Hubble Wraps Final Spacewalk
Frank Morring, Jr.
Johnson Space Center/Houston
Mission updates are also being posted at the On Space blog.
The crew of the space shuttle Atlantis completed all of its work on the Hubble Space Telescope Monday, plus a bonus task, in the fifth and final extravehicular activity (EVA) of the last servicing mission to the orbiting observatory.
Spacewalkers John Grunsfeld and Drew Feustel replaced the No. 2 fine guidance sensor and a second three-battery power module, and managed to upgrade about twice as much of the 19-year-old spacecrafts thermal protection as was planned at the beginning of the spacewalk.
"John, if you're done monkeying around with the telescope, I'll take you back to the airlock," robotic arm operator Megan McArthur radioed to her EVA crewmate.
When Atlantis releases the Hubble from its payload bay Tuesday morning, it will mark the end of an unprecedented 19 years of maintenance and upgrades by visiting astronauts, who corrected a serious optical flaw in the telescope and went on to boost its observation power repeatedly over the course of five visits. Grunsfeld, an astronomer/astronaut who will get a little time on the telescope during its post-servicing checkout period, has made eight spacewalks on the telescope during three shuttle missions.
In contrast with EVAs two and four, the final spacewalk went relatively smoothly, without any of the stuck bolts or other snags that plagued those two. Grunsfeld wasnt able to break torque on the latch bolt holding the fine guidance sensor in place with his powered pistol grip tool, but he easily turned it when he shifted to muscle power routed through a torque limiter to avoid irreparable damage.
Once the latch was open and Grunsfeld had a firm grip on the unit, McArthur pulled both of them out with the robotic arm to make room for the replacement. As they already had with the battery pack, telescope controllers at Goddard Space Flight Center quickly confirmed that the new Fine Guidance Sensor was electrically "alive."
With that, the spacewalkers moved on to the final job of their EVA -- replacing thermal protection blankets that have degraded over time with New Outer Blanket Layer (NOBL) panels. Although at the outset Grunsfeld and Feustel were cleared only to install NOBL on the telescope's Bay 5 and half of Bay 8, before they were finished they had completed Bay 8 and covered Bay 7 as a "bonus" task.
Robots would have been hard pressed to do what humans have done, said Preston Burch, NASAs Hubble program manager.
Mechanical release of the telescope is scheduled for 8:53 a.m. EDT Tuesday, although EVA astronauts Mike Massimino and Mike Good will be ready to don their spacesuits and free it manually if there is a malfunction. Unless that happens, the fifth EVA marked the beginning of the end of the space shuttle program, which is scheduled to draw to a close with the retirement of the fleet by the end of next year.
This was the last planned EVA out of the shuttle airlock, noted Tony Ceccacci, lead flight director on the Hubble mission.
Photo credit: NASA TV
