Artificial satellites, more than 50 years monitoring environmental health

The Giove A satellite (pictured), a link in the European Galileo satellite navigation system. EFE

Of the more than 2.000 artificial satellites that orbit the Earth, around a dozen have been monitoring the health of the planet for decades using images and accurate data on natural resources, in order to improve the management of energy, water or forests. , among others.

The study and monitoring of the earth's surface and oceans has only been possible thanks to the development of satellite technology that began in the 60-70s through long-term global observations, explains to EFE Francisco Carreño, professor of Hydrogeology at the Rey Juan Carlos University (Madrid).

The information collected is used to make decisions in the efficient management of resources and planning in various areas, including geology and mining, natural hazards, agriculture, forests and natural spaces, meteorology and climatology or land use planning, among others.

Among the programs that “take care of the Earth”, the professor highlights two: the Earth Observation System (EOS), from NASA, which includes missions of satellites and scientific instruments in Earth orbit to observe the Earth's surface, biosphere, hydrosphere, cryosphere and atmosphere, and the Copernicus program, led by the European Commission (EC) in collaboration with the European Space Agency (ESA).

Both - Carreño highlights - stand out, in addition to the global and precise coverage they offer, for the free service of their data.

Within the American program, the Landsat satellites - also operated by the United States Geological Survey - observe the earth's surface at 700 kilometers high and in high resolution; the first of them was launched in 1972 and the last in the series, Landsat-8, in 2013; The launch of Landsat-2021 is scheduled for September 9.

In Europe, the Sentinel mission has provided data since 2014 for applications on an ongoing basis such as gathering information about precision agriculture and water management, among others.

Carreño points out that one of the great specific advances of this high technology is the obtaining of information through multispectral remote sensing (the data are obtained within specific wavelength ranges through the electromagnetic spectrum).

For the researcher, this technique is a great qualitative leap because decades ago, the measurement of numerous variables, such as, for example, the temperature of the oceans consisted of placing thermometers on ships and recording the degrees of the marine waters during sailing days.

However, -continues Carreño- scientifically, these data did not allow to know the complexity and temporal evolution of this oceanic variable, because the measurements were made in a specific way, when the scientific expedition was carried out and data was only obtained during navigation.

Today, daily images are available from different satellites that monitor the circulation of the sea masses and the oscillation of the temperature of the seas on a global scale on a daily basis.

Regarding the use of satellite data in the supervision and management of large forest fires (GIF), Carreño observes that they are a very precise tool to monitor the affected areas and thus be alert to the risk of any of them occurring.

The expert highlights NASA's Fire Information System for Resource Management (FIRMS), which from its website offers data on active fires within 3 hours after satellite observation of the incident.

However, despite these technological advances, Carreño regrets "the non-existence" of a specific satellite mission that measures environmental variables related to the hydrological cycle such as humidity in the ground and the quality of water masses, especially in a scenario future with quality and quantity problems of water resources.

For the expert, soil moisture is a key variable in agricultural studies: on the one hand, it determines the availability of water for plants and the recharge of water in aquifers, but, at the same time, it is difficult to measure in the field, due to the high spatial and temporal variability that it entails.

At this point, it opts for PAZ, a Spanish radar technology satellite designed to meet security and defense needs, as well as other civilian ones, taking more than 100 daily images of up to one meter of resolution, both day and night, and regardless of the weather conditions.

Currently, the Rey Juan Carlos Research Group on Global Terrestrial Change and Environmental Geology, together with the Madrid Institute for Rural Research and Development (IMIDRA), are investigating the PAZ capacity to obtain a detailed mapping of the soil and the variation of humidity in agricultural areas.

This is a “great advance in this field”, concluded the professor. / EFE



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