Great run down of the planned Atlantis mission and its three spacewalks, which could launch as soon as Aug 27. Each spacewalk is scheduled to last at least six and a half hours.
"STS-115 mission specialists Joseph Tanner and Stefanyshyn-Piper will perform the first and third spacewalks of their mission, with their crewmates Daniel Burbank and Canadian Space Agency astronaut Steven MacLean tasked with the second EVA.....MacLean and ISS astronaut Jeffrey Williams will wield the space station’s robotic arm to attach the 17.5-ton truss segment to the outboard end of the station’s Port 1 (P1) truss. Once three of four motor driven bolts have secured the segment to the ISS, Tanner and Stefanyshyn-Piper begin their spacewalk to connect vital power and cooling, deploy two phone booth-sized cylinders – each containing solar arrays masts – and swing out arm-like boxes holding the folded up solar blankets for each array."
It gets even more complicated after that. This mission has one of the heaviest shuttle payloads ever, and is one of the more complicated in shuttle history. Fortunately, the spacewalk duos have had 4 years to practice and can even do one another's jobs.
"The primary goal of EVA 2 on Flight Day 5 seems basic – removing a plethora of locks and restraints that secured the P3/P4 truss segments in place during Atlantis’ launch. But for Burbank and MacLean, the tasks are vital. The two astronauts will spend more than six hours prying open thermal covers and removing 16 launch locks – and six restraints – latching a car-sized wheel called the Solar Alpha Rotary Joint (SARJ) in place. The joint, located between the P3 and P4 truss, will allow outbound port trusses to rotate independently of the ISS so their solar arrays continuously track the Sun. "
The plan is to unfurl the solar arrays on Day 6 of the mission -- and these arrays will eventually provide up to 20% of the power for the completed station. The third spacewalk on Day 7 will primarily do clean up work, deploying a radiator to cool the array and clear the truss for the Mobile Transporter that moves the station's robotic arm. One other notable feature of the mission is the first use of the Quest airlock as a pre-EVA prep area to save time suiting up and egressing the station. By lowering the air pressure in the airlock, astronoauts can save up to an hour's time purging nitrogen from their bloodstreams before exiting the station.
We live in amazing times, my friends.