Spacewalking astronauts John Grunsfeld and Andrew Feustsel successfully performed the fifth and final set of repairs to the Hubble Space Telescope today, installing a new fine guidance sensor and three insulation panels over equipment compartments on the outside of the observatory. With all five spacewalks behind them, the crew of STS-125 now turns their attention to Atlantis' homecoming four days from now.
VISIT OUR COMPLETE STS-125 MISSION ARCHIVE STS-125 ATLANTIS PHOTO GALLERIES VIDEO: FLIGHT DAY 8 HIGHLIGHTS VIDEO: FLIGHT DAY 8 CREW VIDEO DOWNLINK VIDEO: HST VIEWS FROM THE FLIGHT DECK VIDEO: MISSION STATUS BRIEFING VIDEO: FLIGHT DAY 8 STOCC UPDATE ALL-ACCESS SUBSCRIBERS: EVA 5 COVERAGE - PART 1 ALL-ACCESS SUBSCRIBERS: EVA 5 COVERAGE - PART 2 Three major tasks were scheduled for today's spacewalk, including the installation of a new battery package, a refurbished fine guidance sensor and three new insulation panels to replace seriously degraded thermal blankets covering the telescope's equipment bays. Originally, Grunsfeld and Feustel were to install two panels but the installation of the first panel was deferred Sunday when the mission's first spacewalk ran longer then anticipated. Today's spacewalk marks the last time human hands will touch Hubble. The fifth servicing mission to the telescope will add at least five years of life to the observatory. The mission has given it powerful new science instruments to continue making amazing discoveries until at least 2013, perhaps longer, but then HST will be replaced by an even more powerful telescope, the James Webb Space Telescope. In its 19 years of service, the Hubble Space Telescope has become an icon of space exploration and gained fame, and fans worldwide as the most important scientific instrument since Galileo first invented the telescope. In the two decades since launch, scientists have learned more from Hubble's observations than in the entire history of humanity since the first person looked up to the heavens and wondered what the strange lights were. Hubble's orbiting repairmen, keenly aware of the observatory's significance, paid homage to the telescope at the close of today's spacewalk. "As Arthur C. Clarke says, the only way of finding limits on the possible is by going beyond them into the impossible," said Grunsfeld, Hubble Space Telescope's most experienced spacewalker and one its greatest supporters. "On this mission, we tried some things that many people said were impossible, fixing STIS, repairing ACS, achieving all the content that we have in this mission. But we've achieved that and we wish Hubble the very best. It's really a sign of the great country that we live in that we're able to do things like this on a marvelous spaceship like the space shuttle Atlantis. And I'm convinced that if we can solve problems like repairing Hubble, getting into space, doing the servicing that we do traveling 17,500 miles an hour around the Earth, that we can achieve other great things, like solving our energy problems and our climate problems, all things that are in the middle of NASA's prime and core values. "As Drew and I go into the airlock, I want to with Hubble its own set of adventures and, with the new set of instruments we've installed, that it may unlock further mysteries of the Universe." The day began with Grunsfeld and Feustel exiting Atlantis airlock, perhaps the last time an astronaut will ever begin an EVA through the orbiter's airlock, more than an hour ahead of schedule in order to ensure enough time to install all three insulation panels in case other repair work ran long. The first task was to install the final set of new batteries on the telescope. While Grunsfeld worked to remove 14 bolts and disconnect 6 electrical cables plugged into the old set of batteries in Bay 3, Feustel unpacked the new electrical module for installation. The two astronauts then swapped the old and new batteries so that Grunsfeld, riding on the end of the shuttle's robot arm, guided by mission specialist Megan McArthur, could take the new set to the telescope and slide it into the empty bay. Another set of three batteries was installed during the second spacewalk of the mission last Friday. The battery replacement was a high priority for NASA since they are used to store electricity and power the telescope when it is orbiting on the nighttime side of Earth. The new batteries replace the original six that have been inside Hubble since its launch in 1990. Grunsfeld completed installing the new batteries at 9:44 a.m. EDT. Shortly afterward, mission control reported the batteries had a good aliveness test. "I'm happy to report a good aliveness test on the Bay 3 battery," CAPCOM Dan Burbank in mission control radioed to Atlantis. "Really nice work on the batteries, guys," mission specialist Michael Good told Grunsfeld and Feustel from inside Atlantis. "Aliveness test is good, as you heard, so we're on our way here today." Next, the spacewalkers set about the task of installing a refurbished fine guidance sensor (FGS). Hubble Space Telescope has three FGS units which provide extremely fine pointing data to the telescope's computer so that it can accurately orient the aperture at targets billions of light years away. The fine guidance sensors work in concert with fixed head star trackers, which provide rough pointing information, to orient the telescope in the desired direction of the selected target of opportunity. After removing the 900 pound FGS 2 and temporarily stowing it on the side of the orbiter's payload bay, the new unit was unmounted from the transport fixture in the payload bay and installed in the observatory. The old unit was then attached to the transport fixture in its place for return to Earth. With the FGS installation work behind and the crew running an hour ahead of the planned timeline, the two spacewalkers moved to the task of installing the three new outer blanket layer (NOBL) panels. "Well, we're so far ahead, and we're showing a good hour ahead on the flight plan, which is really our limiter today, your reward for doing so well is to install, we believe, all three NOBL's. Like to get your input on that," Burbank radioed to shuttle commander Scott Altman. "And Houston, let me tag up with John and Drew, Altman replied. "How're you feeling, John." "Gee... I don't know, Scooter," Grunsfeld jokingly responded. "I had a feeling. How about you, Drew? You all worn out from free floating?" asked Altman of Drew Feustel. "I feel pretty good, actually. I've got a lot more in me," Feustel replied. With that, the two free-floaters turned toward the final maintenance task for Hubble, the NOBL installation. The new metallic panels were sorely needed. After nearly two decades in the harsh environment of outer space, the original thermal blankets, flexible material called multi-layer insulation, around Hubble had become brittle and tattered. So bad was their condition that the old blankets practically disintegrated in the astronauts' gloves as they worked to make room for the new NOBL panels. Toward the end of the spacewalk, Grunsfeld caused a momentary scare when he accidentally bumped one of the telescope's low-gain antennae, knocking off an end cap. "One last handshake with Mr. Hubble from me," said Grunsfeld a he prepared to leave the telescope one last time. "Okay, I'm off the telescope." "Copy, off the telescope," Mike Massimino replied from Atlantis. "Low gain ant, hold. John, stop. Stop. Stop. Stop. Stop," Michael Good called out when he saw Grunsfeld's boot brush against the antenna. "Okay, we liberated a small piece of something off the end of that." As Feustel chased the piece of debris floating in Atlantis' payload bay, Grunsfeld went to inspect the antenna. "It looks like a little piece of tape." "Is it a little piece of tape?" asked Grunsfeld. "Yeah." "I've got it." "Oh no. I hope the antenna's okay. Oh I feel terrible," bemoaned Grunsfeld. "You hit the low-gain?" Massimino asked. "I tapped the low gain antenna with my foot," answered Grunsfeld. "Okay, I'm sick. It kind of knocked off the end cap." Engineers on the ground analyzed the situation fairly quickly and reported the antenna didn't seem to be affected by the loss of the end cap. Rather dejected, as he prepared to re-enter the shuttle's airlock, Grunsfeld remarked, "Sorry, Mr. Hubble. Have a good voyage." "Consider it a goodbye kiss, John," someone inside Atlantis reassured him. "Ah, thanks." As he headed back inside Atlantis, Scott Altman reminded Grunsfeld, one of Hubble's most enthusiastic supporters over the years, to stop and take stock of what the mission has accomplished. "John, remember, take a moment here," Altman radioed to Grunsfeld. "This is it... the last spacewalk on Hubble and maybe our last visit to space. So enjoy this. You earned it." "Thanks, I appreciate that," Grunsfeld replied. "And Dan, thanks for those kind words (about the health of the telescope). I hope we don't lose too many db (decibels). We really achieved a lot out here. Thanks a lot, Scooter." The final spacewalk of STS-125 officially ended at 3:22 p.m. EDT when the astronauts began repressurizing the shuttle's airlock. The fifth EVA lasted 7 hours and 2 minutes and gave Hubble with a new fine guidance sensor, new batteries and new insulation which, combined with the repairs and upgrades performed in the previous four spacewalks, leaves, in many regards, a brand new Hubble Space Telescope in orbit, ready for at least several more years of productive service. Atlantis is scheduled to return to Earth for a landing at Kennedy Space Center on May 22, shortly after 10 a.m. However, the weather forecast calls for a good chance of rain and lightning to move through the area. If that's the case, Atlantis will likely remain in orbit at least one extra day since only the runway at KSC will be called up for the first day of landing opportunities. The shuttle could, in the worst case, remain in orbit until Monday, but excellent weather is forecast through next week at the backup facility at Edwards A.F.B. in California so flight controllers will have that option for subsequent landing days. (The Spacearium / Space Media Corporation)
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