La satellites' constant gaze on Earth It has become one of our best allies for understanding what we are doing to the planet and how we can protect it. From hundreds of kilometers above the ground, these space platforms observe forests, oceans, glaciers, cities, and the atmosphere, generating data that was previously simply impossible to obtain with such precision and frequency.
Far from being a distant technology or "only for astronauts", satellites are already influencing daily decisions about forest fires, water management, agriculture, air quality, or urban planningAnd all of this fits into a context marked by climate change, the need for sustainable recovery after disasters, and the search for an economic model that combines innovation, sustainability, and social well-being.
What is satellite remote sensing and why does it matter so much to the environment?
When we talk about remote sensing, we are referring to the A set of techniques that allow obtaining and analyzing information about the Earth's surface and atmosphere without needing to be physically present, using sensors installed on satellites. These sensors capture energy in different regions of the electromagnetic spectrum (visible, infrared, microwave, thermal infrared, etc.) and transform it into images or data products.
Thanks to these systems, they can be studied systematically. processes that affect the planet's surface, continental water masses, oceans, vegetation, glaciers, and the atmosphereand even infer information about the Earth's interior. All of this is fundamental to understanding the magnitude and evolution of environmental degradation, pollution, and the effects of climate change.
The great advantage over classic field methods is twofold: on the one hand, satellites offer global, repetitive and homogeneous coveragereaching remote or very difficult-to-access places such as the Arctic, large deserts or jungle areas; on the other hand, they allow the construction of long historical series (from the 70s in many cases) to analyze trends on a decade-scale scale.
Furthermore, in recent years remote sensing has become increasingly integrated with the Geographic Information Systems (GIS) and geolocation technologiesThis facilitates the integration of satellite imagery with digital mapping, socioeconomic data, and information from ground-based sensors. This combination significantly enhances the value of the data for environmental management and land-use planning.
Another key transformation comes from the development of Big Data and Artificial IntelligenceThe volume of information generated by current satellites is gigantic, and advanced data analysis techniques allow for extracting much deeper knowledge: automating land use classifications, detecting patterns in the evolution of forests or crops, identifying pollution hotspots, or feeding increasingly accurate climate models.
Types of satellites and major missions dedicated to the planet
Currently, more than two thousand operational artificial satellitesThey are dedicated to very different tasks: communications (telephony, television, data transmission), navigation and positioning, deep space exploration, and, of course, Earth observation. Most are in low Earth orbit (LEO), between about 200 and 1.200 km in altitude, and the rest are in geostationary orbit, at about 35.000 km, "anchored" over a fixed point on the planet.
Among Earth observation satellites we find platforms equipped with optical, infrared, thermal and synthetic aperture radar (SAR) sensorsEach type of sensor contributes a different piece to the environmental puzzle: visible sensors generate images similar to photographs; infrared sensors reveal the vigor of vegetation or the temperature; radar, on the other hand, can "see" through clouds and work both day and night, which is critical in emergency situations.
Among the major international monitoring programs, two initiatives stand out in particular, making a huge amount of data freely available to the general public:
- NASA's Earth Observing System (EOS)Conceived in the 80s and deployed from the 90s onwards, it comprises a network of satellites specialized in the continuous and detailed monitoring of the Earth's surface, the biosphere, the oceans and the atmosphere, providing long time series since the 70s.
- Copernicus ProgramLed by the European Commission and the European Space Agency (ESA), the program comprises more than 30 satellites, including the Sentinel family. Its objective is to provide accurate, up-to-date, and accessible information to improve environmental management, monitor the impact of climate change, and strengthen public safety against natural and man-made hazards.
The great strength of these programs is the global coverage and open data policyThis allows governments, businesses, universities, and even individual users to download images and analysis products free of charge. This has dramatically increased the number of practical applications, from forest monitoring to evidence-based urban planning.
Spain is also part of this ecosystem with the mission PEACEWithin the National Program for Earth Observation by Satellite (PNOTS), PAZ is a high-resolution SAR radar satellite whose ground segment belongs to the National Institute of Aerospace Technology (INTA). By emitting its own microwave signal, PAZ is able to obtain images. regardless of sunlight and cloud cover, which ideally complements optical and hyperspectral satellites.
PAZ's capabilities are especially useful for hydrology, agriculture, flood zone studies or land managementIts participation in satellite observation constellations strengthens Spain's capacity to contribute to global strategies against environmental degradation.
Satellites, forest fires and ecosystem management
One of the fields where space observation has proven to be of enormous value is in the prevention and management of forest firesThis is a particularly serious problem in Mediterranean regions like Spain. The forest ecosystems in these areas live under the constant threat of fire, exacerbated by heat waves, drought, and rural depopulation.
Research groups such as the Technologies and Methods for Sustainable Management (Tecnatura) group of the Polytechnic University of Madrid They have been working for years on the use of remote sensing to study land cover, with a special focus on forest areas, their composition, and their structure. Their studies have shown that information derived from satellite imagery is fundamental for the environmental management and fire defense planning.
By combining different sensors it is possible Identify the soil cover and distinguish between forests, scrublands, grasslands, or agricultural areasand even to distinguish specific types of vegetation, such as differentiating a riparian forest from a stand of conifers or deciduous species. These details are crucial for assessing the type of fuel available and its potential behavior in the event of a fire.
In parallel, other satellites provide key meteorological variables such as soil temperature, air temperature, or relative humidityThese parameters allow us to estimate the moisture content of the vegetation and, therefore, its flammability. This information is used to develop fire risk indices that help anticipate critical situations and plan preventative measures.
Within this line of work, one of the investigations developed at the UPM has consisted of creating methodologies for generating forest fuel maps using high-resolution images from the QuickBird satellite. This civilian satellite, with a pixel size of about 60 centimeters, allows mapping with a very fine level of detail the surroundings of particularly sensitive areas, such as urbanizations, urban-forest interfaces, or critical infrastructure.
Another related thesis has exploited airborne laser technologies (such as LiDAR) to obtain accurate information about tree heightFrom this data, it is possible to calculate biomass, wood volume, and other structural indicators of the forest, which are essential not only for assessing available fuel but also for sustainable forest management.
The result of these investigations is a set of valuable tools for forestry companies, forest administrations and natural park managersWith updated maps, detailed fuel models, and structural data on forests, it is much easier to design prevention plans, prioritize silvicultural treatments, and assess the impact of fires once they have occurred.
Beyond fire, remote sensing also contributes to the Periodic updating of forest inventories, monitoring of deforestation and degradation, and analysis of vegetation healthThis allows, for example, monitoring deforestation in remote areas such as the Amazon, differentiating between legal and illegal uses, or detecting pests and diseases early.
Climate change monitoring and model validation
In a warming world, researchers around the globe are analyzing dozens of essential variables of the climate system to understand how it changes and where we are headed. These variables include atmospheric, oceanic, cryospheric, and land surface parameters which, observed together, offer a complete picture of the global climate.
Earth observation satellites are essential because They provide continuous and consistent data on a global scaleThis is something that surface station networks, inevitably scarcer and unevenly distributed, cannot offer. They have made it possible to document, for example, the extent and thickness of polar ice, the retreat of mountain glaciers, variations in sea level, and the evolution of large forest areas.
This information is useful for validate and adjust climate modelsThis improves the ability to predict future climate evolution. Systematic comparison between simulations and actual satellite observations allows for the detection of deviations, refinement of model parameters, and a better understanding of the interactions between different components of the climate system.
Furthermore, space observation helps to to measure the direct impact of human activity about the planet. Thanks to satellites, processes such as deforestation, the decrease in ice masses, and the marine pollution from oil spills, the expansion of urban areas or the degradation of soils due to overexploitation.
Technology centers like Eurecat work precisely on the Advanced exploitation of this satellite data through Big Data and Artificial IntelligenceThe aim is to extract more useful knowledge for planning sustainable development in urban, agricultural, and industrial sectors. These capabilities are showcased in international forums such as Climate Summits, where innovative projects focused on reducing emissions, improving energy efficiency, and promoting the circular economy are presented.
Greenhouse gas measurement and air quality
Another major contribution of space technology to environmental protection is the Measurement from space of greenhouse gases and atmospheric pollutantsSpecific satellites can estimate the concentrations of carbon dioxide (COâ‚‚), methane (CHâ‚„) and other gases key to global warming.
By mapping the spatial distribution of these gases, it is possible locate and characterize emission sources This information is valuable for verifying international commitments to reduce emissions and adjusting climate policies on a sound scientific basis. It includes both natural factors (wetlands, volcanoes, fires) and anthropogenic factors (power plants, large industrial areas, cities, hydrocarbon extraction).
Satellites also allow monitoring of urban and regional air qualityIdentifying compounds such as nitrogen dioxide, tropospheric ozone, and particulate matter. Systematically detecting areas with critical levels of pollution helps authorities design air quality improvement plans, traffic restrictions, or changes in urban planning to protect public health.
In this context, satellite data has an additional function: to offer transparency and verifiability in the face of potential cases of greenwashing. As global and independent observations, they allow for a comparison of government and corporate statements with what actually happens on the ground.
Oceans, glaciers and sea level under continuous monitoring
The oceans and ice-covered regions are key components of the climate system, and their evolution is closely monitored from Earth orbit. Satellites help to measure this. sea ​​surface temperature, ocean currents, wave height, salinity, and sea ice concentrationamong other parameters.
In parallel, the extent and thickness of glaciers and polar ice capsThis data is vital to understanding the accelerated melting in areas such as Greenland or Antarctica and to estimating its contribution to the rise in average sea level, which puts millions of people living in low-lying coastal areas at risk.
The combination of optical, thermal, and radar sensors also allows for evaluation coastal erosion, the dynamics of deltas and estuaries, and sedimentation in reservoirsThis information is used to plan coastal defenses, design more resilient infrastructure, or adapt land use in particularly exposed areas.
Water management and precision agriculture from space
In a scenario of recurring droughts and increasing competition for water, satellite observation has become a key tool for sustainable management of water resourcesSpecific sensors allow measuring soil moisture, detecting droughts, estimating water availability in basins and aquifers, and monitoring the quality of surface water bodies.
This data helps administrations and managers to design policies for saving, efficient distribution and prioritization of usesespecially in regions vulnerable to water stress. For example, agricultural areas with inefficient irrigation, urban areas with leaks, or basins with overexploited aquifers can be identified.
In the agricultural sector, the so-called precision farming It uses observation from space to optimize the use of water, fertilizers, and pesticides. Image-derived indicators (such as vegetation indices) allow for understanding the state of crops, detecting water or nutrient stress, and adjusting management plot by plot, in addition to strengthening the food safety.
Applying this information in near real-time translates into higher crop yields, lower input consumption, and a reduced environmental footprint in the agri-food sector. Technologies such as those developed by crop monitoring platforms also support the restoration of degraded soils and the monitoring of agricultural practices aimed at carbon sequestration.
This context also includes the so-called Space EconomyA new economic dimension that combines space innovation with practical solutions to environmental and social challenges. Satellite data-based services support agricultural insurance, early warning systems, sustainability certifications, and ecological restoration projects.
Satellites against natural disasters: advantages, limitations and new techniques
When a natural disaster occurs—flood, hurricane, massive fire, volcanic eruption—satellite monitoring offers two fundamental advantages from a scientific and operational perspective. These phenomena are part of the debate on natural disasters and sustainable developmentAnd satellite information is key to planning effective responses.
The second major advantage is the ability to assess damage in large and hard-to-reach areasBy comparing images taken before and after the event, it is possible to delimit the affected areas, quantify the flooded or burned surface, detect damaged infrastructure, or identify slope movements and landslides.
In the case of floods, for example, SAR radar satellites are especially useful because They can capture images even with dense cloud cover and rainThese are typical conditions for this type of phenomenon. The combined analysis of optical and radar images, along with spectral data, allows for improved detection of structural damage or subtle changes in the terrain that might otherwise go unnoticed.
For disasters that originate in the ocean, such as hurricanes or typhoons, remote sensing is practically the only way to maintain a continuous and global surveillanceSatellites provide information on the formation, trajectory, and intensity of these systems days in advance, allowing time to issue warnings, prepare evacuations, and protect critical infrastructure.
In contrast, earthquake prediction remains a much more complex challenge. Although ground-based instrumentation is still the primary tool for monitoring seismic activity, research is underway to explore the possible detection of pre-seismic signals using satellite thermal imagesThese are linked to the release of hot gases or steam through fissures in the Earth's crust. For now, however, these approaches are in exploratory phases and do not replace traditional seismic methods.
In any case, the use of satellite data in disasters faces several challenges. One of them is the quality and availability of imagesThere are commercial satellites capable of offering resolutions of up to 30 centimeters per pixel, but their cost is high, which limits regular access for many countries and organizations with tight budgets.
Advanced image access platforms, which integrate data from multiple missions, demonstrate how the price of high resolution can reach tens of dollars per square kilometer. Therefore, compromise solutions are often necessary: ​​free images with lower resolution, lower temporal frequency, or specialized sensors that don't always cover all the desired parameters.
Even with these limitations, satellite monitoring is usually effective more cost-effective than continuously deploying large teams of specialists in the fieldIn fact, the trend is to combine both approaches: using spatial data to prioritize where to send brigades, drones, or technicians, and then integrating field information to validate and refine the remote analysis.
Advanced processing, machine learning, and data challenges
The increasing availability of images and time series has boosted the use of machine learning and neural networks to massively process satellite data. Many routine tasks, such as delimiting agricultural plots, identifying crop types, or automatically detecting changes in soil cover, are already being automated.
To do this, it is crucial to have sufficiently large and high-quality training datasetsIn meteorology, for example, parameters such as cloud cover and surface temperature have been recorded since the 80s, feeding into increasingly sophisticated forecasting models. Since the 2000s, missions like NASA's Aqua and Terra have added more detailed information on vegetation indices and changes in forest cover or desertification.
However, when we talk about satellite data related to disastersThe situation is further complicated: extreme events do not occur with the same frequency or in the same locations, and conditions vary considerably from one event to another. This results in scarcer, fragmented, and more difficult-to-normalize datasets, limiting the effectiveness of automated models in predicting or assessing damage with high accuracy.
One of the great challenges for the coming decades will be precisely normalize and enrich these emergency datasetsThis integrates satellite information, field measurements, and socioeconomic data. This will allow for the training of models capable of providing earlier warnings, more refined impact analyses, and better-informed recommendations for action.
Satellites and sustainable ecosystem recovery
The idea of sustainable recovery It goes beyond rebuilding infrastructure after a catastrophe. It's about restoring natural ecosystems to a functional state that guarantees biodiversity and resilience, while integrating the social and economic dimensions in a balanced way.
Remote sensing provides a very specific value here: Their historical archives allow us to know what a territory was like before degradation or disaster.By comparing old and current images, it is possible to estimate the original extent of a forest, the state of a wetland, or the quality of agricultural soil, and to set realistic, evidence-based restoration goals.
During the recovery process, satellites allow to track over time the evolution of vegetation, soil moisture, the appearance of new structures, or the recolonization of speciesOnly when ecological indicators return to their previous state, and ecosystem functionality is restored, can we speak of a successful sustainable recovery.
The European Union is taking steps in this direction with legislative initiatives such as the Nature Restoration Lawwhose objective is to restore 100% of the degraded ecosystems in participating countries by 2050. Within this framework, the systematic use of satellite imagery facilitates both the initial diagnosis and the monitoring of the established objectives.
Technological solutions geared towards agriculture and forestry, such as crop monitoring platforms or forest monitoring services, support soil restoration, fertility control, reforestation, and fire damage assessment. These tools are already being actively used by public and private organizations, but their impact will depend on... governments integrate them into large-scale strategies.
Experience also shows that every catastrophe can become a turning point to rethink the relationship with the environmentCountries like the Netherlands, Iceland, and Australia have developed advanced water management programs, implemented volcanic soils to improve fertility, and carried out massive reforestation with biodiversity criteria in response to major disasters. Satellites help to assess and document these long-term processes of change.
Ultimately, space-based monitoring already offers a multitude of concrete tools for caring for nature, but its real effectiveness depends on the coordination between scientists, policymakers, businesses, local communities and volunteersTechnology alone will not transform the model; it is the way we decide to use it that will determine the degree of protection we provide to the Earth.
Earth observation via satellites has become an essential pillar for understanding how ecosystems change, measuring the impact of our activities, and designing smarter responses to climate change, disasters, and environmental degradation. Integrating this data with Big Data, Artificial Intelligence, ambitious legislation, and social participation opens the door to more responsible management of forests, water, the atmosphere, and cities, and to a sustainable recovery that not only repairs specific damage but also lays the foundations for a more balanced coexistence between society and the planet that sustains it.
