Fwd: NASA's First Secret Shuttle Flight; The Changing Mission of STS-54

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From: "Gary Johnson" <gjohnson144@comcast.net>
Date: January 20, 2014 10:27:26 AM CST
To: "Gary Johnson" <gjohnson144@comcast.net>
Subject: FW: NASA's First Secret Shuttle Flight; The Changing Mission of STS-54

 

 

AmericaSpace

For a nation that explores
January 18th, 2014

 

' ... T-9 Minutes and Counting ... ': NASA's First Secret Shuttle Flight

By Ben Evans

 

Since the conception of the manned spaceflight engineer programme, the intent was to fly a dedicated officer aboard each classified flight. For Mission 51C, it would be Air Force Major Gary Payton (back left). The other NASA crew members were Loren Shriver (front left) and Ken Mattingly (front right), with Jim Buchli and Ellison Onizuka behind. Photo Credit: NASA

"Miracle" is a term which is often applied to many aspects of the space programme: to Yuri Gagarin's pioneering flight to the accomplishment of the first manned lunar landing or to the safe return of Apollo 13. But the launch of Space Shuttle Discovery in January 1985 on Mission 51C marked a miracle of another kind. In a sense, it was quite literally miraculous that the orbiter made it into space at all … both metaphorically and literally, as the Challenger accident investigation would later reveal. When astronauts Ken Mattingly, Loren Shriver, Ellison Onizuka, and Jim Buchli were named as the crew of STS-10 in October 1982, they confidently expected to launch aboard Challenger in September of the following year on the first classified mission for the Department of Defense. It would put the shuttle's advertised ability as a "truck" for the United States' largest and most sensitive national security sentinels to the ultimate test.

Unfortunately, the mission quickly ran into problems when the Inertial Upper Stage (IUS) booster, built by Boeing for the Air Force, failed to properly inject the first Tracking and Data Relay Satellite into geostationary orbit in April 1983. Mattingly's mission was manifested to use the same type of rocket stage. The flight hung in limbo whilst an investigation board pored over the failure and made recommendations, and Boeing spent a year correcting the problems and recertifying the booster. By November 1983, Mattingly's flight had been redesignated as Mission 41E and rescheduled for July of the following year, but within a few months it was delayed yet again. When NASA issued an updated manifest in May 1984, it had vanished entirely and Mattingly's crew were reassigned to 51C, still with Challenger and set for December. "That," said Loren Shriver, "is when we started to learn that the numerical sequence of the numbers of the missions … didn't mean a lot."

For a time, Shriver wondered if he would ever fly, but unlike other missions, payloads were very much interchangeable; they were a DoD crew. "You were kind of linked to it," he recalled, "as long as there was some thought that it was going to happen, and it never did completely go away. It just went kind of inactive for a while, then came back as 51C." When he was assigned to the mission, Shriver was not surprised that his crewmates were all active-duty military officers. "I think NASA believed that it didn't have to do that," he recalled, "but I think it also believed that things would probably go a lot smoother if they did."

It became a staple of each Department of Defense mission for a patriotic crew patch, with little indication as to its primary objective. Photo Credit: NASA

Flying a classified mission posed its own problems for Mattingly. Within NASA, he had become familiar with the practice of sharing information, particularly about the shuttle. With a Department of Defense payload, the crew could not publicly discuss the particulars of their flight and the exact details were made available to only a handful of engineers, technicians, and Air Force managers. "I had some apprehension," Mattingly said, "about could we keep the exchange of information timely and clear in this small community when everybody around us is telling anything they want and we're keeping these secrets. Security was the challenge of the mission."

Cipher locks were placed on training materials, "but then you had to give the code to a thousand people, so you could go to work!" They were given a classified meeting room in the astronaut office, a classified safe for their documents … and a classified phone, with an unlisted number. In the entire span of their training time together, the phone rang just once. It was a sales call, asking Mattingly if he wanted to buy a new long-distance service!

The ridiculous levels of secrecy became even more laughable at other times, particularly when the astronauts were obliged to "disguise" the places where they were doing their training. They would file T-38 flight plans to Denver, then file new ones to the San Francisco Bay area, then rent a car to eventually reach their military destination at Sunnyvale in California. They were asked to do their mission training during the daytime and at night, to keep the launch time secret from prying eyes, or anyone who could be bothered to put two and two together, but all this furore never convinced Mattingly than anyone really cared. On one occasion, their office secretary booked motel rooms for them—"secretly," of course—but the four astronauts, crammed into a decrepit old rental car, with Ellison Onizuka at the wheel, had a surprise when they arrived. Jim Buchli spotted it first.

"Stop here," he said. "Now, let's go over this one more time. We made extra stops to make sure that we wouldn't come here directly … and they can't trace our flight plan. We didn't tell our families. We didn't tell anyone where we were. And we can't tell anyone who we're visiting. Look at that." Four sets of eyes peered over toward their "secret" motel … and beheld an enormous banner, emblazoned with the legend: WELCOME, 51C ASTRONAUTS. "How's that for security?" chuckled Mattingly.

When the countdown clock began ticking, nine minutes before launch, it must have caught the assembled spectators by surprise. Mission 51C was indeed the quietest human launch ever conducted by NASA, a fact which sat uneasily with Public Affairs staff and public alike. Photo Credit: NASA

When Challenger returned from her previous flight in October 1984, she was scheduled to be relaunched on 8 December for 51C, but inspections revealed that almost 5,000 of the delicate thermal protection tiles had become debonded during re-entry. One tile, located in the vicinity of the left-hand wing chine, had completely separated from the airframe and, although not a catastrophic problem in itself, revealed a far more worrying issue. A vulcaniser material, known as "screed," used to smooth metal surfaces under tile bonding materials, had softened to such an extent that its "holding" qualities were impaired. Subsequent investigation revealed that repeated injections of a tile waterproofing agent called "sylazane," coupled with the effects of six high-temperature re-entries, had caused degradation in the bonding material. By the time Challenger flew her next mission, the use of sylazane had been scrapped. In the interim she was reassigned to Mission 51E, scheduled for launch in February 1985, and 51C switched to Discovery with a launch date in late January 1985. Years later, Loren Shriver did not remember any significant mission impact, other than the six-week launch delay, from switching orbiters.

Due to the classified nature of the flight, some Air Force officials did not even want the precise launch date, or even the astronauts' names, released to the public. Loren Shriver was not alone in his amazement at this excessive insistence on secrecy. "We weren't going to be able to invite guests for the launch in the beginning," he told the NASA oral historian. "This is your lifelong dream and ambition. You're finally an astronaut and you're going to go fly the Space Shuttle and you can't invite anybody to come watch …We finally got them talked into letting us invite … 30 people, and then maybe some car-pass guests, who could drive out on the causeway … but trying to decide who, among all of your relatives and your wife's relatives, are going to be among the 30 who get to come see the launch, well, it's a career-limiting kind of decision if you make the wrong decision. You have part of the family mad at you for the rest of your life!"

Fortunately, Shriver's family and most of his wife's relatives were from Iowa, which was sufficiently distant for many to be unable to make the journey to Florida. Privately, Shriver and his crewmates worried that their inability to discuss the mission openly might compromise their preparedness and the thoroughness of their training. It must have been an unusual sight to behold the 51C stack, sitting on Pad 39A, with only a select number of military and NASA personnel knowing precisely when the launch would take place; in fact, the media had been told to expect liftoff within a three-hour "block" of time, sometime between 1 p.m. and 4 p.m. EST on 23 January 1985. Freezing weather conditions kept Discovery on the ground that afternoon, but the situation seemed to have improved marginally by the following day. For the spectators at KSC, the famous countdown clock, which normally ticks away the final minutes and seconds, showed a blank face and all communications between launch controllers and the flight crew were kept quiet. Then, at 2:41 p.m. EST, the blackout suddenly ended with a statement from the launch commentator:

" … T-9 minutes and counting. The launch events are now being controlled by the ground launch sequencer … "

In one of relatively few images ever publicly released from Mission 51C, astronauts Loren Shriver (bottom), Ellison Onizuka (left), and Jim Buchli pose for a photograph in Discovery's flight deck. Photo Credit: NASA

The remainder of the countdown proceeded normally, and Discovery lifted off at 2:50 p.m. and thundered into the cold blue Florida sky. Ascent was interesting, because communication between the orbiter and Mission Control was kept strictly under wraps, with only the voice of the commentator reading off a string of standard calls pertaining to the performance of the main engines, the fuel cells, the Auxiliary Power Units, and the shuttle's steadily increasing altitude and velocity. No indication was given as to the precise duration of the mission—one source reported that NASA would reveal this information a mere 16 hours before the scheduled landing—and, with the exception that the classified payload would be deployed later that day, very few other details were released about the flight. Many of the accredited members of the press who were in attendance mocked the "secrecy"; one NBC journalist quipped that "a Russian tourist on a Florida beach, a hundred miles away, could have called the Kremlin with the exact launch time!"

Today, almost three decades later, 51C remains classified, but rumours have emerged over the years that Discovery's crew possibly deployed a spacecraft codenamed "Magnum"—a signals intelligence satellite, operated by the National Reconnaissance Office for the CIA—which was boosted into near-geostationary orbit by its IUS. Reports have suggested that the TRW-built Magnum weighed somewhere between 4,800-6,000 pounds (2,200-2,700 kg) and was notable for its physical size, featuring 100 m-wide umbrella-like reflecting dish antennas to collect radio frequency signals from Earth. Aviation Week noted that Discovery entered an orbit of 126 x 322 miles (204 x 519 km), inclined 28.45 degrees to the equator, and executed three engine burns during its first four circuits of the globe. The payload was then deployed during the seventh orbit. Deployment was the responsibility of the entire crew, although this crew was unusual in that it included a unique military expert: Major Gary Eugene Payton of the Air Force, a member of a new cadre of payload specialists, known as manned spaceflight engineers, specifically chosen by the Department of Defense for these classified missions.

From its earliest conception the shuttle was dominated by the ambitions of the Air Force, and an assumption had long been made that the Department of Defense would employ the reusable spacecraft to carry many of its classified payloads. A new launch site was being built at Vandenberg Air Force Base, Calif., for near-polar missions, and efforts also encompassed the design and construction of a dedicated Mission Control, known as the Shuttle Operations and Planning Center (SPOC). However, as the 1970s wore on and military budgets withered under Jimmy Carter's Democratic administration, the Air Force opted to delay the SPOC in favour of making modifications to NASA's Johnson Space Center in Houston, Texas, to support its missions. Parallel plans to permanently assign one orbiter (probably Discovery) to military objectives and hire a dedicated Air Force astronaut corps to fly the missions were abandoned, and it was decided to use personnel already detailed to NASA. "The only opportunity for an Air Force program," wrote space historian Michael Cassutt, "seemed to be in NASA's new class of payload specialists." It was Air Force Under-Secretary Hans Mark (later to become Deputy Administrator of NASA under Jim Beggs) who introduced the new manned spaceflight engineer position in January 1979 and assigned responsibility for its development to Lieutenant-Colonel Robert Christian of Los Angeles Space Division. Early guidelines called for candidates to have between three and 10 years' of active military service, to rank between a first lieutenant and a major, to be able to pass NASA's required flight physicals, to hold a degree in engineering or science, and to have at least two years' experience in programme acquisition, test, and launch support, or flight and missile operations. By August, 14 officers had been selected—a dozen from the Air Force and two from the Navy—although two of them declined the invitation and only one was replaced. Consequently, 13 manned spaceflight engineer candidates arrived at Air Force Space Division in El Segundo, Calif., in February 1980, under Christian's command. Their number included David Vidrine, the naval officer who would later, briefly, be considered for a seat on Mission 41C, as well as Gary Payton and the man who would serve as his 51C backup, Keith Wright.

Their selection was trumpeted by the Air Force as illustrative of the service's bright future in space, although little interest was shown in NASA's offer to invite the 13 candidates to Houston for two years of training and evaluation. "At that time," grumbled one senior officer, "any Air Force guy who went to NASA never came back!" The Air Force's rejection led the civilian space agency to close ranks, refusing further assistance for the manned spaceflight engineers and insisting that it had neither chosen them, nor was it able to control them.

Commander Ken Mattingly (right) had already announced his retirement from NASA to return to the U.S. Navy by the time Mission 51C took place. By his own admission, only the first shuttle mission from Vandenberg Air Force Base might have encouraged him to stay. A year later, the loss of Challenger sounded the death-knell for shuttle flights from the West Coast. Photo Credit: NASA

"I was naïve enough to believe that the payload side would be treated by NASA the same way the Air Force launch people treated us," Gary Payton explained later. "In the world I came from, payload requirements would drive the time of day you launched, the time of year; everything. In 1980, NASA was still worried about getting the shuttle to fly, so we were not paid much attention. It was a rude awakening." Some space agency officials felt that the newcomers should be considered as "engineers," not "fliers," and should not participate in any flight-related training until they were formally assigned to a shuttle crew. Frustrations over the excessive secrecy imposed on the Department of Defense missions often boiled over into disputes. Nevertheless, the manned spaceflight engineers proceeded with their duties, working on the development of military payloads, including the Navstar Global Positioning System, the Defense Satellite Communications System, and others, and the group completed training in December 1981. By the late summer of the following, 14 more candidates had been selected, including two women and one black officer, with a broader range of academic credentials, ranging from bioenvironmental research to computer science and weapons engineers to rescue pilots.

In June 1982, several classified payloads were carried into orbit aboard STS-4 and several manned spaceflight engineers were involved in the preparation and execution of this mission. Even so, their relationships with NASA astronauts were poor. Ken Mattingly, who commanded STS-4, described them as "sour." At around this time, Gary Payton and Keith Wright were announced as payload specialist candidates for the STS-10 mission and a handful of others—Jeff Detroye, Eric Sundberg, Brett Watterson, Frank Casserino, and Daryl Joseph, all from the first MSE group—were assigned to support follow-on flights. Their roles would be to operate military experiments and observe the deployments of classified satellites. In the summer of 1983, Payton was assigned as the prime manned spaceflight engineer on Ken Mattingly's STS-10 crew.

Some sources have speculated over the years that the inclusion of manned spaceflight engineers was a method of preventing the NASA crew from gaining too much knowledge of the classified payload. For his part, Loren Shriver did not see Payton's role in this way; he was very much like any other payload specialist, assigned to the crew to complete his own experiments and tasks. "Gary had a specific purpose," he said, "but I don't think it was to make sure that we didn't learn about what the details of the mission were. As a matter of fact, we all got briefed into the mission and we knew exactly what was going on." Many of their efforts were effectively hamstrung by the failure of the IUS in April 1983, and, although Cassutt has noted that several payloads were "dual-configured" and could be launched by either the shuttle or an expendable Titan booster, it would seem that Magnum was designed specifically for deployment from the orbiter's payload bay. As a result, it could not be cancelled, only moved to the next available shuttle opportunity. "In any case," Cassutt wrote, "because of Magnum's importance, the DoD exercised its launch-on-demand option, pre-empting the next Shuttle-IUS spot on the manifest." According to the January 1984 manifest, Mission 51C was to have been an IUS flight to deploy the second Tracking and Data Relay Satellite (TDRS), but by May its slot had been taken by Magnum. The TDRS was moved a couple of months downstream and reassigned to 51E.

If Gary Payton's role was as an observer of Magnum and the IUS, then responsibility for the actual deployment of the payload fell to Ellison Onizuka—the first Asian-American astronaut, of Japanese-American parentage—and North Dakota-born Jim Buchli. Certainly, the deployment itself went perfectly, for Onizuka would soon be assigned to another IUS deployment flight, Mission 51L, with a TDRS. Onizuka said in a pre-flight interview for 51L that he was "very familiar" and "very comfortable" with the performance of the IUS, strongly suggesting that the earlier problems with the booster had been overcome by the spring of 1985. (Certainly, changes had been implemented in the nozzle design and four successful altitude-chamber firings were performed.)

Discovery touches down at the Kennedy Space Center on 27 January 1985, following the shortest operational flight in the shuttle's 30-year history. Photo Credit: NASA

To this day, 51C remains the shortest operational flight of the shuttle; when Discovery touched down at KSC at 4:23 pm EST on 27 January, she chalked up a mission of just over three days. It was the final flight for Ken Mattingly, who had already announced his retirement from NASA in July 1984 to return to active duty in the Navy as head of space programmes for the Naval Electronic Systems Command in Virginia. In fact, he took up his new post only two weeks after 51C landed. Years later, Mattingly admitted that only one other mission might have kept him with the civilian space agency. "The only mission that I really thought I could get interested in was the first Vandenberg mission," he told the NASA oral historian, "and [Bob Crippen] was already doing that, so I decided it was probably best to change assignments."

It would appear that the Navy originally wanted Mattingly to head up its new Naval Space Command at Dahlgren, Va., but the 51C delays meant that he either had to drop the shuttle flight or lose the assignment. "I wanted to stay and finish the mission," he said, "because we spent so much time on it and it was a particularly good one for me, because those guys [on the crew] were so good." In Mattingly's mind, 51C was really "Loren's mission," with Shriver cutting his teeth as a pilot before moving on to command his own shuttle flight. It is interesting that all three NASA members of the crew went on from the closeted world of Department of Defense operations to participate in three of the most dramatic and visible missions of the decade: Buchli would be aboard a joint Spacelab mission with West Germany in October 1985, Shriver would later command the flight to deploy the Hubble Space Telescope … and Onizuka, tragically, would secure his own place in history as a member of Challenger's final crew.

 

 

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AmericaSpace

For a nation that explores
January 19th, 2014

 

'Vanilla to Chocolate': The Changing Mission of STS-54

By Ben Evans

The American eagle delivers a fifth star, representing the fifth operational Tracking and Data Relay Satellite (TDRS), in the STS-54 crew patch. Image Credit: NASA

When the STS-54 shuttle crew released their official crew patch in the summer of 1992, they paid tribute to two important payloads aboard their mission. The first was NASA's fifth Tracking and Data Relay Satellite (TDRS-F), which would form the latest component in a critical geostationary-orbiting constellation to maintain near-continuous voice and data communications between the shuttle and other important scientific spacecraft with ground stations. Attached to a Boeing-built Inertial Upper Stage (IUS) booster, TDRS-F would be deployed from Shuttle Endeavour's payload bay late on the first day of the six-day mission. Within the bright-red circular frame of the STS-54 patch, a fearsome bald eagle held an enormous, eight-pointed star in its talons and was about to add it to a collection of four stars already in place. According to the crew, this represented the placement of the fifth TDRS into orbit, alongside its four cousins, launched in 1983, 1988, 1989, and 1991. Behind the eagle, the glorious blue and white Earth was juxtaposed with the unfathomable blackness of space; a blackness which, on this patch, was conspicuously devoid of stars. "The blackness of space," noted the patch description, "represents our other primary mission of carrying the Diffuse X-ray Spectrometer to orbit to conduct astronomical observations of invisible X-ray sources within the Milky Way Galaxy."

In command of the STS-54 mission was John Casper, a veteran of the classified STS-36 shuttle flight. His four crewmates included fellow veterans Don McMonagle as pilot and mission specialists Greg Harbaugh and Mario Runco, together with "rookie" Susan Helms. Today a lieutenant general in the U.S. Air Force and commander of the 14th Air Force (Air Forces Strategic) and the Joint Functional Component Command for Space at Vandenberg Air Force Base, Calif., she holds the record for achieving the highest rank of any female military astronaut. On STS-54, she also became America's first active-duty military female spacefarer.

Within months of entering NASA in January 1990, Helms was persuaded to join the ranks of the all-astronaut rock band, "Max Q," playing keyboards. Helms had taken lessons for 11 years, as well as having played concert drums and xylophone in marching bands and choirs and as part of a jazz combo. In an interview with Michael Cassutt, she described her tastes as "pop, Top 40, everything but country and western," and fellow Max Q member Kevin Chilton described her as "hugely talented" and capable of listening to a song on the radio and playing it. "She was able to teach us harmonies," said Chilton. On STS-54, Helms carried a mini-keyboard as part of her personal kit and managed to tap out a one-finger version of the Air Force anthem "Wild Blue Yonder" whilst in orbit.

 

Keyboard maestro Susan Helms brings music to the middeck of the Earth-circling Endeavour during STS-54. Photo Credit: NASA

In addition to TDRS-F, Endeavour was carrying the twin detectors of the Diffuse X-ray Spectrometer, mounted on Hitchhiker plates on opposite walls of the forward payload bay. This instrument originally formed part of a much larger Spacelab payload, known as the Shuttle High Energy Astrophysics Laboratory (SHEAL), and would have flown alongside the Goddard Space Flight Center's Broad Band X-Ray Telescope (BBXRT). However, the completion of the latter, ahead of schedule, and the deletion of another instrument from the ASTRO-1 mission, caused it to be moved forward on the shuttle manifest and it flew in December 1990. As for the DXS, it was moved around as a secondary payload on a couple of flights, before coming to rest on STS-54.

Designed to acquire the first-ever spectra of the diffuse low-energy "soft" X-ray background in the energy band between 0.15-0.284 keV, the DXS comprised a pair of large-area lead-stearite Bragg crystal spectrometers. Each contained a curved panel of Bragg crystals mounted above a position-sensitive proportional counter, across which a spectrum would be dispersed to enable all portions to be measured simultaneously. However, whilst all wavelengths were observed at the same time, the various wavelengths came from different directions in the sky, and therefore the spectrometers "rocked" backward and forward to obtain complete spectral coverage along an entire arc of the sky. The two spectrometers and their associated instrumentation were built at the Space Science and Engineering Center at the University of Wisconsin at Madison. Unique in its ability to "sort" detected X-rays by wavelength, the DXS identified large quantities of hot gas in the interstellar medium, close to our Solar System. Although classed as a secondary payload, the importance of the instrument was such that provision was included in the STS-54 manifest for a one-day extension to seven days, "if DXS requires additional time to achieve mission success." Although scheduled to fly for less than six days, Endeavour was equipped with enough consumables to support a seven-day "basic" mission, plus two additional days to cater for unforeseen contingencies, such as weather or other difficulties.

As 1992 drew to a close, STS-54 appeared to be a relatively "vanilla" mission, planned for mid-January of the following year. Then, on 25 November, NASA announced its decision to add EVAs onto three future shuttle missions to "fine-tune the methods of training astronauts for assembly tasks in space" and "increase the spacewalk experience levels of astronauts, ground controllers and instructors." The agency noted that such excursions would only be added on the proviso that they did not impact primary mission objectives … and the first flight to benefit from the change was STS-54. It had long been recognized that an immense number of EVAs, later to be nicknamed "The Wall of EVA," would be needed to assemble and maintain Space Station Freedom, and the difficulties experienced by the STS-49 crew during their effort to capture the Intelsat-603 satellite in May 1992 had led them to lobby for more expertise within the astronaut corps.

Greg Harbaugh (with red stripes on the legs of his suit) and Mario Runco perform mass-movement tasks during their EVA. Photo Credit: NASA

In fact, on the first day of 1993, of the 90 or so astronauts on active flight status, only eight had EVA experience. For STS-54, Greg Harbaugh and Mario Runco had undergone generic spacewalk training, in case they had to go outside and manually close the payload bay doors, but their work moved swiftly into high gear in the final days before and after Christmas as plans were finalised for a five-hour EVA. Their tasks included moving around Endeavour's payload bay with and without large objects (including each other) as well as completing close alignment tasks and installing equipment. It was mandatory for their EVA to conclude at the scheduled time, because it was assigned a lower priority than the DXS observations, which had to be suspended whilst Harbaugh and Runco were outside. After the mission, it was intended that the spacewalkers would repeat their activity in the Houston water tank to help improve future training practices.

Liftoff of STS-54 on 13 January 1993 was delayed by a little more than seven minutes to await the resolution of a Launch Systems Evaluation and Advisory Team violation. Under the combined thrust of her three main engines and twin Solid Rocket Boosters (SRBs), Endeavour speared for the heavens at 8:59 a.m. EST and successfully entered a 28.45-degree-inclined orbit shortly afterward. Six hours and 13 minutes into the mission, high above the Pacific Ocean, to the north of Hawaii, the TDRS-F payload and its attached IUS were released and Casper and McMonagle manoeuvred the orbiter to a safe separation distance.

An hour after deployment, the first stage of the IUS ignited to achieve geostationary transfer orbit, and the second stage fired some five hours later to circularize the orbit. Thirteen hours after launch, the TDRS separated from the IUS and underwent a complex process of unfurling its solar arrays, space-to-ground communications boom, and its C-band and single-access antennas. The numerically renamed "TDRS-6″ thereby became the fifth operational satellite in a constellation which supported the shuttle and important scientific missions, including Hubble and the Compton Gamma Ray Observatory. (An earlier satellite, TDRS-B, was lost in the Challenger accident.) On Endeavour's seventh orbit, the DXS instrument began scanning. Despite problems due to high particle counts, which triggered a high-voltage shutdown, an additional 15 orbits of data collection were authorized to complete its objectives. The spectrometers acquired a total of more than 80,000 seconds of good data.

Elsewhere, inside Endeavour's crew cabin, depressurization was executed on the third day of the flight in anticipation of Harbaugh and Runco's EVA. The two men entered the floodlit payload bay at 5:48 a.m. EST on 17 January, closely monitored by Susan Helms, who acted as the intravehicular crew member. During the excursion, the spacewalkers translated themselves around the payload bay, both with and without large items and climbed into foot restraints without the benefit of handholds. "To simulate carrying a large object," noted NASA's pre-mission press kit, "the astronauts will carry one another." They also worked with the IUS "tilt table" at the rear of the bay and returned to the airlock after four hours and 27 minutes. Yet the spacewalk brought the shuttle program's EVA total to barely 110 hours, far short of the 400 hours anticipated for construction of Space Station Freedom, and in response to this problem NASA added two further EVAs to STS-51 and STS-57.

The fifth Tracking and Data Relay Satellite (TDRS-F) is deployed on 13 January 1993. Photo Credit: NASA

Despite their numerical order, STS-51 was scheduled to occur after STS-57, with launch originally scheduled for July 1993. In the first week of February, NASA announced its intention to "continue extravehicular activity tests" with spacewalkers Carl Walz and Jim Newman. "The addition of the spacewalk to STS-51 will allow us to continue refining our knowledge of human performance capabilities and limitations during spacewalks," said Ron Farris, the chief of the EVA Section at the Johnson Space Center. "This EVA constitutes a continuing commitment by NASA to advance our preparations for future EVA missions, such as the Hubble Space Telescope servicing and Space Station Freedom assembly flights."

Two weeks later, on 17 February, an EVA by astronauts David Low and Jeff Wisoff was added to STS-57, then scheduled for late April. The scope of this mission hinted at its importance for the forthcoming Hubble servicing flight: with "procedures using the Shuttle's mechanical arm" planned to "involve work by astronauts on a platform at the end of the Shuttle's arm." Moreover, when combined with STS-54 and the spacewalks already planned for the first Hubble servicing mission, STS-61 in December, this meant that NASA was aiming to fly four EVA flights in 1993 … tying a record previously set in 1984. "In a sense," said Ron Farris, "it will be a banner year for EVA and will be somewhat representative of the EVA efforts required to build and maintain Space Station Freedom."

Spacewalking induced a peculiar sensation in Mario Runco. Years later, describing the experience to a Smithsonian interviewer, he related a free moment in the EVA, waiting for Harbaugh to finish up a task. "I was standing, facing outboard on a work platform," Runco said. "The platform locks your feet down and frees your hands for work." During underwater training before launch, he enjoyed bending over backward at the knees ("sort of like doing the limbo") and expected it to be a comfortable stretch, relieving all of the pressure points induced by his suit. "But in space, the viscosity of the water wasn't there to slow me down," he continued, "so when I relaxed to stand up straight again, the suit 'twanged' forward at what seemed like an incredible velocity. It really felt like I would come right out of the foot restraint and go tumbling off into space, even though I knew I couldn't." Gazing directly into the ethereal blackness of space, Runco was brought face to face with what he could only describe as a first-hand glimpse at God's handiwork.

Aside from the drama of the EVA, the five astronauts oversaw a range of medical and biological experiments in the middeck, monitoring the effect of microgravity exposure upon the skeletal muscles of rodents, growing seeds of Arabidopsis thaliana (a small, cress-like plant, with white flowers), and supporting 28 commercial investigations into biomedical testing and drug development, control of ecological life-support systems, and the agricultural manufacture of biological-based materials. On a somewhat lighter note, a collection of children's toys were flown as an educational resource. The "Physics of Toys" investigation involved schools in the hometowns of four of the astronauts and was specifically focused on elementary children. "Live" demonstrations on 15 January were led by John Casper, and the toys involved a car and track, klacker balls, a basketball, magnetic marbles, swimmers, a mouse, and a balloon helicopter.

Endeavour's departure from orbit on the morning of 19 January proceeded without incident, and the orbiter touched down in Florida at 8:37 a.m. EST, concluding a mission of just a few minutes shy of six full days. STS-54 had begun its life as a "vanilla" shuttle flight, which had turned to chocolate, and its importance for the future construction of the International Space Station (ISS) would be truly profound.

 

 

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