A quarter-century ago, tonight, seven men rocketed rocketed into the night for the second servicing call to the Hubble Space Telescope. Coming hard on the heels of shuttle Endeavour’s historic STS-61 mission in December 1993—during which astronauts fixed the telescope’s aberrated vision with corrective optics—the flight of Discovery on STS-82 turned Hubble from a repaired observatory into a brand-new scientific instrument, fit for the 21st century. “I would think the only other instrument that would rival it in historical value,” said STS-82 Mission Specialist Steve Hawley, one of only a handful of humans to have seen Hubble twice in space, “would be Galileo’s original telescope.”
Launched on 11 February 1997, STS-82 was originally intended to support “at least three” and ultimately four sessions of Extravehicular Activity (EVA) by two alternating teams of spacewalkers: Payload Commander Mark Lee and Mission Specialists Steve Smith, Greg Harbaugh and Joe Tanner. The quartet were assigned to the crew in May 1995, with Lee—then serving as chief of the astronaut office’s EVA Branch—and Harbaugh bringing previous spacewalking experience to the table. Smith and Tanner, conversely, were seasoned spaceflight veterans, but had yet to make their first career EVAs.
Those EVAs would install the new Space Telescope Imaging Spectrograph (STIS) in place of Hubble’s aging Goddard High Resolution Spectrograph (GHRS) and also remove the Faint Object Spectrograph (FOS) and replace it with the Near-Infrared Camera and Multi-Object Spectrometer (NICMOS).
These two new instruments promised enormous potential for Hubble’s future. STIS would perform two-dimensional spectroscopic mapping of planets, stellar nebulae and whole galaxies and its high degree of sensitivity was expected to resolve fine details in star formation, identify supermassive black holes and investigate matter distribution in the Universe.
Meanwhile, NICMOS provided a spectrometer, coronagraph and polarimeter to furnish Hubble with near-infrared capability. And to reach its requisite low operating temperatures, NICMOS carried a dewar of solid nitrogen and carbon dioxide, which would cool it for up to five years.
The high-priority status of both instruments placed them inevitably onto EVA-1, to be installed by Lee and Smith. A day later, Harbaugh and Tanner would fit a Fine Guidance Sensor (FGS) to replace one of three existing devices, which was exhibiting signs of mechanical wear. They would also install a new Engineering/Science Tape Recorder (ESTR) and an Optics Control Electronics Enhancement Kit (OCEK).
The third spacewalk, EVA-3, would see Lee and Smith replace a Reaction Wheel Assembly (RWA) and one of four Data Interface Units (DIUs). The astronauts would also pluck out a second ESTR and fit a Solid State Recorder (SSR) to support the anticipated high data-rates of STIS and NICMOS.
Finally, on EVA-4 Harbaugh and Tanner would replace one of two Solar Array Drive Electronics (SADE) and add protective covers over key hardware elements to replace material which had degraded in the harsh atomic oxygen environment at Hubble’s altitude. Following STS-82, the telescope would be put through an eight-week Servicing Mission Orbital Verification (SMOV) of the additions and enhancements, before returning to full science operations.
In early 1996, with less than a year remaining before launch, the remainder of the crew was announced. Commander Ken Bowersox had previously piloted STS-61 and was thus intimately involved with Hubble. His pilot would be Scott “Doc” Horowitz, newly returned from another flight, and the seven-strong team was rounded out by Steve Hawley, tasked with operating the shuttle’s Canadian-built Remote Manipulator System (RMS) mechanical arm. Hawley had previously been responsible for the deployment of Hubble during shuttle Discovery’s STS-31 mission in April 1990.
Training required the astornauts to spend a great deal of time in the water tank of the 40-foot-deep (12-meter) Neutral Buoyancy Simulator (NBS) at the Marshall Space Flight Center (MSFC) in Huntsville, Ala., and submerged in the 25-foot-deep (7.6-meter) Weightless Environment Training Facility (WET-F) at the Johnson Space Center (JSC) in Houston, Texas. Construction of the large Neutral Buoyancy Laboratory (NBL) at JSC had begun in April 1995, primarily to train spacewalkers for International Space Station (ISS) assembly tasks, and according to Hawley STS-82 was the last shuttle mission to exclusively utilize Marshall’s NBS.
The much larger NBL was formally transferred to NASA upon its completion in December 1996, a few weeks before Discovery launched. The training in the NBS, however, was highly realistic because the astronauts could operate in an “integrated” manner with the spacewalkers and the RMS.
“You actually had the real space-suited crewmember on a real arm,” Hawley said. “It’s underwater, but you can actually maneuver him around. The experience was extremely valuable to learn the task that he had to do and the task that I had to do and learn how to communicate back and forth. In fact, we got to where you could run each EVA day pretty much end-to-end, as it would really work, with quite high fidelity.”
To enable the multitude of servicing tasks, the STS-82 crew carried numerous tools and aids with them into orbit, which included handrails and handholds, transfer equipment, protective covers, tethers, grapple and stowage fixtures, and foot restraints.
A 17-inch (43-cm) titanium-aluminum Power Ratchet Tool was designed for tasks requiring controlled torque, speed or turns and could be used in cases where right-angle access to telescope components was required. The Multisetting Torque Limiter was used in conjunction with the power tools and hand tools which interfaced with bolts or latches and was designed to prevent damage caused by the application of torque, whilst NASA’s new Pistol Grip Tool fulfilled a key recommendation from the first Hubble servicing crew, who highlighted the need for a smaller, more efficient piece of equipment for very precise tasks.
In spite of delays to several shuttle flights in 1996, the mission stuck fast to its target launch date of February 1997. Originally scheduled to fly on the 13th, it actually flew two days earlier, on the 11th. At first glance, this seemed surprising, in view of numerous minor issues in the weeks preceding the mission.
During Discovery’s rollout to the pad in mid-January, whilst on the crawlerway, the stack was halted when a large, Y-shaped crack was identified on the deck plating of the Mobile Launch Platform (MLP). Despite its alarming appearance it was determined that the MLP’s integrity had not been compromised and the rollout continued.
Then, in the hours before liftoff, the loading of propellants into the External Tank met with delay, due to the need to assess the gaseous nitrogen purge system and monitor unusually high concentrations of trapped oxygen in the orbiter’s midbody and payload bay. The precise time was adjusted slightly to 3:55:17 a.m. EST at T-9 minutes, based on a final computation of Hubble’s orbit. Exactly on time, to the very second, Discovery turned night into day across the Florida coast as she speared into one of the shuttle’s highest orbits, with an apogee of 356 miles (574 km).
Two days into the flight, the crew completed their rendezvous with Hubble and Hawley grappled it with the RMS arm and berthed it in the shuttle’s payload bay for five days of servicing work. Late that same evening, Lee and Smith—clad in their bulky space suits—became the first astronauts to depart an airlock which had been relocated from the middeck into Discovery’s payload bay.
EVA-1 was described as “the Superbowl of EVAs” on account of the installation of the long-awaited STIS and NICMOS instruments. But it began rather inauspiciously. Whilst the astronauts were still inside the airlock, one of Hubble’s solar arrays unexpectedly “windmilled” a quarter-turn, reorienting itself from a horizontal to a vertical configuration, then stabilizing.
“That was one of the more memorable things from the flight,” Hawley said later, with a measure of understatement. “We coincidentally were trained to recognize an uncommanded slew of the solar arrays. If, for some reason, the solar array drive motor should fail in some manner and they’ll start to drive, you’re trained to recognize that. You can send a command that will disable the motor so the solar arrays don’t drive into something.”
Hawley and Tanner were on Discovery’s aft flight deck when the incident occurred and they exchanged anxious glances. Both knew that the array was not supposed to drive so rapidly, but with external cameras focused on the airlock hatch—and not Hubble—there were few people in Mission Control who were aware of the uncommanded motion. Hawley and Tanner were certain that EVA-1 would be scrubbed.
It later became clear that the External Airlock—which had been moved from the orbiter’s middeck into the payload bay as part of ISS modifications—was partly to blame. “They had replumbed the way the air is evacuated from the airlock volume,” said Hawley. “As luck would have it, the way the air exited was through a pipe that came out under the [telescope].” It was this evacuation of air which had impinged on Hubble’s array and caused the uncommanded slew.
Somewhat later than planned, Lee and Smith began EVA-1. Venturing into open space for the first time in his astronaut career, Smith was electrified. “Oh my gosh…beautiful!” he gushed. “It was worth the wait!”
Quickly, the two men set to work, with Smith riding the RMS and Lee free-floating in the payload bay. They opened Hubble’s aft shroud doors to remove the GHRS and FOS, both of which were stowed for return to Earth. Manipulating a suited crewman on the end of the mechanical arm was entirely new ground for Hawley. “We had enough camera views that I could see what [Smith] was doing,” he said later. “I knew what his next step was going to be, so it was easy for me to put him where he needed to be.”
About 2.5 hours into the EVA, the STIS was in place. Two hours later, NICMOS followed suit. Tolerances were incredibly tight, with no more than 0.5 inches (1.2 cm) clearance in some cases, requiring Lee to verbally guide both Smith (who had a face-full of instrument) and Hawley (who was operating the RMS from inside the shuttle’s cabin).
In fact, the question of who actually fitted the new devices proved a subject of humor. Since Smith was physically holding them, it might seem that he installed it. Not so, joked Hawley, for it was he who maneuvered the RMS—with Smith and the instrument—into place.
The following night, it was the turn of Harbaugh and Tanner. Working quickly, the two men replaced the degraded FGS. Late in the spacewalk, they noticed cracks and wear in the Teflon outer coat of the telescope’s 17-layered thermal blanketing on the side facing toward the Sun and into the direction of travel. Some of the cracks were as long as eight inches (20 cm) and were not, said Harbaugh, “tiny little spider cracks”.
Moreover, a small “crater”, caused by a Micrometeoroid Orbital Debris (MMOD) impact, was spotted in one of Hubble’s antennas. “In several places, it’s cracked,” said Tanner. “It’s just gotten old, it looks like.” Although there was no obvious crumbling, he recommended that care be taken when touching the insulation. It was clear that a more comprehensive fix would be necessary and planning began to utilize STS-82 to effect repairs.
With the second spacewalk over, the crew had fulfilled their minimum requirements for mission success. Lee and Smith were next, departing the airlock for EVA-3 to change the DIU, which was never intended for orbital replacement.
“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,” said Harbaugh. “It’s is not a piece of cake.” With Lee anchored to the RMS, and Smith free-floating, the DIU was replaced successfully. The spacewalkers then exchanged one of the telescope’s engineering science tape recorders for a new solid-state recorder and concluded EVA-3 by replacing one of the RWAs, which had failed a year earlier.
Shortly after Lee and Smith returned inside Discovery, it was decided to insert an unscheduled fifth EVA to repair Hubble’s damaged thermal insulation. In the meantime, Harbaugh and Tanner floated outside to begin EVA-4, whose primary objectives included the replacement of one set of SADE for the solar arrays and the installation of covers over magnetometers. This latter task required them to ascend about 60 feet (18 meters) “above” the payload bay and attach thermal blankets over two areas of degraded insulation around Hubble’s light shield.
From inside the crew cabin, Lee compared Tanner’s ascent to “riding your Harley”, whilst the spacewalker admired the view and remarked that it was fortunate he did not suffer from a fear of heights. During the course of the EVA, Horowitz and Lee worked on Discovery’s middeck to fabricate four insulation patches to be installed the following night. In total, 35 pages of instructions were transmitted up to the shuttle, employing spare insulation pieces, Kapton tape, parachute cord and alligator clips.
Following a good night’s sleep, Lee and Smith left the airlock for what they expected to be the final time on 17 February. They attached thermal blankets onto three key equipment compartments at the top of the Support Systems Module, at Hubble’s midpoint, where critical data-processing, electronics and instrument telemetry packages were housed.
Following this work, the men began cleaning up their work site and returned to the airlock, when flight controllers noticed a potential problem with one of the four RWAs. Although the RWA fitted on EVA-3 was operating without problems, one of its older siblings had begun to exhibit discrepancies.
“They would like to perform some testing on it that may take 15-30 minutes, just to assure themselves that nothing is wrong with it,” Capcom Marc Garneau told the spacewalkers. “In the meantime, because we want to keep open the possibility of changing it out today, we’d like to hold off doing anything further.” Lee and Smith entered the airlock and connected their suits’ utilities to the shuttle’s Servicing and Cooling Umbilical (SCU).
Had the call come from the ground to replace the RWA, it would be have been necessary to repressurize the airlock, open the internal hatch and retrieve a spare unit from Discovery’s middeck. Fortunately, engineers ran a series of tests and powered up the three “old” RWAs to assess them for problems.
Engineers worked to modify software originally written to test the newly-installed RWA so that it could test the troublesome unit, which required a couple of hours. At length, when the software commanded the RWA to put high torque on the wheel, success was achieved. A record-setting sixth EVA on a single shuttle mission evaded them and Lee and Smith returned inside Discovery, wrapping up five spacewalks and a total of 33 hours and 11 minutes.
After a job exceptionally well done, Hubble’s solar arrays were oriented toward the Sun to provide electrical power and recharge its batteries. As Hawley grappled the telescope with the RMS, payload controllers commanded its aperture door to open and Hubble and Discovery parted company on 19 February. Two days later, it was time for the final curtain to fall on STS-82. Originally, Discovery was scheduled to land at the Kennedy Space Center (KSC) in Florida at 1:50 a.m. EST on the 21st, but Entry Flight Director Wayne Hale called off the first attempt, due to the presence of off-shore showers and low cloud cover over the Shuttle Landing Facility (SLF).
The next opportunity to land was at 3:32 a.m., requiring the irreversible deorbit burn to occur at 2:21 a.m. At length, Bowersox was given the “Go” to begin the burn, committing Discovery to a 71-minute-long descent. Re-entering the upper atmosphere over the Pacific Ocean, the shuttle swept across the entire continental United States and appeared as a bright streak as it passed over Texas.
“I think we just flew over Houston,” Bowersox radioed at one stage.
“You certainly did,” replied Capcom Kevin Kregel, “and you lit up the entire sky with the orbiter and its trail. It was pretty impressive.”
“It was a pretty good view from here, too,” said Bowersox. “We almost saw the Astrodome.”
Touching down on Runway 33 at 3:32 a.m., the STS-82 landing was aided for the first time by 52 halogen lights, positioned at 200-foot (60-meter) intervals along the centerline. The work undertaken by Discovery’s crew had turned Hubble from a 1970s spacecraft with 1980s optics into an observatory for the 21st century.
“Three hundred years from now,” said Project Scientist David Leckrone, “none of us in all likelihood will be remembered as individuals, but certainly the Hubble Space Telescope will be remembered…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.”
The astronauts were also pleased and relieved that their mission was complete. After almost two years of training, Lee declared that he was ready to buy his crewmates a drink. “Up here,” he said whilst in orbit, “we’ve got some orange mango and some lemonade, but that’s as stiff as it gets. So I’m ready for a margarita!”