The Space Shuttle, or Space Transportation System (STS), was a partially reusable spacecraft system operated by NASA from 1981 to 2011.

It was designed to launch like a rocket, maneuver in Earth orbit like a spacecraft, and land on a runway like a glider.

The Space Shuttle system consisted of three major components:

Orbiter Vehicle (OV):

The reusable, aircraft-like vehicle that housed the crew and payload.

The orbiter used its three main engines during launch and glided to a runway landing upon returning to Earth.

External Tank (ET):

The non-reusable tank that held the liquid hydrogen and liquid oxygen propellant for the orbiter's main engines during launch.

It was jettisoned before reaching orbit and disintegrated upon reentry.

Solid Rocket Boosters (SRBs):

Two reusable rockets that provided most of the initial thrust at liftoff.

They were jettisoned and recovered by parachute after about two minutes of flight.

Space Shuttle fleet and missions

NASA's fleet included five operational orbiters and one atmospheric test vehicle:

Enterprise (OV-101):

A prototype used only for atmospheric flight and landing tests, it never flew in space.

Columbia (OV-102):

The first to fly in space in 1981 and was lost during reentry in 2003.

Challenger (OV-099):

Built to replace Enterprise and was destroyed in a catastrophic explosion shortly after launch in 1986.

Discovery (OV-103):

Launched in 1984 and flew more missions than any other shuttle.

Atlantis (OV-104):

Launched in 1985 and flew the final shuttle mission, STS-135, in 2011.

Endeavour (OV-105):

Built to replace Challenger after the disaster and first flew in 1992.

Over its 30 years of operation, the program completed 135 missions.

Key missions included:

Deploying and servicing the Hubble Space Telescope.

Deploying numerous other satellites and interplanetary probes.

Conducting scientific experiments in orbit using facilities like the European-built Spacelab.

Participating in the Shuttle-Mir program by docking with the Russian Mir space station.

Playing a crucial role in the construction of the International Space Station (ISS).

Reasons for retirement

The Space Shuttle program was officially retired in 2011 for several reasons:

Safety concerns:

The fatal accidents involving Challenger (1986) and Columbia (2003) highlighted significant safety risks inherent to the program.

High operating costs: The cost per launch was much higher than originally projected, with each mission costing hundreds of millions of dollars.

Time-consuming refurbishment: The goal of "routine" spaceflight was not realized, as extensive and time-consuming refurbishment was required between each flight.