America's space shuttle was a delta winged craft that could be launched like a rocket．Two recoverable solid fuel rockets boosted it into space．The shuttle then could move under its own power of three built-in engines．To avoid the heat caused by friction upon reentering the Earth's atmosphere，special heat-resistant tiles and thermal blankets were part of the design and fixed to the outside fuselage．
Waiting to be launched，at the Control Centre at Cape Kennedy，on the 28th January 1986，Commander Dick Scobee，pilot Mike Smith and three astronauts made up the experienced crew of the space shuttle ‘Challenger’．On board were two other crew members，both new to space travel．One was an engineer，GREg Jarvis，and the other a woman，Christa McAuliffe，a teacher．She was specially selected to broadcast lessons from space to schools in the United States．The main aim of the mission was to launch a satellite that would improve communications between future shuttle flights and mission control．
The flight had been postponed for a few hours but the countdown had officially begun，and lift-off was expected at11：38 a．m．Friends and family were sitting in a grand-stand to watch．The main engines started up，followed by the blast of the two solid fuel boosters．Challenger rose in a cloud of smoke and flames．
Steadily the‘Challenger’rose higher and higher．Then，at a height of 13km above the ocean，tonnes of liquid fuel ignited in a huge ball of fire．
This tossed the spacecraft around and caused it to break up into fiery pieces which left trails of steam and smoke in the sky．
Later，after closely examining film of the launch，experts came to the conclusion that the accidentwas caused by the failure of two rubber rings．These helped seal the two halves of the casing of one of the large booster rockets．The two halves came apart，causing the fuel to ignite into a massive explosion．
All the astronauts were killed and it proved a tragic set-back to the‘Challenger’ projects．However，the joints of the solid rocket boosters were redesigned and other improvements made．Newer and better space vehicles once more took to orbiting the Earth．
Circle the letter that completes each sentence．
1．To steer the space shuttle in space ____．
A．five power units were needed
B．three power units were needed
C．two power units were needed
2．The main intention of the ill-fated space project ____ ．
A．was to broadcast lessons to schools
B．was to give experience to new astronauts
C．was to launch a communications satellite
3．The cause of the accident ____ ．
A．was the failure of rubber rings that sealed the cockpit of the spacecraft
B．was the fact that fuel ignited when parts of a booster rocket parted
C．was due to overfilling of fuel tanks which ignited in a ball of fire
keys: BCB
