Discovery astronauts Saturday gave generally good reviews to the new technique that could be used to repair potential space shuttle heat damage: Working at the end of a wobbling 100-foot extension pole and robotic arm.
They confided that it did feel strange at times. British-born astronaut Piers Sellers said he was "like a bug on the end of a fishing rod here."
In what was scheduled to be a 6.5-hour spacewalk, the first of three planned orbital excursions, Sellers and Michael Fossum said they could do most of the mock tasks called upon them with only moderate difficulty and an occasional audible grunt.
That is what NASA wanted to hear, especially after a still-unresolved problem with a shuttle heat shield. The technique was developed to make sure there is never a repeat of the Columbia disaster, which killed seven astronauts in 2003. Foam from the shuttle's external tank struck Columbia's wing during launch, creating a breach that allowed fiery gases to penetrate the shuttle during the return flight to Earth.
Last year, emergency spacewalking repairs were needed because of heat shield damage to Discovery.
The astronauts had traveled to the international space station, where they dropped off German astronaut Thomas Reiter, who was to become the third member of the station's crew.
Fossum and Sellers may get a chance to use the boom for a real repair on their third spacewalk, now scheduled for next Wednesday. NASA managers on Saturday were still evaluating whether a piece of fabric filler protruding from the thermal tiles on Discovery's belly needs to be removed by the spacewalkers. If it is, Fossum and Sellers may have to go back on the boom and yank out the filler.
NASA officials were concerned that astronauts could not work well from the extension boom that is attached to the similar-sized shuttle robotic arm. The agency's top spacewalk officer said working that way could be like painting a house from the top of a rickety ladder.
But as Fossum and Sellers were finishing up, NASA officials said they found less sway and oscillating than expected.
Fossum said one drill technique was "beyond my ability" and "too much motion to handle" from the boom. Aside from that one mock-drilling, using a numerical rating scale for the wobbles they experienced and the force they needed to compensate, the worst Fossum reported was a 5 on a 1-10 difficulty scale. That translates to doable but with "moderately objectionable deficiencies."
"I think we got all we needed there," Discovery pilot Mark Kelly told the spacewalkers, telling them to end their tests and start clean up.
The spacewalkers marveled at the view from 210 miles above Earth.
"It's beautiful," Fossum said. "The thin glow of the moonlit Earth below."
With both astronauts attached to the end of the boom, which was attached to the 50-foot shuttle arm, Sellers noted: "It's very crowded at the end of this boom."
After Sellers took a solo turn on the end of the boom, Fossum could not join his fellow spacewalker because the tether that keeps him attached to the boom would not retract. The astronauts lost time trying to fix it, finally giving up and getting a new line to replace it, but they fell behind schedule and had to skip some tasks.
Much of the time, Sellers and Fossum were playing pretend on purpose. They simulated repair maneuvers. From the ground the movements looked like ballet combined with swimming, all in slow motion with bulky spacesuits and zero gravity.
The ride on the boom-arm combo was not bad at all. As he was being moved into position on the extension, Sellers called it "a very slow gentle sway in and out of the bay."
While waiting for Fossum, Sellers did a couple of flips. The two spacewalkers let out frequent "woo-hoos" and Sellers occasionally grunted while making his required acrobatics.
The spacewalkers finished their first task, a bit behind schedule, immobilizing a cable cutter on the station's mobile transporter, or railroad car, and rerouting a cable through it. A duplicate cable cutter accidentally cut a cable leading to the transporter late last year, and NASA wanted to make sure it does not happen again because the cable is a conduit for power, data and video images.
The transporter moves along the space station and is used for constructing the complex. The severed cable will be replaced during a second spacewalk set for Monday.
When Mission Control pointed out to Sellers that he could view Britain over his left shoulder, he said, "Wow! Oh, my goodness. It's a beautiful day in Ireland."
As he looked down at the Caspian Sea several minutes later, Fossum said, "Ha, ha, ha. This is a good view... I'm in a dream; nobody wake me up."