What is Earth Observation? A Simple Guide to EO Technology and Applications

22nd Feb 2023
What is Earth Observation? A Simple Guide to EO Technology and Applications

When we think of launching a craft into space, we often think about looking towards the void and exploring the solar system (and beyond). In fact, satellites are more often a matter of monitoring our own planet in a way that provides the most useful information. The observation of the Earth and its environment has become big business, and a continual source of crucial data.

When Sputnik-1 became the first artificial satellite successfully launched into space, it would pave the way for Earth observation, and the multitude of technologies and industries that now rely on satellites to function. Over time, a system of stations that collected the satellite’s data would be built, and this experimental launch would pave the way for future missions, including NASA Earth observation missions.

So, what is Earth observation and how does it work? In this article, we explore more about the types of observation, and what we can do with the data.

This is the first of a series of features discussing Earth observation science, and how tracking the world from space can provide useful information, such as the mapping of fallout after natural disasters, such as recent earthquakes in Syria and Turkey.

Earth Observation Explained

In layman’s terms, Earth observation satellites are those that are orbiting the Earth and gathering data about Earth that can be used for many different purposes such as tracking data regarding disaster monitoring and natural changes as well as societal changes and impacts, pollution, and more. Exactly what data is created by the satellites depends on the sensor technology that is used, and what the ambition of the satellite mission is.

According to data from the Union of Concerned Scientists (UCS) satellite database, which provides an overview of satellites in orbit and their purposes, there are over 1,000 active satellites in space observing the Earth or with the purposes of “Earth Science”. Every major space agency and power is generating data to better understand the Earth. The UCS database (released in 2022) counted satellites in the following categorizations:

  • Optical Imaging: 426 satellites.
  • Meteorology: 170 satellites.
  • Electronic intelligence: 113 satellites.
  • Radar imaging: 90 satellites.
  • Earth Science: 75 satellites.
  • Hyperspectral or Multispectral imaging: 41 satellites.

There were also 79 different satellites with no specific purpose listed as well as other miscellaneous satellites collecting video and thermal data, for example.

NASA Earth Observation Missions

Of course, as you would expect, NASA has a continual focus on EO. Their Earth Observing System (EOS) is explained as “a coordinated series of polar-orbiting and low inclination satellites for long-term global observations of the land surface, biosphere, solid Earth, atmosphere, and oceans.”

The EOS Project Science Office (EOSPSO) has the goal of sharing their research and Earth observation from space with the science research community as well as the public, increasing our understanding of our own planet.

As of this date, the program has 30 active missions involving Earth observations, but NASA’s innovations can be dated back to the 1960s when work began on TIROS-1, a weather satellite that also utilised experimental data collection to give a broader understanding of meteorology. TIROS was a success, and proof of the potential Earth observation applications. The ATS (Applications Technology Satellite) program was set up, and saw ATS-3 capturing colour images over two decades. The satellite was able to provide a communications link for numerous rescue operations, including earthquakes and even the 1980 eruption of Mount St. Helens in Washington.

NASA has plans to launch further EO satellites in the coming years, but they aren’t the only players in this industry. While the UK’s space industry is perceived as fledgling, producing satellites is something that Brits have a rich history of, and with numerous space launches to come in 2023 and beyond, the UK is bound to become an even bigger player in the industry. There are also over 300 space organisations in the UK working in the space applications sector, and the UK collaborates closely with the ESA, participating in Copernicus, SMOS, CryoSat, Aeolus, TRUTHS, Biomass, and other European programs.

Earth Observation techniques and its Applications

The applications for Earth observation technologies are evolving, along with science.

Earth observation methods can be split into either passive or active. This is based on the signal source. Passive sensors track signals that have been reflected by objects and territories. Things like heat and light levels can be detected using passive sensors.

Active sensors can collect different kinds of data, as they emit a signal to scan the specific area, detecting things like radiation.

We’ve discussed the uses of Earth observation satellites already here on Orbital Today, but this is a world that continues to evolve, and uses change.

While a full list of satellite uses will be published as part of this series, a few examples can show you the sort of applications EO science and technology can offer. 

Search and Rescue

In the event of a ship or plane being out of the tracking systems, satellites can quickly provide data and potentially help to save lives, leading the search and rescue efforts. In a similar way, the technology can be used to track things like illegal fishing, bunkering, and drilling, making it useful for government agencies.

Town and City Planning

Imaging can help us with mapping urban settlements, and this data can be crucial when it comes to planning and expanding, for instance, building upon the transport system. 

Tracking Deforestation

An undeniable trend we see in Earth observation is deforestation, which can now be tracked to a more detailed degree. EO helps to map areas of deforestation and start to address this crucial problem.

Disasters and Catastrophes

In the fallout of a natural disaster or catastrophe, satellite imagery can be used to establish damage, and start to lead rescue missions. It can even be used to navigate with up-to-date images of a city, for instance, following an Earthquake. The insurance industry also uses the data from Earth observation, helping to establish where payouts are due and the levels of damage in the area.

Forecasting Weather

Data from Earth observation satellites have been predicting our weather for many decades now, and this continues to be one of the best examples of how we can use this data from space.

Climate Change

Earth observation helps us to understand climate change, as well as predicting trends and even mitigating the potential impacts of rising temperatures around the world. The use of satellites has already helped us to better understand the risks of the climate crisis.

There are, of course, many other uses of Earth observation technologies, and the resolution and quality of imaging technologies continue to grow at pace.

An Ever-Changing Observation

All over the world, we are seeing huge agencies focusing on new ways to track Earth observation. In the UK, plans to double the presence within the space market over the next decade means that observation satellites, already a huge part of the country’s offering to the world, will continue to grow.

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