A quarter-century has now passed since five astronauts roared into orbit to complete the fifth-longest space shuttle mission at that time. Aboard Atlantis for her lengthiest voyage to date, STS-43 Commander John Blaha, Pilot Mike Baker, and Mission Specialists Shannon Lucid, Jim Adamson, and David Low spent almost nine days aloft, deploying a critical NASA communications and data-relay satellite and supporting a wide range of biomedical, scientific, and technological experiments. In so doing, STS-43 harked back to the past and demonstrated the bones of technologies of the future, some of which went on to bear fruit in the International Space Station (ISS).
As outlined in yesterday’s AmericaSpace history article, the crew had been in training for almost 15 months by the time they launched on 2 August 1991. Originally baselined to spend five days in space, STS-43’s envelope was expanded to nine days, in order to accommodate a broad plate of scientific research. Upon achieving orbit, however, the primary focus for the five astronauts was the deployment of NASA’s fifth Tracking and Data Relay Satellite (TDRS). Known alphabetically as “TDRS-E” before deployment, and “TDRS-5” after insertion into a 22,300-mile (35,700-km) geosynchronous orbit, the satellite was the fifth in a series of platforms which would provide communications and data-relay services for the shuttle, the future space station, and major scientific spacecraft, including the Hubble Space Telescope (HST). It followed on the heels of the first TDRS, deployed by the STS-6 crew in April 1983, together with a pair of similar satellites, launched in the post-51L era. Another TDRS had been lost on the ill-fated final voyage of Challenger in January 1986.
Folded up for launch, like an insect in a cocoon, TDRS-E was mounted atop a Boeing-built Inertial Upper Stage (IUS) booster, which would provide the impetus to deliver it from the shuttle’s altitude in low-Earth orbit up to geosynchronous orbit. The complex filled about three-quarters of Atlantis’ 60-foot-long (15-meter) payload bay and was secured in place by means of a donut-shaped Airborne Support Equipment (ASE) structure. The latter acted as a “tilt-table,” responsible for hoisting TDRS-E from its horizontal launch configuration firstly to an angle of 29 degrees for telemetry and other checks and finally to the deployment angle of 58 degrees above the payload bay.
All five STS-43 crew members were aboard Atlantis’ flight deck for the deployment, each assigned a different task. Lucid and Adamson oversaw the checkout of the IUS systems and ensured that everything was ready, whilst Baker kept the shuttle in the proper attitude and Low handled the cameras for still and video imagery. Meanwhile, according to Lucid, “John’s job was just to make sure the rest of us were all doing our jobs.” At 29 degrees, the IUS systems were transferred to internal batteries, ahead of raising the stack to 58 degrees, whereupon the booster’s ordnance—fitted with compressed springs—physically ejected the payload at a rate of 12 cm (4.7 in) per second.
Deployment occurred some six hours into the mission and the huge stack surprised Lucid as it swept silently over Atlantis’ crew cabin and into the blackness. Twenty minutes later, Blaha executed a burn of the shuttle’s Orbital Maneuvering System (OMS) engines to create a safe separation distance, prior to the ignition of the IUS motor. Over the next few days, the newly renumbered “TDRS-5” was brought to fully-functional status and prepared for several weeks of rigorous testing. By early October 1991, it was declared operational in its prime orbital “slot” of 175 degrees West longitude. From this position, TDRS-5 fulfilled NASA communications and data-relay services in the west, with its sibling TDRS-4—deployed by the STS-29 shuttle crew in March 1989—providing a similar function in the east. A pair of earlier TDRS satellites were relegated to serve as on-orbit spares.
When fully unfurled, these satellites were colossal in size and scope, resembling a gigantic windmill. They measured 57 feet (17.4 meters) in diameter across the span of their twin solar arrays, extending from a central hexagonal “bus,” and could transmit in a single second the entire content of a 20-volume encyclopedia. The solar arrays generated 1,800 watts of electrical power, supplemented by on-board nickel-cadmium batteries for use whilst in Earth’s shadow. In addition to supporting unmanned scientific spacecraft, the TDRS network enabled voice and data communications with shuttle crews for 85-98 percent of each orbit, as well as during re-entry, as opposed to the 20 percent achievable in previous times.
All told, three generations of TDRS satellites were flown: TDRS-A through G were launched aboard the shuttle between April 1983 and July 1995, followed by TDRS-H through J aboard expendable Atlas IIA boosters from June 2000 to December 2002. More recently, a third generation has seen TDRS-K flown in January 2013 and TDRS-L in January 2014, with at least one more (TDRS-M) targeted to follow in the near future. As of June 2015, TDRS-E had been moved to a “storage” location at 167 degrees West.
However, on the evening of 2 August 1991, with their own TDRS successfully deployed, the five astronauts of STS-43 were able to turn their attention to a wide range of experiments in Atlantis’ middeck and payload bay. The scientific focus of the mission—which had already resulted in an extension of the mission from five to nine days—had also been manifested in the shape of the crew patch, which resembled an Erlenmeyer lab flask. Interestingly, the flat base, conical-bodied and cylindrical-necked nature of this flask also bore a close resemblance to the Mercury spacecraft, which had lofted Al Shepard on the United States’ first piloted space mission, 30 years earlier, in May 1961.
In the shuttle’s cabin, investigations into protein crystal growth, the processing of polymer membranes, combustion science studies, and liquid-to-liquid diffusion in microgravity conditions were undertaken, as were observations of terrestrial aurorae and measurements of the effect of acceleration on delicate experiments. Additionally, feasibility experiments were carried out to evaluate the usefulness of fiber-optic technology for video and audio communications between the payload bay and the crew cabin. In the payload bay was the Shuttle Solar Backscatter Ultraviolet (SSBUV) instrument to calibrate the measurements taken by a fleet of ozone-monitoring satellites. The latter required two astronauts to work together, with Baker maneuvering Atlantis into an Earth-viewing or solar-viewing attitude and Adamson opening SSBUV’s canister lid to start and stop its different modes.
Flying a matter of months after Iraqi dictator Saddam Hussein’s retreating troops ignited oilfields in Kuwait, the effects upon Earth’s atmosphere were profound. “The planet’s beautiful,” recalled John Blaha after the flight, but noted that when they flew over the Middle East and its shroud-like palls of smoke, “boy, it looked like the planet was out of focus.” This environmental tragedy was juxtaposed by the power and beauty of the rest of the Home Planet. The astronauts flew right over the eye of Hurricane Fefa in the Pacific Ocean and on one occasion Blaha remembered floating in the flight deck one morning, eating breakfast, and watching his home world drift past him. “What a lucky person I am,” he wistfuly remarked later, “to be able to see this scene.”
Atlantis broke new ground at the end of her STS-43 mission, by becoming the first post-Challenger flight in which the Shuttle Landing Facility (SLF) at the Kennedy Space Center (KSC) in Florida was scheduled as her primary landing site. With the successful returns of STS-38 in November 1990 and STS-39 in May 1991, NASA’s improved sense of confidence prompted the agency to place Edwards Air Force Base in California on “reserve” status for the first time in five years. Landing in Florida eliminated the $1 million cost and the additional week of processing time needed to fly the orbiter across the continent from California and was seen by NASA as a key step in moving from the post-Challenger mindset of over-conservatism to one of full shuttle operations.
In the early summer of 1991, the decision by Bill Lenoir, a former astronaut and then-NASA Associate Administrator for the Office of Space Flight, to resume landings at KSC aroused great criticism, with many engineers and managers arguing that shuttles should continue to land at Edwards until “tougher tires” had been fitted and tested. The damage to STS-39’s tires after touching down in a crosswind raised further concern. Even Shuttle Program Manager Bob Crippen insisted that KSC landings would only be approved if strict rules were met. In the weeks before STS-43, he announced it was “likely” that Atlantis would be directed instead to Edwards.
Ultimately, conditions in Florida were perfect and on 11 August Blaha and Baker guided their ship smoothly onto Runway 15, touching down at 8:23 a.m. EDT. The next mission, STS-48 in September, would go a step further by attempting to land at KSC in darkness, but Crippen remained cautious. “We’re still going to land at Edwards,” he told journalists. “The weather is going to end up dictating that. I’m budgeting for about 60 percent of the flights landing at Edwards and 40 percent at KSC.” By the end of the Shuttle era, in July 2011, Crippen’s 60-40 prediction had proven accurate, but fell in favour of KSC. Of the 133 shuttle missions which successfully landed, a total of 78 touched down in Florida, 54 at Edwards, and a single flight at White Sands in New Mexico.
This is part of a series of history articles, which will appear each weekend, barring any major news stories. Next week’s article will focus on the 45th anniversary of the “Apollo 17 Decision,” the selection of the final group of humans to voyage to the Moon in the 20th century.