16. The Space Shuttle
Even before the mighty Saturn V rocket had carried the final Apollo astronauts to the moon, NASA was working to identify its replacement. On January 5, 1972, President Richard Nixon announced that NASA would begin developing a reusable system, a group of components called the Shuttle Transportation System, or STS. More commonly, before and after its development, this system was known simply as the space shuttle.
The STS comprises three major elements: a large external tank (ET) containing liquid hydrogen and liquid oxygen, two solid-rocket boosters (SRBs), and the winged orbiter. Because the orbiter is the most familiar component, and the most complex, it is often referred to as the shuttle. However, the technically minded will remember that the term “space shuttle” refers to the entire assembly, not just the orbiter.
On September 17, 1976, the first test shuttle was presented to the public. Initially, the name given to the new spacecraft was Constitution, a reflection of the bicentennial celebration. However, due largely to the success of the “Star Trek” television series, a massive write-in campaign convinced NASA to rename the orbiter Enterprise. Although never equipped to fly in space, Enterprise completed a number of successful approach and landing tests (ALTs), landing for the first time on August 12, 1977, at Edwards Air Force Base.
The first shuttle designed for spaceflight was christened Columbia, and was delivered to the Kennedy Space Center on March 25, 1979. Columbia, the orbiter component of the first true space shuttle was launched on April 12, 1981, a dramatic celebration of Yuri Gagarin’s trip into space 20 years earlier. STS-1, the mission’s formal designation, validated the shuttle’s design and introduced a new era in human spaceflight. It has been the only human-rated vehicle certified for reusability (100 missions) and able to return with as much cargo as it launches. Over the next five years, NASA would add three more orbiters to the fleet: Challenger, Discovery, and Atlantis.
In the Soviet Union, politicians and military leaders were still reacting to advances in the American space program, and were working to develop their own space shuttle. Beginning in 1976, the Soviets undertook what would become the most expensive program in their history, the construction of the space shuttle Buran, or “Snowstorm.” Although similar in many ways to the American shuttle, Buran had its own unique design, and relied on the massive Energia rocket and two other liquid-filled boosters to carry it into space. The absence of engines such as those used on the American orbiter allowed for an increased cargo capacity. Buran flew only once, without human occupants, landing automatically at the Baikonur Cosmodrome.
On January 28, 1986, the space shuttle Challenger was destroyed during its initial ascent, killing all seven astronauts on board. The tragedy was caused by a faulty O-ring, a cylindrical seal on the right-hand solidrocket booster, and which grew brittle, losing elasticity during unseasonably cold weather. Seventy-three seconds after it was launched, the O-ring failed, allowing a jet of hot gas to escape the booster shell, cutting into the external tank strut like a blowtorch. The failure of the strut allowed the ET to break apart from the space shuttle. The accident that followed was catastrophic.
A new space shuttle was delivered in May 1991. The orbiter was named Endeavour, for the first ship commanded by the 18th-century explorer James Cook. Although Discovery was the first orbiter to return to space following the Challenger disaster, the construction of Endeavour represented a specific political decision to continue support for America’s space shuttle program, despite technical and administrative limitations discovered during the Challenger investigation.
Throughout the years following the space shuttle’s return to flight, NASA enjoyed a highly productive series of missions. In 1989, the Magellan spacecraft was launched to Venus, the first planetary mission launched from the space shuttle. The same year, the orbiter Atlantis sent the Galileo spacecraft toward Jupiter, initiating a mission that vastly increased our knowledge of the outer solar system. In 1990, the orbiter Discovery sent the Hubble Space Telescope, a device that would ultimately change our fundamental perception of the universe, into orbit. A flaw in the telescope’s optics was corrected three years later by the crew of Endeavour.
In 1994, the space shuttle program encouraged relations between the United States and a newly independent Russia by hosting cosmonaut Sergei Krikalev, the first Russian to fly aboard the shuttle. This relationship was enhanced when the orbiter Atlantis docked with the Russian space station Mir in 1995, a mission that included Washington astronaut Dr. Bonnie Dunbar. In 1998, Endeavour made the first trip to the International Space Station, joining the Russian and American modules, Zarya and Unity.
In 2003, 15 minutes before completing its 28th mission, the orbiter Columbia disintegrated during re-entry, causing the loss of all seven astronauts on board. A section of insulation from the external tank had broken loose during launch, striking the orbiter’s left wing, damaging the leading edge, and compromising the orbiter’s thermal protection system. As it re-entered the atmosphere, the damaged wing allowed hot, ionized gas to enter the wing’s interior, leading to the destruction of the orbiter.
On July 26, 2005, the United States returned to space with Discovery, over objections from safety officers and engineers. Despite modifications made following the Columbia disaster, insulating foam was seen breaking loose from the external tank. Although Discovery was able to safely complete its mission, NASA grounded the space shuttle until 2006. Most recently, the orbiter Endeavour traveled into space carrying teacher Barbara Morgan, who had originally been the backup astronaut for teacher Christa McAuliffe who was killed during the Challenger accident.
Although the space shuttle program continues, it has been officially announced that the fleet will be retired in 2010, making way for the Orion spacecraft. Despite concerns about overall safety and the effect of bureaucracy on prudent design decisions, the space shuttle has proven itself to be a remarkable spacecraft, making possible a wealth of exploration missions and expanding mankind’s role in space.