A new fully loaded tank will be installed on the second spacewalk of the mission Thursday night. The old one will be returned to Earth aboard Discovery.
The tanks are massive by spacewalking standards: Nearly 5 feet long, 7 feet wide and 4 feet high. The old one has been up there since 2002.
A moment of concern arose 1½ hours into the spacewalk when Olivas noticed fraying on the index finger of his right glove, following the tank removal. Mission Control evaluated the problem for several minutes before giving him a "go" to remain outside. The stitching defect was deemed minor; deeper damage likely would have forced an early end to the spacewalk.
Minutes later, Stott reported a high reading of her carbon dioxide levels. When asked if she felt any symptoms, she replied, "No. Nothing." Mission Control said it appeared to be "a weird sensor" and that her suit was operating fine.
Then there was a half-hour communication outage between Mission Control and the shuttle-station complex Tuesday night. A severe thunderstorm at the satellite relay station in New Mexico was to blame.
"You're going to be on your own here," Mission Control told the 13 space fliers before contact was lost. The spacewalkers' work to retrieve some science experiments was rearranged because of the outage.
Shortly before the spacewalk began Tuesday evening, the space station officially got its new $5 million treadmill that is named for Colbert. It was one of the first items to be unloaded from the moving van that was delivered by Discovery.
Colbert, known for his Comedy Central program "The Colbert Report," was out of the country Tuesday. But he said through his New York publicist that "my treadmill will ... help trim down those famously fat astronauts." The word "my" was underlined. "Lay off the Tang, Chubby!"
The Colbert treadmill appeared to be the chubby one. As the treadmill was being pushed across the threshold, it bumped into a camera and dislodged it. An astronaut nudged the camera back into place.
Colbert originally wanted a space station room named after himself and even won an online vote earlier this year for naming rights. NASA instead went with Tranquility for the yet-to-be-launched chamber, in honor of Neil Armstrong and Buzz Aldrin's landing on the moon's Sea of Tranquility 40 years ago this summer. The treadmill became COLBERT, short for Combined Operational Load Bearing External Resistance Treadmill.
The treadmill is in more than 100 pieces. The bags containing all those parts will remain in a corner of the space station until September, when Stott has time to put together the running machine.
Stott, the space station's newest resident, hitched a ride up aboard Discovery. She will spend the next three months in orbit.