Keep the shuttle flying: Fwd: 25 Years Since the STS-32 Mission to Snatch LDEF

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From: "Gary Johnson" <gjohnson144@comcast.net>
Date: January 5, 2015 at 5:45:04 PM CST
To: "Gary Johnson" <gjohnson144@comcast.net>
Subject: FW: 25 Years Since the STS-32 Mission to Snatch LDEF

AmericaSpace
For a nation that explores
January 3rd, 2015

'What You Saw Was What You Got': 25 Years Since the STS-32 Mission to Snatch LDEF (Part 1)
By Ben Evans
Twenty-five years ago, next week, the crew of Shuttle Columbia retrieved the giant Long Duration Exposure Facility (LDEF). The satellite's orbit had degraded to such an extent that it was only weeks away from an uncontrolled re-entry. Photo Credit: NASA
Twenty-five years ago, next week, on 9 January 1990, the crew of Columbia rocketed into orbit on a mission which would begin to turn away from the trauma of the Challenger disaster and set the sights of the shuttle program on the future. Astronauts Dan Brandenstein, Jim Wetherbee, Bonnie Dunbar, Marsha Ivins, and David Low embarked on a flight which would both deploy and retrieve Earth-circling satellites and which would set a new record for the longest mission in the shuttle's history at that time and even offered the crew a humorous opportunity to don Santa suits and sneak an inflatable birthday cake aboard Columbia for their commander.
The first player in the story of STS-32 had actually risen to orbit almost six years earlier, aboard Challenger on Mission 41C in April 1984. The Long Duration Exposure Facility (LDEF) was a 12-sided, bus-sized satellite, intended to accommodate experiments for long-term exposure to the harsh radiation and microgravity environment of low-Earth orbit. However, no one could have foreseen at the time of its launch how long-term its tenure away from the Home Planet would be. Original plans called for Brewster Shaw's crew to retrieve it from space on Mission 51D in February 1985, but then a team of astronauts under the command of Dan Brandenstein spent several months preparing for the intricate task, with an anticipated launch date of 19 March. Unfortunately, the cancellation of Mission 51E in early March had a knock-on effect upon Brandenstein's flight and the LDEF retrieval was again delayed. Brandenstein and his crew eventually flew Mission 51G in June 1985, and by the time of the Challenger disaster the following January the recovery of LDEF was anticipated no earlier than Don Williams' Mission 61I in September 1986.
The satellite was a peculiar object, measuring 29.8 feet (9.1 meters) long and 14 feet (4.2 meters) in diameter and weighing 21,000 pounds (9,520 kg). At its most basic, it was a frame of aluminum rings and longerons, loaded with trays for 57 experiments. Shortly after the formation of NASA in October 1958, researchers began to seriously consider building a satellite that could carry materials science samples in order to assess how the harsh environment caused them to degrade over time. By the early 1970s, these ideas had acquired a name, the Meteoroid and Exposure Module (MEM), to be carried aloft by the shuttle and retrieved a few months later. As the name implied, its focus was upon the impact of micrometeoroid damage on satellites and how best to protect them. Subsequently renamed LDEF, the contracts for its design and development were granted to NASA's Langley Research Center in Hampton, Va.
Emblazoned with the surnames of the crew, STS-32 patch includes Syncom 4-5, Columbia and LDEF in pride of place. Image Credit: NASA
The structure was complete by 1978 and, after tests, was kept at Langley until a shuttle flight became available. By this point, its objectives had expanded from micrometeoroid research to studies of changes in material properties over time, performance tests of new spacecraft systems, evaluations of power sources, and conducting crystal growth and space physics. The satellite was designed to be reusable and adaptable for differing lengths, though ultimately it would fly only once. Its length was divided equally between six bays for the experiment trays, with a central "ring" at the midpoint connected by longerons to the end frames. Aluminum "intercostals" linked each longeron to adjacent rows of longerons on each side and removable bolts joined the longerons to the end frames and intercostals. This meant LDEF could be made "shorter" or "longer" if a mission required it. Experiment trays were then clipped into the rectangular openings between the longerons and intercostals.
Two grapple fixtures for the shuttle's Canadian-built Remote Manipulator System (RMS) mechanical arm were provided: one to allow it to be held for deployment and retrieval and a second to send signals to initiate the experiments. It had no attitude control system and, said one engineer, "what you saw was what you got": a passive container with no maneuvering capabilities. It was designed to remain in orbit by being placed into a "gravity gradient" attitude, with one end facing Earth, making an on-board propulsion system unnecessary. This also freed it from acceleration forces or contamination caused by thruster firings.
The orientation of LDEF also meant that the two "ends" would be subjected to a unique thermal environment, although all parts of the satellite were subjected to daily temperature changes as the Sun "rose" and "set" every 90 minutes and solar angles changed annually. Heat management was accomplished by coating the interior surfaces with high emissivity black paint, which kept thermal gradients across the structure to a minimum and maximized heat transfer across LDEF's body. The experiments were also spread evenly to equalize thermal properties across the satellite. Eighty-six trays—72 around the circumference, six on the Earth-facing end, and eight on the space-facing end—accommodated the 57 experiments. These covered four disciplines: materials and structures, power and propulsion, science and electronics, and optics. They captured interstellar gas atoms to better understand the Milky Way Galaxy's formation, observed cosmic rays and micrometeoroids, studied shrimp eggs and tomato seeds, and investigated the impact of atomic oxygen on different materials, including solar cells.
The STS-32 stack rolls into the mist on its way to Pad 39A. Photo Credit: NASA, via Joachim Becker/SpaceFacts.de
With the entire shuttle fleet grounded in the wake of the Challenger tragedy, the fate of the satellite was rendered precarious. Trajectory specialists estimated that by early March 1990, at the very latest, LDEF—which lacked its own propulsion capability—would be unable to maintain itself in orbit and would tumble back into Earth's atmosphere and a fiery destruction. Since many of its experiments promised to yield valuable data, particularly as NASA devised new materials for Space Station Freedom, it was imperative that a shuttle mission be staged as soon as possible after Return to Flight (RTF) to bring LDEF home.
That was the task of Dan Brandenstein's STS-32 crew, named by NASA in November 1988 for launch in November of the following year. The assignment of Brandenstein seemed unsurprising, given that he had already trained to lead the LDEF retrieval and was only days away from commanding the mission in March 1985. Having said this, many of the pilots in the astronaut office regarded STS-32, with its rendezvous commitment, as one of the "plum" shuttle mission assignments and felt that Brandenstein, who had replaced John Young as chief of the corps in April 1987, was picking the best flight for himself. Whatever the reality, one other crew member had also trained extensively for the LDEF retrieval. Mission Specialist Bonnie Dunbar would be at the controls of Columbia's RMS arm to grapple the giant satellite and maneuver it into a berth in the payload bay.
The other members of the STS-32 crew were all rookies, but all would contribute hugely to the space program in the following years. Pilot Jim Wetherbee would go on to become the only U.S. astronaut to command five missions, and flight engineer Marsha Ivins would enjoy a 36-year career with the space agency and install the Destiny laboratory module onto the International Space Station (ISS), whilst David Low—son of former NASA Deputy Administrator George Low—would prove instrumental in drawing the Russians to the negotiating table as partners in the ISS.
Expected to be the first shuttle crew to spend Christmas in orbit, this gag photograph of the STS-32 crew fell flat when the mission was postponed until January 1990. Photo Credit: NASA, via Joachim Becker/SpaceFacts.de
One of Low's key roles on STS-32 was the deployment of the U.S. Navy's Syncom 4-5, the fifth and final military communications satellite in a series which traced its genesis back to 1978. Four of these drum-shaped, Hughes-built spacecraft had been placed into orbit on a series of pre-Challenger shuttle flights and, although one suffered a catastrophic failure of its Ultra-High Frequency (UHF) electronics, another was triumphantly retrieved, "hot-wired" and returned to full operations. The Syncom to be released under Low's auspices, therefore, would be essential in completing the "minimum-size" constellation of four satellites needed by the Navy.
Columbia required several tries before finally making it into space for STS-32. Launch was originally planned for 18 December 1989, which—judging from the ten-day duration—would have made Brandenstein's crew the first team of shuttle astronauts to remain in orbit over Christmas. This fact evidently played so much on their minds that they privately organized an impromptu crew portrait to be taken, in which they posed in Santa suits, hats, and dark glasses. Fortunately, their NASA name tags at least made them identifiable. Unfortunately, problems with getting Pad 39A ready for its first launch in almost four years resulted in a delay until no sooner than 8 January 1990, so the Santa joke fell flat.
Since the return to flight of STS-26, most missions had lasted around five days, but STS-32 was to break this cycle by approaching the shuttle program duration record of 10 days and seven hours, set by the Spacelab-1 crew in December 1983. (The press kit reported that STS-32 was to last nine days and 21 hours.) Although the deployment of Syncom 4-5 and the retrieval of LDEF would consume only the first three days and did not specifically require a lengthy mission, NASA wanted to exercise the opportunity to demonstrate the shuttle's capabilities, because it planned to modify Columbia for a series of Extended Duration Orbiter (EDO) flights lasting up to a month.
Processing of the orbiter involved modifications to support the longer mission. A fifth set of cryogenic oxygen and hydrogen tanks were installed underneath Columbia's payload bay floor, and by the end of November 1989 the shuttle had been rolled out to Pad 39A, marking the first use of this launch complex since Mission 61C. After a delay until 8 January to finish work on the pad, the weather became the next issue. "Our main concern," said Air Force meteorologist Ed Priselac on the 6th, "is that low-level cloudiness will not clear out of here very quickly." The threat also included rain showers and high-altitude clouds, which reduced the prospects of acceptable weather on the 8th to just 40 percent. The odds of successfully launching that day were reduced yet further by the relatively short, 54-minute "window," which had been precisely timed to allow Columbia to rendezvous with LDEF on the third day of the mission.
STS-32 launches on 9 January 1990, in pursuit of LDEF. Photo Credit: NASA
NASA engineers also expressed concerns that pad hardware used to load cryogenic propellants into the External Tank (ET) might leak, but these concerns proved unfounded. Otherwise, the attempt on 8 January proceeded smoothly: The crew were strapped into their seats by mid-morning, although the clock was held at T-9 minutes by unsatisfactory conditions at the Shuttle Landing Facility (SLF) runway. In an effort to keep the option of launching open, the clock was restarted and counted down to T-5 minutes—the point at which Jim Wetherbee would start the Auxiliary Power Units (APUs)—but was held again. Just when it seemed that the weather might just co-operate, a faulty electronics component signaled a possible glitch with Pad 39A's sound suppression water system. A team of engineers were hurriedly sent to check the system and were satisfied that everything was normal, but then the weather closed in once again and prompted a scrub.
Brandenstein's crew had more luck the next day and STS-32 thundered into space precisely on the opening of the hour-long launch window at 7:35 a.m. EST on 9 January 1990. A picture-perfect ascent established them on an orbital "racetrack" to reach LDEF and retrieve it on 12 January. In the meantime, the astronauts spent their first day in space by concentrating on two major objectives: checking out the RMS arm, which Bonnie Dunbar called "a beautiful piece of hardware," and preparing to deploy Syncom. At 8:18:39 a.m. EST on the 10th, a little under 25 hours after launch, the satellite was released as Columbia flew above Africa. Low radioed to Mission Control that the deployment looked good. A few minutes later, Brandenstein and Wetherbee performed a separation maneuver to create a safe distance before the first engine burn. Syncom's manufacturer, Hughes, was exceptionally pleased with the performance of their product. "It was as good as you can get," said spokesman Tom Bracken. "Everything looks great."
A series of maneuvers by the satellite's own propulsion system were required to achieve its "slot" in geostationary orbit at an altitude of 22,300 miles (35,900 km). The first, at 8:53 a.m., involved Syncom 4-5 firing its solid-fueled motor to boost itself into an elliptical transfer orbit. This was later circularized and the perigee raised to geostationary altitude. During this time, Dunbar uncradled the RMS and used one of its cameras to photograph the first Syncom burn. Several additional maneuvers were made by the satellite to achieve its final orbit, which it accomplished by 13 January. Following a month-long period of checks, it was declared operational and joined its siblings. Later in 1990 and 1991, it was used to support military communications during the U.S.-led Operations Desert Storm and Desert Shield in Iraq.
The success of Syncom 4-5 was the last time that one of these frisbee-like deployments was performed from the shuttle, marking the end of an era in many respects. Yet only a fraction of the STS-32 mission had passed. Ahead lay an intricate rendezvous profile which would put the capabilities of Columbia, her crew, and the collective brain of NASA to the ultimate test.

Copyright © 2015 AmericaSpace - All Rights Reserved

AmericaSpace
For a nation that explores
January 4th, 2015
'The Granddaddy of All Experiments': 25 Years Since the STS-32 Mission to Snatch LDEF (Part 2)
By Ben Evans

The 12-sided Long Duration Exposure Facility (LDEF) was intended to spend less than a year in orbit, but ended up remaining for almost six years, traveling the equivalent distance from Earth to Saturn. Photo Credit: NASA, via Joachim Becker/SpaceFacts.de
A quarter-century ago, next week, the crew of Columbia embarked on the longest shuttle mission in history at the time, deploying one satellite, retrieving another, and setting the sights of NASA on the Space Station Era. As described in yesterday's AmericaSpace history article, STS-32 astronauts Dan Brandenstein, Jim Wetherbee, Bonnie Dunbar, Marsha Ivins, and David Low were tasked with placing the U.S. Navy's fifth and final Syncom 4 military communications satellite in orbit and capturing NASA's Long Duration Exposure Facility (LDEF), whose retrieval had been repeatedly delayed in the aftermath of the Challenger tragedy. By the time Brandenstein and his crew reached LDEF on the morning of 12 January 1990, three days into their mission, the satellite was thought to be only a matter of weeks away from an uncontrolled and destructive re-entry.
With the successful deployment of Syncom 4-5 behind them, the astronauts turned their attention to LDEF. At the time of their launch, they trailed the giant satellite by about 1,700 miles (2,730 km) and were closing on their quarry by about 37 miles (60 km) with each orbit of Earth. Three flawless maneuvers were performed by Brandenstein and Wetherbee on 9 and 10 January to reduce this distance, and Flight Director Bill Reeves exulted to journalists that everything was proceeding smoothly toward the rendezvous. On the morning of the 12th, the astronauts were awakened to music from Mission Control: Bring it Home, set to the melody of Let it Snow. Due to the extreme sensitivity of LDEF's 57 materials science experiments, the final approach was as unobtrusive as possible to minimize the risk of contamination. From a distance of 25 miles (40 km) down to just one mile (1.6 km), Columbia's radar and star tracker locked onto their target and permitted Brandenstein to move closer. He then took manual control of his ship, passing "below" and "ahead" of the satellite, then pitching the shuttle's nose "upwards" to achieve a position directly "above" LDEF. Jim Wetherbee, positioned in the commander's seat on the flight deck, related that this was essential to keep the closure rates slow and smooth when approaching such a massive object.
Wetherbee was astonished as the gigantic LDEF "hung" above Columbia's cavernous payload bay. By this point, the astronauts—who had watched computer-generated views in simulators for more than a year, since their assignment to STS-32 in November 1988—saw the real thing, waiting to be captured. It had traveled almost 800 million miles (1.3 billion km), or roughly the distance between Earth and Saturn, and had completed 32,000 orbits of the Home Planet. As they looked at it, the crew noticed that LDEF had suffered some damage during its six years aloft: A small solar cell had apparently dislodged itself and was flying in formation with the satellite, whilst a number of holes, apparently from micrometeoroid impacts, were evident. After the retrieval, the Interim Operational Contamination Monitor (IOCM) in the shuttle's payload bay revealed that it had also sustained a fair amount of particulate debris.
Like a giant frisbee, the Syncom 4-5 satellite departs Columbia's payload bay on 10 January 1990. Photo Credit: NASA
From her perch on the aft flight deck, Bonnie Dunbar focused the wrist camera of the Canadian-built Remote Manipulator System (RMS) mechanical arm onto LDEF's starboard side and prepared to grapple it. Brandenstein then performed a yaw maneuver to align the wrist camera with the grapple fixture. By this point, the satellite was directly above the cabin, as the pilots maintained formation in an inverted orientation. When she saw the grapple fixture in the wrist camera monitor, Dunbar went in for the kill. She rotated the camera by 180 degrees to the correct retrieval position, and at 10:16:05 a.m. EST on 12 January 1990, whilst over the Atlantic Ocean, near Brazil, she grasped it.
Brandenstein called Mission Control. "Houston, Columbia," he said, "we have LDEF!"
"You've made many scientists very happy that their LDEF experiments are finally coming home," replied Capcom Tammy Jernigan. In the background, the crew could hear the sound of applause. In fact, it was the first of many accolades for the astronauts that day. Lead Flight Director Al Pennington called it "the culmination of a lot of work by a lot of people," and NASA Administrator Dick Truly expressed his admiration as he "watched America's space program at its best." According to LDEF Chief Scientist William Kinard, the excitement of investigators from around the world, from the United States to Europe and even as far afield as Australia, was audible. Immediately after the retrieval, Columbia's General Purpose Computers (GPCs) commanded the RMS to align LDEF with the payload bay's berthing guides and Dunbar lowered the satellite into position at 3:49 p.m. EST. "It looks like LDEF is going to join us for the ride home," Bill Reeves remarked.
Marsha Ivins, meanwhile, had spent the past 4.5 hours painstakingly photographing each and every surface of the satellite for the benefit of engineers. To assist, Dunbar rotated LDEF slowly on the end of the mechanical arm. Due to the sheer size of the satellite, there was a real risk that the crew might not be able to latch it properly into the payload bay and, in a worst-case scenario, might have to leave it behind it orbit. "So we wanted to at least get the pictorial data," Dunbar recalled. "We also put video down to the ground. That took several hours, but we were able to do that and then got it latched and brought it back." By the time that Ivins' 4.5-hour period of focused photography was done and the RMS stowed, the crew had been awake for almost 17 hours, but, according to Brandenstein, "all the faces up her are smiling and happy." Clearly, the triumph had raised their spirits—to such an extent, in fact, that they transmitted cartoon picture to Mission Control the following morning, showing LDEF literally imprisoned within a web of overgrown tomato seeds. "We saw something … strange," Brandenstein grinned, "so we got it on the video recorder and thought we would show it to you." The tongue-in-cheek cartoon was a quip at the 12 million tomato seeds flown by students aboard LDEF, which had seemingly overgrown after their long stay in orbit!
Twenty-five years ago, next week, the crew of Shuttle Columbia retrieved the giant Long Duration Exposure Facility (LDEF). The satellite's orbit had degraded to such an extent that it was only weeks away from an uncontrolled re-entry. Photo Credit: NASA
With both primary objectives of their mission—the deployment of the Syncom 4-5 and the successful recovery of LDEF—now behind them, the crew settled down to a week of scientific and medical experiments. Planned for nine days and 21 hours, STS-32 was expected to come within ten hours of the duration of the longest shuttle mission to date, STS-9. "This is the second longest shuttle mission we've had so far," said David Low on 13 January, "so we can do some good science experiments up here and get some very good medical data." His words would prove ironic, if not a little prophetic, for Columbia would break her own endurance record, set during STS-9, and fly for almost 11 days.
One avenue of study for the astronauts was materials processing in microgravity, and Dunbar spent a great deal of her time tending the Fluids Experiment Apparatus (FEA) in the middeck. This device was capable of heating, cooling, mixing, stirring, or imposing centrifugal force on gases, liquids, or solids and had been carefully designed to meet industrial requirements. Dunbar supervised the processing of seven samples of indium—a well-characterized material with a low melting point—to assess the effect of disturbances induced by the shuttle's thruster firings or the movements of crew members. It was anticipated that results could lead to more advanced versions for Space Station Freedom. The FEA was activated a few hours after STS-32 reached orbit and ran successfully for almost a full week, until a sensor indication showed that it had exceeded its touch-temperature limit. The unit shut itself down, as programmed, but the astronauts reported that it did not seem to be hot. Nevertheless, after a week of operations, it had achieved more than three-quarters of its objectives.
Meanwhile, Ivins and Low tended to a series of protein crystal growth investigations. Ivins was also responsible for the American Flight Echocardiograph (AFE), an off-the-shelf ultrasound device, specially modified for carriage aboard the shuttle. It had the potential to non-invasively generate three-dimensional, cross-sectional imagery of the heart or soft tissues and display it on a monitor. During the mission, the echocardiograph was used in conjunction with a Lower Body Negative Pressure (LBNP) instrument, which resembled a collapsible set of "trousers," which drew fluids into the legs as a countermeasure for the punishing effects of a return to terrestrial gravity.
The STS-32 crew is pictured aboard Columbia's middeck. Front row (from left) are Marsha Ivins, Bonnie Dunbar, and David Low, with Jim Wetherbee (left) and Dan Brandenstein in the background. Photo Credit: NASA, via Joachim Becker/SpaceFacts.de
Several commanders had objected to the medical experiments, but since becoming chief of the astronaut office, Brandenstein had seen them as part of the job. "I was very demanding on the experiments that they do have real merit," he told the NASA oral historian, "and be well-organized and have a test plan, not a willy-nilly type experiment." During his tenure as chief astronaut, Brandenstein had convinced the rest of the office that science was part of their job when in orbit. "You lead by example," he said, but his enthusiasm was perhaps pushed a little far by physician-astronaut Manley "Sonny" Carter, who talked the crew into "the granddaddy of all experiments"—an incredibly painful muscle biopsy. Surprisingly, Brandenstein's crew were game and volunteered to have hunks of muscle pulled out of their legs both before and after the mission.
Despite its impressive success, the flight was not entirely smooth sailing. On 11 January, several liters of water oozed from a leaking dehumidifier onto the middeck. After switching it off and activating a backup, Brandenstein joked that his crew had won the Plumber of the Year award … but not Housekeeper of the Year. A more serious problem arose on the 14th, when he was awakened by Mission Control, following an indication of trouble with one of Columbia's Inertial Measurement Units (IMUs), a critical part of the navigation hardware. Although he reset the unit and returned to sleep, Flight Director Al Pennington worried that any other problems could result in an early end to the mission. Another key issue factoring into the chance of an early landing was the weather outlook at Edwards Air Force Base, Calif., where skies were forecast to be overcast, with a chance of snow flurries, on 17 and 18 January. Thankfully, a shortened mission was unnecessary and revised weather estimates predicted dry conditions, scattered clouds, and light winds—coupled with frigid temperatures—for the 19th.
With LDEF in her payload bay, Columbia would tip the scales at a mammoth 227,960 pounds (103,400 kg), which meant that the dry lakebed Runway 17 would be too soft and perhaps cause controllability problems. NASA therefore decided to land on the concrete Runway 22, but even that posed its own challenges. The presence of LDEF shifted the orbiter's center of gravity "forward," meaning that without deft handling of the vehicle, the nose gear might "slap" down too hard onto the runway. In a press conference, fielded whilst in orbit, Brandenstein told journalists that he needed to maintain sufficient speed after main gear touchdown in order to gently rotate the nose down.
Columbia lands at Edwards Air Force Base, Calif., after the longest shuttle mission to date. Photo Credit: NASA
Despite hopes that the weather would co-operate for a landing at 1:59 a.m. PST (4:59 a.m. EST) on 19 January, a wave-off seemed likely because a dusting of snow at Edwards the previous day had left water on the runways, and there was a chance of fog. According to spokesman Kyle Herring on the evening of the 18th, the weather remained marginal. Notwithstanding this potential obstacle, the crew marched through their pre-landing checks of Columbia's flight surfaces and controls … but to no avail. As feared, the fog prompted a 24-hour delay. "We're looking and watching the weather," said Bill Reeves on the evening of the 19th. "Edwards is improving for tomorrow."
In fact, no fewer than four landing opportunities existed on 20 January, followed by three more on the 21st and the shuttle could conceivably remain aloft until the 22nd if needed, possibly producing a record-setting 13-day flight. The mission could have landed in Florida or at White Sands, N.M., but NASA elected to hold out for Edwards, aware that its wide runway provided a more forgiving environment for Columbia with the heavy LDEF payload aboard. As they waited for the weather to improve, the STS-32 crew enjoyed a light day on the 19th, quietly surpassing the STS-9 record in the mid-afternoon. Brandenstein also became the most experienced shuttle astronaut, having notched up more than 570 hours on three missions. In doing so, he surpassed Bob Crippen, but admitted that each and every hour was enjoyable. On the 17th, he had celebrated his 47th birthday in orbit and an inflatable plastic cake had been smuggled aboard by his crewmates. He also received a chorus of pre-recorded greetings from the rest of the astronaut office and a message from basketball star Larry Bird, who congratulated him on the "slam dunk with LDEF." When questioned by Mission Control about his age, Brandenstein, alluding to Einstein's theory of relativity, replied that he had hoped that flying at Mach 25 would have slowed down the aging process. …
The return to Earth on 20 January was successful, although a switch failure in one of the computers during de-orbit preparations led Mission Control to wave off the first landing opportunity of the day. Ironically, the particular computer which failed carried the backup flight software to be used if the four primaries failed. To play things safe, the backup software was loaded into one of the primaries and the failed unit was shut down for the rest of the flight. It was a nail-biting time. Brandenstein and Wetherbee were minutes away from firing the Orbital Maneuvering System (OMS) engines to begin the irreversible de-orbit burn, with touchdown scheduled for midnight PST (3:00 a.m. EST), when the computer glitch arose. The engines were finally fired for five minutes at 12:30 a.m. PST (3:30 a.m. EST), slowing Columbia and dropping her into the upper reaches of the atmosphere. No radio "blackout" was experienced, because constant communications were possible through the Tracking and Data Relay Satellite System (TDRSS).
Soaring through the darkness, Columbia touched down on concrete Runway 22 at 1:35:35 a.m. PST (4:35:35 a.m. EST). "Welcome home. Outstanding job," radioed Capcom Mike Baker from Mission Control, as Brandenstein brought the vehicle smoothly along the centreline. "You showed the shuttle at its best, deploying and retrieving satellites." All six wheels stopped a minute later, setting a new shuttle program duration record of 10 days, 21 hours, one minute, and 39 seconds … a record which would endure for another two and a half years. "Records are there to be broken," admitted Bonnie Dunbar, "but we were just glad to get another day in space." For Dunbar, the breaking of records would characterize the rest of her career. On her next mission, also aboard Columbia, in June 1992, she would exceed her own record from STS-32, by spending 14 days aloft. That would be the first in a series of long-haul flights, featuring a new system known as the Extended Duration Orbiter (EDO).
Emblazoned with the surnames of the crew, STS-32 patch includes Syncom 4-5, Columbia and LDEF in pride of place. Image Credit: NASA
Columbia herself returned to Florida on 26 January and LDEF was removed from her payload bay. Excited scientists had been permitted to photograph their precious payload from the aft flight deck windows at Edwards, but it was not until the orbiter was back on the East Coast that they could get their hands on the satellite properly. For the next two months, radiation levels were monitored, infrared video surveys were made, contamination was recorded, and thousands of photographs were taken. LDEF was intact, but certainly weathered after six years in space. Clear evidence existed of "pitting" as a result of micrometeoroids punching into her outer surfaces, and some erosion to a Kevlar thermal cover on her space-facing end. "I think the conclusion that we all came away with," said William Kinard, "is that you have to be cautious in designing a spacecraft."
Organic materials exhibited severe erosion from atomic oxygen, whilst "coated" composites generally survived and maintained their mechanical properties, but due to the extended nature of the mission a few of the thin polymeric films and blankets had been completely destroyed; they had deposited their debris on adjacent areas of the spacecraft. A low-density particulate "cloud" was also spotted in LDEF's wake and many of the satellite's surfaces showed brownish discoloration. Yet the six years endured by LDEF in the harshest environment known to mankind had actually provided a tremendous service to the engineers and technicians, who were at that time working on the kinds of materials best suited for Space Station Freedom. In many ways, the achievements of STS-32—from its long duration to putting the shuttle through its pace in dramatic and spectacular fashion—had laid many of the foundations for what NASA would need in order to build the station.

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