Launching Into History
The End of an Era
The launch of the Space Shuttle Atlantis, scheduled for July 8, 2011, will herald the end of an era for the United States. Mission STS-135 will mark the beginning of the end for the United States Space Shuttle program. With a span of over 40 years, the Shuttle program endured its share of challenges, yet its successes were celebrated with the world.
Before the Apollo 11 moon landing in 1969, NASA began early studies of space shuttle designs. In 1969 President Richard Nixon formed the Space Task Group, chaired by vice president Spiro T. Agnew. This group evaluated the shuttle studies to date, and recommended a national space strategy including building a space shuttle. The goal, as presented by NASA to Congress, was to provide a much less-expensive means of access to space that would be used by NASA, the Department of Defense, and other commercial and scientific users.
During early shuttle development there was great debate about the optimal shuttle design that best balanced capability, development cost and operating cost. Ultimately the current design was chosen, using a reusable winged orbiter, reusable solid rocket boosters, and an expendable external tank.
The program was formally launched on January 5, 1972, when President Nixon announced that NASA would proceed with the development of a reusable space shuttle system. The final design was less costly to build and less technically ambitious than earlier fully reusable designs. The initial design parameters included a larger external fuel tank, which would have been carried to orbit, where it could be used as a section of a space station, but this idea was killed due to budgetary and political considerations.
The plan for the use of the space shuttle was to be focused on completing assembly of the International Space Station, or ISS, by 2010, after which it would be retired.
The prime contractor for the program was North American Aviation, later Rockwell International, now Boeing, This was the same company responsible for building the Apollo Command/Service Module. The contractor for the Space Shuttle Solid Rocket Boosters was Morton Thiokol, now part of Alliant Techsystems. Building the external tank was Martin Marietta, now Lockheed Martin. Rocketdyne, now Pratt & Whitney Rocketdyne, part of United Technologies, was used for the space shuttle main engines.
America's fleet of Space Shuttle orbiters were named after pioneering sea vessels which established new frontiers in research and exploration. NASA delved through the history books to find ships which achieved historical significance through discoveries about the world's oceans or the Earth itself. Another important criterion in the selection process was consideration for the international nature of the Space Shuttle program. The name of NASA's newest orbiter, Endeavour was selected from names submitted by school children around the world. Atlantis is named for the primary research sailing vessel used by the Woods Hole Oceanographic Institute from 1930 to 1966 and was the first vessel to use electronic sounding devices to map the ocean floor. The ill-fated Challenger was named for an American naval research vessel that sailed the oceans in the 1870s. Columbia was named for the sloop captained by Robert Gray who, on May 11, 1792, maneuvered his ship through dangerous inland waters to explore British Columbia and what are now the states of Washington and Oregon. Discovery was named for one of the two ships used by the British explorer Captain James Cook when he discovered Hawaii and explored Alaska and northwestern Canada in the 1770s. It was also the name of one of Henry Hudson's ships that explored Hudson Bay in 1610-1611. Yet another ship named Discovery was used by the British Royal Geographical Society in 1875 to explore the region of the North Pole, and yet another was built by the Society in 1901 to explore the Antarctic regions. This last ship Discovery still exists. The other of Cook's ships is the namesake for the Shuttle Endeavour. This ship was used in astronomical research, and its observations enabled the astronomers of the day to determine accurately, for the first time, the distance between the sun and the Earth. It was also noted as the ship that first explored New Zealand. Its voyages were the first long-distance sea voyages in which no crewmembers died of scurvy; Captain Cook forced the crew to eat a high vitamin C diet that prevented the disease.
The first orbiter was originally planned to be named Constitution, but a massive write-in campaign from fans of the Star Trek television series convinced the White House to change the name to Enterprise. Amid great fanfare, the Enterprise, designated OV-101, was rolled out on September 17, 1976, and later conducted a successful series of glide-approach and landing tests that were the first real validation of the design.
The winged Space Shuttle orbiter, a manned launch vehicle officially named Space Transportation System or STS, is launched vertically, usually carrying five to seven astronauts (although eight have been carried) and up to 50,000 lb of payload into low earth orbit. When its mission is complete, the shuttle can independently move itself out of orbit using its Maneuvering System (it orients itself appropriately and fires its main OMS engines, thus slowing it down) and re-enter the Earth's atmosphere. During descent and landing the orbiter acts as a re-entry vehicle and a glider, using its OMS system and flight surfaces to make adjustments.
The shuttle is the only winged manned spacecraft to achieve orbit and land, and the only reusable space vehicle that has ever made multiple flights into orbit. Its missions involve carrying large payloads to various orbits (including segments to be added to the International Space Station, providing crew rotation for the International Space Station, and performing service missions. The orbiter has also recovered satellites and other payloads from orbit and returned them to Earth. It has also been used to return large payloads from the ISS to Earth, as the Russian Soyuz spacecraft has limited capacity for return payloads. Each vehicle was designed with a projected lifespan of 100 launches, or 10 years' operational life.
The first fully functional orbiter was the Columbia, designated OV-102. It was delivered to Kennedy Space Center on March 25, 1979, and was first launched on April 12, 1981 with a crew of two. Challenger, OV-099, was delivered in July 1982. Originally built and used as a Structural Test Article (STA-099), Challenger was converted to a complete shuttle when this was found to be less expensive than converting Enterprise from its Approach and Landing Test configuration. Discovery, OV-103, was completed in November of 1983, and Atlantis, OV-104, in April 1985.
Endeavour , OV-105, was built to replace Challenger which was destroyed during ascent due to O-Ring failure on the right solid rocket booster on January 28, 1986, with the loss of all seven astronauts on board. Endeavor was built using structural spare parts originally intended for the other orbiters, and delivered in May 1991. Columbia, which broke up on reentry killing all seven crew members, on February 1, 2003, has not been replaced. Out of the five fully functional shuttle orbiters built, three remain. Enterprise, which was used for atmospheric test flights but not intended for orbital flight, had many parts taken out for use on the other orbiters. It was later visually restored and is on display at the National Air and Space Museum's Steven F. Udvar-Hazy Center. NASA also maintains warehoused extensive catalogs of recovered pieces from the two destroyed orbiters.
Many other vehicles were used in support of the Space Shuttle program, mainly terrestrial transportation vehicles.
- The Crawler-Transporter carries the Mobile Launcher Platform and the space shuttle from the Vehicle Assembly Building at Launch Complex 39 to Pad A.
- The Shuttle Carrier Aircraft are two modified Boeing 747s. Either can fly an orbiter from alternative landing sites back to the Kennedy Space Center.
- A 36-wheeled transport trailer, the Orbiter Transfer System, originally built for the U.S. Air Force's launch facility at Vandenberg Air Force Base in California (since then converted for Delta IV rockets) that would transport the orbiter from the landing facility to the launch pad, which allowed both "stacking" and launch without utilizing a separate VAB-style building and crawler-transporter roadway. Prior to the closing of the Vandenberg facility, orbiters were transported from the OPF to the VAB on its undercarriage, only to be raised when the orbiter was being lifted for attachment to the SRB/ET stack. The trailer allows the transportation of the orbiter from the OPF to either the SCA-747 "Mate-Demate" stand or the VAB without placing any additional stress on the undercarriage.
- The Crew Transport Vehicle (CTV), a modified airport jet bridge, is used to assist astronauts to egress from the orbiter after landing. Upon entering the CTV, astronauts can take off their launch and re-entry suits then proceed to chairs and beds for medical checks before being transported back to the crew quarters in the Operations and Checkout Building.
The Space Shuttle Program has had two major disasters.
Crew of Space Shuttle Challenger. Front row from left, Mike Smith, Dick Scobee, Ron McNair. Back row from left, Ellison Onizuka, Christa McAuliffe, Greg Jarvis, Judith Resnik. Photo courtesy of NASA
The Space Shuttle Challenger disaster occurred on Tuesday, January 28, 1986, when Space Shuttle Challenger broke apart 73 seconds into its flight, leading to the deaths of its seven crew members. The spacecraft disintegrated over the Atlantic Ocean, off the coast of central Florida, at 11:38 am EST. Disintegration of the entire vehicle began after an O-ring seal in its right solid rocket booster, or SRB, failed at liftoff. The O-ring failure caused a breach in the joint it sealed, allowing pressurized hot gas from within the solid rocket motor to reach the outside and impinge upon the adjacent SRB attachment hardware and external fuel tank. This led to the separation of the right-hand SRB's aft attachment and the structural failure of the external tank. Aerodynamic forces promptly broke up the orbiter. The crew compartment and many other vehicle fragments were eventually recovered from the ocean floor after a lengthy search and recovery operation. Although the exact timing of the death of the crew is unknown, several crew members are known to have survived the initial breakup of the spacecraft. However, the shuttle had no escape system and the astronauts did not survive the impact of the crew compartment with the ocean surface. The disaster resulted in a 32-month hiatus in the shuttle program and the formation of the Rogers Commission, a special commission appointed by United States President Ronald Reagan to investigate the accident. The Rogers Commission found that NASA's organizational culture and decision-making processes had been a key contributing factor to the accident. NASA managers had known that contractor Morton Thiokol's design of the SRBs contained a potentially catastrophic flaw in the O-rings since 1977, but they failed to address it properly. They also disregarded warnings from engineers about the dangers of launching posed by the low temperatures of that morning and had failed to adequately report these technical concerns to their superiors. The Rogers Commission offered NASA nine recommendations that were to be implemented before shuttle flights resumed. Many viewed the launch live because of the presence on the crew of Christa McAuliffe, the first member of the Teacher in Space Project. Media coverage of the accident was extensive: one study reported that 85 percent of Americans surveyed had heard the news within an hour of the accident. The Challenger disaster has been used as a case study in many discussions of engineering safety and workplace ethics.
The Space Shuttle Columbia disaster occurred on February 1, 2003, when shortly before it was scheduled to conclude its 28th mission, STS-107, the Space Shuttle Columbia disintegrated over Texas during re-entry into the Earth's atmosphere, resulting in the death of all seven crew members. Debris from Columbia fell to Earth in Texas along a path stretching from Trophy Club to Tyler, as well as into parts of Louisiana. The loss of Columbia was a result of damage sustained during launch when a piece of foam insulation the size of a small briefcase broke off from the Space Shuttle external tank under the aerodynamic forces of launch. The debris struck the leading edge of the left wing, damaging the Shuttle's thermal protection system (TPS), which shields it from heat generated with the atmosphere during re-entry. While Columbia was still in orbit, some engineers suspected damage, but NASA managers limited the investigation, on the grounds that little could be done even if problems were found. NASA's original Shuttle design specifications stated that the external tank was not to shed foam or other debris; as such, strikes upon the Shuttle itself were safety issues that needed to be resolved before a launch was cleared. Launches were often given the go-ahead as engineers came to see the foam shedding and debris strikes as inevitable and irresolvable, with the rationale that they were either not a threat to safety, or an acceptable risk. The majority of Shuttle launches recorded such foam strikes and thermal tile scarring. During re-entry of STS-107, the damaged area allowed the hot gases to penetrate and destroy the internal wing structure, rapidly causing the in-flight breakup of the vehicle. An extensive ground search in parts of Texas, Louisiana, and Arkansas recovered crew remains and many vehicle fragments. Mission STS-107 was the 113th Space Shuttle launch. It was delayed 18 times over the two years from its original launch date of January 11, 2001, to its actual launch date of January 16, 2003. A launch delay due to cracks in the shuttle's propellant distribution system occurred one month before a July 19, 2002, launch date. The Columbia Accident Investigation Board (CAIB) determined that this delay had nothing to do with the catastrophic failure six months later. The Columbia Accident Investigation Board's recommendations addressed both technical and organizational issues. Space Shuttle flight operations were delayed for two years by the disaster, similar to the Challenger disaster. Construction of the International Space Station was put on hold, and for 29 months the station relied entirely on the Russian Federal Space Agency for resupply until Shuttle flights resumed with STS-114 and 41 months for crew rotation until STS-121.
Two shuttles have been destroyed in 134 missions, both with the loss of their entire crew totaling 14 astronauts. This gives a 2 percent death rate per astronaut-flight, and an average failure rate of 1 in every 65 missions. The original disaster potential, though disaster is not defined as fatal or non-fatal, was estimated during shuttle development at one every 75 missions.
In addition to the initial function of servicing the International Space Station, Space Shuttle Missions have been also been used in the servicing of the Mir, the Soviet/Russian space station; the Hubble Telescope; and numerous satellites. Missions flown in the higher earth orbit included servicing the Chandra X-Ray Observatory as well as certain satellites used for defense. Interplanetary missions of the Space Shuttle included servicing the Magellan Probe, Galileo Spacecraft and Ulysses Probe. Furthermore various experiments were carried out in Science, Astronomy, crystal growth, and space physics.
Upon its retirement at the conclusion of STS-135, NASA planned to replace the shuttle with Project Constellation consisting of the Ares I and Ares V launch vehicles and the Orion Spacecraft; however, in early 2010 the Obama administration asked Congress to instead endorse a scaled-back plan with heavy reliance on the private sector. The program is no longer an active NASA project.