在21 世纪到来之际,人类向“数字地球”这一地球信息科学新领域发起了挑战。这是在信息社会、知识经济、可持续发展时代背景下,由空间科学、信息科学、地球科学和环境科学的相互交融,在全球及区域尺度上的一次大整合、大聚焦。是面向21 世纪地球系统科学思维模式的开拓性大跳跃。对地观测技术系统的蓬勃发展,是 “数字地球”的不可缺少的基础。数字地球的发展,离不开对地观测技术系统的支撑。

Digital Earth is a global strategic idea. It is centered on the use of digital data acquisition, storage, transmission and processing technology to control and operate the global affairs. Digital Earth is an information Earth for processing the natural and social economic issues by means of digital technology; it is a virtual Earth capable of mosaicing voluminous data, displaying multiple resolution and 3-D data. Earth Observation is a basis for constructing the Digital Earth. The information on Earth observation is one of the core information sources. “Digital Earth” has involved many new theories and techniques: acquiring raw digital data for the Earth, data standard, interactive operating techniques, voluminous data storage and compression, distributive object technique, spatial data warehouse, virtual phenomena, knowledge & distributed intelligence, graphic search engine, WebGIS and various kinds of application models. Only earth observation technology from the space can provide global, repeated and continuous data covering the earth surface. China has launched a series of returnable satellites and 3 meteorological satellites. On October 14, 1999, Resources-1 satellite was successfully launched. This is an Earth Resources Satellite called CBERS, developed jointly by China and Brazil. Recently, China has paid special attentions to Ocean-color small satellite. A proposal for 3-dimensional mapping of an Earth observing small satellite has been approved. In the last 10 years, we have developed several sets of airborne remote sensing systems, which include high altitude airborne remote sensing operational system and disaster monitoring system. The Remote Sensing Satellite Ground Receiving Station of China was built in 1986. At present, the station can receive 7 kinds of data. The essential task for the strategy of “Digital Earth” is to provide true and reliable data completely and promptly. It is not easy to implement this task. Therefore, the governments, enterprise and companies of all countries are needed to devote their efforts to support the construction of “Digital Earth”, to enable data sharing, and to make convenience for using computer network and exploring the information resources. At present, the demands of category index system and spatial resolution for a study on a global scale is roughly equivalent to the categories at a scale of 1∶200000 to 1∶500000. These data meet the demands of most academic activities such as CEOS, IGBP and Global Mapping programs since the Second World War.