM...08...16...15...EVA-4: OBSS OSE installation
Fri 12:22 PM...08...17...45...EVA-4: EV3: EWIS antenna installation
Fri 12:32 PM...08...17...55...EVA-4: EV1: EWIS antenna installation
Fri 02:02 PM...08...19...25...EVA-4: Lab debris shields (C2-3)
Fri 02:32 PM...08...19...55...EVA-4: Lab debris shields (C2-2)
Fri 03:02 PM...08...20...25...EVA-4: CP1 WETA antenna installation
Fri 04:17 PM...08...21...40...EVA-4: Payload bay cleanup
Fri 04:42 PM...08...22...05...EVA-4: Airlock ingress
Fri 05:02 PM...08...22...25...EVA-4: Airlock repressurization
Fri 05:17 PM...08...22...40...Post-EVA spacesuit servicing
Fri 06:07 PM...08...23...30...Transfer tagup
Fri 08:37 PM...09...02...00...ISS crew sleep begins
Fri 09:07 PM...09...02...30...STS crew sleep begins

"We will close the hatch between the station and the shuttle the night before we undock," Kelly said. "When we wake up the next morning, there are some things we need to do with the tunnel to get it ready to undock. And then we command the undocking and some springs will push off the shuttle at a specific rate. The pilot, Charlie Hobaugh, is actually doing the flying during the undocking.

"He'll back away to about 600 feet and then he will manually fly the shuttle - very similar to what we do during the docking when we go from underneath the space station to in front of it. But he'll fly the shuttle all the way around, probably a full lap (360 degrees). We do that to take photo documentation of the outside of the space station just to make sure that it's as we expect it to be."

After the fly around, the astronauts will use the shuttle's robot arm a final time to carry one a so-called late inspection to make sure no space junk or micrometeoroids hit the shuttle's critical nose cap or wing leading edge panels while Endeavour was in orbit.

"If we see something during those inspections that we don't like, there are several things we can do," Kelly said. "One is do nothing, if there is damage that's OK to land with. The other is we could potentially send our EVA crew members out to repair it. Or we could go back to the space station and dock and use that as a safe haven for the crew.

"After that day, we use the next day to get the shuttle back configured from kind of a spaceship to a re-entry vehicle. There's a lot of work to be done there. We check out the flight control system. We check out the reaction control system jets, make sure they're all working OK. And then the very next day we come back."

THE END

Additional coverage for subscribers:
VIDEO: STS-118 PRE-LAUNCH NEWS CONFERENCE PLAY
VIDEO: MONDAY MORNING'S STATUS BRIEFING PLAY
VIDEO: SUNDAY COUNTDOWN AND WEATHER UPDATE PLAY
VIDEO: CREW ARRIVES AT KENNEDY SPACE CENTER PLAY
VIDEO: COMMENTS FROM EACH OF THE ASTRONAUTS PLAY
MORE: STS-118 VIDEO COVERAGE
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