WHAT IS A SPACE SHUTTLE...?

SPACE SHUTTLE....:

The Shuttle sits on top of Mobile Launcher Platform (MLP). It consists of Orbiter (on top), External Tank (at centre), and Solid Rocket Boosters (to the right and left of External Tank). Two Tail Service Masts (TSMs) to the either side of the Orbiter's tail provide umbilical connections for propellant loading and electrical power. The Shuttle is a partially reusuable launch system composed of three main assemblies: the reusable Orbiter Vehicle (OV), the expendable External Tank (ET), and the two reusable Solid Rocket Boosters (SRBs). The tank and boosters are jettisoned during ascent, so only the orbiter goes into orbit. The vehicle is launched vertically like a conventional rocket, and the orbiter glides to a horizontal landing, after which it is refurbished for reuse. 

The Orbiter resembles an airplane with double-delta wings, swept 81° at the inner leading edge and 45° at the outer leading edge. Its vertical stabilizer's leading edge is swept back at a 45° angle. The four elevons, mounted at the trailing edge of the wings, and the rudder/speed brake, attached at the trailing edge of the stabilizer, with the body flap, control the Orbiter during descent and landing. 

The Orbiter has a large 60 by 15 ft (18 m by 4.6 m) payload bay, filling most of the fuselage. The payload bay doors have heat radiators mounted on their inner surfaces, and so are kept open for thermal control while the Shuttle is in orbit. Thermal control is also maintained by adjusting the orientation of the Shuttle relative to Earth and Sun. Inside the payload bay is the Remote Manipulator System, also known as the Canadarm, a robot arm used to retrieve and deploy payloads. Until the loss of Columbia, the Canadarm had been used only on those missions where it was needed. Since the arm is a crucial part of the Thermal Protection Inspection procedures now required for Shuttle flights, it will probably be included on all future flights. 

Orbital Vehicle Three Space Shuttle Main Engines (SSMEs) are mounted on the Orbiter's aft fuselage in a triangular pattern. The three engines can swivel 10.5 degrees up and down and 8.5 degrees from side to side during ascent to change the direction of their thrust and steer the Shuttle as well as push.

The Orbital Manoeuvring System (OMS) provides orbital manoeuvres, including insertion, circularization, transfer, rendezvous, abort to orbit, and abort once around. 

The Reaction Control System (RCS) provides attitude control and translation along the pitch, roll, and yaw axes during the flight phases of orbit insertion, orbit, and re-entry. 

The Thermal Protection System (TPS) covers the outside of the Orbiter, protecting it from the cold soak of -121 °C (-250 °F) in space to the 1649 °C (3000 °F) heat of re-entry 

The orbiter structure is made primarily from aluminium alloy, although the engine thrust structure is made from titanium. 

The External Tank (ET) provides 2.025 million litres (535,000 gallons) of liquid hydrogen and liquid oxygen propellant to the SSMEs. It is discarded 8.5 minutes after launch at an altitude of 60 nautical miles (111 km) then burns up on re-entry. The ET is constructed mostly of aluminium-lithium alloy about 1/8 inch thick. 

Two Solid Rocket Boosters (SRBs) provide about 83% of the vehicle's thrust at liftoff and during the first stage ascent. They are jettisoned two minutes after launch at a height of about 150,000 feet (45.7 km), then deploy parachutes and land in the ocean to be recovered. The SRB cases are made of steel about 1/2 inch (1.27 cm) thick.