The most basic definition of Earth observation is as simple as it sounds: observing the planet to learn more about it. Much of today’s activity in Earth observation (sometimes just ‘EO’ for convenience), is space-based, satellites carrying imaging equipment for remote sensing of activities and phenomena down below.
But humans were observing the Earth long before satellites. In its fullest definition, Earth observation encompasses anything used to observe and study the planet. Buoys taking measurements at sea, weather stations, airborne observation, wind gauges, thermometers for temperature, and seismometers for earthquakes are all aspects of EO that provide critical observations about the Earth.
Satellite-based Earth observation always involves some manner of sensors or imaging technology. Remote sensing can either be passive, such as taking photographic images of the Earth’s surface from high above. (If you don’t have a satellite, a plane window or tall building still qualifies.) Or it may be active, such as radar waves sent down from the satellite and then reflected back up to be recorded and analyzed.
Remote sensing offers the opportunity to study not just the surface of the Earth, but the atmosphere above it, revealing essential information about weather, climate, pollution, and other atmospheric phenomena. Remote sensing of the Earth’s surface can show us what’s happening with infrastructure such as bridges and dams. Or with volcanoes and glaciers, forests, floods, fires, and human and animal populations. Those are just a few examples of the objects of remote sensing.
One of the most important capabilities of remote sensing, however, is its ability to let us peer below the Earth’s surface to see whatever opportunities or threats may be hidden. Underground moisture, pollution, soil conditions, and infrastructure can all be studied by remote sensing technology, and over vast areas, without digging holes all over the planet.
In the science of Earth observation, an image taken at a given time or a specific location can only tell you about that one moment and place. One and done.
The planet, however, is in a constant state of flux. In fact, almost nothing about the Earth doesn’t fluctuate to some degree. Sometimes quickly, like the weather and the tides. Or much more slowly, like growing bulges near a dam or volcano, for example, or the shrinking of a glacier or growth of a desert, that take place over longer periods and need ongoing observation.
Underground, there are also continuous changes that people rarely think about. Beneath the surface, out of sight and mind, changes in soil moisture content, especially near major infrastructure, tell a story that takes place over time and must be consistently monitored if we’re to appreciate what that story is telling us.
Global monitoring is an approach to Earth observation that studies the planet continually and can see changes in phenomena that take place over time. Ongoing global monitoring can ensure that what was safe and normal in January is still safe and normal in July and then again in December — or if something has changed that needs closer examination. In the underground soil moisture example above, changes in underground moisture near dams, levees, mining operations, water and sewer systems, or roads and railways can indicate problems that need attention, sometimes immediate attention.
ASTERRA uses an active form of remote sensing that deploys satellite-based synthetic aperture radar (SAR) on a band of the electromagnetic spectrum (the L-band) that’s able to penetrate the Earth’s surface to locate and assess underground soil moisture. ASTERRA’s ongoing Earth observation and monitoring solutions are used by a number of industries and government agencies to determine the source and characteristics of soil moisture, and especially what it says about the surrounding environment and structures.
ASTERRA gathers data from three different satellites and can revisit the same area every 10 to 14 days for ongoing monitoring. Orbiting 390 miles above the surface, the satellites have a view of more than a thousand square miles of territory as they travel around the Earth.
ASTERRA Recover is used by water utilities and pipe system managers to locate leaks from the underground conduit of processed water for human consumption to see where repairs must be made. It offers the same leak detection capabilities to sanitation managers, to keep wastewater from seeping into the environment.
ASTERRA MasterPlan is used to assess the condition of underground pipe systems, for both processed water and wastewater. MasterPlan uses years’ worth of amassed ASTERRA satellite data plus ongoing monitoring of current conditions to provide data that helps managers prioritize pipe replacement decisions and create long-term replacement master plans.
ASTERRA EarthWorks has multiple applications for its soil moisture monitoring capabilities.
The mining industry uses EarthWorks to monitor moisture near tailings dams, the earthen structures that contain the often toxic waste of mining operations. And to monitor the hillsides, roads, and other moisture-holding ground that needs to remain stable.
Operators of earthen levee systems and water retention dams use EarthWorks to monitor seepage across entire systems; unseen seepage can be a precursor to catastrophic and deadly failure.
For the transportation industry, EarthWorks can locate moisture under roads and railways that can lead to sinkholes, and in the hillsides above and below that can fail from excess moisture.
Owners and managers of large property developments use EarthWorks to monitor hillsides, parking areas, airport runways, and other assets that can be damaged by underground soil moisture.