Astronauts will replace three batteries for the International Space Station and fix Atlantis' robot arm extension camera cable on today's spacewalk, the second of the STS-132 mission.
The crew began the day at 1:20 a.m. CDT to "Start Me Up" by the Rolling Stones, played for Piers Sellers, who with Garrett Reisman will drive the station's robotic arm during the spacewalk.
Spacewalkers Stephen Bowen and Michael Good are expected to egress from the Quest airlock at 6:15 a.m. to get an early start on their outing.
During the spacewalk, Ken Ham, Atlantis' commander, will provide photo and television support, and pilot Tony Antonelli will serve as the IVA, or spacewalk choreographer. Tracy Caldwell Dyson, ISS flight engineer, will assist with spacewalk preparations as well.
Her Expedition 23 counterparts, commander Oleg Kotov and Alexander Skvortsov, Mikhail Kornienko, Soichi Noguchi and T.J. Creamer, all flight engineers, will work on varied space station activities, including packing unneeded supplies into the Progress and Soyuz spacecraft.
Atlantis, as photographed during the mission's first spacwalk. Credit: NASA
STS-132 mission specialists Stephen Bowen and Michael Good switched their spacesuits to battery power at 5:38 a.m. CDT, signifying the start of today's 6.5-hour spacewalk 35 minutes early.
Bowen's first activity was to address a snagged cable on the camera on the end of Atlantis' robotic arm extension orbiter boom sensor system.
"Okay, I have it unsnagged," radioed Bowen, just seconds after being given the go for the task by Mission Control.
"Well done superhero," replied Tony Antonelli, Atlantis' pilot and the spacewalk choreographer. "Now let's see if you can handle the tie wraps."
This brief task was added after discovering early in the mission that the pinch in the cable was inhibiting the camera from maneuvering correctly. Bowen looped a tie wrap on two cables to relieve the snag, enabling full use if needed of a laser range imager and intensified video camera on the extension's pan-tilt assembly.
Credit: NASA TV
The primary work for Bowen and Good is to exchange three batteries on the station's port, or left side truss. The spacewalk may be extended to accomplish a fourth battery exchange.
If time permits, the spacewalkers will attempt to tighten bolts connecting a back-up space-to-ground antenna dish to its boom, both of which were installed during the first spacewalk.
Bowen, lead for this spacewalk, is wearing the spacesuit with a solid red stripe. Good's suit has a band of red and white barber pole stripes.
Having successfully freed a snagged camera cable at the end of Atlantis' orbiter boom sensor system, Stephen Bowen, together with spacewalker Michael Good, have moved on to replacing at least three of the "B"-side port 6 (P6) solar array's six batteries.
Each of the International Space Station's two wings of the four arrays are designated either A or B. The six "A"-side P6 batteries were replaced on the STS-127 mission in July 2009.
The new batteries are designated by letters A through F; the old batteries numbered one through six. Good will remove an old battery from the solar array's integrated electrical assembly using two "scoops" that Bowen will have installed to make it possible to maneuver the 40-by-36-by-18-inch, 375 pound batteries.
Credit: NASA TV
After removing two bolts, Good will hand off the first old battery, number one, get out of the foot restraint in which he was working, move closer to Bowen and take hold of the battery again. Bowen will then release the battery, move slightly farther down the station's backbone, or truss, and position himself to take hold of the battery.
Good will hand the old battery to Bowen and then move himself closer to take hold of it once again. The process, called "shepherding," creates the appearance the spacewalkers are "inch-worming" along the truss, except that one person is always holding a battery.
To install the old battery in a temporary storage location on the integrated assembly, Good will use one of the scoops to attach it to a tether. The spacewalkers will then remove the first new battery, battery A, from the Integrated Cargo Carrier (ICC) launched on Atlantis and shepherd it back for installation in slot 1.
The next step will be to remove battery 2, shepherd it to the pallet to be installed in slot A, and remove battery B to be installed in slot 2.
The astronauts will continue the process until three new batteries have been installed, then they'll remove the first old battery from its temporary storage location and install it in the vacant spot on the pallet. The order will be:
Battery 1 to temporary storage
Battery A to Slot 1
Battery 2 to Slot A
Battery B to Slot 2
Battery 3 to Slot B
Battery C to Slot 3
Battery 1 to Slot C
Each of the batteries has 38 lightweight nickel hydrogen cells providing 8 kilowatts of electrical power. Designed to work for 6.5 years, the batteries Bowen and Good are replacing were launched in November 2000.
Spacewalkers Stephen Bowen and Michael Good finished replacing three solar array batteries as was the plan for their spacewalk at about 10 a.m. CDT, nearly four hours and 30 minutes into their planned 6.5-hour outing.
Working ahead of schedule, flight controllers gave the astronauts the go to replace the fourth battery, battery D on the Port 6 (P6) truss Channel B power string, an activity originally slated for the STS-132 mission's third spacewalk. Bowen and Good installed that battery at 10:52 a.m. CDT.
Credit: NASA TV
After cleaning up the battery worksite and stopping at the Quest airlock, Bowen and Good then moved over to the new back-up Space-To-Ground Antenna (SGAnt) that was installed during Monday's spacewalk to tighten the bolts connecting its dish to its boom, eliminating the 1-millimeter gap between them.
"Great job, that does it, SGAnt is on firmly," capcom Steve Swanson radioed from Mission Control
The antenna anchored, the spacewalkers worked to remove a tether that was holding the dish and boom together and then released the gimbal, or launch, locks, allowing the antenna dish to rotate.
At 12:47 p.m. CDT, spacewalkers Steve Bowen and Michael Good began repressurizing the International Space Station's Quest airlock, ending the STS-132 mission's second of three planned spacewalks seven hours and nine minutes after it began.
The two astronauts successfully unsnagged a camera cable at the end of Atlantis' robotic arm extension, replaced four batteries for the port 6 (P6) solar arrays -- one more than planned, and tightened the bolts holding the dish to the boom on the new back-up Space-to-Ground Antenna (SGAnt) installed during the mission's first spacewalk.
"Great job," commented pilot and spacewalk choreographer Tony Antonelli after Bowen and Good were back inside the airlock. "You guys did really good work with the batteries on the truss but especially getting them back on the pallet."
"And a good job to the guys on the ground," he continued. "They came up with a really good procedure for dealing with the SGAnt dish. It was easy to follow, straightforward and it led to success. So, great work."
"I agree, that was really good," replied Bowen.
"Tony, great job today keeping up and leading us through it man," added Good. "You were all over the place."
"You had a lot of procedures to follow there, Tony," Bowen said.
"Oh yeah, and I forgot Steve-O, you fixed the pan and tilt unit on the [orbiter boom's intensified video camera] ITVC. I completely forgot that was today," said Antonelli.
"That was earlier today," confirmed Bowen.
Credit: NASA TV
This was the 238th spacewalk conducted by U.S. astronauts, the fifth for Bowen and the third for Good. It was the 145th in support of International Space Station assembly and maintenance, totaling 908 hours, 7 minutes.