STS-82 MISSION ARCHIVE Updated: 6 a.m., 2/21/97 Hubble Space Telescope Servicing Mission Launch: Feb. 11, 1997 By William Harwood CBS News/Kennedy Space Center The following copy originally was posted on the CBS News "Up To The Minute" Current Mission space page (http://uttm.com/space/missions/current.html). Comments and corrections welcome! TABLE OF CONTENTS: Shuttle Discovery blasts off (filed 2/11/97) Astronauts discuss Hubble overhaul in CBS interview (filed 2/12/97) Astronauts capture Hubble Space Telescope (filed 2/12/97) Astronauts stage first of four spacewalks (filed 2/14/97) Second spacewalk meets objectives (filed 2/15/97) Engineers assess insulation problem; EVA-2 details (filed 2/15/97) Shuttle crew dodges space debris (filed 2/15/97) Third HST spacewalk complete; fifth EVA added (filed 2/16/97) Fourth spacewalk completes HST overhaul (filed 2/17/97) Insulation fixed in final spacewalk (filed 2/18/97) Shuttle astronauts launch Hubble telescope (filed 2/19/97) Shuttle Discovery glides to smooth landing (filed 2/21/97) ==================================================================== Shuttle Discovery blasts off (filed 2/11/97) The space shuttle Discovery rocketed into orbit today and set off after the $3.1 billion Hubble Space Telescope for an overhaul expected to give astronomers an unprecedented view of the universe in its infancy. With commander Ken Bowersox and pilot Scott "Doc" Horowitz at the controls, Discovery vaulted away from pad 39A at 3:55:17 a.m., right on time after a near-flawless terminal countdown. Putting on a spectacular pre-dawn show, Discovery climbed skyward atop a brilliant pillar of fire visible for hundreds of miles around, launching into the plane of Hubble's orbit as the telescope sailed 320 miles above central Africa. The shuttle's initial orbit measured 360 miles by 215 miles. Over the next two days, Bowersox and Horowitz plan to fire the shuttle's maneuvering jets in a carefully orchestrated sequence to slowly close the gap. The shuttle will approach Hubble from directly below and if all goes well, astronaut Steven Hawley, operating Discovery's 50-foot-long robot arm, will pluck the 25,000-pound telescope out of open space around 3 a.m. Thursday. Earlier in the countdown, engineers were somewhat concerned about higher than usual concentrations of oxygen in the shuttle's payload bay and midbody area. But analysis indicated there were no major leaks in any of the shuttle's systems and engineers now believe the excess oxygen came from boxes in the cargo bay housing equipment to be installed on the Hubble Space Telescope. There were no other problems of any significance during the remainder of the countdown and initial concern about low clouds over the space center evaporated as launch time approached. The ascent was problem free. This evening, ground controllers plan to orient Hubble into the "capture attitude" with the open end of the telescope tube pointing toward deep space, away from the direction of the shuttle's approach. This is a safety precaution to minimize the chance for any shuttle debris or rocket exhaust from entering the business end of the telescope. At 8 a.m. Wednesday, a door will be commanded to close the end of the tube and at 1:30 p.m., the telescope's twin high-gain antennas will be stowed flush against the spacecraft's body. As it turns out, Discovery's servicing mission is extraordinarily well timed. Late last week, one of the instruments that will be replaced during the upcoming service call, the Goddard High Resolution Spectrometer shut itself down after an internal electrical problem. The unexpected shutdown blocked a planned observation of Mars Friday night, but officials said the overall impact to Hubble's mission was minimal. "The team got together on Friday and looked at all the options to try to turn it back on again and decided the additional observations weren't worth the effort," said Ken Ledbetter, a senior engineer with the Hubble project. "So the decision was made just to leave it off. ... This is an example of 'just in time.' If this had happened a month or a year before launch, we would have found some way to work around the problem. But it didn't justify the effort." ==================================================================== Astronauts discuss Hubble overhaul (filed 2/12/97) The Discovery astronauts will rendezvous with the Hubble Space Telescope this evening, using the shuttle's robot arm to pluck it out of open space shortly before 3 a.m. Thursday. The first of four back-to-back spacewalks to service the $3.1 billion observatory is scheduled to get underway around 11:20 p.m. Thursday. Early today, commander Kenneth Bowersox, robot arm operator Steve Hawley and lead spacewalker Mark Lee discussed the mission with CBS Radio. Bowersox said he particularly looks forward to the final stages of the rendezvous, as Discovery approaches Hubble from directly below using a contamination-free approach developed for dockings with the Russian Mir space station. "The part that's going to be the most exciting is as we close to within less than a mile when we'll be able to make out the shape of the telescope," said Bowersox, a veteran of a 1993 mission to repair Hubble's optical system. "It'll be up above us as we rendezvous from below and silhouetted against the black of space. I think what I'm looking forward to the most is the color of the telescope as it reflects the blue of the ocean. It'll actually start to glow. "What we'll be trying to avoid is using fuel," he added. "We want to save as much as we can so that when we get up there, we'll be able to raise the Hubble to a higher orbit using the fuel we have left over from the rendezvous. So we'll be trying to be as fuel efficient and careful as possible as we close in tight to the telescope." If all goes well, astronauts Mark Lee and Steve Smith will stage the crew's initial spacewalk Thursday evening. Today, the astronauts checked out their spacesuits, called EMUs, and other equipment while ground controllers readied Hubble for capture. "We're doing EMU checkout today and we're ready to hop in and walk out the door," Lee joked. "We're ready to go. We've been checking out the tools, the EMUs are fine, we checked out the arm today. The biggest thing is you want to go out with every thing full up and right now it's looking like we're in real good shape." But he cautioned: "Every task has a little bit of concern with it. There are not any that are worry free." Of particular concern are Hubble's fragile solar arrays. Both will remain fully extended through the service work, requiring the astronauts be very, very gentle when it comes to jarring the telescope. "We did some testing in the water to see how we could keep the forces down," Lee said. "The tolerance we're trying to keep under, two inches of movement of the solar arrays, is fairly conservative. So we don't expect, from our spacewalking, to cause any damage to the solar arrays at all. But we won't know for sure how delicate they are until we get up there and do a few initial maneuvers." While Discovery's flight does not have the do-or-die flavor of the 1993 repair mission, Bowersox said his crew feels just as much pressure. "I guess it's the public's perception, maybe, that there's a little bit less pressure and I think it's true there's probably a few less unknowns on this mission because some of the tasks have been done before," he said. "But I can guarantee for the crew on board there's more pressure on this flight. We want to do our best and we want to make sure we don't leave the telescope in worse shape than we find it." Assessing the difficulty of the service work, Lee said in general the tasks are comparable to those in the 1993 repair mission. "A number of the orbital replacement units were made for (spacewalk) changeout when they were first designed and they are fairly straight forward," he said. "Several of the others, though, require use of both hands ... and they get a little bit more difficult because you don't know exactly what to expect. There are a lot of unknowns." Hawley, who holds a Ph.D. in astronomy, used the shuttle's robot arm to launch Hubble in 1990. Coming full circle, he plans to haul it back on board early Thursday. In Hawley's view, Hubble represents one of the premier instruments in modern astronomy. "I would think the only other instrument that would rival it in historical value would be Galileo's original telescope when he was able to look at Jupiter and detect the moons and fundamentally change the way we thought about the universe at that time," Hawley said. "I think it's not unfair to make that sort of comparison. Hubble is revolutionizing how we think about the universe we live in. I would say it's almost unrivaled in history." And that's part of the public's fascination with Hubble, a combination of science and awe. "It's a little bit of both," Hawley said. "At first, it's the phenomenal pictures. I think they're captivating. The other part of the answer, though, is probably the fact that with Hubble we're actually able to begin to address some of the most fundamental questions that people have ever thought about. The idea that you can actually figure out how stars are made, where the universe comes from, what it's ultimate fate may be, how old is it, how big is it, are there other planets out there, I believe the public is excited about the prospect that we might actually be able to definitively answer some questions like that." ==================================================================== Astronauts capture Hubble Space Telescope (filed 2/12/97) Astronaut Steven Hawley, the man who launched the Hubble Space Telescope in 1990, used the shuttle Discovery's robot arm to pluck it out of open space today for a major overhaul that will give the $3.1 billion observatory a new lease on life and improve its already keen vision. "We wish you could see the expression on Dr. Stevie's face," commander Ken Bowersox radioed Houston as Hawley grappled the 25,000-pound telescope at 3:34 a.m. "It looks like he just shook hands with an old friend." "We watched it from down here, Sox," astronaut Marc Garneau replied from mission control. "It was certainly an absolute thrill for us to see it on television and congratulations to all of you for an outstanding rendezvous and a great capture. We're looking forward to getting out there and starting to work on that telescope." About a half hour later, a few minutes past 4 a.m., the telescope was mounted vertically on a rotating service platform at the back of Discovery's cargo bay, locked into position by three large motor-driven latches. "It looks in very good condition," said Kenneth Ledbetter, a senior Hubble manager at NASA headquarters in Washington. "We were very pleasantly surprised. There appears to be no additional damage to what was already there when we saw it last. So the telescope has survived very well for the past three years." Chief Hubble scientist Ed Weiler agreed, adding, "I think I speak for a lot of astronomers by saying that seeing that beautiful spacecraft for the first time in three years was like seeing your best friend who you hadn't seen for three years. Not only that, but the friend doesn't seem to have aged at all. The spacecraft looked beautiful." The successful capture of the 25,000-pound telescope sets the stage for a dramatic overnight spacewalk by astronauts Mark Lee and Steve Smith to install two new state-of-the-art instruments that will extend Hubble's vision into the infrared and greatly improve the observatory's productivity. The cargo bay excursion is scheduled to begin at 11:20 p.m., but it could get started up to an hour or so ahead of schedule depending on how eager the crew might be to get to work. While the instrument replacement is the No. 1 priority of the 82nd shuttle mission, a variety of other complex tasks await the shuttle crew over the weekend. During three successive spacewalks, Lee, Smith, Greg Harbaugh and Joe Tanner will work in alternating two-man teams to install new data recorders, computer gear, solar array control electronics and other hardware, including a fine guidance sensor and a new momentum wheel assembly to improve attitude control. "All the EVAs are important, but tomorrow is really the Superbowl of EVAs," said Weiler, using NASA's acronym for spacewalk. "If that goes well, I think it will really put Hubble into a position of having world-class scientific capability well into the 21st Century." After breaking out tools and setting up work platforms, Lee and Smith will remove the telephone booth-size Goddard High Resolution Spectrograph from the telescope, an instrument that was designed in the 1970s and '80s. They will replace it with the state-of-the-art $120 million Space Telescope Imaging Spectrograph, a new instrument that is vastly more capable than the one it is replacing. Lee and Smith have blocked out about two hours for the instrument swap out. They then will remove the Faint Object Spectrometer from Hubble and install the $100 million Near Infrared Camera and Multi-Object Spectrograph, or NICMOS, in its place. NICMOS will extend Hubble's vision into the infrared region of the spectrum, allowing astronomers to study light from the dawn of space and time that might hold clues about how galaxies formed and evolved. Throughout today's rendezvous and capture, flight controllers paid close attention to propellant consumption. Discovery reached orbit Tuesday with a 200-foot-per-second "underspeed," that is, the shuttle was traveling 136 mph slower than predicted when its main engines shut down. There was also a slight out-of-plane error. This is not unusual and both errors were corrected during a rocket firing later. But it required about 200 pounds of additional propellant from Discovery's on-board supplies. One of the objectives of the Hubble servicing mission is to boost the telescope to a slightly higher, more stable orbit. Three rocket firing sessions are planned during spacewalks two, three and four. But exactly how much reboost Hubble gets will depends on how much propellant is available and how well Bowersox did during today's rendezvous to conserve rocket fuel. Lead flight director Jeff Bantle said the predicted rendezvous propellant consumption was 690 pounds. As it turned out, Bowersox only used 650 pounds and as it now stands, roughly 900 pounds of fuel is available for reboost operations. While additional analysis is required, Bantle said that should allow the shuttle crew to increase Hubble's altitude by four miles or so. "We've still got some big mission objectives left, but the rendezvous today went very well," he said. "It went just exactly as we planned it. All the systems on board the vehicle worked well and the propellant we used during the rendezvous was slightly less than even we could have hoped for. So we're looking forward to four days of EVA activity hopefully followed by a very successful deploy." ==================================================================== Astronauts stage first of four spacewalks (filed 2/14/97) 9 p.m. update: Astronauts prepare for early spacewalk The Discovery astronauts are running more than one hour ahead of schedule preparing for this evening's spacewalk, the first of four on tap to overhaul the Hubble Space Telescope. Astronauts Mark Lee and Steven Smith originally were scheduled to float into Discovery's cargo bay around 11:20 p.m. to begin work to replace two instruments aboard the $3.1 billion observatory. But a few minutes before 9 p.m., the crew called down saying they are about an hour and 15 or 20 minutes ahead of schedule. If they maintain this pace, the spacewalk could begin as early as 10 p.m. or so. Frequent updates will be posted here once the spacewalk begins. Check back often! 10 p.m. update: Spacewalk delayed; solar array movment assessed Astronauts Mark Lee and Steven Smith delayed the start of a planned six-hour spacewalk when one of the Hubble Space Telescope's two solar arrays suddenly began rotating. The telescope's on-board computer systems shut down the solar array drive electronics unit to stop the motion while ground controllers assessed the situation. The array movement coincided, to within one second, with airlock depressurization. As it turns out, Discovery is equipped with an external airlock, installed for space station construction missions. The depressurization vent on that airlock faces the telescope and engineers now believe the escaping air might have hit the array and caused its unexpected motion. The spacewalk, meanwhile, remains on hold until ground controllers can regain video from the orbiter for a detailed assessment of the array issue. 10:40 p.m. update: Spacewalk delayed; solar array movment assessed Engineers believe one of the Hubble Space Telescope's two solar arrays moved suddenly shortly before 10 p.m. when it was hit by a gust of air from the shuttle Discovery's airlock, which was being depressurized. Astronauts Mark Lee and Steven Smith remain in the airlock, which still has an internal pressure of five pounds per square inch. The spacewalk is on hold until this issue is resolved. Video from Discovery at 10:35 p.m. showed Hubble's right-side array (as viewed from the crew cabin) tilted up from the horizontal by about 45 degrees. The astronauts said there were no signs of any damage from its brief excursion. "From all appearances, from what we can see, the arrays are normal, just slewed off," an astronaut radioed. "That's what we understand," replied astronaut Jeff Hoffman in mission control. "The best thing we can get out of these visuals is to reassure everybody that every thing is nominal." Discovery's external airlock has four depressurization valves: Two on an aft-facing hatch and two on a hatch at the top of the airlock. It appears the astronauts ultimately will be cleared to press ahead with tonight's spacewalk, using the upper depressurization valves instead to avoid any additional impact on Hubble. The spacewalk originally was scheduled to begin at 11:20, so the delay caused by the solar array issue should not have any impact on the timeline, assuming the EVA begins before midnight. As for Hubble, when the array was blown out of position, the telescope's on-board DF-22 computer automatically shut down the solar array drive electronics unit to stop the unexpected motion. 11:20 p.m. update: Astronauts cleared for spacewalk Floating in the shuttle Discovery's external airlock, astronauts Mark Lee and Steve Smith have been cleared to press ahead with a planned six-hour spacewalk to install two new scientific instruments aboard the Hubble Space Telescope. They originally planned to begin the excursion around 10 p.m., an hour and 20 or so minutes ahead of schedule, but the EVA was put on hold when one of Hubble's two solar arrays suddenly moved. See below for details. Engineers are convinced the movement caused no damage and the delay essentially put the crew back on the original timeline. Or close to it. It now appears they will exit the airlock within the half hour. 11:50 p.m. update: Hubble spacewalk begins Astronauts Mark Lee and Steve Smith floated into the shuttle Discovery's cargo bay around 11:45 p.m., kicking off a planned six-hour spacewalk to install two new instruments aboard the Hubble Space Telescope. The spacewalk officially began at 11:34 p.m. when the astronauts, still in Discovery's external airlock, switched their suits to internal power. "Oh my gosh... beautiful!" Smith exclaimed at the view from 360 miles up. "It was worth the wait." "You guys look really good out there," astronaut Joe Tanner radioed from the flight deck. "It was worth the wait," Smith repeated. After an hour or so of work to set up tools and work platforms in the shuttle's cargo bay, the astronauts will remove the Goddard High Resolution Spectrograph from Hubble and replace it with the Space Telescope Imaging Spectrograph, or STIS, a state-of-the-art instrument that will greatly improve Hubble's productivity. The swap-out will take about two hours. After that, Lee and Smith will remove the Faint Object Spectrometer from Hubble and install a new instrument called the Near Infrared Camera and Multi-Object Spectrometer, or NICMOS. The STIS will actually replace the functions of both the instruments being removed. NICMOS will extend Hubble's vision into the infrared region of the spectrum. A Detailed overview of the flight is available from the Space Telescope Science Institute. 1:30 a.m. update: Instrument swap-out underway Two spacewalkers aboard the shuttle Discovery have removed the Goddard High Resolution Spectrometer from the Hubble Space Telescope and are gearing up to install a new instrument, the Space Telescope Imaging Spectrograph, in place of the one the instrument they just removed. The astronauts are running ahead of schedule and so far, no major problems have been encountered. 2:30 a.m. update: New spectrometer installed The $120 million Space Telescope Imaging Spectrometer has been installed and hooked up to the Hubble Space Telescope. As of this writing, astronauts Mark Lee and Steve Smith are three hours into a planned six-hour spacewalk, either on or ahead of schedule. Smith currently is stowing the Goddard High Resolution Spectrometer, which was removed to make way for STIS, after which the spacewalkers will begin work to install a new infrared camera. Again, they've had no problems of any significance and the work is proceeding smoothly. 3:45 a.m. update: Astronauts install new infrared camera Astronauts Mark Lee and Steve Smith are installing the NICMOS infrared camera system into the Hubble Space Telescope. They already have installed a new state-of-the-art spectrometer and once the camera is in place and connected, the spacewalkers will have accomplished the primary goals of the 82nd shuttle mission, equipping the telescope with new instruments that will extend its vision and improve productivity. As of 3:42 a.m., the spacewalk had been underway for about four hours. If they get done with NICMOS in time, Lee and Smith might go ahead and install a reaction wheel assembly, a device that helps Hubble move from one target to the next. Will advise. 7 a.m. update: Astronauts wrap up first spacewalk Two astronauts aboard the shuttle Discovery installed a pair of new science instruments aboard the Hubble Space Telescope this morning before wrapping up a six-hour 42-minute spacewalk to accomplish the primary goal of the 82nd shuttle mission. "It's been a great day," astronaut Jeff Hoffman radioed the crew from Houston. "Sorry we made this a little bit more exciting than we had in mind, but we feel like everything turned out pretty good," replied astronaut Joe Tanner, who coordinated the spacewalk from Discovery's flight deck. "You accomplished absolutely everything in the timeline, which means this was a 100 percent successful EVA, which is a great way to start," Hoffman said. "From an astronomical point of view, it is almost impossible to imagine the Hubble Space Telescope being any better than it's been for the last three years, but you guys have made it so. There are an awful lot of astronomers who are looking forward to the next few years with a lot of anticipation. Thanks." "We couldn't agree more with you, Jeff," called Tanner. "It's been a great day for NASA and a great day for the Hubble program." Astronauts Mark Lee and Steve Smith began the excursion at 11:34 p.m. Thursday and returned to the safety of Discovery's airlock at 6:16 a.m. Flight planners originally blocked out six hours for the spacewalk, but it ran a bit longer than expected due to a few very minor snags, including a bit of trouble latching shut two instrument bay doors toward the end of the outing. But with old-fashioned elbow grease and a power wrench, the astronauts closed out the installation without any major problems. "We had a good time," Smith radioed. "We hope those two items produce great science." "I know there are a lot of folks who are happy and relieved right now, Steve and Mark," Tanner radioed earlier from Discovery's flight deck. ==================================================================== Second spacewalk meets objectives (filed 2/15/97) 10:45 p.m. (2/14) update: Harbaugh, Tanner begin second Hubble maintenance spacewalk Astronauts Gregory Harbaugh and Joseph Tanner floated out of the shuttle Discovery's external airlock around 10:30 p.m. to kick off a planned six-hour spacewalk, the second of four to upgrade the Hubble Space Telescope with fresh components. The cargo bay excursion officially began at 10:25 p.m. when the two astronauts switched their spacesuits to internal power. Unlike a spacewalk Thursday night by astronauts Mark Lee and Steve Smith, Harbaugh and Tanner had no problems getting out of Discovery's airlock, using a different procedure to vent air overboard to avoid jostling Hubble's fragile solar arrays. A gust of air from an airlock vent spun one of the arrays 90 degrees Thursday night, an unexpected event that delayed the start of the first spacewalk by nearly an hour and a half while engineers studied the problem. There were no such snags tonight. This evening's spacewalk has three primary objectives: Installation of a new fine guidance sensor, one of three that Hubble uses to lock onto and track astronomical targets; installation of calibration equipment to help ground controllers fine-tune the guidance sensor; and installation of a new data recorder to replace one that failed aboard the telescope earlier. As Harbaugh and Tanner set up tools and work platforms in Discovery's cargo hold, astronaut Jeffrey Hoffman in mission control, a veteran spacewalker who helped repair Hubble in 1990, told Tanner to enjoy his first cargo bay outing. "Welcome to space and it's nice seeing a big smile on your face," Hoffman said. "Have a good one." "Thank you, Jeff. I think you're going to see us smiling a lot today," Tanner replied. 11:50 p.m. update: Fine guidance sensor disconnected; replacement work on track Greg Harbaugh has completed disconnection of electrical cables between the Hubble Space Telescope and one of its three fine guidance sensors. After attaching handrails to the unit, Harbaugh and Joe Tanner will remove it and install a replacement unit. So far, the spacewalk is proceeding smoothly with no problems of any significance and the astronauts have taken a moment here and there to enjoy the view from 360 miles up. "It's pretty awesome," Tanner observed as the shuttle sailed above Australia. "Pretty impressive," Harbaugh concurred. One observation: Multi-layer insulation, or MLI, around the fine guidance sensor housing is cracked and crumbly looking, showing the effects of long-duration exposure to the harsh environment of space. "In several places, it's cracked, it's just gotten old it looks like," Tanner said. "I don't see anyplace where it's crumbling, but I would recommend, I guess, that we be especially careful at not touching any of this MLI." Some of the cracks, he and Harbaugh reported, were six to eight inches long, "they're not just tiny little spider cracks. Something could sort of go flying off." The crew of a 1993 mission to repair Hubble's flawed optical system did not see any such cracking, "further evidence that with time, any of the man-made materials we have on orbit do experience degradation," said Jerry Ross, a veteran spacewalker monitoring the flight from mission control. "The specific concern with respect to the Hubble Space Telescope is if that starts breaking off then it could contaminate the optics of the machinery and then degrade the capabilities of the Hubble Space Telescope to continue to do the great science it's been doing," Ross said. There's no evidence of any such contamination at present, but it's something to keep in mind looking ahead to space station. 2:15 a.m. update: Fine guidance sensor installation complete Concerned about ripped insulation covering various access panels on the Hubble Space Telescope, astronauts Joe Tanner and Greg Harbaugh replaced a bulky fine guidance sensor today, completing the installation at 1:59 a.m. The delicate task of inserting the big instrument, one of three that helps Hubble lock onto targets, occurred during orbital darkness, making the job a bit trickier than it might have been in daylight. "I guess we would end up doing this at night, wouldn't we Greg," Tanner said, aligning the sensor assembly with its housing in the telescope as he floated on the end of Discovery's robot arm. "Well sure. Anybody could do it in the daytime," Harbaugh joked as Discovery soared over the Pacific Ocean just west of Central America. Being especially careful not to damage a critical mirror assembly at the rear of the guidance sensor, Tanner slipped the unit into place. "The mirror is at the opening, Joe," Harbaugh said as Tanner maneuverd the sensor into its housing. "Keep it going like that, perfect! ... You're there, you're in the guide rail.,.." "I don't even feel it," Tanner reflected. "...very nice." Then, at 12:41 a.m.: "I think it's in there, yes sir!" Harbaugh said after the new sensor was latched in place. The equipment bay was relatched at 1:59 a.m. to complete the guidance sensor swapout. The only problem encountered was trouble with a torque wrench, but that was quickly resolved. With the guidance sensor installation complete, the astronauts turned their attention to replacing a data and engineering tape recorder in equipment Bay 8. When Tanner and Harbaugh reached the site, however, they noticed the outer layer of the MLI protective blanket over the bay access door was ripped and torn in several places, prompting concern it might crumble and break away during the recorder changeout, posing a contamination threat to the telescope. But ground controllers told the astronauts to press on with the recorder replacement and after the spacewalkers carefully opened the access doors, Tanner began disconnecting the old recorder. Earlier, the astronauts took a moment to enjoy the view from 360 miles up. "Wow, what a picture this is," Harbaugh laughed at one point as Discovery sailed into darkness over the Pacific Ocean. "Man, oh man!" "Yeah, how about it?" Tanner said. "That's about the best seat in the house right down there." "You got that right." 3:30 a.m. update: Tape recorder installation complete; solar array survey Astronauts Greg Harbaugh and Joe Tanner installed a new science and engineering tape recorder aboard the Hubble Space Telescope early today, accomplishing the second objective of their planned six-hour spacewalk. The installation went smoothly an an initial "aliveness" test around 3 a.m. showed the device was properly hooked up and electrically active. The final item on the agenda today is installation of an optical control electronics kit that will enable ground controllers to adjust a critical mirror in the fine guidance sensor installed earlier. Before pressing ahead with that task, however, Harbaugh and Tanner spent a few moments photographing one of Hubble's solar arrays from below to document its condition after more than three years in space. The array generally appeared to be in good condition, although the astronauts noticed a small penetration similar to a small bullet hole. Back on Earth, engineers debated what, if anything, to do about insulation that has ripped and pulled away from Hubble's skin in several places. In general, "the Hubble looks in great shape," commented astronaut Jerry Ross in mission control. "I know the MLI (multi-layer insulation) is something probably the project managers wish had upheld the rigors of space a little bit better than maybe it has in some areas. There's one face of the telescope that's essentially always facing the sun and also into the velocity vector. So one side is exposed to all the detrimental effects of space while the other side is pretty much in pretty good shape." Before today's spacewalk ends, shuttle commander Ken Bowersox plans to fire Discovery's small vernier steering jets for 20 minutes or so to boost the shuttle - and Hubble - to a slightly higher, more stable altitude. The maneuver should raise the orbit by an average of two nautical miles. Two more "reboost" firings are planned during the final two spacewalks early Sunday and Monday. "If we were to have a camera outside actually looking at it, you wouldn't hardly notice this," lead flight director Jeff Bantle said before launch. "Using the vernier jets is going to be like normal attitude control. In fact, all of our reboost is planned while the crew is outside doing the cleanup in the bay." The 11-year solar cycle causes Earth's atmosphere to swell slightly, which increases the amount of drag, or friction, satellites experience as they plow through the extreme upper reaches of the atmosphere. To offset this increased atmospheric drag, NASA needs to boost Hubble a total of 16 nautical miles by the end of the next servicing mission in 1999. Flight controllers hope to raise the altitude a total of about four nautical miles during the current mission. 6 a.m. update: Discovery boosts Hubble's altitude; spacewalk ends Shuttle commander Ken Bowersox and pilot Scott Horowitz fired Discovery's small vernier steering jets early today for 22 minutes to gently boost the Hubble Space Telescope to a slightly higher, more stable orbit. With its payload bay facing in the direction of travel, Discovery's small "downward," or in this case, backward-firing vernier thrusters were fired in a rocking, side-to-side motion to slowly climb along the velocity vector to raise Hubble's orbit by about one-and-a-half miles. Similar rocket firings are planned early Sunday and Monday to gain a total of about four nautical miles. Astronauts Greg Harbaugh and Joe Tanner, meanwhile, were wrapping up a successful seven-hour-plus spacewalk, stowing tools and preparing to re-enter Discovery's airlock. During their excursion, Harbaugh and Tanner installed a new fine guidance sensor, a replacement science and engineering data recorder and an electronic kit that will enable engineers on Earth to calibrate the guidance sensor. There were no major problems and so far, all of the mission's major (and minor) objectives have been met. Today's seven-hour 26-minute spacewalk officially ended at 5:52 a.m. when Discovery's airlock was repressurized. The airlock's outer hatch was closed at 5:44 a.m. and the astronauts switched their suits to shuttle power at 5:51 a.m. ==================================================================== Engineers assess insulation problem; EVA-2 details (filed 2/15/97) Two spacewalkers aboard the shuttle Discovery replaced one of three sensitive guidance systems aboard the Hubble Space Telescope today and installed a new science and engineering data recorder, reaching the halfway point in a $350 million overhaul. In a somewhat surprising discovery with a potentially serious impact, the astronauts also found numerous large rips and tears in the silvery insulation protecting the telescope's outer surface from harmful ultraviolet light and erosion by atomic oxygen in the extreme upper atmosphere. The insulation is called MLI for "multi-layer insulation and it varies in thickness from 10 to 20 layers. Engineers on Earth are debating whether Discovery's crew should attempt to repair any of the tears during upcoming spacewalks and whether the damage poses any threat to Hubble's long-term health. "In several places, it's cracked, it's just gotten old it looks like," spacewalker Gregory Harbaugh radioed mission control. "I don't see any place where it's crumbling, but I would recommend, I guess, that we be especially careful at not touching any of this MLI." Some of the cracks were six to eight inches long, "they're not just tiny little spider cracks," Harbaugh said. "Something could sort of go flying off." The crew of a 1993 mission to repair Hubble's flawed optical system did not see any such cracking, "further evidence that with time, any of the man-made materials we have on orbit do experience degradation," said Jerry Ross, a veteran spacewalker monitoring the flight from mission control. "The specific concern with respect to the Hubble Space Telescope is if that starts breaking off then it could contaminate the optics of the machinery and then degrade the capabilities of the Hubble Space Telescope to continue to do the great science it's been doing," Ross said. Project scientist David Leckrone agreed, saying "If some of this material broke loose and began floating around the telescope, particularly up toward the aperture end of the telescope, we would have some concerns about that." Kenneth Ledbetter, a senior Hubble manager at NASA headquarters in Washington, said the damage apparently occurred over the last three years due to the constant expansion and contraction caused by repeated passes into and out of Earth's shadow. The insulation appeared to be in good shape during a Hubble repair mission in 1993 and Ledbetter said engineers are studying possible long-term fixes that could be implemented during an already planned 1999 servicing mission. "Obviously, we need to look at what we can do in '99," Ledbetter said. "We'll probably spend a few months looking into what we can take up in '99 to repair some of these. As bad as it looked, we probably can survive until '99." But it does not appear much, if anything, can be done during the current flight. Still, the astronauts may be asked to repair some of the bigger rips - some measure 18 inches or so in length - during a fourth and final spacewalk overnight Sunday. Harbaugh and Joseph Tanner accomplished the primary goals of the crew's second spacewalk today by installing a new fine guidance sensor and a new recorder to replace one that failed earlier in Hubble's mission. Today's work, coupled with the installation of two new science instruments Friday, accomplished the minimum requirements for mission success. Leckrone said functional tests of the new science instruments show both came through launch and installation "with flying colors. It was as though they were still on the ground. This is, once again, a tribute to the overall gentleness of the servicing process." "It wil be several weeks and even months before we've completed getting these instruments fully up to operation and getting far along in our calibration and getting started on our science observations," he said. "But we're off to a very good start." While the science instruments were the top priorities of the Hubble servicing mission, the fine guidance sensor installed today came in a very close second. Hubble is equipped with three such sensors, which are used to lock onto guide stars so the telescope can smoothly track astronomical targets. The sensors also can be used for astrometric studies of stellar motion. "We have three fine guidance sensors on board the spacecraft," Leckrone said. "Two of these have shown clear indications of wearing out. Yet we have only one spare. If one fine guidance sensor stopped operating properly, this would have an effect on efficiency, but we could continue to do science on the Hubble. However, if two of them stopped operating, science would stop. So we can't let that happen." The guidance sensor removed today will be returned to Earth, refurbished and upgraded and re-installed during the upcoming 1999 maintenance mission. The guidance sensor removed in 1999 will be re-installed in 2002. In that fashion, NASA will replace all three of Hubble's original guidance sensors, which are crucial to the telescope's performance. "They stabilize the pointing of the telescope," Leckrone said. "If you hit a tee shot from Washington, DC, westard and you could control the trajectory of the ball with the same level of precision, you could hit a hole in one in Denver. And that, in fact, is what our fine guidance sensors do. They're very precise, very complex optical instruments and we're absolutely dependent on them to do science." Harbaugh and Tanner floated out of Discovery's external airlock around 10:30 p.m. Friday to kick off the second of four planned Hubble upgrade spacewalks. The cargo bay excursion officially began at 10:25 p.m. when the two astronauts switched their spacesuits to internal power. Unlike a spacewalk Thursday night by astronauts Mark Lee and Steve Smith, Harbaugh and Tanner had no problems getting out of Discovery's airlock, using a different procedure to vent air overboard to avoid jostling Hubble's fragile solar arrays. A gust of air from an airlock vent spun one of the arrays 90 degrees Thursday night, an unexpected event that delayed the start of the first spacewalk by nearly an hour and a half while engineers studied the problem. There were no such snags Friday night. The first item on the agenda was the fine guidance sensor replacement, work that ended up taking place during orbital darkness. "I guess we would end up doing this at night, wouldn't we Greg," Tanner said, aligning the sensor assembly with its housing in the telescope as he floated on the end of Discovery's robot arm. "Well sure. Anybody could do it in the daytime," Harbaugh joked as Discovery soared over the Pacific Ocean just west of Central America. Being especially careful not to damage a critical mirror assembly at the rear of the guidance sensor, Tanner slipped the unit into place. "The mirror is at the opening, Joe," Harbaugh said as Tanner maneuverd the sensor into its housing. "Keep it going like that, perfect! ... You're there, you're in the guide rail..." "I don't even feel it," Tanner reflected. "...very nice." Then, at 12:41 a.m.: "I think it's in there, yes sir!" Harbaugh said after the new sensor was latched in place. The equipment bay was relatched at 1:59 a.m. to complete the guidance sensor swapout. The only problem encountered was trouble with a torque wrench, but that was quickly resolved. With the guidance sensor installation complete, the astronauts turned their attention to replacing a data recorder in equipment Bay 8. The work went smoothly, as did installation of a cable kit that will allow ground controllers to calibrate the new fine guidance sensor. While Harbaugh and Tanner packed up their tools and prepared to re-enter the shuttle's airlock, shuttle commander Ken Bowersox and pilot Scott Horowitz fired Discovery's small vernier steering jets for 22 minutes to gently boost the space telescope to a slightly higher, more stable orbit. With its payload bay facing in the direction of travel, Discovery's small "downward," or in this case, backward-firing vernier thrusters were fired in a rocking, side-to-side motion to slowly climb along the velocity vector to raise Hubble's orbit by about one-and-a-half miles. Similar rocket firings are planned early Sunday and Monday to gain a total of about four nautical miles. Today's seven-hour 26-minute spacewalk officially ended at 5:52 a.m. when Discovery's airlock was repressurized. The airlock's outer hatch was closed at 5:44 a.m. and the astronauts switched their suits to shuttle power at 5:51 a.m. ==================================================================== Shuttle crew dodges space debris (filed 2/15/97) Erring on the side of caution, flight director Bryan Austin ordered shuttle commander Kenneth Bowersox to fire Discovery's small steering jets at 10:02 a.m. to move the spacecraft safely away from a small six-inch square piece of space debris that otherwise might have passed within a scant half-mile or so of the orbiter. The potentially dangerous debris is from a Pegasus rocket body and the shuttle crew knew about the possibility of a close encounter before they took off last Tuesday. Earlier today, the astronauts carried out a planned maneuver to boost the Hubble Space Telescope to a slightly higher, more stable orbit (see below for details). Two more such sessions were planned for early Sunday and Monday. But based on updated radar tracking, flight controllers predicted the Pegasus debris would pass within about a half mile of Discovery around 11:20 a.m. To avoid any chance of a close encounter, Austin ordered Discovery's crew to carry out another Hubble reboost maneuver to increase the shuttle's altitude by another half mile. The procedure ended uneventfully at 10:12 a.m. ==================================================================== Lee and Smith stage third Hubble spacewalk; fifth EVA added (filed 2/16/97) 10:20 p.m. update: Lee and Smith begin third Hubble maintenance spacewalk Astronauts Mark Lee and Steven Smith floated into the shuttle Discovery's cargo bay around 10:15 p.m. tonight to begin the crew's third spacewalk to service the Hubble Space Telescope. The spacewalk officially began at 9:53 p.m. when the astronauts switched their spacesuits to internal battery power. They remained inside the airlock for another twenty minutes or so while engineers debated a problem with Lee's suit status display. But after several switch cycles the display began working properly and the astronauts were cleared to proceed. The first item on the agenda was to replace a data interface unit on the telescope, an electronic black box that reformats and relays commands from Hubble's central computer to various subsystems. The DIU was not designed to be replaced in orbit and the work promises to be especially challenging. "The DIU is really a tough nut because you have got a whole bunch of connectors you have to unfasten and reconnect and any one of them could be balky and create problems," astronaut Gregory Harbaugh said before launch. "It is not a piece of cake." For this evening's replacement, Lee was anchored to Discovery's robot arm while Smith was the designated "free floater." The work is expected to take about two hours. Other items on the agenda include installation of a new state-of-the-art digital data recorder capable of storing 12 gigabytes of information and a reaction wheel assembly that helps Hubble move from one target to another. Periodic updates will be posted here throughout this evening's spacewalk. Check in often! 11:40 p.m. update: Data interface unit unbolted from Hubble Astronaut Mark Lee has unbolted a data interface unit "black box" from the Hubble Space Telescope as part of a tricky two-hour replacement procedure. The DIU was not designed to be replaced in space and hooking up all the connectors while working in a bulky, pressurized spacesuit is not considered an easy task. Here's how retiring astronaut Story Musgrave described it: "The connections on that box do not have the great big wing tabs, the four-to-five-inch wing tabs that you can get in there and rotate easily with a gloved hand," Musgrave said. "Taking a connector off is much easier than putting a connector on. To take a connector off, all you need to do is rotate the collar a certain amount and then the connector will come right off. Putting a connector on, you have to clock the connector ... so the pins in the socket will match up. You have to go on absolutely squarely and clocked correctly and while you're holding that, then you need to put the right force on the collar." The new DIU is equipped with pre-installed connectors with extensions that, in turn, will be hooked up to the cables that originally plugged directly into the original data interface unit. At 11:37 p.m., spectacular video from Discovery showed Lee holding the old DIU with Hubble and the Earth in the background. A truly gorgeous shot! 1 a.m. update: New data interface unit installed; initial checkout good In a bit of electronic brain surgery, astronaut Mark Lee replaced a critical computer system aboard the Hubble Space Telescope today, wiring it into place with 18 connectors in a task billed as one of the most difficult in a $350 million overhaul. The work appeared to go smoothly, so smoothly in fact that Lee's crewmates joked about being put to sleep. "That's nine," Lee said at one point, tightening down a connector. "Are you sure that wasn't six, Mark?" Joe Tanner joked from Discovery's flight deck. "Don't confuse me... you worried me there for a minute," Lee laughed. "You're doing that so well you're putting us to sleep down here," Tanner replied. "Well, I'm not sleeping!" Lee said. The data interface unit that was replaced today malfunctioned prior to the telescope's deployment following a 1993 mission to repair its flawed optical system. The telescope's release into open space was delayed three hours when the DIU suffered a failure in its internal electronics. After troubleshooting, mission managers decided to press ahead with deployment, relying on the unit's redundant components to keep the observatory healthy until the current mission could be launched. The decision paid off. At 12:53 a.m., flight controllers told Discovery's crew an initial "aliveness" test showed the new computer was working properly. "Fantastic!" one of the astronauts replied. A few minutes later, the astronauts had a bit of trouble closing the access door over the equipment bay where the DIU was bolted into place because of the longer cables used to connect the new unit. 1:30 a.m. update: Astronauts ready digital data recorder for installation; discuss ripped insulation and possible repairs There has been quite a bit of discussion this morning about the ripped and torn multi-layer insulation (MLI) discovered Saturday in numerous places on the telescope. The astronauts plan to carry out a series of tests today to determine how strong the foil-like insulation is, whether it can be taped or tethered without crumbling and how many tears the crew might be able to repair during a fourth and final spacewalk Sunday night and Monday morning. There are two potentially serious issues involved with the insulation situation. The material protects the telescope from harmful ultraviolet light and degradation from atomic oxygen. In addition, engineers and scientists are concerned that if the insulation flakes away, particles could either contaminate the telescope's sensitive systems or interfere with routine observations. Hubble does not make any significant orbital changes and any flakes of insulation likely would remain close to the telescope. A shuttle servicing mission already is scheduled for 1999, when some sort of repair work is likely. The question today is what, if anything, can Discovery's crew do? The astronauts have insisted on having a say in any final decisions regarding what tests to run today and mission control has promised a detailed discussion later this morning, after the primary objectives of today's spacewalk have been met. Will advise. "The damage to the MLI blankets on HST has many folks concerned," mission control told the crew earlier in a daily package of notes uplinked to the shuttle. "We are currently investigating potential repair options, but concede that it will be a difficult task. The primary objectives of these additions is to retrieve and bring inside the items which we believe may be used to execute the repairs. Another objective is to perform an evaluation to determine how well Kapton tape adheres to the MLI in its current degraded state, and return some further qualitative assessment of the brittleness exhibited during handling. We are continuing to develop opeionts and will send further instructions prior to EVA 4." Meanwhile, with the new data interface unit in place, Lee and Smith swapped places, with Smith taking Lee's place on the end of the robot arm. Hubble was rotated to give the astronauts access to equipment bay five, where the telescope's three science and engineering data recorders are located. One of them was replaced Saturday. Today, the astronauts worked to install a state-of-the-art digital recorder capable of storing 12 gigabits of data. The older recorders could only store 1.2 gigabits per machine. Unlike the 1970s-era instrument it's replacing, the solid state recorder has no moving parts. Data is stored in RAM until ground controllers order a replay. Before starting the recorder replacement, Lee took a moment to say hi to his wife, astronaut Jan Davis. "While we've got a break here, I'd like to say hello to my wife, Jan, down there watching," Lee said, floating on the end of the shuttle's robot arm. "I'm sure she wishes she was up here working on Hubble, too. She's probably having a few margaritas right now." "You wish you were, too, huh?" joked Tanner. "Yeah, me too," Lee said. "I've been trying to write her all kinds of messages, but I just haven't been able to get on the computer." Later, the astronauts marveled at the view from 360 miles up. "Holy cow, I've got the Hubble Space Telescope, Shark's Bay, planet Earth and the moon in my view," Lee radioed. "What a great place to be." "Just an average day for a couple of spacewalkers," Tanner replied. 4:20 a.m. update: New reaction control wheel assembly installed; recorder checks out Astronauts Mark Lee and Steve Smith wound up another successful spacewalk today, installing a new computer relay device, a solid-state data recorder and a new reaction wheel assembly in the Hubble Space Telescope as part of a $350 million overhaul. All three components passed initial "aliveness" tests, giving ground controllers confidence the devices will work properly once Hubble is released back into open space. "You guys are batting 100 percent, the RWA aliveness test was completely successful," astronaut Marc Garneau radioed from mission control around 4 a.m. With their final official task complete, Lee examined an access panel to deterimine the severity of rips in multi-layer insulation noticed earlier in the flight. He reported the MLI did not appear to be brittle in any way, easing concerns about flaking, but ground controllers told him not to remove any of the torn insulation for additional analysis (details will be posted shortly, including an interesting exchange between Lee and Tanner about the condition of the MLI). In addition, Lee demonstrated that Kapton tape will not be useful repairing any rips or tears. The tape stuck to the MLI, but just barely. And so, at the six-hour 30-minute point in their spacewalk, Lee and Smith are cleaning up and preparing to re-enter Discovery's airlock. 4:50 a.m. update: Astronaut describes damaged insulation Astronaut Mark Lee, floating in front of equipment bay seven on the Hubble Space Telescope, gave ground controllers a detailed description of the condition of tattered insulation covering one of several access panels. The insulation is used widely on Hubble to provide UV protection and to serve as a shield against atomic oxygen. Engineers are trying to find a way to repair some, if not all, of the damage. Lee's report was not optimistic. "In this corner it's ripped from there all the way down across the corner," Lee said, tracing one rip with his finger. "And there's a whole bunch of little scales in this area, a line there, another rip through here with what looks like a very small impact. Over on this side, there's a rip from up above all the way down following my line, another one across the corner. Over here there's a piece just about falling off by the latch. In this area, it looks like another minor impact..." "Lean to your left if you can while you're doing all that," Tanner radioed from the flight deck, asking Lee for an unobstructed TV view. "All right. Over here there's a crack that goes over to this area, one that goes across the bottom, one that goes up through the middle here, one that comes over there, a small one in the middle and another couple of small cracks on the left side. So basically, this thing is just falling apart, it's cracking all over the place. To repair one particular spot would just totally open up a few more. Here's a crack that goes across the hinge line, another one down here." Lee then tested the MLI's brittleness. The concern here was to find out how susceptible the insulation is to flaking away, a major concern given Hubble's sensitive optical and electrical systems. "Here's a piece right here that's pulled back," Lee said. "It doesn't appear to be brittle. I'll go ahead and crinkle a corner... all right, I crinkled a corner, made a crease in it, it's not brittle at all. ... If you want me to, this piece is almost off, I can take it off and bring it in if somebody wants to see it." Mission control declined. Lee said the piece he was referring to didn't protect anything and Tanner asked flight controllers to reconsider. "Discovery, Houston, for Joe T. The issue was discussed again and the decision was not to remove any of the MLI," Marc Garneau radioed from Houston. Lee then tested Kapton tape to determine how well it might hold two halves of an MLI rip together. But he reported the tape did not stick well in the vacuum of space. "It barely sticks," he said. "It just comes off like that, it just rolls right down." This issue will be discussed in more detail later and when it is, details will be posted here. In the meantime, commander Ken Bowersox pressed ahead with a third series of rocket firings to slightly increase Hubble's altitude. Two such reboost maneuvers were carried out Saturday. 5:15 a.m. update: Spacewalk No. 3 officially ends Astronauts Mark Lee and Steve Smith ended a seven-hour 11-minute spacewalk at 5:04 a.m. when they repressurized Discovery's airlock. Lee, Smith, Greg Harbaugh and Joe Tanner now have logged a total of 21 hours and 20 minutes of spacewalk time during three of four planned cargo bay excursions. For the record, the longest spacewalk in shuttle history occurred in May 1992 when Rick Hieb, Pierre Thuot and Tom Akers spent eight hours and 29 minutes in the shuttle Endeavour's cargo bay to repair an Intelsat communications satellite. NOTE: In the previous entry, readers may have gotten the impression Bowersox was proceeding with today's reboost maneuver while Lee and Smith were still in the cargo bay. In fact, the maneuver did not begin until 5:11 a.m., after both spacewalkers were back in Discovery's airlock. 7:40 a.m. update: Flight director, astronauts discuss possible fifth spacewalk; news briefing at 9:45 a.m. Flight director Jeff Bantle and shuttle commander Ken Bowersox discussed possible repair work today to fix several large tears in the MLI insulation protecting the Hubble Space Telescope. The work would require the astronauts to construct shield-like blankets that would then be secured over particularly sensitive areas using tethers. Bantle suggested the possibility of combining the repair work with the tasks already scheduled for a fourth and final Hubble servicing spacewalk scheduled to get underway at 11:20 p.m. this evening. Bowersox replied that he thought the best approach might be to press ahead with the spacewalk as currently planned, take a day off to rig the blankets and review procedures and then to stage a fifth, unplanned, spacewalk the next night to carry out the insulation repair work. In that case, the crew would give up a day off later in the flight and landing would remain on tap Feb. 21. Here's part of the discussion (keep in mind that "tonight" refers to the crew's night, i.e., early this morning EST; likewise, "tomorrow" refers to the crew's tomorrow, which begins after wakeup this evening): BANTLE: The two main options as I see them, number one would be to fabricate (the repair kits) tonight and install them in the EVA. It appears a bit rushed. It may be doable, we just have to see how it all starts coming together. I also know we've been working kind of long EVAs, kind of long days for a number of different reasons. So we need to keep that in mind, too. The other option, if it doesn't all come together in the next several hours such that we feel comfortable, an option would be to spend tomorrow getting all the fabrication (done), kind of make that more like the off duty day and slide the EVA back a day and the deploy back a day. We don't have the extra consumables to just extend the flight an additional day, so tomorrow would be more like the off duty day. So anyway, any thoughts you have on that? We don't have to decide right now, we can see in the next couple of hours how things come together... BOWERSOX: OK, Jeff. We've been talking and we appreciate the details. We're not hard over on any particular plan yet, but what's making a lot of sense to us is sort of go along with our nominal plan now for EVA 4, let you guys get a little more maturity and development on all the other MLI repairs, except for the MLI blankets. The MLI repair kit the guys have trained on, we'd like to go ahead and add that onto EVA 4. But then consider a sort of leisurely discussion of the extra repair blankets after EVA 4 then use our day off-slash-contingency day for a short fifth EVA and take a little time off after that. That seems to make sense to us and then go ahead and do deploy day and deorbit prep day kind of per the previous plan. A news briefing is planned for 9:45 a.m., after today's meeting of NASA's mission management team. Will advise. 8:45 a.m. update: Flight director recommends fifth spacewalk Flight director Jeff Bantle has sided with the Discovery astronauts, telling commander Kenneth Bowersox he will recommend a fifth spacewalk to repair ripped and tattered insulation over three critical equipment bays. Under this scenario - and it is thought to be a done deal - astronauts Greg Harbaugh and Joe Tanner would carry out a fourth spacewalk this evening as planned to install a new solar array drive electronics unit and new protective covers over a pair of magnetometers at the tip of the telescope tube. In addition, they would use clips to install spare insulation blankets over specific tears in the insulation near Hubble's light shield, using an MLI insulation repair kit carried aloft for just that purpose. The astronauts have trained to make such repairs and no major problems are anticipated. A fifth spacewalk would be staged late Monday and into Tuesday morning to install what amounts to homemade chicken wire over three critical equipment bays to prevent the insulation currently in place from peeling away any more than it already has. Bay 10 houses Hubble's science instrument control and data handling system and engineers believe some of this vital equipment could overheat and effectively burn out if the insulation situation worsens. Bay 8 houses pointing and safemode electronics (critical for recovering from failures) and other electronic controls. Bay 7 houses another data interface unit and a solar array drive electronics unit. All three bays need protection to prevent problems down the road. Deferring these repairs until Monday/Tuesday will give the astronauts and ground controllers more time to perfect the repair procedures. A news conference to discuss all this is on tap around 9:45 a.m. "I think we're all converged to about the same page, which is for tomorrow's EVA to do those things we're prepared to do," Bantle said. "We'll work on the timeline for that and then that'll give us some time, another day, to fabricate the additional MLI repair for bays 7, 8 and 10. I think that's where the teams are headed at this point." "That makes a lot of sense to us," Bowersox replied. "We like what you've got for a plan now, we think it's good to make this decision, go ahead and go ahead with EVA 4 pretty much as we planned it and look at adding something on later." 9:50 a.m. update: Mission management team officially approves fifth spacewalk NASA's mission management team has officially approved the addition of a fifth spacewalk Monday night to attempt repairs of insulation over critical equipment bays on the Hubble Space Telescope. More details after an upcoming news conference. 11:15 a.m. update: Mission status briefing Senior NASA managers say the addition of a fifth spacewalk to repair four areas on the Hubble Space Telescope where protective insulation has peeled away does not represent any sort of crisis for the giant observatory. NASA, they say, is simply taking advantage of the opportunity to implement some protective measures that might provide a bit of extra margin between now and 1999 when the next Hubble servicing mission is scheduled. The issue is simple: The insulation provides the thermal control needed to maintain a safe operating temperature inside the telescope. This prevents electronic gear in the equipment section from getting too hot and it prevents the upper part of the telescope tube, called the light shield, from warping, which could affect internal optical alignment. After Discovery's crew pulled Hubble on board for a regularly planned overhaul, engineers noticed several sections where the multi-layer insulation had cracked and peeled. Virtually all of the damage was on the side of the telescope that always faces the sun, the so-called "hot side." Two of those sections are located on the light shield and two more are located over critical equipment bays at the midpoint of the telescope. The cracks are thought to have been caused by ultraviolet radiation and erosion by atomic oxygen in the extreme upper atmosphere. No thermal problems or performance degradation were present prior to Hubble's capture by Discovery and scientists believe it would take a considerable amount of time for any such effects to show up even if Discovery's crew did nothing. But when the astronauts blasted off, they took an emergency MLI repair kit into space with them as a routine contingency measure. The kit consists of two 1-by-3-foot sections of MLI insulation and adjustable cords to tie them into position. During a fourth spacewalk this evening, astronauts Greg Harbaugh and Joe Tanner will install these sections over the insulation tears at the top of the light shield after installing a solar array drive electronics unit. During a fifth spacewalk Monday night and Tuesday morning, Mark Lee and Steve Smith will Velcro spare insulation strips together and mount them over tears in the insulation on the access doors leading to equipment bays 7, 8 and 10 (see above for details). "We've asked the shuttle program to exercise our contingency EVA day that we had available to us," said John Campbell, the mission payload manager. "We decided to use that day. It's not terribly urgent. If we don't get it done, we have options. After we deploy, we won't see any difference from where we were before we berthed with the orbiter. We can make our way to '99 and make the repair then in a pre-planned way." Project scientist Edward Weiler cautioned reporters not to blow the insulation issue out of proportion. He said the current issue is not nearly as serious as the optical problems that crippled Hubble until a dramatic 1993 repair mission. "I would be very comfortable flying away right now without having to make these repairs," he said. "Because right now, we know when we fly away we'd see no difference than pre-mission. I can't say for sure, but we might go all the way to '99 without seeing a difference. But if we started seeing an increase in temperatures, we have an option of slowly restricting the pointing of the telescope. That's not a science impact. It might be an efficiency impact or a convenience impact, but we have that option. Should we exercise that option? No. We have a contingency EVA plan. There's no reason to just fly away." ==================================================================== Fourth spacewalk accomplishes mission objectives (filed 2/16/97) Astronauts Greg Harbaugh and Joe Tanner wrapped up a $350 million overhaul of the Hubble Space Telescope today and then carried out an impromptu repair to shore up cracked and peeling insulation on the giant observatory. A fifth cargo bay excursion is on tap tonight for a tricky bit of insulation repair before the $3.1 billion telescope is released back into open space at 1:41 a.m. Wednesday. Today's spacewalk had three major objectives: 1. To replace one of two Solar Array Drive Electronics (SADE) units, systems used to control the motion of Hubble's solar panels. There ws nothing wrong with the unit being replaced, but it exhibited higher-than-normal temperatures in the past and engineers believe a replacement is warranted to preclude problems down the road. 2. To install protective covers over two magnetic sensors located at the top of the telescope tube. These sensors detect Earth's magnetic field and provide data that help Hubble's central computer determine the telescope's orientation in space. 3. To install protective multi-layer insulation blankets over two areas near the top of the telescope tube where existing insulation has cracked and peeled away due to the effects of UV radiation and atomic oxygen over the past seven years. The bottom line: Done, done and done. "With the installation of the solar array drive electronics and the magnetometer covers, we have indeed completed all the tasks we outlined for this mission," said Kenneth Ledbetter, a senior Hubble manager from NASA headquarters. "And that was more than even what we had considered fully successful." With the current mission winding down, Ledbetter said, engineers are beginning to focus on a 1999 shuttle servicing flight, studying what can be done to provide more complete repairs to Hubble's thermal insulation. "We know now we'll be making some new blankets and be prepared to install those," Ledbetter. "The patches we made today and the ones we will continue to make tomorrow are essentially temporary patches. We expect them to fully ensure the telescope will not have major thermal problems between now December '99." Today's six-hour 34-minute spacewalk officially began at 10:45 p.m. Sunday and ended at 5:19 a.m. Harbaugh, Tanner and fellow spacewalkers Mark Lee and Steve Smith now have logged a cumulative 27 hours and 54 minutes of spacewalk time in four back-to-back cargo bay excursions. The crew's fifth and final spacewalk this evening is expected to last about four hours. The shuttle record for spacewalk time in a single flight is some 35 hours, a mark set in December 1993 when Hubble's flawed optical system was repaired during another five-spacewalk mission. Installation of the new solar array control system and the magnetometer covers wrapped up all of the shuttle mission's original objectives to refurbish the Hubble Space Telescope. Over the past four days, Harbaugh, Tanner, Lee and Smith have installed two new science instruments, a new fine guidance system, a computer data relay device, two engineering and science data recorders and other equipment to give the observatory a new lease on life. The third objective was added to the mission after the astronauts and engineers on Earth discovered torn and tattered insulation on the side of the telescope that always faces the sun. Four areas of damage were identified that demanded attention: Two near the top of the telescope tube and two more over three equipment bay doors where sensitive electronic gear is housed. Harbaugh and Tanner successfully rigged spare thermal blankets from a repair kit over the two tears near the tip of the telescope to wind up today's spacewalk. To fix the insulation over the equipment bays, Lee and Smith plan to use parachute cord, alligator clips and insulation borrowed from another repair kit to rig up a sun shade of sorts to make sure the equipment in the bays stays cool. "We feel those are the three areas that are the most critical to go patch," Ledbetter said. Today's spacewalk began with the solar array drive unit swap out, a sort of electronic transplant. Harbaugh, anchored to the end of the shuttle's robot arm and assisted by Tanner, disconnected eight thick data and power cables, one at a time, and connected them in turn to the new box. The original then was unbolted from Hubble and the already wired up replacement was mounted in its place. Ground controllers then carried out an "aliveness" test to confirm the new unit was working properly. "OK, SADE 2R is installed," Harbaugh radioed at 1:16 a.m. as he wrapped up the complex replacement procedure. The work took about two hours, which is just about what flight planners predicted. The only problem encountered was a bent pin in one of the connectors that link the control unit to the space telescope's electrical system. As it turns out, Harbaugh and Tanner recently practiced handling a bent pin during a pre-flight simulation and they had no trouble at all correcting the problem and pressing ahead with the installation. The unit Harbaugh installed is the same "black box" removed from Hubble during a 1993 repair mission because of transistor failures. The device was refurbished and is now back in place aboard the space telescope. It should be noted there was nothing specifically wrong with the unit replaced today. But engineers have noticed slightly high temperatures in the device and its replacement was considered a prudent precaution. With the changeout behind them, Harbaugh and Tanner were moved to the top of the space telescope to install protective covers over two magnetometers that sense the telescope's orientation with respect to Earth's magnetic field. "Looks like you're riding your Harley, there, Joe," Mark Lee called from the crew cabin as arm operator Steve Hawley hoisted the spacewalkers high above the cargo bay. "It's a great ride, too," Tanner replied. "Not as much wind noise, though." A few moments later, passing one of Hubble's deployed high gain antennas, he told Hawley: "Boy, that high gain sure is close... I know you didn't need any more pressure." "No, you're not helping, Joe," Hawley joked, guiding the arm between the antenna and a solar array. "Wow, look at that aurora up there," Harbaugh interrupted. "Yeah, we had an aurora when you were doing SADE, too, but we didn't want to bother you," astronaut Steve Smith radioed from the flight deck. "Perfect height to see the U.S." Near the top of the giant telescope, Tanner said at one point, "Boy, I'm glad I'm not too afraid of heights." "I'm glad you're not too!" joked Harbaugh, sharing a ride on the shuttle's robot arm. "Be sure you're tethered!" "You can be sure I am. I'm looking for more tethers to attach." Installation of the magnetic sensor covers went smoothly, completing the last objective of Hubble's overhaul. At that point, the astronauts turned their attention to repairing two large tears in the insulation covering Hubble's light shield, the upper section of the telescope's tube. The high gain antennas were deployed earlier, ahead of schedule, to give the astronauts room to make repairs. First, Harbaugh and Tanner mounted a 1-by-3-foot section of spare insulation over a horizontal tear, securing the blanket with clips and adjustable cords. Then they mounted a second blanket over a large nearby vertical rip. Throughout the spacewalk, Harbaugh and Tanner marveled at the view from their perch on the end of the robot arm. "The question for the EVA folks is, which looks farther away, the Earth or the shuttle at this point?" astronaut Jeffrey Hoffman radioed from Houston. "It's a close call," Tanner replied. "The Earth," said Harbaugh. "It almost looks like I could touch it." "The view is just unbelievable," agreed Tanner. ==================================================================== Astronauts install insulation in final spacewalk (filed 2/17-18/97) 10:30 p.m.: Fifth spacewalk begins Astronauts Mark Lee and Steve Smith floated into the shuttle Discovery's airlock shortly before 10:30 p.m. to kick off a planned four-hour spacewalk to repair peeling insulation on the Hubble Space Telescope. The spacewalk, the fifth and final such excursion planned for Discovery's mission, officially began at 10:15 p.m. when the astronauts switched their spacesuits to internal battery power. This spacewalk was added to the mission Sunday after engineers decided torn and peeling insulation on the telescope demanded immediate attention. While Hubble probably could have operated normally without repairs until a 1999 servicing mission, NASA managers ordered the crew to fix some of the larger rents to make sure critical equipment does not overheat in the event of additional degradation. During the crew's fourth spacewalk Sunday night and Monday, astronauts Greg Harbaugh and Joe Tanner completed a $350 million overhaul of the Hubble Space Telescope and installed two blankets over peeling insulation at the top of the observatory's tube. The repair was relatively straight forward, involving a patch kit that was carried aloft on the off chance insulation problems were, in fact, discovered. But the patch kit only included two one-by-three foot blankets and both were used during the fourth spacewalk. Lee and Smith were forced to use jury-rigged comonents to shore up the insulation covering equipment bays 7, 8 and 10, a much trickier job. Shuttle pilot Scott "Doc" Horowitz spent much of the day Monday fashioning the emergency repair kit using parachute cord, alligator clips and insulation originally included as part of a solar array bi-stem repair kit. "We are using up absolutely everything we have and if we get something cut the wrong length, then we will have done a bad thing," astronaut Jeff Hoffman radioed from mission control. Then he told the crew he expected them to keep the shuttle "as neat as your garage." The equipment bays in question house Hubble's science data handling system, critical data interface units and other control equipment. All of it generates heat, which must be carefully regulated. If the insulation over the bays suffers sufficient degradation, the equipment could overheat and malfunction. The cracked and peeling insulation is located on the side of the telescope that always faces the sun. Engineers believe seven years of exposure to harmful ultraviolet radiation and the effects of atomic oxygen conspired to weaken the outermost layer of the multi-layer insulation, or MLI. Mission planners are studying what might be done in 1999 to implement more extensive repairs. This status report will be updated frequently throughout the shuttle crew's final spacewalk, so check in often and don't forget to reload the page to get the latest info! 12:45 a.m.: Insulation repair work complete Astronauts Mark Lee and Steve Smith have repaired tattered insulation over three critical equipment bays aboard the Hubble Space Telescope, adding a bit of insurance that additional insulation degradation will not cause sensitive electronic gear to overheat and malfunction. The astronauts had virtually no problems rigging hand-fashioned thermal blankets over rips and tears in the insulation covering equipment bays 7, 8 and 10. In fact, the spacewalkers finished the repairs about an hour ahead of schedule. They currently are storing tools and cleaning up Discovery's cargo bay, work expected to take about an hour or so. 1:25 a.m.: Engineers mull additional repair work Engineers monitoring the Hubble Space Telescope's myriad systems have detected what might be a problem with one of the observatory's reaction wheel assemblies, devices that help the telescope move from one target to another. The astronauts replaced a different RWA earlier in the mission and they have a spare unit inside Discovery's crew cabin in case another replacement is needed. "In the last half hour, Goddard has noticed a glitch on one of the RWAs, not the one you changed out but RWA number two in bay six," radioed astronaut Marc Garneau from Houston. "They would like to perform some testing on it that may take 15 to 30 minutes just to assure themselves that nothing is wrong with it. In the meantime, because we want to keep open the possibility of changing it out today, we'd like you to hold off doing anything further and we would like you to go into the airlock and connect to the SCUs and we'll get back to you as soon as we have confirmation on the state of the RWA." "OK, we'll go to the airlock," said one of the two spacewalkers. Mark Lee and Steve Smith were in the process of stowing tools and cleaning up the cargo bay when Garneau's call came up. They returned to the shuttle's airlock and reconnected their spacesuits to orbital power and air. They have plenty of battery power for an extended spacewalk. Should an RWA replacement be required, the astronauts would have to repressurize Discovery's airlock, open the internal hatch and retrieve the spare RWA from the shuttle's lower deck where it is stowed. Then they would have to go back out into the cargo bay to carry out the replacement procedure. Will advise... 2:45 a.m.: NASA rules out sixth spacewalk... for now Flight director Jeff Bantle has ruled out staging an unplanned sixth spacewalk today to replace a suspect reaction wheel assembly (see below for details) aboard the Hubble Space Telescope. Instead, astronauts Mark Lee and Steve Smith, in the process of closing out a fifth spacewalk after repairing torn insulation on the telescope, have been told to finish cleaning up Discovery's cargo bay and to return to the shuttle's crew cabin as originally planned. Engineers at the Goddard Space Flight Center in Greenbelt, Md., meanwhile, are continuing to run tests on reaction wheel assembly No. 2 in equipment bay 6 aboard the telescope to determine whether the device is healthy or whether a replacement is warranted. A spare RWA is stowed in Discovery's crew cabin and if necessary, astronauts Gregory Harbaugh and Joe Tanner could stage a sixth spacewalk overnight tonight to install the new device. In that case, Hubble would be released into space Wednesday, after the spacewalk's conclusion and after a procedure to boost the telescope to a slightly higher altitude. Whether a sixth spacewalk takes place Wednesday or not, Discovery would land Friday as originally planned at the Kennedy Space Center. 3:45 a.m.: Astronauts Lee, Smith end fifth Hubble spacewalk Astronauts Mark Lee and Steve Smith repressurized the shuttle Discovery's airlock at 3:32 a.m., officially ending a five-hour 17-minute excursion that began at 10:45 p.m. Monday. Lee, Smith, Greg Harbaugh and Joe Tanner have now logged 33 hours and 11 minutes of spacewalk time over five payload bay excursions, second only to a 1993 mission to fix Hubble's flawed optical system. That flight required some 35 hours of spacewalk time to complete. Today's outing was added to the current mission Sunday, after engineers became concerned about cracked and peeling insulation on the side of the telescope that always faces the sun. Early today, Lee and Smith successfully rigged impromptu sunshades over three equipment bays to protect sensitive electronic equipment from overheating. That work went faster than expected, but another potential glitch cropped up as the astronauts were wrapping up their spacewalk: Possible problems with reaction wheel No. 2 in equipment bay 6 (see below for details). Hubble is equipped with four RWAs, two in equipment bay six and two more in bay one. The devices use 23-inch-wide, 100-pound wheels spinning at up to 3,000 rpm to control Hubble's movement. By varying the speed and braking of the wheels, ground controllers can move the telescope to aim at various targets. Only three RWAs are required for science operations, but engineers four healthy units when Discovery departs Wednesday in case of a subsequent failure later. After briefly considering the possibility of a sixth spacewalk this morning to replace the unit with a spare, flight director Jeff Bantle told Lee and Smith to go ahead and return to Discovery's crew cabin while engineers continued testing the reaction wheel system. A sixth spacewalk, if required, will be staged overnight using a spare RWA carried aloft in Discovery's cabin. "It's been kind of amazing, because all the nominal things have gone nominal, but there have been a lot of other things to keep everybody working hard," radioed astronaut Jeff Hoffman from mission control. Hoffman was one of four spacewalkers who successfully repaired Hubble's optical system in 1993. "I'll also say we are right now getting a beautiful view with the elbow camera of the Hubble telescope," he continued. "It's actually, externally, I have to say it's not quite as beautiful as we left it three years ago, but we all know that beauty is only skin deep and the real guts of the Hubble are even better now because of the great work you guys have done. Hubble is going to do some great work after you let it go tomorrow and we're all looking forward to that." The astronauts are officially scheduled to release Hubble back into open space at 1:41 a.m. Wednesday. But if a sixth spacewalk is ordered to replace the reaction wheel assembly, Hubble's deploy will be delayed until later in the day. In that case, the reaction wheel replacement would be carried out by Harbaugh and Tanner. 5:40 a.m.: Sixth spacewalk ruled out; HST cleared for release Engineers at the Goddard Space Flight Center have concluded that reaction wheel assembly No. 2 aboard the Hubble Space Telescope is operating normally, clearing the way for the observatory's re-launch from the shuttle Discovery at 1:41 a.m. Wednesday after a $350 million overhaul. Flight controllers were briefly concerned the reaction wheel assembly, one of four aboard the space telescope, had malfunctioned, possibly requiring a sixth spacewalk by the Discovery astronauts to install a replacement. As it turns out, the RWA (see the next entry for operational details) simply started up a bit slowly and is now working just fine. "We've just completed a test on reaction wheel number two," astronaut Kay Hire radioed Discovery from mission control. "It's good, it checks out just fine." "Well great, that's good news," one of the astronauts replied. The crew then pressed ahead with a complex maneuver to boost Hubble to a slightly higher, more stable altitude before its release early Wednesday. Four such reboost maneuvers were carried out in all, raising Hubble's altitude by about eight nautical miles. Hubble is equipped with four RWAs, two in equipment bay six and two more in bay one. The devices use 23-inch-wide, 100-pound wheels spinning at up to 3,000 rpm to control Hubble's movement. By varying the speed and braking of the wheels, ground controllers can move the telescope to aim at various targets. Only three RWAs are required for science operations, but engineers want four healthy units when Discovery departs Wednesday in case of a subsequent failure later. Earlier in the mission, the astronauts installed a new reaction wheel assembly in equipment bay 2. Late last night, engineers fired up the original three RWAs aboard Hubble to warm them up prior to the telescope's deployment Wednesday. "They go immediately into an idle mode where if everything were perfect and there were no drifts or no torques or whatever, they would just sit there at zero," said program scientist Edward Weiler. "But all reaction wheels have a natural bias and two of them went up to about 20 to 40 rpm. This one sat at about point three rpm. Then it went down to zero and then it slowly started to go up. We had to make a call." Engineers quickly modified software originally written to test the RWA installed earlier by the astronauts so the program could be used to test the unit that appeared to be malfunctioning. "That took about two hours," Weiler said of the software re-write. "We uplinked the procedure about 3:20 a.m. or so Central Time and finally it got to the command to put high torque on the wheel and that's when the thing just took off and we knew it was just fine." As it turns out, this same reaction wheel exhibited almost exactly the same behavior when it was fired up in 1993 after a previous shuttle repair mission. Weiler said scientists are now eagerly standing by to resume science operations after Hubble's redeployment. "This thing is a new telescope. It's HST-2," he said. "Scientifically, when you look at the three main instruments, they were all built in the 1990s. They replaced things that were built in the 1970s, early 1980s. Just think of the computer you had on your desk in the early 80s compared to what you have now." 9 a.m.: NASA managers call Hubble repair mission complete success While the fat lady hasn't sung quite yet, NASA managers say a $350 million overhaul of the Hubble Space Telescope has been "110 percent" successful, setting the stage for a new era in space science after the observatory is released back into open space early Wednesday. Project scientist David Leckrone eloquently put the shuttle Discovery's five-spacewalk overhaul into perspective, saying "300 or 400 years from now none of us in all likelihood will be remembered as individuals. But certainly, the Hubble Space Telescope will be remembered 300 or 400 years from now as a high point in human civilization. That's an awe-inspiring thought and something that motivates us to do our very best for Hubble and for science, and that's what we're doing." The Discovery astronauts plan to release Hubble back into open space around 1:41 a.m. Wednesday. "We still have to deploy, we sill have to get the telescope back up and running and we still have several months of commissioning activities and calibration activities ahead of us," Leckrone said. "Nevertheless, it's difficult for me not to be excited about where we are this morning. I'm very proud of what we've accomplished here, it's a magnificant technical achievement and a major step forward for science." Lead flight director Jeff Bantle said the astronauts, equipped with more than 200 individual tools, installed or removed some 4,500 pounds of hardware during five spacewalks, hooked up and disconnected 150 electrical cables and installed 12 square feet of thermal blankets to shore up Hubble's peeling and cracking insulation. "From my viewpoint, we did more than we set out to do," said John Campell, a senior NASA manager at the Goddard Space Flight Center. "I'd say we're 110 percent successful." Campbell said the rest of the day would be spent powering up the telescope's myriad systems and readying the complex spacecraft for release. "We've been somewhat dormant on the orbiter," he said. "The orbiter has been ... providing us power, communications, attitude control. For us, it's been almost like being pampered by your mother for a week's vacation. It took care of us, got us on TV, fixed a bit of sunburn and now we're ready to go back to work. ... There is a lot of commanding we have to do and we look forward to being off and on our own and back doing science." When Hubble finally floats off into space, "we're going to be leaving with a better observatory than when we came," Campbell said. "We're going to have two new instruments that are going to open up new doors for science, we have a data recorder that's going to be 10 times more capable than what we had and we've restored the other systems we set out to restore to full health. So we've got a fully healthy spacecraft and a spacecraft that has improved capability in terms of science and data management." ==================================================================== Astronauts launch Hubble Space Telescope (filed 2/19/97) 12:15 a.m.: Hubble Space Telescope positioned for release Astronaut Steve Hawley, operating the shuttle Discovery's 50-foot-long robot arm, picked up the 25,500-pound Hubble Space Telescope around midnight and positioned it over the right side of the orbiter's cargo bay for release at 1:41 a.m. after six days of captivity. Once Hawley releases Hubble from the robot arm, shuttle commander Kenneth Bowersox plans to carefully back Discovery away using the orbiter's smallest jets in a maneuver designed to avoid producing exhaust plumes that might contaminate the telescope. After looping up above the observatory, Discovery will fall behind and move away, its $350 million overhaul mission complete. During five back-to-back spacewalks by alternating two-man teams of astronauts, Discovery's crew equipped the telescope with two new science instruments, a new fine guidance sensor, two data recorders, a computer command decoder, new solar array drive electronics and a reaction wheel assembly to help Hubble move from one target to another. All of the instruments have passed initial aliveness and functional tests and while it will take two months or more to fully activate the new instruments, project managers are confident the observatory will soon be back in business. "From my viewpoint, we did more than we set out to do," said John Campell, a senior NASA manager at the Goddard Space Flight Center. "I'd say we're 110 percent successful." In addition to installing new instruments and subsystems, the astronauts also patched up Hubble's cracked and peeling insulation during an unplanned fifth and final spacewalk. That work, too, came off without a hitch. 1:45 a.m.: Hubble Space Telescope released from shuttle Discovery The refurbished Hubble Space Telescope, equipped with new instruments, subsystems and impromptu bandages over its cracked and peeling insulation, was released into open space today after a $350 million orbital overhaul. Astronaut Steve Hawley, operating the shuttle Discovery's robot arm, gently launched the 25,500-pound observatory at 1:41:26 a.m. as the two spacecraft sailed 384 miles above Africa. As applause broke out in mission control, shuttle commander Ken Bowersox fired Discovery's small steering jets to slowly pull away from the silvery telescope, shining brightly in orbital sunlight "Houston, Discovery, HST is free to study the stars," Bowersox radioed as the telescope serenely receded. A few moments later, the astronauts switched their KU-band antenna from communications mode to rendezvous radar mode and television was temporarily lost. Hubble was deployed at the high point of its orbit, the highest altitude the observatory has ever achieved thanks to a series of reboost maneuvers carried out by Discovery's crew earlier in the mission that raised the telescope's orbit an average of eight nautical miles 9 a.m.: Astronauts discuss Hubble repair mission After two years of endless training and a dramatic five-spacewalk flight to refurbish the Hubble Space Telescope, lead spacewalker Mark Lee says he's more than ready to buy his crewmates a drink. And he wasn't referring to Tang. "You go out there and you spend probably 25 or 30 hours in the spacesuit and it tires you out," he said today after the Hubble was released. "Up here, we've got some orange mango and some lemonade but that's about as stiff as it gets. So I'm ready for a margarita. "There was a lot of satisfaction and relief on my part, because we had been training on this for almost two years," he added. "There were a lot of critical tasks and a lot of problems during the mission, little things. But everything was accomplished and I'm really happy we were able to adapt to the situation." Lee and his three spacewalking crewmates - Gregory Harbaugh, Steve Smith and Joe Tanner - looked on this morning as flight engineer Steve Hawley released the space telescope into its own orbit at 1:41 a.m. after a remarkably successful six-day service call. NASA Administrator Daniel Goldin told the crew in a congratulatory phone call that their mission, coupled with a dramatic 1993 flight to repair Hubble's flawed optical system, stand out as major successes for NASA and the shuttle program. "It was unbelievable," Goldin said. "Five spacewalks this time, five spacewalks last time, NASA astronauts 10, failures zero! It was wonderful!" The only real problem during the repair mission was impromptu work to repair peeling insulation on the side of Hubble that always faces the sun. The astronauts had to fashion makeshift sunshades out of a variety of on-board material, following 35 pages of instructions radioed up from mission control in Houston. "In some respects it probably was like Apollo 13 on the ground, where a group of experts got together and threw on the table all the items we had available to us and then put their minds together to fashion the thermal shields that we installed," said Smith. "They did their work on the ground, they told us what to do, we made suggestions ... and came up with the best solution with the materials we had at hand." Tanner said the insulation problem "was not that serious. It was just the surface foil of the multi-layer insulation that was degrading because of exposure to the sun. The plan to fix it was quite interesting, however, because we don't have all the materials that they would probably want us to have up here to fix it. So they had to go through a list of things we had on board and use those items, come up with a fabrication plan, and then put together an installation plan to cover up as much of this foil insulation as we possibly could." Lee equated the flight to "winning the superbowl. It takes a lot teamwork, dedication, leadership, good organization, a lot of support from different people and that's what NASA had. It was great." "I don't think anything threw us for a loop," Harbaugh agreed. "I think we did an excellent job, both on the ground and on board, adapting to the situation. There was an awful lot of preparation work that went into this flight. When we had some things go wrong, such as the insulation, the team on the ground that supports us went to work and came through like true professionals and just did a spectacular job. I think the end product was terrific." So did program scientist Edward Weiler. At a post-deploy news conference, he played a videotape of Hubble against the backdrop of Earth, saying: "I'd like to introduce you to a new astronomical facility in space. It's not the Hubble Space Telescope. It's really the Hubble Space Telescope-2. We now have three main core instruments ... and these are all instruments built in the 1990s with today's technology and far surpass anything we had on the old space telescope." Weiler then quoted Goldin, who likes to say "I don't know what I don't know." "We have two discovery instruments on the telescope now, brand new ones," Weiler said. "The most exciting things we're going to find we don't know about. If we knew what we were going to find there would be no sense launching these things. So I think that's the true message. We just don't know what we're going to see with these new instruments." With Hubble now back out in open space on its own, engineers at the Goddard Space Flight Center and the Space Telescope Science Institute are working through a complex series of procedures to slowly reactivate, calibrate and test the telescope's myriad systems, including the new NICMOS infrared camera and the Space Telescope Imaging Spectrograph, or STIS. "It's been sitting in the mother's nest in the shuttle and now our little baby's back on its own so we've got to bring it back to life," Weiler said. He said engineers intend to quickly re-activate the Wide Field-Planetary Camera, a workhorse visible-light camera installed during the 1993 rescue mission that has generated a steady stream of amazing photographs. "That should be ready to start doing routine science again in three to four weeks," Weiler said. "In the meantime, we'll be turning on and calibrating and testing out the new NICMOS and STIS. We hope to have the first images from the NICMOS and the first data from the STIS in a releasable form in perhaps eight to ten weeks. We should start entering routine science with both instruments shortly thereafter." ==================================================================== Shuttle Discovery glides to smooth landing (filed 2/21/97) After blazing across the southern United States like a fiery comet, the shuttle Discovery floated to a ghostly nighttime landing at the Kennedy Space Center today to wrap up a successful five-spacewalk mission to upgrade the Hubble Space Telescope. With commander Ken Bowersox and pilot Scott "Doc" Horowitz at the controls, Discovery landed on runway 15 at 3:32:26 a.m., nine days 23 hours 37 minutes and nine seconds after blastoff Feb. 11 from nearby pad 39A. "Wheels stopped, Houston," Bowersox called as the shuttle rolled to a halt. "Welcome back after a second successful Hubble servicing mission," astronaut Kevin Kregel radioed from mission control in Houston. "You made those five spacewalks look easy." Running one orbit late because of cloudy weather, Bowersox and company began their descent with a four-minute 56-second rocket firing at 2:21 a.m. to slow the ship buy about 345 mph to drop out of orbit. The "burn" changed Discovery's orbit from a near circular 385-by-359 miles to an elliptical 385-by-34 miles, setting up a steep plunge across the southern United States. Just 18 minutes before touchdown, Discovery streaked across the Houston area at 8,700 mph, putting on a spectacular sky show for area residents. Camera views from the Johnson Space Center showed an incandescent streak of ionized plasma trailing away behind the blazing shuttle, almost giving it the appearance of a doomsday comet or meteor. "I think we just flew over Houston," Bowersox radioed a few moments later, as Discovery banked out over the Gulf of Mexico. "You certainly did, and you lit up the entire sky with the orbiter and its trail," Kregel replied. "It was pretty impressive." "It was a pretty good view from here, too," Bowersox said. "We almost saw the Astrodome." Touchdown originally was planned for 1:50 a.m., but a layer of clouds over the landing site forced entry flight director Wayne Hale to order a one-orbit delay. It was a good call. By the time Discovery pulled into position again for a deorbit rocket firing, conditions had improved enough for Hale to give the astronauts a "go" for re-entry. "I think you made the right call on the weather," Bowersox radioed Houston after landing. "It was just gorgeous coming in." Discovery's landing closed out a 10-day mission spanning 4.1 million miles and 149 complete orbits. "We're very happy to have a successful completion to this 82nd flight of the shuttle program and have the Discovery back at its home base," Hale told reporters. "This mission to repair the Hubble Space Telescope and upgrade its science instruments is a mission that combines the best of many different organizations in putting together an effort that a lot of people have put their hearts and lives into for the past three years. We're very pleased to have accomplished everything we set out to do and more. After catching up with Hubble and hauling the 25,500-pound observatory on board Feb. 13, the crew staged a series of back-to-back spacewalks to carry out a $350 million overhaul. The primary goal of the 82nd shuttle flight was accomplished during the first spacewalk by astronauts Mark Lee and Steve Smith, who installed two new science instruments that will improve Hubble's scientific productivity and extend its vision into the infrared region of the spectrum. During three subsequent spacewalks by Lee, Smith, Gregory Harbaugh and Joe Tanner, the astronauts installed new computer gear, a fine guidance sensor, solar array drive electronics, a reaction wheel assembly and other equipment, meeting all the mission's pre-launch objectives. In addition, the astronauts managed to install makeshift sunshades over cracked and peeling insulation that protects Hubble from the ravages of the sun's harsh glare. Harbaugh and Tanner completed part of the repair work during the fourth spacewalk while Lee and Smith finished the job during a fifth, unplanned excursion that was added to the flight after the problem was discovered. It will take engineers at the Goddard Space Flight Center more than two months to fully calibrate and prepare the two new science instruments for normal operations. But Hubble's Wide Field Planetary Camera, installed during a 1993 mission to repair Hubble's flawed optical system, should be back in operation in a few weeks. END OF FILE