Fwd: The High-Altitude Mission of STS-48

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From: "Gary Johnson" <gjohnson144@comcast.net>
Date: September 15, 2014 11:12:20 AM CDT
To: "Gary Johnson" <gjohnson144@comcast.net>
Subject: FW: The High-Altitude Mission of STS-48

 

 

AmericaSpace

For a nation that explores
September 13th, 2014 

 

'Gentlemen's Hours': The High-Altitude Mission of STS-48 (Part 1)

By Ben Evans

The Upper Atmosphere Research Satellite (UARS) is readied for deployment by Discovery's Remote Manipulator System (RMS) mechanical arm, early in the STS-48 mission. Photo Credit: NASA

Late in September 2011, the skies above the Pacific Ocean were illuminated by an astonishing, though not unexpected, fire show. NASA's 13,000-pound (5,900-kg) Upper Atmosphere Research Satellite (UARS), launched two decades earlier—this week in September 1991—returned to Earth in a blaze of glowing debris, with the remnants splashing down in a remote stretch of the Pacific. Originally anticipated to operate for just two years, the UARS mission was extended several times, and even when budget cuts forced it to be decommissioned in June 2005 no less than six of its nine instruments were still fully functional. Its orbit was slightly lowered by flight controllers in December 2005, in anticipation of an eventual destructive re-entry, and in October 2010 the crew of the International Space Station (ISS) was obliged to perform a debris avoidance maneuver in response to a conjunction with the aging satellite. Its eventual descent to Earth on 24 September of the following year brought a rather high-profile closure to a mission which had proven instrumental in changing our perception of the Home Planet.

Built by General Dynamics, under an initial $145 million contract with NASA which soon expanded into a billion-dollar program, UARS could trace its heritage to well before the loss of Challenger. It was originally scheduled to be launched by the shuttle in October 1989 as a long-duration observatory to monitor gas concentrations and pressures, the effects of solar irradiance, and ozone concentrations in Earth's fragile atmosphere. From its 373-mile (600-km) vantage point, inclined 57 degrees to the equator, the satellite would have the capability to observe up to 80 degrees in latitude, thus affording it essentially global coverage of Earth's stratosphere and mesosphere.

This, in turn, would enable UARS to make measurements over the full range of local time zones in all major geographical locations, every 36 days. The instruments aboard the satellite were expected to produce the most complete data on solar energy inputs, terrestrial winds, and atmospheric composition ever gathered. These explored the composition and distribution of nitrogen and chlorine compounds, together with ozone, water vapor, and methane, measured thermal emissions to create vertical abundance profiles of atmosphere gases, determined temperatures and pressure characteristics of high-altitude winds, and analyzed the effect of solar ultraviolet radiation.

Surrounded by the surnames of the crew, the STS-48 patch depicts UARS and shuttle Discovery in the quest to better understand the workings of Earth's upper atmosphere. Image Credit: NASA

Significantly, UARS's 10 instruments were designed to operate as a single experiment, capable of providing atmospheric scientists with an opportunity to make simultaneous measurements of all factors affecting ozone depletion. Four of those instruments measured the concentrations and distributions of gases known to play an integral role in the depletion process. The Cryogenic Limb Array Etalon Spectrometer examined concentrations of nitrogen and chlorine, ozone, water vapour, and methane, whilst the Improved Stratospheric and Mesospheric Sounder also monitored carbon dioxide, nitrous oxide, nitric acid, and carbon monoxide. Meanwhile, the Microwave Limb Sounder provided the first "global" data set on chlorine monoxide (the key intermediate compound in the ozone-destruction cycle), and the Halogen Occultation Experiment observed vertical distributions of hydrofluoric acid and members of the nitrogen family.

Two other instruments—the High-Resolution Doppler Imager and the Wind Imaging Interferometer—provided the first direct measurements, on a global scale, of horizontal winds responsible for dispersing chemicals and aerosols in the upper atmosphere. Elsewhere, the Solar Ultraviolet Spectral Irradiance Monitor, the Solar Stellar Irradiance Comparison Experiment, and the Particle Environment Monitor studied the effect of incoming solar energy on the atmosphere. Additionally, the Active Cavity Radiometer Irradiance Monitor offered accurate determination of total solar activity over the long term to aid climatic studies.

When the STS-48 crew was announced in December 1990, they confidently anticipated launch in November of the following year, but shuttle delays in the spring of 1991 actually conspired to bring their flight forward. Original plans for Discovery saw her flying the STS-39 mission for the Department of Defense in March, followed by the deployment of the fifth Tracking and Data Relay Satellite (TDRS-E) on STS-43 in July and finally UARS in November. When Discovery found herself grounded for more than six weeks, due to cracks on the lug hinges of her External Tank's umbilical door drive mechanism, STS-43 was pushed onto sister ship, Atlantis, and the UARS mission was brought forward to October and, finally, September. With a scheduled operational lifetime of 20 months, a fall launch was highly desirable in that it would enable UARS researchers to observe at least two winters in the northern hemisphere and at least one season examining the much-publicized "hole" in the ozone layer above Antarctica. For STS-48 commander John Creighton—nicknamed "J.O."—it made a pleasant change to fly somewhat earlier than planned.

By the time he was named to STS-48, Creighton had already flown two shuttle missions, the most recent of which—STS-36 in February 1990—had been delayed on a number of occasions, most notably when he came down with a cold. After his return from STS-36, he worked for a time in the astronaut office's Mission Development Branch and by his own admission was surprised when he received his next flight assignment so early.

With launch almost a year away, Creighton and his crewmates—his pilot, Ken Reightler, and mission specialists Charles "Sam" Gemar, Jim Buchli, and Mark Brown—were given low priority in the simulators for the first few weeks. That changed with Discovery's delays. "All of a sudden," Creighton recalled, "we found out we were going to leapfrog a couple of other flights and be sooner, rather than later, so then we really had to scramble. That was a tough nine or ten months of very intense training."

Operating on what Commander John Creighton described as "gentlemen's hours," the STS-48 crew heads for the launch pad on 12 September 1991. Photo Credit: NASA, via Joachim Becker/SpaceFacts.de

In addition to its high orbital inclination of 57 degrees to the equator, UARS also demanded one of the highest altitudes ever reached by the shuttle: some 373 miles (600 km), slightly less than the Hubble Space Telescope (HST). "We set a world altitude record for a winged vehicle" at a 57-degree inclination, Creighton proudly said of STS-48 and to this day he retains the commemorative plaque to prove it. His launch was finally set for 12 September 1991, and after a brief, 14-minute delay, caused by noisy interference on the air-to-ground communications link, Discovery roared into space at 7:11 p.m. EDT. The early evening launch time, and the requirement for them to rise from their beds in the early afternoon, prompted Creighton to describe STS-48 as "gentleman's hours."

Most of the STS-48 crew had flown before. Jim Buchli, in fact, was only the second person to fly as many as four times on the shuttle and had served a stint as deputy chief of the astronaut office, but for Ken Reightler it was his first mission … and it surpassed all of his expectations. Years later, he told a Smithsonian interviewer, with more than a hint of humor, that the task of the pilot was "to start the Auxiliary Power Units, to lower the landing gear and to make the mission commander look good."

That said, Reightler's role in an emergency situation would be quite different: to instinctively respond to any contingency, to hold a great deal of knowledge about the shuttle's systems and hundreds of switches and controls, and to potentially exercise that knowledge, in a timely manner, to save his own life and those of his crewmates. Jim Buchli had likened a shuttle launch to being strapped onto the front of a freight train at full speed. Not surprisingly, on STS-48, Reightler was anxious to perform at his peak. One concern was his bulky orange partial-pressure suit, which he felt was "pulling" on his body and might make it difficult for him to reach switches. "To bolster my confidence, right after liftoff, I started systematically reaching around the cockpit as the G-forces started to build," he related.

At length, glancing periodically over at his rookie pilot, Creighton politely asked "Would you knock that off?" Reightler did just that, "and the rest of the ride to orbit was a dream come true."

 

Copyright © 2014 AmericaSpace - All Rights Reserved

 

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AmericaSpace

For a nation that explores
September 14th, 2014 

'To Make Sure We Didn't Make the News': The High-Altitude Mission of STS-48 (Part 2)

By Ben Evans

 

Discovery rockets into orbit on 12 September 1991 to begin a five-day mission to deploy the Upper Atmosphere Research Satellite (UARS). Photo Credit: NASA

Late in September 2011, the skies above the Pacific Ocean were illuminated by an astonishing—though not unexpected—fire show. NASA's 13,000-pound (5,900-kg) Upper Atmosphere Research Satellite (UARS), launched two decades earlier, this week in September 1991, returned to Earth in a blaze of glowing debris, with the remnants splashing down in a remote stretch of the Pacific. Originally anticipated to operate for just two years, the UARS mission was extended several times and even when budget cuts forced it to be decommissioned in June 2005 no less than six of its nine instruments were still fully functional. Its orbit was slightly lowered by flight controllers in December 2005, in anticipation of an eventual destructive re-entry, and in October 2010 the crew of the International Space Station (ISS) was obliged to perform a debris avoidance maneuver in response to a conjunction with the aging satellite. Its eventual descent to Earth on 24 September of the following year brought a rather high-profile closure to a mission which had proven instrumental in changing our perception of the Home Planet.

As described in yesterday's AmericaSpace history article, the STS-48 mission to deploy UARS entered one of the highest orbits ever attained by the shuttle: 373 miles (600 km), which also represented the highest-altitude 57-degree-inclined orbit ever reached by the reusable spacecraft. This was just slightly less than the altitude of the Hubble Space Telescope (HST). "We set a world altitude record for a winged vehicle" at a 57-degree inclination, Commander John Creighton proudly said of STS-48, and to this day he retains the commemorative plaque to prove it.

His crew aboard Shuttle Discovery—Pilot Ken Reightler and Mission Specialists Charles "Sam" Gemar, Jim Buchli, and Mark Brown—quickly set to work after their 12 September 1991 launch to prepare for five days of orbital activities. For Reightler, it was his first mission and his arrival in space brought with it the excitement faced by every first-time astronaut. Following orbital insertion, his time came to unbuckle from his seat in Discovery's forward flight deck and float downstairs to the middeck to doff his bulky suit … and as soon as he did so, the view through the overhead windows arrested him. "The orbiter was inverted, flying over Asia," he recalled in a 2001 interview for the Smithsonian, "so I was looking straight down at Earth. I was totally unprepared for the colors, textures, detail and vastness of the scene. It literally took my breath away. No amount of training or looking at slides and movies can prepare you for that moment."

Backdropped by the truss of the Middeck Zero-Gravity Dynamics Experiment (MODE), the STS-48 crew celebrates a successful mission. From left to right are Ken Reightler, Mark Brown, John Creighton, Sam Gemar and Jim Buchli. Photo Credit: NASA

Yet there was work to do. The 13,000-pound (5,900-kg) UARS was one of the largest and heaviest shuttle payloads ever orbited and would be deployed by Mark Brown, using the Canadian-built Remote Manipulator System (RMS) mechanical arm. In anticipation of any problems, Buchli and Gemar were trained to perform a contingency EVA and much of the second day of the mission was spent preparing space suits and lowering Discovery's cabin pressure accordingly.

Deployment of UARS was accomplished at 12:23 a.m. EDT on 16 September. Its release came an orbit later than planned, due to the need to attend to a minor communications issue, but inaugurated a spectacular mission, whose results continued to reverberate to this day. "One of the things they saw," John Creighton told the oral historian, "is that the chloroflurocarbons that come from the industrialised northern hemisphere were migrating down over the Antarctic and that's what was a direct correlation to what was causing the destruction of the ozone layer in the Antarctic spring. It would release all of these things that were trapped in the lower atmosphere and then it would spiral up, because of the circular wind patterns, up into the ozone and then create the "hole." That was kind of exciting to see that what people had long suspected was proven." For a mission devoted to atmospheric science, it proven somewhat serendipitous that Mount Pinatubo—a stratovolcano in the Cabusilan Mountains of the island of Luzon in the Phillippines—had erupted in June 1991, producing the 20th century's second-largest terrestrial eruption.

The events surrounding the event were complicated by Typhoon Yunga, which added a lethal mixture of ash and rain, and although predictions led to the successful evacuation of tens of thousands of inhabitants from the disaster zone, Pinatubo stands as one of the most devastating environmental calamities in history. Earlier volcanic deposits were remobilized, infrastructure was destroyed wholesale, and river systems were significantly altered by the effects of huge amounts of magma, as well as volcanic dust which created an aerosol-rich layer of sulphuric acid haze in the stratosphere that spread around the world and lowered global temperatures by around half a degree Celsius.

In the first few weeks after its deployment from Discovery, UARS's instruments were directed to measure carbon dioxide emissions from the Pinatubo eruption. "And lo and behold," said Creighton, "there was destruction of the ozone layer, right around the equator, because of the eruption of the volcano." Over the next decade, UARS's contributions to atmospheric and solar science were so significant that plans were even afoot for a shuttle mission, involving a single EVA, to either retrieve it or install new instruments. These plans never reached fruition and by September 2001 had been shelved by NASA.

The Upper Atmosphere Research Satellite (UARS) is readied for deployment by Discovery's Remote Manipulator System (RMS) mechanical arm, early in the STS-48 mission. Photo Credit: NASA

STS-48 remained in orbit for five days and the astronauts were fully occupied by a battery of scientific, medical, and technical experiments. Investigations in protein crystal growth, muscular atrophy in rats, and polymer membranes were conducted, measurements of cosmic and gamma radiation were taken, and an intriguing demonstration of a model truss structure for Space Station Freedom was assembled in the middeck. This MIT-funded study, known as the Middeck Zero-Gravity Dynamics Experiment, or "MODE," incorporated accelerometers and strain gauges to examine the behaviour of truss members and the sloshing of fluids (represented in the test by water and silicon oil) and assess the performance of "rotary joints" to steer the station's massive solar arrays.

For the first time, an Electronic Still Camera (ESC)—a modified Nikon F-4 35 mm camera, fitted with a charge-coupled device for digital image storage—was carried into space aboard the shuttle. Today, it is easy to take the real-time downlink capabilities of electronic still cameras for granted, but on STS-48 this was demonstrated for the first time. "The ability," noted NASA's pre-mission press kit, "is expected to greatly improve photo-documentation capabilities in Earth observations and on-board activity on the space shuttle, as well as future long-duration flights, such as Space Station Freedom or a human mission to Mars."

For John Creighton, the MODE tests were particularly memorable. "It was almost being a kid with a Tinker Toy set," he recalled, "putting all those things back together again. We had a little shaker with a bunch of strain gauges on it to vibrate this structure to see how it would react in space. What they were trying to do is verify the computer models down on the ground to make sure that the vibration and the characteristics of this truss would react in space the way they thought they were predicting they would in computers … and that was successful." NASA had been flying spacecraft for several decades, of course, but the behaviour of fluids in partially-empty propellant tanks under microgravity conditions was still imperfectly understood. MODE's clear Plexiglas vials of water and silicon oil enabled the first detailed analyses to take place.

The mission briefly entered the news, early on 17 September, when it became the first shuttle flight to take evasive action to avoid a piece of space junk. Four days after launch, Mission Control advised the astronauts that their trajectory would carry them uncomfortably close to the Soviet Union's car-sized Cosmos 955 satellite—perhaps as close as just 0.7 miles (1.2 km). "With the planned space station," Mark Brown told journalists after the flight, "which will be less maneuverable than a shuttle, NASA will need to study the potential problem of collisions with debris much more carefully." (These proved ironic words, considering the fact that in October 2010 the ISS crew performed an avoidance maneuver associated with the very same satellite, UARS, that Brown had deployed.) A short, seven-second burn of Discovery's Reaction Control System (RCS) thrusters established a 10-mile-wide (16 km) berth between the crew and the defunct Cosmos 955, which had been in orbit for 14 years. "We were all busy conducting experiments," Ken Reightler recalled, years later, "so no one gave this operation much time or attention. I didn't even take a look out the window to see if I could see the intruder go by. I just wanted to make sure we didn't make the news back home!"

Discovery lands in darkness at Edwards Air Force Base, Calif., early on 18 September 1991. Photo Credit: NASA

For Reightler, his big event at the end of STS-48 was lowering the shuttle's landing gear, a few seconds prior to touchdown … and that was something his wife, Maureen, constantly reminded him to do. Discovery's 13th return from space was unusual in two ways: firstly, it was only the second post-Challenger mission to have the Kennedy Space Center (KSC) as its scheduled landing site, and secondly, it would touch down, for the first time in Florida, in darkness. As a result, much of the astronauts' re-entry training had been in darkness, crossing the darkened United States and alighting on a swamp-fringed runway. The actual event turned out to be somewhat different, when rain clouds in Florida forced a one-orbit extension to the mission and an eventual decision to land at Edwards Air Force Base, Calif. Creighton brought Discovery perfectly onto concrete Runway 22, in darkness, at 12:38 a.m. PDT (3:38 a.m. EDT) on 18 September, concluding a mission of just over five days.

As the orbiter's wheels kissed the runway, the astronaut careers of three of the STS-48 crew came to an end. Mark Brown would work extensively on the early transition of the ailing Space Station Freedom into the ISS program, before retiring from NASA, whilst Creighton and Buchli would both depart the astronaut corps in mid-1992. "I could have stayed on and flown once or twice more," Creighton told the oral historian, "but I wanted to get back up to the Northwest sooner or later." His wife was completing her medical residency and the couple moved to Seattle, Wash., where Creighton took a position with Boeing as a production test pilot and instructor. Buchli, too, entered Boeing, but remained in space circles, as manager of Space Station Systems Operations and Requirements within the corporation's Defense and Space Group in Huntsville, Ala. Ken Reightler and Sam Gemar would each fly one more shuttle mission apiece, later in their careers.

 

Copyright © 2014 AmericaSpace - All Rights Reserved

 

 

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