Today, there are more than 1,000 Earth Observation Satellites (EOS) orbiting our planet. These satellites act as the "eyes" in space, constantly monitoring and tracking changes on Earth in ways that were previously unimaginable.
From monitoring weather and natural disasters to planning the sustainable management of natural resources, these satellites have become essential tools for gaining deep and comprehensive insights about our planet. In a world where data plays a critical role in development, the application of satellite-derived information not only supports large-scale decision-making but also paves the way for a more sustainable future.
With cutting-edge technology, the growing number of satellites, and their ability to continuously collect data over vast areas, EOS is no longer just a scientific achievement. It has become a vital instrument for global development and sustainability. Let’s explore how Earth Observation Satellites are transforming our world for the better!
Monitoring the Earth Through Satellites
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NASA's fleet of Earth Observation Satellites has been orbiting the planet since before the year 2000. Each satellite is designed for specific missions, such as monitoring climate change, assessing natural resource usage, and preserving biodiversity.
Source: https://science.nasa.gov/earth-science/missions/
What is Earth Observation Satellite Technology?
Earth Observation Satellite (EOS) technology involves satellites equipped with specialized sensors to collect data from the Earth's surface. These satellites operate through remote sensing, allowing us to observe the planet from a distance and analyze information beyond human perception.
EOS can be categorized into two main types based on the energy source used for data collection. Instruments that rely on natural energy from the sun are called “Passive Instruments”, while those that generate their own energy are known as “Active Instruments.”
Source: https://www.earthdata.nasa.gov/learn/backgrounders/remote-sensing
Passive Instruments
Passive Instrumentsrely on sunlight reflected from the Earth's surface to collect data. These instruments include Radiometers, which measure the intensity of electromagnetic radiation in specific frequency bands, and Spectrometers, which detect, measure, and analyze the spectrum of reflected electromagnetic radiation. Passive instruments typically operate in the visible, infrared, thermal infrared, and microwave portions of the electromagnetic spectrum. However, since they depend on sunlight for imaging, they have limitations in cloudy conditions and cannot collect data at night.
An example is Sentinel-2, which is equipped with the Multispectral Instrument (MSI), a passive instrument that measures sunlight reflected from the Earth's surface. The primary mission of Sentinel-2 is to support agriculture, forestry management, and food security initiatives. However, its data is widely applied in various areas, such as monitoring surface changes, assessing water quality, managing natural disasters, and mapping risk zones. Furthermore, Sentinel-2 plays a crucial role in monitoring natural ecosystems with its ability to differentiate vegetation types and measure biophysical variables like leaf chlorophyll content and leaf water content.
Sentinel-2C monitored wildfires in California, capturing true-color imagery on the left, which reveals smoke from the fires. Meanwhile, the false-color image on the right highlights the large areas affected by the fire, including active fire, which appear as bright orange spots.
Source: https://sentinels.copernicus.eu/web/success-stories/-/copernicus-sentinels-observe-earth-s-extreme-weather-events
Active Instruments
Active Instruments work by transmitting energy from the instrument to the Earth's surface and collecting data based on the backscattered signals. These majority of active sensors operate in the microwave band of the electromagnetic spectrum, allowing them to penetrate the atmosphere, collect data in all weather conditions, and function at night since they do not rely on sunlight as an energy source.
An example, Sentinel-1 is equipped with Synthetic Aperture Radar (SAR), an Active Sensor capable of capturing Earth's surface data in all weather conditions, both day and night. Sentinel-1's primary mission is to provide data services that support environmental management and security. Its applications are diverse, including monitoring topography, imaging for maritime applications, tracking sea ice coverage, measuring soil moisture, and assessing vegetation.
Sentinel-1 captured clear before-and-after images (March 7 compared to March 19, 2021) showcasing the extent of flooding in Kempsey, Australia.
The electromagnetic spectrum consists of energy waves that travel through space and the atmosphere, varying in wavelength and frequency. Some waves are absorbed or reflected by the atmosphere, while others, like visible light, pass through freely.
Every object on Earth has a unique "spectral fingerprint," defined by how it reflects or absorbs electromagnetic energy at various wavelengths. This fingerprint allows us to identify Earth's features and analyze their physical and chemical properties.
Source: https://www.earthdata.nasa.gov/learn/backgrounders/remote-sensing
Challenges of Using Earth Observation Satellites
Despite the high potential of EOS, several challenges remain. However, the technology offers significant advantages, including diverse sensors capable of collecting a wide range of data, continuous data acquisition, and decades of historical records that enable long-term trend analysis. Additionally, EOS provides extensive coverage and access to remote or hard-to-reach areas without physical constraints.
(Left) The first image of Earth captured from space in 1946 by a suborbital rocket over the New Mexico desert. (Right) A 1972 image taken by Landsat 1, the first Earth Observation Satellite dedicated to forestry and agricultural studies, over the state of Texas.
However, this technology does have certain limitations. Some sensors may be influenced by weather conditions, while constraints in temporal resolution (data collection frequency) and pixel resolution may not always meet the requirements for specific analyses. Moreover, transforming satellite data into valuable information often demands specialized expertise, and the costs associated with satellite launches and accessing certain data types remain high.
In the future, EOS technology is expected to evolve towards reducing costs and improving efficiency. This includes the use of small satellites (CubeSats) working together in satellite constellations, as well as the integration of Artificial Intelligence (AI) and Machine Learning (ML) to enable faster and more accurate data analysis.
Applications of Earth Observation Satellites
EOS technology is not just a tool for data collection; it also unlocks opportunities for diverse applications. When combined with AI and ML, it enhances the efficiency and accuracy of satellite data analysis, paving the way for innovative solutions in various fields.
- Agriculture Satellites assist farmers in monitoring crop health and predicting yields.
- Climate and Weather Satellites track indicators of climate change, such as rising sea levels and melting polar ice caps. They also forecast weather patterns and monitor extreme events like hurricanes and droughts.
- Marine and Coastal Studies Satellites observe ocean currents, wave heights, and sea surface temperatures, while monitoring coral reef health and coastal erosion.
- Disaster Management Satellites play a crucial role in tracking flood situations and assessing drought-prone areas, enabling quick and effective disaster response.
- Forestry Resource Management Satellite imagery helps detect forest loss, analyze land-use changes, and assess canopy density. It is also used to monitor areas damaged by wildfires, supporting sustainable restoration efforts.
Example of Burned Scar Detection
Example of Flood Area Detection
The Importance of Using Earth Observation Satellites in Global Resource Management
EOS technology serves as "eyes in space," enabling humanity to see what cannot be observed from the ground. With its ability to collect comprehensive and continuous data, combined with the power of AI and ML, this technology has become an essential tool for solving problems and supporting decision-making across various sectors. It promotes sustainable resource management while mitigating the impacts of environmental changes. In the future, EOS technology will play an even greater role as advancements in science and technology continue to enhance its capabilities.
References
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- eoPortal. Copernicus: Sentinel-2 - eoPortal. Retrieved from https://www.eoportal.org/satellite-missions/copernicus-sentinel-2#eop-quick-facts-section
- Geospatial World. How Many Satellites are Orbiting Around Earth in 2022?. Retrieved from https://geospatialworld.net/prime/how-many-satellites-orbiting-earth/
- NASA. Earth Science Missions. Recovered from https://science.nasa.gov/earth-science/missions/
- NASA. 20 Years Ago: First Image of Earth from Mars and Other Postcards of Home. Recovered from https://www.nasa.gov/history/20-years-ago-first-image-of-earth-from-mars-and-other-postcards-of-home/
- NASA Earthdata. Aktiv instrumenter. Recovered from https://earthdata.nasa.gov/learn/earth-observation-data-basics/remote-sensing/active-instruments
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- NASA Earthdata. Remote Sensing. Recovered from https://www.earthdata.nasa.gov/learn/earth-observation-data-basics/remote-sensing
- PMC. Fifty Years of Earth Observation Satellites. Recovered from https://pmc.ncbi.nlm.nih.gov/articles/PMC2690060/#:~=Although the first images of, radio signals that could be
- Sentinel Online. Copernicus Sentinels Observe Earth's Extreme Weather Events - Sentinel Success Stories. Recovered from https://sentinels.copernicus.eu/web/success-stories/-/copernicus-sentinels-observe-earth-s-extreme-weather-events
- Sentinel Online. Copernicus Sentinel-1 Facilitates Australia's Flood Extent Delineation - Sentinel Success Stories. Recovered from https://sentinels.copernicus.eu/web/success-stories/-/copernicus-sentinel-1-facilitates-australia-s-flood-extent-delineation
- U.S. Geological Survey. Landsat 1. Recovered from https://www.usgs.gov/landsat-missions/landsat-1
