With the R-bar pitch maneuver complete, Stuckow will guide Atlantis through a slow quarter-loop to a point about 400 feet directly in front of the station with the shuttle's tail pointed toward Earth and its open payload bay pointed toward pressurized mating adapter No. 2 on the front of the Destiny module. From there, flying the shuttle from the aft flight deck, Sturckow will manually guide Atlantis to a precision docking.

After leak checks and hatch opening, Yurchikhin, Kotov and Williams will welcome the shuttle astronauts aboard and provide a quick safety briefing.

On past flights, rendezvous and docking would have capped a busy day in space. But for Atlantis' crew, docking will kick off a busy afternoon of work to pull the S3/S4 truss segment from the shuttle's cargo bay so it can be handed off to the station's robot arm and safely "parked" overnight.

"The robotic arm operations will actually start immediately after docking, but even prior to us opening the hatches between the space shuttle and the space station," Archambault said in a NASA interview. "Right after docking Pat Forrester and myself will go ahead and grapple the payload with the space shuttle robotic arm. This is about a 30-minute procedure. Pat will be flying the arm and I'll be assisting him, but it's kind of a tricky procedure in that Pat's going to have to reach across the belly of the shuttle payload bay and over the top of the payload and grab it from the starboard grapple fixture on the payload.

Forrester will have just an inch or so of clearance between S3/S4 and the OBSS heat shield inspection boom mounted along the right wall of Atlantis' payload bay. As he is lifting the payload straight up from its perch in the payload bay, he will have to jog it slightly to the left to avoid the OBSS. It is a delicate procedure because of the payload's inertia and the need to avoid any overshoots that could cause it to hit anything.

A similar maneuver was required last September when the P3/P4 truss segments were installed.

"I am what we call R1 for the space shuttle arm," Forrester said in a NASA interview. "I will reach into the payload bay of the space shuttle and will grapple the S3/S4 truss. The grapple fixture is on the S3 portion, and right after that the hatches will be opened, we'll say our hellos to everyone on board station and then we'll get right back to work. And, with Lee Archambault as my R2, we will pull the S3/S4 Truss out of the bay, put it through a series of maneuvers and bring it to a point where we can turn it over to the computers, what we call automated maneuvers, and then the computers will fly that arm and the truss section attached out to a position where we can hand it off to the space station robotic arm.

"The S3/S4 weighs about 35,000 pounds, very similar to P3/P4. It's just a little bit heavier, and I think to date this will be the heaviest payload that we've delivered to station. The folks, the trainers in the robotic area have simplified things for us and have designed a series of what we would call one-axis maneuvers as we bring it out of the bay and then shift it a little bit to the port side of the orbiter to move it away from the new boom that we carry for inspections. Then we'll bring it out a little bit higher, push it back a little, do a couple other small maneuvers, and then it'll be in a position for the computers to fly. So actually it's a very simple task."

At that point, Archambault said, "I will hurry over to the space station and then assist Suni Williams, who's one of our space station crew members, and she will have the space station robotic arm ready to go. She will move in and double grapple, if you will, the payload with the space station robotic arm. And then once we get the payload grappled with the space station robotic arm, it will now be double grappled, and then I'll hurry back over to the space shuttle and then assist Pat in ungrappling the space shuttle robotic arm from the payload, and that's where we'll complete our arm operations for that day. We'll leave the payload grappled to the space station robotic arm in that handoff position overnight."

Reilly and Olivas will spend the night sealed up in the Quest airlock module as part of a new "camp out" procedure. The airlock's pressure will be lowered from 14.2 pounds per square inch to 10.2 psi to help the spacewalkers purge nitrogen from their blood and prevent the bends when working in their 5-psi spacesuits. The next morning, after a "hygiene break," Reilly and Olivas will begin donning their spacesuits. Archambault, meanwhile, will return to the Destiny module, take control of Canadarm 2 and move S3/S4 up to a pre-install position just a few inches from S1. He will be assisted by Williams.

"On the morning of flight day 4 we're going to start our space station robotic arm operations by performing an automated maneuver, takes about 40 or so minutes, to put it in a pre-install position which is approximately a meter and a half from the S1 truss," Archambault said. "In between that meter and a half and actually installing it, we're going to pause for a few moments at around 45 centimeters, to allow our Space Vision System to go ahead and give me a an updated depiction of my exact position with respect to the S1 truss, and be able to install this thing within a one or two centimeter tolerance."

The Space Vision System uses television cameras and powerful software to measure the precise locations of large black dots attached to the truss elements. The SVS software computes the relative positions of the dots to give the arm operator very precise distance and orientation information. Temperature effects can cause distortions of up to five inches and misalignments of 1 to 2 degrees. The SVS helps compensate for any such effects.

Once S1 and S3 are in close proximity, a large claw on the S1 truss will rotate around a capture bar on the S3 segment to pull the two together. Four motorized bolts on S1 then will drive into attachment fittings on S3, firmly locking the two truss elements together. Three of four bolts must engage to call the operation a success. At that point, Reilly and Olivas, now suited up in the Quest airlock, will float out into space and begin the first of two critical spacewalks to hook up and activate S3/S4.

Continue to Part 6 -->