Sensors used for Earth observation encompass a variety of technologies suitable for capturing different aspects of the Earth’s surface, atmosphere and oceans. Optical sensors, such as multispectral and hyperspectral imagers, use visible and infrared wavelengths to capture detailed images of land cover, vegetation health, and urban development. Radar sensors, including synthetic aperture radar (SAR), penetrate clouds and darkness to map terrain elevation, monitor ice movement, and detect changes in forest structure.
Thermal infrared sensors measure surface temperatures and detect thermal anomalies related to volcanic activity, wildfires and urban heat islands.
Microwave sensors observe ocean salinity, sea surface winds and soil moisture levels, providing essential data for climate and environmental studies.
The different types of Earth observation sensors can be classified into several main categories: optical sensors, which capture images of the Earth’s surface using visible and infrared wavelengths; Radar sensors, which use microwave pulses to measure surface properties and penetrate clouds and vegetation; thermal sensors, which detect heat signatures to monitor temperature variations on the Earth’s surface; and multispectral and hyperspectral sensors, which capture data across multiple narrow, contiguous bands of the electromagnetic spectrum to provide detailed information on vegetation health, land cover, and environmental changes.
Satellites dedicated to Earth observation vary depending on the specific application and mission objectives.
The European Space Agency’s sentinel satellites, part of the Copernicus programme, provide comprehensive environmental monitoring data, including land, ocean and atmospheric parameters. NASA’s Landsat program has been instrumental in long-term global imaging, capturing high-resolution images for land cover mapping, agricultural monitoring, and urban development studies.
Commercial satellite constellations, such as those operated by Planet Labs and DigitalGlobe, offer diverse imaging capabilities for applications ranging from disaster response to urban planning and agricultural management.
Techniques used in Earth observation include remote sensing, which involves capturing and analyzing data remotely using satellite, airborne, or ground-based sensors. Remote sensing techniques use various wavelengths of the electromagnetic spectrum to collect information about the Earth’s surface and atmosphere.
Data processing techniques such as image classification, spectral analysis, and data fusion are used to extract meaningful information from raw sensor data. Geographic information system (GIS) technology integrates and analyzes spatial data, facilitating the visualization, interpretation and modeling of Earth observation data for environmental monitoring, resource management and decision-making .
Earth sensors refer to instruments and systems used to monitor and measure environmental parameters that directly impact Earth’s natural systems, climate and human activities.
These sensors include weather sensors to measure weather parameters such as temperature, humidity, wind speed and precipitation; air quality sensors to monitor pollutants like particulate matter, ozone and nitrogen dioxide; water quality sensors to assess parameters such as pH, dissolved oxygen and turbidity in aquatic systems; and soil sensors to measure moisture content, nutrient levels and soil health indicators.
Earth sensors play a vital role in environmental monitoring programs, providing essential data to assess environmental quality, detect changes, and support sustainable resource management practices across various sectors