1) Diversification of Earth Environment Problems
Most analyses on Earth's environmental problems have focused on forecasting, evaluating and preventing of impacts of the global warming due to greenhouse gas effect. Greenhouse gas from a single country spreads in a short instance and accelerates global climate changes. Greenhouse gas emissions can be clearly recognized as a global problem. However, global environment problems also have natural resource problem aspects, such as food supply.

A global food crisis may not occur suddenly. Instead, sneaking shortage and resulting price rise of major crops may apply pressures to relatively vulnerable areas, which may slowly lead to instability in global food trade systems worldwide. For instance, the current civil wars in Africa are fundamentally related to long-term poverty due to land resource degradation and water resource deficiencies. Moreover, devastation from the wars causes additional problems such as large numbers of refugees. These land and water resource problem may lead to instability of the world political system and , therefore, cause difficulties to individual countries worldwide.

To alleviate and eventually solve these problems, it is necessary to continuously obtain local information on land, water, and vegetation resources at global scale. Ecosystem preservation and genetic resource protection are also influential subjects, which also require a steady flow of local data acquired globally. So far, it is widely believed that low-resolution data is enough for global problems. In fact, high-resolution data, which is useful for local area, should be acquired globally to cope with the problem. Moreover, this is now becoming technically possible.

2) Think Globally and Act Locally------Establishing Global Environment Measures Corresponding to Local Needs.
As shown by the Kyoto protocol of COP3, the focus of global environment problems has shifted from examining the influence and clarifying the mechanism to drafting countermeasures, forming mutual agreement and developing implementation strategies. In the area of greenhouse gas, effective countermeasures for controlling greenhouse gas generation include forest preservation, carbon storage and fixation, carbon emission taxes, emission trade, and energy saving technology development. Policies such as forest preservation and reforestation are expected to be directly linked to regional interests and should therefore be coordinated with regional needs, because a global policy that brings disadvantages to local people is not sustainable.

Consequently, it is necessary to obtain local data to conduct policy globally. In particular, policy issues such as preservation of land and water resources, stabilization of food production by sustainable use of land and water resources, disaster risk mitigation, and various species' preservation by ecosystem conservation should be addressed on a regional basis. Therefore regional data that covers the globe and reflects local needs is necessary to develop realizable policies balancing global viewpoints and regional needs.

3) Popularization of GIS (Geographic Information System)
Today utilizations of the Geographic information System are in the process of getting into full swing in the field of regional planning and development as well as many other fields such as facility management. Regional planning and development need a comprehensive appraisal of environmental resources with various information‚“ and corroboration of planning alternatives by simulations. GIS is now an essential tool enabling to integrate information on environment, resources and human activities through digital base maps. However, in developing areas which need careful examination in the process of regional planning and development, even very basic data such as topography and vegetation do not exist at all, or even if they existed, they seldom become available due to several reasons such as national security reasons. On the other hand, since commercial GIS software has been widely used in recent years, if current data become ready for use, the data provision would have very great impacts. Especially, such information as topography that can be used in many application fields (so-called spatial data infrastructure (SDI)) is expected for distribution.

Popularization of GIS also means that ordinary users can have powerful data processing capability. If it becomes easy to obtain data together with necessary software and input parameters as well through the network, not a small part of the data processing can be conducted by users, which will greatly contribute to reducing processing load of the primary data distributors. High level processing software can be distributed over the net as well, to promote efficient and effective use of the data.

4) ALOS Mission Concept
To help resolve local issues such as food security, water resource scarcity, disaster prevention and biological diversity conservation that also require support and collaboration from the global viewpoint, what kinds of data should be developed.

Information on current status and changes of environmental resources such as soil, water, and vegetation (from forest to farmland) are the basis in analyzing these issues. Though quality of soil may not be easy to acquire by remote sensing, risk of soil degradation caused by erosion is governed by climatic and topographical factors. Regarding water circulation and vegetation, climatic and topographical factors are dominant as well. It is also the case with disaster risks. Of course, information on how people use land (land use Information) is indispensable. Although the climate data may be excluded just because it cannot be directly observed from satellite, it could be concluded that topographic information would be the core part of the common information basis.

Figure 1 illustrates the percentage cover of topographic maps by major regions. It can be found that the percentage cover of 1:1000 to 1:31,600 topographic maps is very low in developing areas such as Africa and Asia. As a matter of fact, topographic maps of this range of scales, mainly 1:25,000 maps are essential for environment conservation planning, resource management and development planning from regional to national scales. They also play central roles in formulating ODA for developing countries. So far, only "temporal" solutions have been explored to meet the information demand. Individual projects might generate a very minimum amount of data for their own purposes or could not help using out-of-dated paper maps might be used. In some cases, satellite imagery might be used as an insufficient substitute. On the other hands, topographic information equivalent to 1:25000 maps can be acquired by satellite observation very efficiently over the continents.

With these backgrounds, mission concept of ALOS (Advanced Land Observation Satellite) was defined as below.

Figure‚P.‚she cover of topographic maps by major regions
(Source:United Nations,"World Cartography vol. XX" 1990)

(1) Generate topographic data as SDI (Spatial Data Infrastructure) at the global scale.
DEM (Digital Elevation Model) data with less than 5-meter errors and with 10 meter grid spacing will be developed. Satellite imagery has advantages in generating DEM of this level, because the measurement techniques are relatively established and elevation data are not likely to change so frequently. By overlaying high-resolution optical sensor data and SAR data on the derived DEM, information on environmental resources like vegetation and soil can be provided. For the areas where the DEM was already developed, we can focus on changes of land surfaces. Combination of DEM and satellite imagery will contribute to the development of global spatial data infrastructure.

(2) Support "sustainable" development at local to regional scale through monitoring global environmental resources.
In addition to the global spatial data Infrastructure, a variety of information on environmental resources provided through ALOS mission can help conservation of environmental resources and sustainable development at the local to regional scale.

(3) Monitor major disasters at the global scale.
Disaster such as drought, volcanic explosion and flooding can threaten sustainable and stable regional development. Being integrated with the other satellites and monitoring systems, ALOS will provide information on major disasters.

(4) Exploration of non-renewable resources
In parallel with the monitoring of land and water related resources, ALOS mission will provide information for exploring non-renewable resources to support regional development.

(5) Technological development for the future earth observation
ALOS is almost a single satellite, which aim at global observation with high-resolution sensors. It poses many challenging research and development topics for sensor development and data processing, which will make significant contributions to the development of next generation earth observation technologies.