Unit 1 Tales of the unexplained Word powerU1M2课件（PPT 24页）.ppt

* * Word power 天马行空官方博客：/tmxk_docin ;QQ:1318241189 Unidentified Flying Objects “flying saucer” Lead-in UFO aliens outer space Brainstorming space Universe beyond the earth’s atmosphere in which all other planets and stars exist the Earth the sun the moon (satellite ) artificial satellite solar system orbit (man-made ) Whether UFOs really exist has puzzled us for a long time . Have you ever thought about exploring space one day ? Travel into or through a place in order to learn about it space exploration (space travel ) Who is he ? Do you know where he is ? He is Yang Liwei, and he is an astronaut . spaceman / spacewoman space shuttle Shenzhou 5 manned spaceship space shuttle unmanned spaceship Placing a satellite into orbit requires a large amount of energy, which must come from the launch vehicle, or device that launches the satellite. The satellite needs to reach an altitude of at least 200 km (120 mi) and a speed of over 29,000 km/h (18,000 mph) to lift into orbit successfully. Satellites receive this combination of potential(势能) energy (altitude) and kinetic(动能) energy (speed) from multistage rockets burning chemical fuels. Apollo Eleven Countdown A rocket launch countdown. A common sound in the nineteen-sixties. But this was not just another launch. It was the beginning of an historic event. It was the countdown for Apollo Eleven -- the space flight that would carry men to the first landing on the moon. Two-and-one-half minutes after the Apollo Eleven launch, the first-stage rocket separated from the spacecraft. Twelve minutes later, the spacecraft reached orbit. Its speed was twenty-nine-thousand kilometers an hour. Its orbit was one-hundred-sixty-five kilometers above the Earth. This was the time for the crew to test all the spacecraft systems. Everything worked perfectly. So, the NASA flight director told them they were go for the moon. They fired the third-stage rocket. It increased the speed of the spacecraft to forty-thousand kilometer