Atlantis crew wraps up fourth and final spacewalk
BY WILLIAM HARWOOD
STORY WRITTEN FOR CBS NEWS "SPACE PLACE" & USED WITH PERMISSION
Posted: June 17, 2007
Astronauts Pat Forrester and Steve Swanson put the finishing touches on a dramatic space station assembly mission today, completing a fourth and final spacewalk to activate a new solar array rotation mechanism and ready the lab complex for a critical sequence of upcoming construction flights.
"I couldn't be more pleased," said lead space station Flight Director Kelly Beck. "The complexity of the tasks that we had was a challenge and the crew just executed perfectly. But then to throw in the Russian segment computer problems we had and still come out of this mission with everything done that we planned to have done is just a real success and we're very proud of it."
Today's spacewalk began at 12:25 p.m. and ended with the start of airlock repressurization at 6:54 p.m. This was the fourth and final spacewalk for the Atlantis astronauts, pushing the crew's total to 27 hours and 58 minutes. Forrester and Swanson logged a total of 13 hours and 45 minutes for the second and fourth EVAs while Reilly and Danny Olivas put in 14 hours and 13 minutes during the first and third outings.
Overall, this was the 87th spacewalk devoted to space station assembly and maintenance since construction began in 1998. With today 's EVA, 48 U.S. astronauts, 15 Russian cosmonauts, two Canadians and four astronauts representing Japan, Germany, France and Sweden have logged 537 hours and three minutes of EVA time building and maintaining the space station.
"It's time for you to come on in," astronaut Jim Reilly radioed from Atlantis' flight deck as the spacewalkers wound up a long day.
"I'll take one last look and if I could, just say happy Father's Day," Forrester replied. "It's been a great way to spend it. I want to say happy Father's Day to my Dad, my father-in-law and for being a father to my two sons. So thanks."
"I'd like to echo the same words," Swanson called. "Thanks for reminding me."
"Absolutely," Reilly said, "a lot of fathers on this flight and we're all enjoying a great Father's Day."
The primary goal of today's spacewalk was an inspection of the drive motors on the starboard solar alpha rotary joint - SARJ - on the right side of the station's main solar power truss; removal of a final few launch locks to permit free rotation; stowage of a keel pin used to anchor the S3/S4 truss element in the shuttle's cargo bay during launch; and installation of a safety stop on the end of the track used by the station's robot arm-carrying mobile transporter.
The spacewalkers also ran a computer cable that eventually will permit astronauts in the U.S. segment of the station to command systems in the Russian segment. They opened a newly installed hydrogen valve that is part of a new U.S. oxygen generation system and attempted to bolt down a micrometeoroid debris shield that could not be put back in place during an earlier spacewalk. Swanson and Forrester were not able to get it anchored, either, so they used tethers to lash it down.
"They completed the remainder of the tasks that we were hoping to accomplish on this mission," Beck said. "They finished preparing the solar alpha rotary joint, so now it is released and free to move. They also cleared the translation path to work site one, which is the new (robot arm) work site that came up on this truss.
"They also opened the oxygen generator system vent valve, that's a valve that Jim Reilly actually installed on the third spacewalk. The configuration was done yesterday by Clay Anderson inside so that we could actually open that valve today. And that was completed. We also had some miscellaneous items that put us a little bit ahead for future missions, things like relocating foot restraints and they also did routing of a node LAN cable ... that gives them a hardline connection between the Russian segment and U.S. segment laptops. So excellent day today.
"Again, with the completion of this fourth spacewalk," Beck said, "we completed all of the EVA objectives that we were planning and then some."
Overnight, ground controllers will test the SARJ, ordering a small 5-degree rotation just to verify normal operations. The S3 rotary joint will be switched into auto-track mode, turning the newly installed S4 solar arrays to stay face-on to the sun, early Monday, after the crew is awake to monitor the operation.
At that point, the station's orientation, or attitude, will be maintained by the lab's control moment gyroscopes. But after a shuttle water dump, ground controllers will carry out a critical test to make sure the revived Russian flight computers can control the station's orientation with Russian rocket thrusters.
"They have good confidence all the software's running appropriately," Beck said. "There are a few systems items they still need to clean up, but it looks like it's in good shape. Tomorrow, we will have sort of an extra-double check, if you will, to make sure everything is running well."
With the shuttle-station complex under the control of Atlantis' rocket thrusters, "we're actually going to hand over attitude control to the Russian segment and control with Russian thrusters and then we'll hand over to momentum (gyro) management," Beck said. If all goes well, "that will finish checking out all the different attitude control systems. Again, we're confident it's going to work but it will be a good double check just to make sure everything's in the proper configuration."
Assuming no problems develop and engineers confirm the Russian guidance and navigation system can, in fact, orient the space station as required, the Atlantis astronauts will be cleared to undock on Tuesday.
"The shuttle crew has some off-duty time (Monday), but then they'll be spending the rest of the day with the station crew packing up last-minute items, making sure all the equipment and transfer items are on the right side of the hatch," Beck said. "At the end of the day, they'll say their final goodbyes and then they'll close the hatches in preparation for undocking the next day."