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STS-125: The mission

A detailed step-by-step preview of space shuttle Atlantis' STS-125 mission to extend the life and vision of the Hubble Space Telescope.

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STS-125: The EVAs

The lead spacewalk officer provides indepth explanations of the five EVAs to service Hubble during Atlantis' flight.

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STS-125: The crew

The seven shuttle Atlantis astronauts hold a press conference one month before their planned launch to Hubble.

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STS-125: NASA leaders

The leaders of NASA's Space Operations and Science directorates give their insights into the upcoming shuttle mission to the Hubble Space Telescope.

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STS-125: Shuttle boss

The head of NASA's space shuttle program discusses the risks and plans for Atlantis' trek to Hubble.

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The Hubble program

An overview of the Hubble Space Telescope program and the planning that has gone into the final servicing mission.

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Hubble's future science

The new instruments to be installed into Hubble and the future science objectives for the observatory are previewed.

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Meet the Hubble crew

Meet the crew launching on Atlantis' STS-125 mission to service the Hubble Space Telescope and learn how each became an astronaut in this special biography movie.

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Today's Hubble spacewalk to replace gyros and batteries
BY WILLIAM HARWOOD
STORY WRITTEN FOR CBS NEWS "SPACE PLACE" & USED WITH PERMISSION
Posted: May 15, 2009

Astronauts Michael Massimino and Michael "Bueno" Good are preparing for a six-and-a-half-hour spacewalk to swap out the Hubble Space Telescope's six stabilizing gyroscopes - the top priority of Servicing Mission 4 - and three of its aging nickel-hydrogen batteries, now operating at half their original capacity.


Mission's first spacewalk was successfully completed yesterday. Credit: NASA
 
"They are 20 years old," said Hubble Program Manager Preston Burch. "They were built a couple of years before we launched in '90. We're so far beyond the design lifetime it's anybody's guess as to how long they could continue to go. We know it's not infinite. So our best judgment is we should go ahead and still change them out."

Hubble's gyroscopes, which help it lock onto and track its targets, are an even more pressing concern. The telescope was designed with redundancy in mind and while it was equipped with six gyros, only three were required for science operations. But gyros 2, 3 and 5 have failed and gyro 6 exhibits symptoms of a problem that eventually could knock it out of action.

"We're flying on one and six," Burch said. "Four is in reserve, However, six, you may recall, has some flaky characteristics that were detected not too long after it was installed on servicing mission 3A (in 1999). We suspect it has to do with the suspension system in it. When you slew the observatory, the drift rate on the gyro changes significantly on it. That's the bad news. The good news is, it changes in a very predictable way. We cleverly put some flight software on board that enables us to use gyro 6 and not be confused or whatever by the shift in the gyro drift bias.

"Now gyro one recently had a sudden surge in its motor current which is indicative of a temporary rotor restriction event. And this has happened (several) times. The current has gone up, but it's come back down. But it's still running at a value slightly higher than normal. So our best experts and our past experience tell us one is living on borrowed time and it could go at any time. Gyro four, although it's off and held in reserve, was used for a long time and has a lot of run time on it. It's up there, it's up around the 50 percent point in terms of probability of failure. It's not clear how long gyro four could last if and when we had to turn it on and use it.

"So the bottom line is, all three of the remaining gyros have got liens against them if you will," Burch said. "Six because of the flaky suspension, one because of the flaky motor current and four because it's got a lot of run time on it. So you ask, how much longer can you guys keep going on gyros, even with a one-gyro science mode, and that becomes highly speculative. ... Our previous calculations showed we could probably get through 2009 with the gyros that we have. I think getting much past 2010 would be a bit of a stretch."

Today's spacewalk was scheduled to begin at 8:16 a.m. Massimino and Good plan to change out all six gyros and to replace three of the telescope's six batteries. The other three, in a different location, will be swapped out during a spacewalk Monday.

During preparations early today, flight controllers informed the astronauts that the new $132 million Wide Field Camera 3, installed during the crew's first spacewalk Thursday, had passed an overnight "functional test.

"Hey, while I've got you guys, the Goddard (Space Flight Center) team reports we got a good functional test on Wide Field 3," astronaut Dan Burbank called from Houston.

"That's great news, Dan," Massimino replied.

For identification, Massimino, call sign EV-3, will be wearing a spacesuit with horizontal broken stripes while Good, EV-4, will use a suit with barber pole stripes. Massimino will be the designated "free floater" while Good will spend much of the day anchored to the end of the shuttle's 50-foot-long robot arm.

This will be the 20th spacewalk devoted to Hubble servicing, the second of five planned for Atlantis' mission, the third for Massimino, veteran of the most recent previous Hubble servicing mission in 2002, and the first for Good. Going into todays's EVA, 15 astronauts have logged 136 hours and 30 minutes working on the space telescope, including seven hours and 20 minutes logged Thursday by Atlantis astronauts John Grunsfeld and Andrew Feustel.

Replacing the gyro packages is not overly complex - each two-gyro rate sensor unit is held in place by three bolts and two electrical connectors - but it requires an astronaut to float well inside the telescope, within inches of delicate equipment that could be damaged by an inadvertent movement.

"The access to the RSUs is really the hard part," said Tomas Gonzales-Torres, the lead spacewalk officer at the Johnson Space Center. "The task itself is a couple of connectors and some bolts and you take a box out. But it's really the access inside of the telescope that makes it difficult."

Massimino described the work as "one of the more challenging (tasks) that we do."

"Mike Good is on the robot arm," he said. "I'm going to get inside the telescope and then more or less I'll stop at one point and he has to rotate me on my back. And then put my feet in the foot restraint - we have a PFR (portable foot restraint) set up inside the telescope - because if I was to try to get in myself there's a good chance I would knock something I'm not supposed to. So pretty much go inside and act like a statute ... and let the other guy control you, move your body around and get your feet in the foot restraint.

"And then, once I'm inside there, I get pretty close to the star trackers, which are the things you don't want to hit. ... My chest will come up within an inch or so of the star trackers. If you damage it, it's kind of like game over. It's the likely end of the telescope. if you just nudge it a little bit, it's not the end of the world but you'd have to recalibrate everything. Because those are the things, part of the system that works with the RSUs that help point the telescope really accurately."

After the rate sensor units are replaced, Massimino and Good will turn their attention to replacing three batteries, in one box, in equipment bay 2. The battery module is mounted on the equipment bay door, held in place by 14 bolts and six electrical connectors.

"Each battery has 22 cells in series along with heaters, heater controllers, pressure measurement transducers and electronics, and temperature-measuring devices and their associated electronics," according to the NASA/Lockheed Martin Servicing Mission 4 media guide. "Three batteries are packaged into a module measuring roughly 36 x 36 x 10 inches and weighing about 475 pounds. Each module is equipped with two large yellow handles that astronauts use to maneuverthe module in and out of the telescope."

Good, on the end of the shuttle's robot arm, will remove the old bay 2 battery module and hand it off to Massimino, who will hand him a new unit. While Massimino stores the old battery pack for return to Earth, Good will move back up to equipment bay 2 and install the replacement.

Here is an updated timeline of today's activity (in EDT and mission elapsed time; includes revision C of the NASA television schedule):


EDT........DD...HH...MM...EVENT

05/15/09

04:31 AM...03...14...30...Crew wakeup
05:46 AM...03...15...45...EVA-2: Preparations begin
07:01 AM...03...17...00...Tile inspection
07:16 AM...03...17...15...EVA-2: Spacesuit purge
07:26 AM...03...17...25...EVA-2: Spacesuit pre-breathe
08:06 AM...03...18...05...EVA-2: Airlock depressurization
08:16 AM...03...18...15...EVA-2: Spacesuits to battery power
08:21 AM...03...18...20...EVA-2: Airlock egress and setup
09:01 AM...03...19...00...EVA-2: Rate sensing unit replacement
12:21 PM...03...22...20...EVA-2: Bay 2 battery pack
01:56 PM...03...23...55...EVA-2: Cleanup and airlock ingress
02:01 PM...04...00...00...HST: Battery aliveness test
02:36 PM...04...00...35...HST: Solar arrays slewed to 90 degrees
02:41 PM...04...00...40...EVA-2: Airlock repressurization
02:51 PM...04...00...50...Spacesuit servicing
03:01 PM...04...01...00...HST: Battery functional test
03:30 PM...04...01...29...Mission status briefing on NTV
03:56 PM...04...01...55...EVA-3: Tools configured
03:56 PM...04...01...55...LIOH and battery config
04:16 PM...04...02...15...Spacesuit swap
04:21 PM...04...02...20...HST: Solar arrays slewed to 0 degrees
04:41 PM...04...02...40...HST: RSU functional test
05:06 PM...04...03...05...HD crew choice downlink
05:11 PM...04...03...10...EVA-3: Procedures review
08:31 PM...04...06...30...Crew sleep begins
08:45 PM...04...06...44...HST update on NTV
09:00 PM...04...06...59...Daily highlights reel
09:01 PM...04...07...00...HST: SSR engineering playback
11:00 PM...04...08...59...ISS-20 pre-launch activities
Here is a description of today's spacewalk from NASA's STS-125 press kit:

"For their first spacewalk of the STS-125 mission, Massimino and Good will spend the bulk of their time replacing three rate sensor units. Each unit is part of a rate gyro assembly, which sense vehicle motion and provide rate data for the telescope. The replacement units will be stored inside a protective enclosure inside the shuttle's cargo bay. Massimino will open the lid of the enclosure to allow Good, who will be riding the space shuttle's robotic arm for the spacewalk, to retrieve the first unit and carry it to the telescope. Massimino will also retrieve a gripper tool that Good will use to maneuver the units into place.

"At the telescope, Good will retract two fixed head star tracker seals, allowing the doors on the telescope bay that the crew will be working in to open. Once open, Good will move a cross aft shroud harness inside the telescope to make room for the foot restraint Massimino will be using. Massimino will retrieve the foot restraint for Good to install, then Good will help Massimino into it. To remove the old rate sensor units, Massimino will disconnect two electrical connectors, while Good removes three bolts. The same connectors and bolts will need to be connected and tightened to install the replacement unit.

"The two spacewalkers will repeat this process two more times as they replace the remaining two rate sensor units. If time permits, Massimino and Good will do some get-ahead work for the third spacewalk of the mission by installing a power input element harness for the Advanced Camera for Surveys before they move the cross aft shroud harness back into place and close the doors on the worksite.

"After the new rate sensor units are installed, Massimino and Good are scheduled to perform the first half of the mission's battery replacement work. They'll be working in the telescope's Bay 2 to replace the first of two batteries. Good will retrieve the old battery by disconnecting six electrical connectors and unscrewing 14 bolts, while Massimino retrieves the new battery from its stowage location inside the shuttle's super lightweight interchangeable carrier. He'll have to unscrew 12 bolts to remove it. The two astronauts will swap batteries at the carrier, and Good will transport the new battery to the telescope for installation, while Massimino stows the old."

Spaceflight Now Plus
Additional coverage for subscribers:
VIDEO: NARRATED PREVIEW OF SPACEWALK NO. 2 PLAY
VIDEO: FLIGHT DIRECTOR'S PREVIEW OF MISSION'S DAY 5 PLAY

VIDEO: FLIGHT DAY 4 HIGHLIGHTS MOVIE PLAY
VIDEO: THURSDAY NIGHT UPDATE FROM HST CONTROL CENTER PLAY
VIDEO: THURSDAY'S MISSION STATUS BRIEFING PLAY
VIDEO: SOFT CAPTURE MECHANISM PUT ON HUBBLE PLAY
VIDEO: SCIENCE INSTRUMENT COMMAND & DATA HANDLING UNIT PLAY
VIDEO: PARTIALLY FAILED SIC&DH UNIT REMOVED FROM HST PLAY
VIDEO: WFPC2 CAMERA STOWED IN ATLANTIS FOR RETURN PLAY
VIDEO: OVERVIEW OF WIDE FIELD CAMERA 3 INSTRUMENT PLAY
VIDEO: SPACEWALKERS INSTALL THE WIDE FIELD CAMERA 3 PLAY
VIDEO: NEW WIDE FIELD CAMERA 3 PREPPED FOR INSTALLATION PLAY
VIDEO: 16-YEAR-OLD WFPC2 CAMERA REMOVED FROM HUBBLE PLAY
VIDEO: LATCHING BOLT ON WPFC2 FINALLY RELEASED PLAY
VIDEO: FIGHTING WITH TROUBLESOME BOLT ON WPFC2 PLAY
VIDEO: FEUSTEL INSTALLS HANDLE ONTO WPFC2 FOR REMOVAL PLAY
VIDEO: HANDLING FIXTURE DEPLOYED TO HOLD OLD CAMERA PLAY
VIDEO: GRUNSFELD INSTALLS SUPPORT POSTS UNDER HST PLAY
VIDEO: FEUSTEL OPENS LATCHES ON INSTRUMENT CARRIER PLAY
VIDEO: ASTRONAUTS EXIT AIRLOCK TO START EVA NO. 1 PLAY
VIDEO: NARRATED PREVIEW OF SPACEWALK NO. 1 PLAY

VIDEO: FLIGHT DAY 3 HIGHLIGHTS MOVIE PLAY
VIDEO: WEDNESDAY NIGHT UPDATE FROM HST CONTROL CENTER PLAY
VIDEO: WEDNESDAY'S MISSION MANAGEMENT TEAM UPDATE PLAY
VIDEO: WEDNESDAY'S MISSION STATUS BRIEFING PLAY
VIDEO: TIME-LAPSE OF MOVING HUBBLE INTO PAYLOAD BAY PLAY
VIDEO: SHUTTLE ATLANTIS' ROBOT ARM CAPTURES HUBBLE PLAY
VIDEO: FIRST UP CLOSE VIEWS OF HUBBLE IN 7 YEARS PLAY
VIDEO: SHUTTLE ENGINE FIRING TO CIRCULARIZE ORBIT PLAY
VIDEO: INSIGHTFUL OVERVIEW OF ATLANTIS' MISSION PLAY
VIDEO: NARRATED PREVIEW ANIMATION OF HUBBLE RENDEZVOUS PLAY

VIDEO: FLIGHT DAY 2 HIGHLIGHTS MOVIE PLAY
VIDEO: TUESDAY NIGHT UPDATE FROM HST CONTROL CENTER PLAY
VIDEO: TUESDAY'S MISSION MANAGEMENT TEAM UPDATE PLAY
VIDEO: SLOW-MOTION OF DEBRIS THAT APPARENTLY HIT TILES PLAY
VIDEO: TILE DAMAGE FOUND DURING INSPECTIONS PLAY
VIDEO: CAPCOM CALLS CREW ABOUT MINOR DAMAGE PLAY
VIDEO: TUESDAY'S MISSION STATUS BRIEFING PLAY
VIDEO: PREVIEW ANIMATION OF HEAT SHIELD INSPECTIONS PLAY

VIDEO: FLIGHT DAY 1 HIGHLIGHTS MOVIE PLAY
VIDEO: THE FULL STS-125 LAUNCH EXPERIENCE PLAY
VIDEO: LAUNCH REPLAY: EXTERNAL TANK CAMERA PLAY
VIDEO: FOOTAGE OF FUEL TANK AFTER JETTISON PLAY

VIDEO: LAUNCH REPLAY: FRONT CAMERA PLAY
VIDEO: LAUNCH REPLAY: BEACH TRACKER PLAY
VIDEO: LAUNCH REPLAY: PAD PERIMETER PLAY | HI-DEF
VIDEO: LAUNCH REPLAY: UCS-23 TRACKER PLAY
VIDEO: LAUNCH REPLAY: CAMERA CS-1 PLAY
VIDEO: LAUNCH REPLAY: CAMERA CS-2 PLAY
VIDEO: LAUNCH REPLAY: CAMERA CS-6 PLAY
VIDEO: LAUNCH REPLAY: VAB ROOF PLAY
VIDEO: LAUNCH REPLAY: PRESS SITE PLAY
VIDEO: LAUNCH REPLAY: WEST TOWER PLAY
VIDEO: LAUNCH REPLAY: CAMERA 009 PLAY
VIDEO: LAUNCH REPLAY: CAMERA 041 PLAY
VIDEO: LAUNCH REPLAY: CAMERA 049 PLAY
VIDEO: LAUNCH REPLAY: CAMERA 050 PLAY
VIDEO: LAUNCH REPLAY: CAMERA 051 PLAY
VIDEO: LAUNCH REPLAY: CAMERA 060 PLAY
VIDEO: LAUNCH REPLAY: CAMERA 061 PLAY
VIDEO: LAUNCH REPLAY: CAMERA 063 PLAY
VIDEO: LAUNCH REPLAY: CAMERA 070 PLAY
VIDEO: LAUNCH REPLAY: CAMERA 071 PLAY

VIDEO: SPACE SHUTTLE ATLANTIS BLASTS OFF! PLAY | HI-DEF
VIDEO: STS-125 POST-LAUNCH NEWS CONFERENCE PLAY
VIDEO: INSIDE MISSION CONTROL DURING LAUNCH PLAY
VIDEO: NARRATED ANIMATION OF DAY 1 INSPECTIONS PLAY

VIDEO: FINAL PRE-LAUNCH READINESS POLLS CONDUCTED PLAY
VIDEO: SHUTTLE'S CREW MODULE HATCH CLOSED FOR FLIGHT PLAY
VIDEO: MISSION SPECIALIST MEGAN MCARTHUR BOARDS PLAY
VIDEO: PILOT GREG JOHNSON BOARDS ATLANTIS PLAY
VIDEO: MISSION SPECIALIST JOHN GRUNSFELD BOARDS PLAY
VIDEO: SHUTTLE COMMANDER SCOTT ALTMAN BOARDS PLAY
VIDEO: CREW DEPARTS QUARTERS FOR LAUNCH PAD PART 1 | PART 2
VIDEO: ASTRONAUTS DON SPACESUITS FOR LAUNCH PLAY
VIDEO: TIME-LAPSE OF LAUNCH PAD GANTRY ROLLBACK PLAY

VIDEO: HUBBLE'S FUTURE AFTER ATLANTIS SERVICING PLAY
VIDEO: TOP DISCOVERIES MADE BY HUBBLE TELESCOPE PLAY
VIDEO: THE ROLLERCOASTER LIFE OF HUBBLE PLAY
VIDEO: WHAT IS HUBBLE'S PLACE IN HISTORY? PLAY
VIDEO: ENTERTAINING LOOK AT ATLANTIS' CREW PLAY
VIDEO: HUBBLE SPACE TELESCOPE HISTORY MOVIE PLAY
VIDEO: A TRIBUTE TO THE CAMERA THAT SAVED HUBBLE PLAY
VIDEO: HUBBLE TELESCOPE PROGRAM BRIEFING FROM SUNDAY PLAY

VIDEO: SUNDAY'S COUNTDOWN STATUS AND WEATHER UPDATE PLAY
VIDEO: THE STS-125 PRE-LAUNCH NEWS CONFERENCE PLAY
VIDEO: SATURDAY'S COUNTDOWN STATUS AND WEATHER UPDATE PLAY
VIDEO: ASTRONAUTS ARRIVE AT THE CAPE FOR LAUNCH PLAY
VIDEO: FRIDAY'S COUNTDOWN STATUS AND WEATHER UPDATE PLAY

VIDEO: NEWS BRIEFING FOLLOWING FLIGHT READINESS REVIEW PLAY

VIDEO: REFRESHER BRIEFING: THE STS-125 MISSION PLAY
VIDEO: REFRESHER BRIEFING: HUBBLE SPACE TELESCOPE PLAY
VIDEO: REFRESHER BRIEFING: THE SEVEN ASTRONAUTS PLAY

VIDEO: BIOGRAPHY MOVIE OF ATLANTIS' CREW PLAY
VIDEO: INTERVIEW WITH COMMANDER SCOTT ALTMAN PLAY | '09 UPDATE
VIDEO: INTERVIEW WITH PILOT GREG JOHNSON PLAY
VIDEO: INTERVIEW WITH MS1 MIKE GOOD PLAY
VIDEO: INTERVIEW WITH MS2 MEGAN MCARTHUR PLAY
VIDEO: INTERVIEW WITH MS3 JOHN GRUNSFELD PLAY | '09 UPDATE
VIDEO: INTERVIEW WITH MS4 MIKE MASSIMINO PLAY | '09 UPDATE
VIDEO: INTERVIEW WITH MS5 DREW FEUSTEL PLAY | '09 UPDATE

VIDEO: SHUTTLE ATLANTIS ARRIVES AT LAUNCH PAD 39A PLAY | HI-DEF
VIDEO: THE SUN RISES ON ATLANTIS DURING ROLLOUT PLAY | HI-DEF
VIDEO: ATLANTIS EMERGES FROM ASSEMBLY BUILDING PLAY | HI-DEF
VIDEO: ORBITER VERTICAL FOR MATING TO FUEL TANK PLAY | HI-DEF
VIDEO: ATLANTIS MOVES BACK TO ASSEMBLY BUILDING PLAY | HI-DEF

VIDEO: ATLANTIS LEAVES LAUNCH PAD 39A IN OCT. PLAY
VIDEO: TIMELAPSE OF THE ROLLBACK GETTING UNDERWAY PLAY

VIDEO: ASTRONAUTS REHEARSE QUICK SHUTTLE EXIT PLAY
VIDEO: CREW BOARDS ATLANTIS FOR MOCK COUNTDOWN PLAY
VIDEO: ASTRONAUTS DON SUITS FOR PRACTICE COUNTDOWN PLAY
VIDEO: CREW'S TRAINING ON ESCAPE BASKETS AND BUNKER PLAY
VIDEO: ASTRONAUTS CHAT WITH PRESS AT LAUNCH PAD PLAY
VIDEO: CREW TEST DRIVES EMERGENCY PAD ESCAPE VEHICLE PLAY
VIDEO: COMMANDER AND PILOT PRACTICE LANDING APPROACHES PLAY
VIDEO: CREW ARRIVES AT CAPE FOR PRACTICE COUNTDOWN PLAY
VIDEO: COMMENTS FROM COMMANDER AFTER ARRIVING PLAY

VIDEO: AERIAL VIEWS OF ATLANTIS AND ENDEAVOUR PLAY | HI-DEF

VIDEO: PRE-FLIGHT BRIEFING: THE STS-125 MISSION PLAY
VIDEO: PRE-FLIGHT BRIEFING: THE FIVE SPACEWALKS PLAY
VIDEO: PRE-FLIGHT BRIEFING: THE SEVEN ASTRONAUTS PLAY
VIDEO: PRE-FLIGHT BRIEFING: NASA LEADERSHIP PLAY
VIDEO: PRE-FLIGHT BRIEFING: SHUTTLE PROGRAM BOSS PLAY
VIDEO: PRE-FLIGHT BRIEFING: HUBBLE OVERVIEW PLAY
VIDEO: PRE-FLIGHT BRIEFING: HUBBLE SCIENCE PLAY

VIDEO: SHUTTLE ARRIVES ATOP PAD 39A PLAY
VIDEO: ATLANTIS EMERGES FROM VEHICLE ASSEMBLY BUILDING PLAY
VIDEO: TIME-LAPSE MOVIE OF ATLANTIS' ROLLOUT TO LAUNCH PAD PLAY

VIDEO: ATLANTIS ROLLS FROM HANGAR TO VAB PLAY
VIDEO: ATLANTIS LIFTED INTO PLACE FOR ATTACHMENT PLAY
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