Discovery: Champion of the Space Shuttle Fleet

DISCOVERY AND THE SPACE SHUTTLE ERA

On August 30, 1984, Discovery launched on its first mission with a six-person crew to deploy three communications satellites and conduct science experiments. NASA

Discovery became the champion of the Space Shuttle fleet not simply because it flew more missions—thirty-nine in all—than Columbia, Challenger, Atlantis, and Endeavour. It also served longer—twenty-seven years—spending altogether 365 days in space. Its flight history began in 1984 as the fleet was starting its busiest two years and ended in 2011 as the shuttle program wound down. Most distinctively, Discovery flew every type of mission and served every purpose for which the Space Shuttle was designed. Discovery had no rival in the variety of its missions and the range of firsts it attained.

Discovery’s story is the full Space Shuttle story in microcosm. Its thirty-nine-episode narrative traces high and low points in the four-decade quest by the United States to make human spaceflight in Earth orbit routine, practical, economical, and safe. Discovery alone lifts the story from tragedy back to triumph as the return-to-flight vehicle after both shuttle accidents. Its flight history makes Discovery a robust icon for the entire shuttle era.

The Space Shuttle came into being in the 1970s to continue American spaceflight after the space race and landings on the moon. With no national appetite for an expensive grand venture—a space station or a mission to Mars—and with social problems at home, the United States settled on a new Space Transportation System (STS): a fleet of shuttles designed for missions in Earth orbit. Flying often on various types of missions, shuttles presumably would reduce the cost of human spaceflight and expand its purpose. If they proved successful, shuttles might later pave the way to a space station or deep-space expeditions.

The key element, often called the workhorse or space truck or spaceplane, was a reusable orbiter, large enough to carry both people and payloads and versatile enough to keep dreams alive for a more exotic future. Attached to twin solid rocket boosters and pumping liquid hydrogen and oxygen propellants from an enormous external tank into its three internal launch engines, the vehicle streaked from Earth to orbit in eight and a half minutes. Shedding the boosters and tank during ascent, the spacecraft operated in the altitude range of 115 to 400 miles (185 to 645 kilometers) on stays ranging from two to eighteen days. Covered with a novel thermal protection system made of tiles and blankets, the orbiter descended from space to land on a runway. After several weeks of servicing, the orbiter was ready for its next mission.

The Space Shuttle stack included the orbiter, its external propellant tank, and two reusable solid rocket boosters. Here, Discovery ascends on the STS-114 return-to-flight mission in 2005. NASA

Discovery set records in number of missions flown, total time and distance in orbit, and total number of crew members. NASA

Discovery made its final touchdown on March 9, 2011, to end the STS-133 mission to the International Space Station. The reusable Space Shuttle orbiter operated as a launch vehicle, crew ship, cargo carrier, and glider. NASA

The reusable shuttle would enable humans to begin living and working in space on a routine basis and using space near Earth for practical purposes. In the heady early days of development, planners envisioned spaceflight service as regular as an airline, with a fleet of five or more orbiters launching from sites in Florida and California as often as once a week. This forecast proved overly optimistic for a variety of reasons.

The Space Transportation System was meant to serve all of the nation’s launch needs for commercial, scientific, and national security access to space. The plan called for the shuttle to become the sole launch vehicle for all types of payloads. With more onboard engineers and scientists than pilots, shuttle crews offered retrieval of errant satellites, in-orbit servicing of balky or failed equipment, hands-on laboratory research, and the skills for assembly of large space structures. Although for various reasons a large customer base did not materialize, in its first decade the shuttle served the needs of government, industry, and the scientific community as planned.

Skeptics doubted the economic benefits of the Space Shuttle before it began service and continued to challenge the wisdom of this approach to spaceflight throughout its history. Yet from the successful first launch in 1981 to the 1986 launch tragedy, the shuttle ramped up in frequency and duration of flights. Nine missions launched in 1985, and 1986 was to have been even busier, with three orbiters and fifteen launches at an average rate of more than one per month. Spaceflight was beginning to seem routine. After the January 1986 Challenger accident brought shuttle flights to a halt for almost three years, the schedule gradually built up to seven and eight missions per year in the 1990s. Launches continued with few pauses for seventeen years until the Columbia accident temporarily grounded the shuttle again.

Discovery made its debut as the shuttle program was gaining momentum. Its first mission, STS-41D in August–September 1984, was twelfth in the program’s schedule. Discovery immediately entered service for satellite deliveries and national security missions. In fewer than two years on duty until the first accident, Discovery flew six times, including three consecutive missions, rapidly approaching Challenger’s record of nine flights in three years. The future champion was proving its mettle.

The heart of this book is a mission log that presents Discovery’s missions in chronological order for easy reference, but first it is helpful to look at its history thematically to see trends and evolution in the shuttle program. Although every shuttle mission had several objectives, missions generally were designated by their primary purpose or payload into distinct types: commercial, national security, servicing, science, Mir visits, and International Space Station assembly or logistics. Discovery flew multiple missions of each type.

During the 1980s, most Discovery missions deployed communications satellites. In this view from the STS 51I mission in 1985, an Australian satellite with attached boost motor rises from the payload bay. Boost stages sent the satellites to geosynchronous orbit. NASA

Discovery’s first role was to deliver commercial satellites to low Earth orbit, from which they were propelled by attached stages to more distant geosynchronous orbits. Five of Discovery’s first six missions served customers from the communications satellite industry, and its first two post-Challenger missions deployed NASA Tracking and Data Relay System (TDRS) satellites. Some of the commercial missions also delivered a satellite for the U.S. Navy. For satellite deliveries, the shuttle truly served as a cargo truck; two or three satellites were packed in the payload bay to be released one at a time when the orbiter reached the proper altitude and alignment. Discovery’s first mission was the first shuttle flight to carry three satellites. In all, Discovery delivered sixteen communications satellites for the United States, Canada, Mexico, the Arab League, and Australia. They represented the growing market of non-spacefaring nations eager to join a global telecommunications network.

The commercial sector was crucial to the effort to make human spaceflight more economical and routine, and NASA’s business plan depended on a growing and active customer base for satellite deliveries and also for research projects. NASA cultivated commercial customers with attractive pricing and incentives, including the opportunity for a corporate payload specialist to join the crew. The first commercial payload specialist, Charles D. Walker of McDonnell Douglas, flew on Discovery twice and Atlantis once to conduct experiments in a potentially lucrative manufacturing process. Saudi Arabia and France placed payload specialists on Discovery to witness the deployment of their satellites, as did Mexico on Atlantis. Three members of Congress took advantage of this courtesy and persuaded NASA to put them on crews—Senator Jake Garn on Discovery in 1985, Representative William Bill Nelson on Columbia in early 1986, and Senator John Glenn on Discovery in 1998.

Discovery crews completed two of the five servicing missions that extended the life of the Hubble Space Telescope well beyond its planned ten years. In this view from the 1999 servicing mission, astronauts Steven L. Smith and John M. Grunsfeld, working at the end of the long robotic arm, have opened a bay to replace gyroscopes in the pointing and attitude control system. NASA

Commercial payloads occasionally prompted another mission type: servicing. Twice Discovery crews combined deployments with retrievals for repairs or returns when satellites failed to reach their required orbits. The crew of Discovery’s second mission celebrated the first in-orbit satellite retrieval with a 2 Up, 2 Down sign when they successfully deployed two satellites and picked up two others to bring home for refurbishing. Another Discovery crew brought an idle satellite into the payload bay, installed a new ascent motor, redeployed it, and watched it ignite on its intended path. These servicing episodes demonstrated important crew skills and built crew experience for future projects, notably servicing the Hubble Space Telescope and assembling a space station.

Discovery’s science missions typically included retrievable research satellites and instruments mounted in the payload bay. This ATLAS 2 suite of instruments for atmospheric and solar physics investigations flew on the STS-56 mission in 1993. NASA

Policy changes after the Challenger accident took commercial satellites off the shuttle and seriously eroded the commercial market for shuttle flights. Commercial experiments continued to fly as secondary payloads, but Discovery’s role soon shifted from satellite delivery to other types of missions.

The Department of Defense reserved Discovery’s third flight for the first dedicated, classified, national security shuttle mission, about which little is known beyond the names of the first all-military crew and the first U.S. Air Force payload specialist who was not in the NASA astronaut corps. The primary payload was presumed to be an electronic intelligence satellite. Although the shuttle was designed and developed with national security needs in mind, the air force grew reluctant to rely on the shuttle and NASA as the sole launch provider, preferring instead to maintain its own capacity for assured access to space. Even before the Challenger accident and subsequent grounding of the fleet, the Department of Defense began to ease away from the shuttle. It completed its backlog of planned national security missions when flights resumed and then abandoned the shuttle except for occasional small, unclassified payloads.

From 1984 through 1992, Discovery flew four of the ten Department of Defense missions. The first two of these were strictly classified, but allegedly spy satellites were deployed for the National Reconnaissance Office. The other two missions were publicly linked to the Strategic Defense Initiative (Star Wars), one unclassified and the other partially cloaked in secrecy. Editorial cartoonists mocked the military missions by portraying the shuttle in disguise or as invisible, but the point was to question militarization of space and the place of secrecy in a public space program defined by its open conduct. The issue dissipated as the air force returned to its preferred rockets and the Space Shuttle moved on to almost exclusively civilian tasks.

In 1990 and again in 1997 and 1999, Discovery and its crews made history, first by deploying the heralded Hubble Space Telescope and then by returning twice to service, repair, and redeploy it. Discovery was not scheduled for the urgent first visit to install corrective optics, but it drew duty for the second and third of five servicing missions. Spacewalking teams updated the telescope with newer technologies and extended its life by repairing or replacing worn components. With skill and finesse, Discovery crews demonstrated the value of humans in space for efficient performance of complex tasks. In-orbit servicing benefited the astronomical community by adding years of continued telescope operations and also built the experience base for future large assembly projects such as the International Space Station.

On missions to the Hubble Space Telescope, the orbiter’s name seemed especially apt. Namesake of the exploring ships of Henry Hudson and Captain James Cook, Discovery furthered the tradition of exploration and discovery through improved observation of the universe.

Discovery’s primary occupation in the 1990s, however, was to support science. On ten missions during the decade, this orbiter carried satellites, observatories, or laboratories for scientific research. It also delivered the sun-circling explorer called Ulysses. NASA’s science missions had several purposes: to exploit microgravity as a laboratory environment, to understand better the changes in humans and other organisms during long stays in space, to take advantage of the clear viewing of Earth and cosmos from above the atmosphere, and to pursue both basic and applied science in quest of benefits for people on Earth.

Discovery made the first and last of nine shuttle missions to Russia’s Mir space station, seen here during the shuttle’s final departure in 1998. NASA

Discovery is seen approaching the International Space Station on its last mission, STS-133 in February 2011, making its thirteenth trip to the orbital outpost. NASA

Discovery’s science missions covered a range of disciplines—primarily Earth and atmospheric observations, materials processing, biology, and biomedicine. Several times it carried a Spacelab or SPACEHAB laboratory module in the payload bay, where scientists worked in shifts around the clock. Other times it carried a platform loaded with largely automatic devices, or it released and recovered a small, free-flying satellite for particular experiments. Discovery flew two Mission to Planet Earth flights among its science missions in the 1990s.

Discovery opened 1995 with the first of nine shuttle missions to the Russian space station Mir