Wrong-Way Pin Leads To Complications

Astronauts Steve Swanson and Joseph Acaba ended the second spacewalk of the STS-119 mission to the International Space Station at 7:21 pm EDT Saturday. They prepared a worksite so the STS-127 spacewalkers can more easily change out the Port 6 truss batteries later this year.

On the Japanese Kibo laboratory, Swanson and Acaba installed a second Global Positioning Satellite antenna that will be used for the planned rendezvous of the Japanese HTV cargo ship in September. They also photographed areas of radiator panels extended from the Port 1 and Starboard 1 trusses and reconfigured connectors at a patch panel on the Zenith 1 truss that power Control Moment Gyroscopes.

There was one rather significant glitch during the spacewalk... and it was due to human error. The Associated Press reports Acaba accidentally inserted a pin upside down, jamming the deployment of an equipment storage platform outside Kibo.

After struggling with the balky pin, the spacewalkers tied off the unpressurized cargo carrier attachment system (UCCAS) in hopes engineers on the ground will determine a way to free the stuck pin during Monday's third and final spacewalk.

"Even with it being installed in the opposite location, he just drew a card of bad luck ... if it had been rotated just a little bit more or maybe a little bit less, it might have cleared just fine," Glenda Laws-Brown, STS-119 Lead Extravehicular Activity Officer, said Saturday evening.

"Some days you're lucky, and some days you're less lucky," she added, also noting there is no "up" and "down" in space... which makes the error easy to understand. Nevertheless, time spent trying to solve the pin issue meant other items on the agenda were bumped to Monday's excursion.

A second, more dramatic -- but ultimately less significant -- problem occured near the end of the six hour, 30-minute spacewalk. Due to Acaba's and Swanson's movements at the end of the station's truss assembly, the onboard gyros that maintain the station's attitude in orbit overheated, triggering an alarm.

The problem was "nothing to worry about," Mission Control stated, and the docked shuttle Discovery briefly assumed control of maintaining the station's orbital attitude while the gyroscopes cooled.

FMI: www.nasa.gov/shuttle