Passage 26
学霸导读 科学的进步让人类更加了解太空。然而人类在发展的过程中也给太空环境带来了压力，比如“太空垃圾”。
In 1997, Lottie Williams was walking through a park in Oklahoma, in the U.S., with her friends. Suddenly something tapped her on the shoulder and fell to the ground. She picked the object up. It was about as heavy as an empty soda can. L 1 , scientists told her it was a piece of a Delta-H rocket that had been used to launch a satellite.
Many countries around the world have sent satellites into space. We need satellites to send and receive TV and radio signals, to r 2 the weather and for many other things. But when they become old or they break down or we don’t need them any more, we just leave them there. They become space junk.
Scientists think there are about 16，000 objects larger than 10 centimeters wide f lying around Earth， and tens of millions of smaller objects， too. They travel at around 7 kilometers a second. That’s fast！ And it’s their speed that makes these pieces of space junk really d 3 . If one small piece of space junk hits something at high speed， it can do a lot of damage. Luckily， there haven’t been many collisions （ 撞击 ）. But in 2009， an old Russian satellite hit and destroyed an American satellite—and that c 4 2，000 new pieces of space junk！
Pieces of space junk re-enter the Earth’s atmosphere every day. But Lottie Williams is the o 5 person who has been hit. The piece that hit her was light, and the air in the atmosphere had slowed it down. Most space junk burns up and doesn’t reach the Earth’s s 6 . But in 2011, a metal ball 35 centimeters wide fell to Earth in Namibia, Africa. It made a hole in the ground 30 centimeters d 7 and over 3 meters wide. Lottie was lucky for she wasn’t hit by that!
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高频词汇
tap /tæp/ v. 轻敲，轻拍
launch /lɔːntʃ/ v. 发起，发动，发射，发行
satellite /'sætəlaɪt/ n. 卫星
atmosphere /'ætməsfɪə（r）/ n. 大气（层）