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美国航宇局的陆地卫星,是观测地面的“空中眼睛”,它源源不断地向人们报告着地球表面的变化,在迄今发射的所有卫星中,它是有益于人类的、具有最大潜力的一种卫星。陆地卫星在技术上虽然仍是一个实验系统,但它已经得到了广泛的应用,从而节省了许多时间和财力。陆地卫星的未来目标,将是一个完全工作型的世界性系统。预计它将产生巨大的经济利益,可能每年要获得数十亿美元的收入。但比这更重要的是,陆地卫星通过提供大量的资料,有能力帮助解决人类最紧迫的问题,对有限的地球资源进行更加有效的管理。陆地卫星的照片,可以显现出一种植物与另一种植物的不同;人口稠密的城市与人口稀少的农村的不同;清洁的水源与污染的水源的不同。比如,不同的农作物在图象上会显
NASA’s terrestrial satellite, the “sky eye” that observes the ground, continually reports changes in the surface of the Earth to humans, the most promising of all the satellites launched so far Kind of satellite Terrestrial satellite technology is still an experimental system, but it has been widely used, thus saving a lot of time and money. The future goal of Landsat will be a fully working, cosmopolitan system. It is expected to generate enormous economic benefits, possibly billions of dollars a year. But more important than this, terrestrial satellites can manage limited resources on Earth more efficiently by providing vast amounts of information, capable of helping to solve the most pressing human problems. Photos of terrestrial satellites can show the difference between a plant and another plant; the difference between a densely populated city and a sparsely populated rural area; and a difference between a clean water source and a polluted water source. For example, different crops will be visible in the image