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Spacewalkers to begin replacing giant batteries BY WILLIAM HARWOOD STORY WRITTEN FOR CBS NEWS "SPACE PLACE" & USED WITH PERMISSION Posted: May 19, 2010 
Astronauts Michael Good and Stephen Bowen are gearing up for a planned six-and-a-half-hour spacewalk, the first of two devoted to replacing six of the International Space Station's oldest solar array batteries.
NASA's Damage Assessment Team, based on imagery and other data collected earlier in the mission, has not spotted any damage that could cause problems during re-entry. While flight controllers are still considering using the repaired inspection boom for additional surveys of Atlantis' left wing leading edge panels, the inspections are not considered a requirement. "Although the regular suite of imagery was not obtained, the teams used all the available assets to perform an engineering assessment on the thermal protection system," NASA's Mission Management Team said in an overnight message to the crew. "The DAT cleared the TPS for entry based on these assessments. For the RCC (reinforced carbon carbon nose cap and wing leading edge panels), the DAT has high confidence, based on all available data, that there were no signatures indicating any damage from ascent debris. Based on these conclusions, there were no requirements from the DAT for additional docked surveys. Even without the full suite of imagery the MMT felt that it was a very low risk to wait until late inspection for the next survey." The so-called late inspection is typically carried out after undocking to look for any signs of damage that might have occurred since the initial post-launch examination. Today's spacewalk is scheduled to begin around 7:15 a.m. EDT. This will be the 145th spacewalk devoted to station assembly and maintenance since construction began in 1998, the ninth so far this year and the second of three planned by the Atlantis astronauts. Good, call sign EV-2, is a veteran of two Hubble Space Telescope spacewalks while Bowen, call sign EV-1, will be making his fifth excursion, his second during the current mission. Today's excursion is the first of two devoted to replacing batteries in the P6 solar array at the far left end of the space station's power truss. The space station's solar array batteries are charged during daylight and provide the lab's electrical power during orbital darkness. The P6 array, one of four NASA-supplied solar generators, was launched in November 2000. Six of its nickel-hydrogen batteries were replaced during a shuttle flight in July 2009 and the other six, well past their 6.5-year design life, are being replaced during Atlantis' mission. "These aren't double As," Good joked before launch. "One of my brothers likes to give me a hard time about flying up in space and changing batteries, he thinks this is not a very difficult task, not a big deal. But these are like 400-pound nickel-hydrogen batteries, they're the size of a big suitcase, probably bigger than the airlines would let you take on without charging you extra. And they're pretty tricky. ... The alignment and the tolerances are very tight."
"This whole battery R & R is like a shell game, or one of those puzzles where you move the numbers around," said Lisa Shore, the lead spacewalk officer for Atlantis' mission. "The first thing you need to do is create an open spot to start the shuffle. So we'll install some handling aids onto the first battery we intend to remove. We're also going to install a ball stack, it's a metal tether that can be rigidized to temporarily stow the battery during the EVAs." Good will be responsible for removing batteries from the truss and installing their replacements while Bowen moves batteries to and from the cargo carrier. After the first battery is removed from P6 and mounted on the ball stack, Bowen will pull a replacement battery from the cargo carrier. Both astronauts will carefully maneuver the massive power pack into place, taking special care not to damage fragile cooling fins on the back side. Once the new battery is in place and electrically connected, the astronauts will move the old battery from its temporary mounting point and install it in the cargo carrier for return to Earth. That process will continue until at least three and possibly four batteries are installed. The remainder will be installed during the third and final spacewalk Friday. "It's all about batteries," Good said before launch. "We're doing six of them on this flight and I get to do them all, with Steve on one EVA and Garret (Reisman) on the other. We've got to get them all done. They come up on a pallet in the shuttle's payload bay, the arm gets them out there to the very end of the truss on the space station, out there amongst the solar arrays. And that's probably got my biggest concern spacewalking wise, just getting through those batteries." Lessons learned during the 2009 battery replacement work will be applied, but Good said problems are not unexpected. "They got through them all, but they had a lot of curve balls thrown at them," he said. "The batteries are out there on this pallet, and they're on the end of the arm, and it's stretched out as far as it can go to get them out there, just to get them close. It can't actually get them all the way out to where we're going to be installing them. So we're going to take them off the pallet, shepherd them over to where they're going to go in and out of the truss, and it's kind of tricky to get them in and out." Each battery is held in place by two bolts and "it seems like it would be pretty simple just to put them in and screw two bolts in," Good said. "But they go in on these posts, and they have to align just perfectly, and you have to overcome a soft dock to get them set in there before you can drive the bolts. And if you don't get it all the way in there just right, you could drive that bolt all you want, but you'd never catch a thread to make it draw into the slot where it goes. So there's going to be some work there." Said Bowen: "A single stuck bolt, something slightly misaligned (can cause problems). ... It's a very delicate task. Hopefully we'll learn from the first one we do, we'll get into a groove and just be able to work our way through each of the batteries. How many batteries we get done on EVA-2 really sets up EVA-3." Here is an updated timeline of today's activity (in EDT and mission elapsed time; includes revision D of the NASA television schedule): EDT........DD...HH...MM...EVENT 05/19 02:20 AM...04...12...00...Crew wakeup 03:00 AM...04...12...40...EVA-1: Airlock repress/hygiene break 03:45 AM...04...13...25...EVA-1: Airlock depress to 10.2 psi 04:05 AM...04...13...45...ISS daily planning conference 04:10 AM...04...13...50...EVA-1: EVA prep 05:40 AM...04...15...20...EVA-2: Spacesuit purge 05:55 AM...04...15...35...EVA-2: Spacesuit prebreathe 06:45 AM...04...16...25...EVA-2: Crew lock depressurization 07:15 AM...04...16...55...EVA-2: Spacesuits to battery power 07:20 AM...04...17...00...EVA-2: Airlock egress 07:35 AM...04...17...15...EVA-2: Setup 07:45 AM...04...17...25...EVA-2 (Good): Worksite prep 07:45 AM...04...17...25...EVA-3 (Bowen): Inspection boom cable repair 08:05 AM...04...17...45...EVA-2 (Bowen): Worksite prep 08:45 AM...04...18...25...EVA-2: Temp stow battery 09:20 AM...04...19...00...EVA-2: P6 battery A/2 replacement 10:25 AM...04...20...05...EVA-2: P6 battery B/3 replacement 11:30 AM...04...21...10...EVA-2: P6 battery C replacement 12:05 PM...04...21...45...EVA-2: Install battery on pallet 12:40 PM...04...22...20...EVA-2: Cleanup and ingress 01:00 PM...04...22...40...SSRMS maneuvers to SARJ clear 01:45 PM...04...23...25...EVA-2: Airlock repressurization 01:55 PM...04...23...35...Spacesuit servicing 03:25 PM...05...01...05...ISS daily planning conference 04:00 PM...05...01...40...Mission status briefing on NTV 04:05 PM...05...01...45...EVA tagup 05:20 PM...05...03...00...ISS crew sleep begins 05:50 PM...05...03...30...STS crew sleep begins 06:00 PM...05...03...40...Daily highlights reel 10:00 PM...05...07...40...HD crew highlights   The final planned flight of space shuttle Atlantis is symbolized in the official embroidered crew patch for STS-132. 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