The Space Shuttle Endeavour is launched on its first mission, STS-49.

From 1981 to 2011, the U.S. National Aeronautics and Space Administration (NASA) operated one of humanity's most ambitious and iconic spacecraft systems: the Space Shuttle. Officially known as the Space Transportation System (STS), a designation stemming from a visionary 1969 plan for a fully reusable fleet, the Space Shuttle was the only element of that grand scheme to receive funding and come to fruition. This partially reusable low Earth orbital spacecraft system redefined human spaceflight for three decades, embarking on 135 missions that spanned a remarkable 1,323 days in orbit.

The journey began with four crucial orbital test flights, commencing with STS-1 in 1981, which paved the way for operational missions starting with STS-5 in 1982. Launched exclusively from the historic Kennedy Space Center (KSC) in Florida, these magnificent machines served as workhorses in space. Over its storied career, the Space Shuttle deployed countless satellites, launched groundbreaking interplanetary probes such as Galileo and Magellan, and delivered the revolutionary Hubble Space Telescope (HST) into orbit. Furthermore, it provided an unprecedented platform for conducting diverse science experiments, fostered international cooperation through the Shuttle-Mir program with Russia, and played an absolutely pivotal role in the construction and ongoing servicing of the International Space Station (ISS), essentially building humanity's permanent outpost in space.

Anatomy of a Space Shuttle Mission

The Space Shuttle system was an engineering marvel, comprising three major components that worked in concert to achieve orbit and return safely. At its heart was the Orbiter Vehicle (OV) itself, often referred to simply as the "Shuttle." This winged craft housed the crew and payload bay and was equipped with three powerful Rocketdyne RS-25 main engines. Flanking the Orbiter were two immense, recoverable Solid Rocket Boosters (SRBs), providing the majority of the initial thrust. Completing the trio was the massive, expendable External Tank (ET), painted a distinctive rust color, which held the cryogenic liquid hydrogen and liquid oxygen propellants for the Orbiter's main engines.

A Space Shuttle launch was a truly spectacular event. The entire stack, standing vertically like a conventional rocket, ignited with incredible force. Both SRBs and the Orbiter's three main engines roared to life simultaneously, drawing fuel from the ET. After about two minutes, having consumed their solid propellant, the SRBs separated from the main assembly and parachuted back into the ocean, where they were recovered, refurbished, and reused for future missions—a key aspect of the Shuttle's partial reusability. The Orbiter's main engines continued to burn, pushing the craft higher and faster, until the ET was spent. The External Tank was then jettisoned, burning up harmlessly in the atmosphere. With the main engines cut off, the Orbiter's two smaller Orbital Maneuvering System (OMS) engines fired briefly to achieve final orbit insertion, beginning the crew's mission in space.

Upon mission completion, the Orbiter's journey back to Earth was equally complex. The OMS engines were again utilized for a carefully calculated deorbit burn, slowing the spacecraft just enough to begin its controlled descent. Reentry into Earth's atmosphere was a fiery process, with the Orbiter protected by thousands of specially designed thermal protection system (TPS) tiles, which dissipated the intense heat generated by atmospheric friction. Gliding unpowered like a massive aircraft, the Orbiter, functioning as a sophisticated spaceplane, executed a precise runway landing. These landings most frequently took place at the dedicated Shuttle Landing Facility at KSC in Florida. However, in certain circumstances, landings occurred at Rogers Dry Lake at Edwards Air Force Base in California. In such cases, the Orbiter would then be ferried back to KSC atop the modified Shuttle Carrier Aircraft (SCA), a specially adapted Boeing 747, a sight almost as impressive as the launch itself.

The Iconic Fleet: A Legacy of Exploration and Sacrifice

The Space Shuttle program involved a fleet of six vehicles in total, each with its own story. The very first orbiter, Enterprise, constructed in 1976, was never designed for spaceflight. Instead, it was an atmospheric test vehicle, crucial for proving the aerodynamic characteristics of the design through a series of Approach and Landing Tests (ALT). It laid the foundational groundwork for the operational orbiters that would follow.

Four fully operational orbiters were initially delivered to NASA: Columbia, Challenger, Discovery, and Atlantis. These magnificent machines carried the hopes and dreams of a nation into orbit, pushing the boundaries of human endeavor. Tragically, the program was marked by profound losses. In 1986, the Space Shuttle Challenger disintegrated shortly after launch during mission STS-51L, claiming the lives of all seven astronauts aboard. Years later, in 2003, the Space Shuttle Columbia broke apart during reentry on mission STS-107, resulting in the loss of its seven-member crew. These accidents served as somber reminders of the immense risks inherent in space exploration.

To help fill the void left by Challenger, a fifth operational orbiter, Endeavour, was constructed in 1991, largely using spare parts from other orbiters. Endeavour's addition allowed the program to continue its vital work. Following Atlantis's final, poignant flight on July 21, 2011, the three surviving operational orbiters—Discovery, Atlantis, and Endeavour—were officially retired, bringing an end to an era. This retirement left a significant gap in American human spaceflight capability, as the United States temporarily relied on Russia's dependable Soyuz spacecraft to transport its astronauts to the International Space Station. This reliance continued until the historic launch of the SpaceX Crew Dragon Demo-2 mission in May 2020, which marked the return of American crew launch capability from U.S. soil.

A Notable Achievement: STS-49 and the Intelsat Rescue

Among the Space Shuttle's 135 missions, STS-49 stands out as a testament to ingenuity and perseverance. This mission, launched on May 7, 1992, marked the maiden flight of the Space Shuttle Endeavour, the newest addition to the fleet. The primary objective of its nine-day journey was audacious: to recover the stranded Intelsat 603 communications satellite. Two years prior, this valuable satellite had failed to fire its upper stage and was left in an unusable Low Earth Orbit.

The plan was to capture the massive satellite, attach it to a new, fully functional upper stage, and then relaunch it to its intended geosynchronous orbit, thereby salvaging a critical piece of space infrastructure. What followed were several challenging attempts to grapple the spinning satellite. Ultimately, the crew resorted to an unprecedented and highly complex maneuver: the first and only three-person Extravehicular Activity (EVA), or spacewalk, in the history of spaceflight. Astronauts Pierre Thuot, Richard Hieb, and Thomas Akers worked together outside the orbiter, physically capturing the satellite by hand in a remarkable display of teamwork and skill. This monumental EVA also held the record as the longest spacewalk ever undertaken until STS-102 in 2001, underscoring the sheer difficulty and success of this incredible rescue mission.

Frequently Asked Questions About the Space Shuttle

What was the Space Shuttle's primary purpose?
The Space Shuttle, officially known as the Space Transportation System (STS), was designed as a versatile, partially reusable spacecraft system. Its primary purposes included deploying satellites and interplanetary probes, conducting scientific research in orbit, participating in international space programs like Shuttle-Mir, and crucially, building and servicing the International Space Station (ISS).
How many Space Shuttles were built and flown?
Six Space Shuttle orbiters were built in total. Five of these were fully operational and flew missions: Columbia, Challenger, Discovery, Atlantis, and Endeavour. The sixth, Enterprise, was built for atmospheric flight tests and never flew into space.
What happened to the Space Shuttle program?
The Space Shuttle program officially concluded in 2011, with the final flight of Space Shuttle Atlantis. Two orbiters, Challenger (1986) and Columbia (2003), were tragically lost in accidents, resulting in the deaths of 14 astronauts. The three surviving operational orbiters (Discovery, Atlantis, and Endeavour) were retired and are now museum exhibits.
How did the Space Shuttle launch and return to Earth?
The Space Shuttle launched vertically, powered by its two Solid Rocket Boosters (SRBs) and three main engines fueled by an external tank (ET). The SRBs and ET were jettisoned during ascent. For its return, the orbiter would fire its Orbital Maneuvering System (OMS) engines to deorbit, reenter the atmosphere protected by thermal tiles, and then glide to a runway landing much like an airplane, usually at Kennedy Space Center or Edwards Air Force Base.
What made STS-49 a particularly significant mission?
STS-49, the maiden flight of Space Shuttle Endeavour in 1992, was highly significant for successfully rescuing the stranded Intelsat 603 satellite. It involved the only three-person spacewalk (EVA) in history, where astronauts physically captured the satellite by hand, before attaching a new upper stage and relaunching it to its correct orbit, showcasing extraordinary ingenuity and teamwork.