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  3. The 10th launch of the space shuttle Challenger was scheduled as the 25th space shuttle mission. Francis R. (Dick) Scobee was th

The 10th launch of the space shuttle Challenger was scheduled as the 25th space shuttle mission. Francis R. (Dick) Scobee was th

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问题    The 10th launch of the space shuttle Challenger was scheduled as the 25th space shuttle mission. Francis R. (Dick) Scobee was the mission commander. The crew included Christa McAuliffe, a high-school teacher from New Hampshire. The five other crew members were Gregory B. Jarvis, Ronald E. McNair, Ellison S. Onizuka, Judith A. Resnik, and Michael J. Smith.
   After several launch delays, NASA officials overruled the concerns of engineers and ordered a liftoff on a cold morning, Jan. 28, 1986. The mission ended in tragedy. Challenger disintegrated into a ball of fire. The accident occurred 73 seconds into flight, at an altitude of 14020 meters and at about twice the speed of sound.
   Strictly speaking, Challenger did not explode. Instead, various structural failures caused the spacecraft to break apart. Although Challenger disintegrated almost without warning, the crew may have briefly been aware that something was wrong. The crew cabin tore loose from the rest of the shuttle and soared through the air. It took almost three minutes for the cabin to fall to the Atlantic Ocean, where it smashed on impact, killing the seven crew members.
   All shuttle missions were halted while a special commission appointed by President Reagan determined the cause of the accident and what could be done to prevent such disasters from happening again. In June I986, the commission reported that the accident was caused by a failure of O rings in the shuttle’s right solid rocket booster. These rubber rings sealed the joint between the two lower segments of the booster. Design flaws in the joint and unusually cold weather during launch caused the O rings to allow hot gases to leak out of the booster through the joint. Flames from within the booster streamed past the failed seal and quickly expanded the small hole. The flaming gases then burned a hole in the shuttle’s external fuel tank. The flames also cut away one of the supporting beams that held the booster to the side of the external tank. The booster tore loose and ruptured the tank. The propellants (火箭燃料) from the tank formed a giant fireball as structural failures tore the vehicle apart.
   The commission said NASA’s decision to launch the shuttle was flawed. Top-level decision makers had not been informed of problems with the joints and O rings or of the possible damaging effects of cold weather.
   Shuttle designers made several technical modifications, including an improved O-ring design and the addition of a crew bail-out system. Although such a system would not work in all cases, it could save the lives of shuttle crew members in some situations. Procedural changes included stricter safety reviews and more restrictive launching conditions. The space shuttle resumed flying on Sept.29, 1988, with the launch of the redesigned shuttle Discovery. (465 words)
The crew died as a direct result of ______.
选项 A、the smash of the cabin on impact on water
B、the explosion of the spacecraft into a fireball
C、the disintegration of the spacecraft
D、the breakdown of the booster
答案A
解析 意为，“机舱落到水面时的冲击力”。第三段指出，严格地讲，“挑战者”号航天飞机并没有爆炸(虽然大家看到了火球)，各种结构上的故障使它解体了，机舱与其他部分分离后落下，用了三分钟左右的时间到达大西洋水面，落向水面的冲力摧毁了机舱，使七名机组人员丧生。这是他们丧生的直接原因。C意为：“航天飞机的解体”。这相对于冲击力来说是间接原因。D意为：“助推器的故障”。根据第四段第二句，问题的确始于宇航飞机右边的火箭助推器上的O形圈。但是，这不是让宇航员丧生的直接原因。
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