HOUSTON - TheHubble Space Telescope will get its final tune-up Monday by a pair ofspacewalking astronauts, the last two people who will ever touch the agingobservatory.
Thespacewalkers are Atlantis astronauts John Grunsfeld and Andrew Feustel, who planto float out into their shuttle?s cargo bay and add new batteries, insulation anda guidance sensor to the 19-year-oldHubble.
Today?sorbital work is slated to begin around 9:16 a.m. EDT (1216 GMT) but could start early since the crew is ahead of schedule, NASA officials said. It will mark thelast of five ambitious spacewalks in five days by the Atlantis crew to add upgradesand make repairs aimed at extending Hubble?s mission life to at least 2014, ifnot beyond.
The 11-day missionis NASA?s fifth and final service call on the observatory before the spaceagency retires its shuttle fleet next year, so there?s a push among Atlantis?crew to get everything done. After this mission, Hubble will neversee humans again.
?It?s kindof like being in a horse race, we?re in the homestretch,? Hubble programmanager Preston Burch told reporters here at NASA?s Johnson Space Center lateSunday. ?We?ve done just about everything we set out to accomplish.?
Finalupgrades on tap
Today,Grunsfeld and Feustel plan to replace a second set of batteries and one ofHubble?s old fine guidance sensors.
About thesize of a baby grand piano, the sensor is one of three that help the spacetelescope keep its camera eye steady. They can also be used for astrometry, theultra-precise science of star positions and their motions.
The spacewalkersalso plan to install new thermal insulation panels to ward off Hubble?sdeterioration from the harsh space environment. Grunsfeld and Feustel plan toadd at least one new insulation panel, and may add a second one that adifferent team of spacewalkers were unable to install on Sunday when they ranout o time.
Over thecourse of their back-to-back spacewalks, the seven Atlantis astronauts have installeda newcamera for deep-space viewing, a super-sensitive spectrograph to study the compositionof the universe, and resuscitated two other instruments - Hubble?s advancedcamera and an older spectrograph - both of which were never built to be fixedin space.
The vital maintenance,like today?s spacewalk, has added new batteries, gyroscopes and a science data computer.The astronauts also added a docking ring so a robotic spacecraft can latch ontoHubble years from now and send it into the Pacific Ocean when its sciencemission is over.
The $1.1billion mission caps a $10 billion investment in Hubble since its inception.The Atlantis crew will release Hubble back into its 350-mile (563-km) orbit onTuesday.
Hubblehugger?s last chance
ThatGrunsfeld, an astrophysicist-turned-astronaut, is part of Hubble?s lastspacewalking crew is fitting in a way. He?s making his third trip to the iconicobservatory and has a reputation as being Hubble?s biggest fan.
?He is the chiefHubblehugger of the astronaut corps,? Burch told SPACE.com late Sunday.
Like fellowAtlantis spacewalker Michael Massimino and the shuttle?s skipper Scott Altman,Grunsfeld was on NASA?s 2002 service call on Hubble. But he also visited theobservatory in 1999.
On thisflight, where Grunsfeld has served as the spacewalking chief, he is performingthree out of the five spacewalks alongside Feustel. He told SPACE.combefore launch that while he expect to stay focused on his orbital work, therewill be some time to reflect on today?s last-ever spacewalk on the Hubble SpaceTelescope.
?Every timewe climb on the telescope, you know grabbing a handrail, it?s giving Hubble ahug,? Grunsfeld said. ?At the very end, we?re going to take one last look atthe Hubble and just go, ?wow,? you know. This has been quite an experience.?
SPACE.comis providing continuous coverage of NASA's last mission to the Hubble SpaceTelescope with senior editor Tariq Malik in Houston and reporter ClaraMoskowitz in New York. Clickhere for mission updates, live spacewalk coverage and SPACE.com'slive NASA TV video feed.
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