Earth-observation satellites are used for a variety of purposes, including land and forest monitoring, mapping of water and mineral resources, weather and climate observations, and soil assessment. These satellites play a crucial role in collecting valuable data and imagery that helps scientists, researchers, and policymakers make informed decisions about the Earth's environment and resources.

1. Land and forest monitoring:
Earth-observation satellites provide valuable information about land use and land cover changes. They can monitor deforestation, urban expansion, and changes in agricultural practices. By analyzing satellite imagery, scientists can assess the health and extent of forests, monitor wildlife habitats, and detect illegal activities such as logging or land encroachment.

2. Mapping of water and mineral resources:
Satellites equipped with remote sensing instruments can detect and map water bodies, including rivers, lakes, and reservoirs. This information is crucial for managing water resources, assessing water availability, and monitoring changes in water bodies over time. Earth-observation satellites also help in identifying and mapping mineral deposits, which is essential for resource exploration and management.

3. Weather and climate observations:
One of the primary applications of Earth-observation satellites is weather and climate monitoring. These satellites provide real-time data on atmospheric conditions, cloud cover, sea surface temperatures, and other meteorological parameters. This information is used for weather forecasting, tracking severe weather events like hurricanes and typhoons, and studying long-term climate patterns such as El Niño and La Niña.

4. Soil assessment:
Satellites can also help in assessing soil conditions, including soil moisture, composition, and erosion. By analyzing satellite data, scientists can identify areas at risk of soil degradation, monitor agricultural practices, and improve land management strategies. This information is crucial for sustainable land use planning, crop yield estimation, and soil conservation efforts.

In conclusion, Earth-observation satellites are used for a wide range of purposes, including land and forest monitoring, mapping of water and mineral resources, weather and climate observations, and soil assessment. These satellites provide valuable data and imagery that contribute to our understanding of the Earth's environment and resources, and help in making informed decisions for sustainable development.