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Space exploration
The International Space Station - Space shuttles

 

columbia shuttle

In 1984, President Ronald Reagan authorized the building of a large, permanent space station "within a decade." Designs for the new station changed often and the estimated cost increased. The promised completion date slipped later and later. In 1993, President Bill Clinton directed NASA to redesign the proposed space station to reduce the cost and amount of time it would take to build. The United States, Brazil, Canada, Japan, Russia, and the ESA would become partners in a program to build the redesigned space station. The International Space Station would be built from several pressurized modules and solar power panels.

Construction began in 1998. Russia launched the first module, called Zarya, in November of that year. A month later, the space shuttle Endeavour carried the module Unity into orbit and docked it with Zarya. A crew of one American astronaut and two Russian cosmonauts moved into the station in 2000.

Space shuttles

During the 1950's and the 1960's, aviation researchers worked to develop winged rocket planes. Advocates of winged spaceplanes pointed out that such vehicles could land on ordinary airfields. Adding wings to a spacecraft increases the vehicle's weight, but wings make landing the vehicle much easier and cheaper than splashdowns at sea. Ocean landings require many ships and aircraft, and the salt water usually damages the spacecraft beyond repair.

NASA began to develop a reusable space shuttle while the Apollo program was still underway. In 1972, U.S. President Richard M. Nixon signed an executive order that officially started the space shuttle project. The shuttles were designed to blast off like a rocket and land like an airplane, making up to 100 missions.

The space shuttle system consists of three parts: (1) an orbiter, (2) an external tank, and (3) two solid rocket boosters. The nose of the winged orbiter houses the pressurized crew cabin. From the flight deck at the front of the orbiter, pilots can look through the front and side windows. The middeck, located under the flight deck, contains additional seats, equipment lockers, food systems, sleeping facilities, and a small toilet compartment. An air lock links the middeck with the payload bay, the area that holds the cargo. The tail of the orbiter houses the main engines and a smaller set of engines used for maneuvering in space.

The external tank is attached to the orbiter's belly. It contains the liquid propellants used by the main engines. Two rocket boosters are strapped to the sides of the external tank. They contain solid propellants.

The designers of the space shuttle had to overcome a number of major technological challenges. The shuttle's main engines had to be reusable for many missions. The shuttle needed a flexible but reliable system of computer control. And it required a new type of heat shield that could withstand many reentries into Earth's atmosphere.

The shuttle era begins

In 1977, NASA conducted flight tests of the first space shuttle, Enterprise, with a modified 747 jumbo jet. The jet carried the orbiter into the air and back on several flights and released it in midair on several more.

The shuttle's first orbital mission began on April 12, 1981. That day, the shuttle Columbia was launched, with astronauts John W. Young and Robert L. Crippen at the controls. The 54-hour mission went perfectly. Seven months later, the vehicle made a second orbital flight, proving that a spacecraft could be reused.

Although the first four shuttle flights each carried only two pilots, the crew size was soon expanded to four, and later to seven or eight. Besides the two pilots, shuttle crews included mission specialists (experts in the operation of the shuttle) and payload specialists (experts in the scientific research to be performed).

The large capacity of the space shuttle's orbiter opened the possibility of including other passengers besides NASA astronauts and scientists. Citizens who participated in shuttle missions included representatives of the companies launching payloads and members of the U.S. Congress.

In 1984, NASA created a special "Space Flight Participant" program to offer the opportunity of space travel to more Americans. President Reagan announced that the first participant would be a schoolteacher. Later flights were expected to carry journalists, artists, and other interested civilians.


Contributor: James Oberg, M.S., Spaceflight Engineer; author, UFOs and Outer Space Mysteries.
Source : World Book 2005

Space exploration
 
What is space?
Getting into space and back
Living in space
Microgravity
Meeting basic needs in space
Communicating with Earth
The dawn of the space age
Space probes
Probes to Venus
Probes to Jupiter and beyond
Probes to comets
Human beings enter space
Apollo: Mission to the moon
Exploring the moon
Returning to Earth
The International Space Station
Space shuttles
Types of shuttle missions