1. Unit 4 vocabulary/ page 44 L.1/ What caused the explosion? 1F. Dwaikat

2. U. 4/ L. 1 vocabulary incident: a definite and separate occurrence /an event space shuttle: a spacecraft winged orbiter: a spacecraft, having wings, that orbits a planet or moon without landing on it cargo: goods carried by a ship, aircraft, or other vehicle; freight crew: a group of people working together tank: a large container that provides fuel 2F. Dwaikat

3. propellant: a rocket fuel that propels or provides thrust. boosters : a device for increasing power or effectiveness. launch: to set or thrust a craft in motion O-ring: a rubber ring used in machinery as a seal; A flat ring made of rubber or plastic vital: essential; very important U. 4/ L. 1 vocabulary 3F. Dwaikat

4. by-product: a secondary result; a side effect. something produced in the process of making something else. e.g: When plants produce carbohydrates by photosynthesis, oxygen is released as a by-product. brittle : easily damaged premature : occurring before the normal or expected time SRBs: Solid Rocket Boosters U. 4/ L. 1 vocabulary 4F. Dwaikat

5. SRBs Solid Rocket Boosters external fuel tank winged orbiter 5F. Dwaikat

6. NASA Image of the final Solid Rocket Booster (right) being mated to a Delta II rocket (blue). Two boosters (white) can be seen already attached. Solid Rocket Boosters (SRBs) (or Motors, SRMs) are used to provide thrust in spacecraft launches from the launch-pad up to burnout of the SRBs 6F. Dwaikat

7. A Space Shuttle External Tank (ET) on its way to the Vehicle Assembly Building. 7F. Dwaikat

8. orbiter: something that orbits, especially a spacecraft that orbits a planet or moon without landing on it. It carries the crew & the cargo. 8F. Dwaikat

9. The Challenger’s crew 9F. Dwaikat

10. O-ring seal; joint 10F. Dwaikat

11. Space Shuttle Columbia launching 11F. Dwaikat

12. The Challenger’s explosion 12F. Dwaikat