In today's 3rd EVA (spacewalk) of the Discovery Return to Flight mission (STS-114), astronaut Stephen Robinson was able to remove the protruding gap-filler from two places on the orbiter's belly, thereby fixing one of the biggest concerns for NASA officials prior to clearing the vehicle for the scheduled re-entry and landing. The gap-filler was some material placed between a few of the tiles near the forward landing gear to ensure that the tiles did not hit eachother during the vibrations on launch. It serves no other purpose, which is why officials gave the green light to simply removing the material. Also on today's EVA, astronaut Soichi Noguchi worked on a some minor, scheduled things on ISS. Noguchi was also stationed in a position to act as a "relay" between Robinson and ISS should direction communication between the two have failed for any reason. Today's EVA lasted 6 hours.
Though an hour was scheduled for the repair/removal of the gap filler, it took Robinson "about 12 seconds" to pull out the protruding material. That is, the material came out quite easily and did not even require the improvised saw which was constructed for the EVA--Robinson was able to pick it out with his fingers. Today's spacewalk was a first for ISS and NASA: it is the first time that the ISS' robotic arm, SSRMS or CanadArm2, was used to hold an astronaut below the orbiter, and was the first time that work has ever been performed on the belly of the shuttle while in orbit. Cameras on the shuttle's robotic arm, SRMS or CanadArm, were used to give the astronauts in ISS, the flight controllers, and engineers, a better picture of what was going on during the "repair." It was as historic as the first shuttle mission to repair the Hubble Space Telescope, and further expands our capabilities for on-orbit repairs.
I'd like to step back and say something here, about the press coverage of this particular EVA, but before I can do that I think I should remind readers about my background briefly. I have a Master of Science in Aerospace Engineering. My thesis, "Analysis of Robotic Grasp Requirements for Telerobotic Satellite Servicing," required in-depth study of what humans have done in space, and what they may have to do. With this understanding, I then analyzed how robots could do similar tasks, and developed a grasp taxonomy (classification scheme) for robots. My work on my thesis, combined with my experiences in robotics and working with robots in neutral buoyancy at UMd's Space Systems Laboratory, made me quite confident that this repair operation would be accomplished. That is, I didn't expect it would be necessarily "easy," but I knew that the engineers in Houston tried their removal methods in the Neutral Buoyancy Lab at Johnson Space Center, and knowing what humans are capable of in space, combined with knowledge of how CanadArm2 works and its capabilities, I was confident that this would be a successful repair.
My frustration came in hearing the press talk about it. They seemed to harp on the "never been done before" aspect of it, which considering the very nature of spaceflight, seemed absurd, or as I so often put it, "making a mountain out of a molehill." Spaceflight is not easy. EVA is not easy. There is almost nothing "standard" or "routine" about it, no matter how many times we've been to space in ANY vehicle, there is always something to be learned and something new to be done. Though I imagine that even the NASA engineers and astronauts were somewhat unnerved at the first thought of what they'd have to do, there was a fairly quick realization and acknowledgement that it was certainly possible, and not necessarily as intimidating as it seemed at first glance. I'm proud to see what was accomplished today, and I hope that the press coverage of the success of today's activities will spur further interest in spaceflight and maybe even inspire the next generation (i.e. those in elementary, middle, and high school now) to consider engineering jobs and further our national investment in the space program.
The next big task for Discovery will be to come home safely. The re-entry and landing are scheduled for approximately 04:37 US Eastern Time on Monday morning. Though the tiles, gap-filler, and wing leading-edge reinforced carbon-carbon have all been inspected, repaired (in the case of the gap-filler), and cleared for re-entry, the vehicle is still not 100% cleared. Engineers believe that a thermal blanket below the crew cabin may have been struck by a piece of debris, "possibly a paper cover for one of the orbiter's thrusters," which has caused an 8" section of the blanket to "puff up" on the hull. Right now, engineers are attempting to determine if the blanket can rip off and possibly hit the shuttle upon re-entry. However, the engineering analysis on this topic is expected to be completed and presented to NASA officials within 48 hours, so I assume we'll hear the results soon thereafter. Full details on this story can be found at Space.com.