Humans have always looked up into the night sky and dreamed about space.
In the latter half of the 20th century, rockets were developed that were powerful enough to overcome the force of gravity to reach orbital velocities, paving the way for space exploration to become a reality.
在20世纪30年代和40年代，纳粹德国看到使用远距离火箭弹作为武器的可能性。后期在第二次世界大战中，伦敦200英里范围的V-2导弹，其拱形60英里高过英吉利海峡，在时速超过3500英里攻击。二战结束后，美国和苏联建立了自己的导弹计划。
On Oct. 4, 1957, the Soviets launched the first artificial satellite, Sputnik 1, into space. Four years later on April 12, 1961, Russian Lt. Yuri Gagarin became the first human to orbit Earth in Vostok 1. His flight lasted 108 minutes, and Gagarin reached an altitude of 327 kilometers (about 202 miles).
The first U.S. satellite, Explorer 1, went into orbit on Jan. 31, 1958. In 1961, Alan Shepard became the first American to fly into space. On Feb. 20, 1962, John Glenn’s historic flight made him the first American to orbit Earth.
Landing On The Moon
“Landing a man on the moon and returning him safely to Earth within a decade” was a national goal set by President John F. Kennedy in 1961. On July 20, 1969, astronaut Neil Armstrong took “one giant leap for mankind” as he stepped onto the moon. Six Apollo missions were made to explore the moon between 1969 and 1972.
During the 1960s, unmanned spacecraft photographed and probed the moon before astronauts ever landed. By the early 1970s, orbiting communications and navigation satellites were in everyday use, and the Mariner spacecraft was orbiting and mapping the surface of Mars. By the end of the decade, the Voyager spacecraft had sent back detailed images of Jupiter and Saturn, their rings, and their moons.
天空实验室，美国第一个空间站，是20世纪70年代的人类太空飞行的亮点，因为是阿波罗 - 联盟测试计划，世界上第一个国际载人（美国和俄罗斯）的太空任务。
In the 1980s, satellite communications expanded to carry television programs, and people were able to pick up the satellite signals on their home dish antennas. Satellites discovered an ozone hole over Antarctica, pinpointed forest fires, and gave us photographs of the nuclear power plant disaster at Chernobyl in 1986. Astronomical satellites found new stars and gave us a new view of the center of our galaxy.
航天飞机
1981年4月，哥伦比亚发射航天飞机在大多数民用和军用太空任务可重复使用的航天飞机一段依赖迎来。二十四成功的航天飞机发射完成许多科研和军事需求，直到一月28,1986，当升空后刚刚73秒，挑战者号航天飞机爆炸。七名船员被打死，其中包括克里斯塔·麦考利夫，来自新罕布什尔州的一名老师谁也一直在太空中第一位平民。
哥伦比亚灾难是第二次航天飞机的悲剧。2003年2月1日，航天飞机解体而重新进入地球大气层，造成所有七名机组人员。这场灾难发生在得克萨斯州，并在肯尼迪航天中心计划于土地前几分钟。调查确定的灾难是由一块泡沫绝缘材料是断绝了航天飞机的推进剂贮箱，损坏了航天飞机的左翼的边缘造成的。这是一个航天飞机的113次航天飞机飞行的第二个损失。每个灾害后，航天飞机飞行作业暂停了两年多。
Discovery was the first of the three active space shuttles to be retired, completing its final mission on March 9, 2011; Endeavour did so on June 1. The final shuttle mission was completed with the landing of Atlantis on July 21, 2011, closing the 30-year space shuttle program.
海湾战争证明了卫星在现代冲突的价值。在这场战争中，联军能够利用自己的空间“高地”的控制，实现了决定性的优势。卫星被用来提供对敌军编队和动作，敌方导弹攻击预警，而在特征的沙漠地形精确导航信息。卫星的优点允许联军迅速地把战争的结束，挽救了许多生命。
Space systems continue to become more and more integral to homeland defense, weather surveillance, communication, navigation, imaging, and remote sensing for chemicals, fires, and other disasters.
国际空间站
国际空间站是在地球低轨道的一个研究实验室。与许多不同的合作伙伴促进其设计和施工，这个高空飞行实验室已成为太空探索合作的象征，与以前的竞争对手，现在一起工作。
The station has been continuously occupied since the arrival of Expedition 1 in November of 2000. The station is serviced by a variety of visiting spacecraft: the Russian Soyuz and Progress; the American Dragon and Cygnus; the Japanese H-II Transfer Vehicle; and formerly the Space Shuttle and the European Automated Transfer Vehicle. It has been visited by astronauts, cosmonauts, and space tourists from 17 different nations.
Space launch systems have been designed to reduce costs and improve dependability, safety, and reliability. Most U.S. military and scientific satellites are launched into orbit by a family of expendable launch vehicles designed for a variety of missions. Other nations have their own launch systems, and there is strong competition in the commercial launch market to develop the next generation of launch systems.
The Future Of Space Exploration
Modern space exploration is reaching areas once only dreamed about. Mars is focal point of modern space exploration, and manned Mars exploration is a long-term goal of the
United States. NASA is on a journey to Mars, with a goal of sending humans to the Red Planet in the 2030s.
美国国家航空航天局(NASA)及其合作伙伴已经向太空发射了人造卫星,兰德斯,and rovers, increasing our knowledge about the planet. The Curiosity Rover has gathered radiation data to protect astronauts, and the MARS 2020 Rover will study the availability of oxygen and other Martian resources.