More than 700 Earth observing satellites orbit the globe. Flying miles above the planet, the spacecraft use remote sensing instruments, such as cameras, radar, lidar and radio receivers to monitor a wide range of weather and environmental conditions as well as radio communications. Some sensing systems already collect gigabytes and even terabytes of data per hour. And because each sensor type has its own unique way of analyzing information, the world can be surveyed for abundant reasons in details as small as 10 inches, reports MIT Technology Review.
“The progress we have seen is stunning,” says Anne Hale Miglarese, founder and CEO of Radiant Earth Foundation, a non-profit organization creating training data libraries of satellite imagery that can be used to improve machine learning algorithms meant to support research around agriculture, conservation and climate change. Soon researchers will be able to build a digital twin of the Earth on a daily basis.
“We’ll see buildings going up, ships crossing the sea, and we will be able to monitor the physical footprint of climate change,” says Miglarese.
Scientists armed with sensing data — from ocean temperatures, storm system, snow cover, vegetation, pollution, artificial lights and more — gain a deeper understanding of global events and processes so expansive they cannot be studied easily from the ground. Not only that, researchers can uncover hidden worlds obscured by tropical jungles or sheets of ice. Here are five discoveries made by Earth observing satellites flying high in the sky.
Ancient Ruins
Space archaeologist Sarah Parcak, a professor at the University of Alabama at Birmingham, uses satellites orbiting high above Earth to discover clues to ancient civilizations. Her most memorable find occurred in 2010, while looking at satellite images of Egypt. The region was normally an unremarkable region of sandy soil, but in these particular images, which were taken during a wet time of the year, Parcak noticed the outlines of buildings and streets of what turned out to be the 3,000-year-old city of Tanis. The ancient ruins stood out in the photos because rain had soaked into mud bricks, making them easy to distinguish from the sandy ground, Parcak told The Guardian.
Since, then Parcak has discovered 18 new pyramids and thousands of new tombs and has scoured satellite images looking for evidence of ancient civilizations, including the Vikings and the Romans. In 2016, she won a $1 million TED Prize, which she used to build the citizen science platform, GlobalXplorer. It allows any person to search high-resolution images for hints of archaeological sites. “We’ve had about 90,000 users find almost 20,000 previously unrecorded potential sites there, 700 of which we think are of major archaeological importance,” Parcak told The Guardian.
Invasive Species
Around the world, invasive plants and animals, introduced more often than not by humans, crowd out native species. They decrease biodiversity and degrade wildlife, pushing parts toward extinction, according to the U.S. Department of Agriculture. In the fragile ecosystem of the Galapagos Islands, for instance, the quinine tree, Cuban cedar, blackberry, guava and others threaten indigenous plants, reports The Darwin Foundation. The organization, which was founded to ensure the conservation of the environment and biodiversity of the archipelago, is currently collaborating with universities to use remote sensing imagery from satellites to locate a variety of invasive plant species in order to eradicate them.
In a project with Brown University, researchers from the Darwin Foundation are analyzing images donated by the commercial satellite company Maxar (formerly DigitalGlobe). Their network of spacecraft collects high-resolution images of the planet daily, capturing photos in a wide spectrum of light, including infrared. Multi-spectral images pick up different concentrations of chlorophyll in plants and can be used to characterize specific species.
By combining data from these images with camera data taken with low-flying drones, researchers trained a computer model to find invasive plants in satellite images alone. They have created maps of the most dominant invasive plants on Santa Cruz island, namely blackberry, guava and Cuban cedar, and are working on the maps for the islands of Floreana and Santiago.
Lost Continents
Not all Earth observing satellites turn cameras on our planet. A satellite from the European Space Agency named GOCE (for Gravity field and steady-state Ocean Circulation Explorer) had an incredibly sensitive instrument designed to measure Earth’s gravity, which changes across the globe, depending on the topography and the density of material below the surface. GOCE orbited Earth from 2009 to 2013, gathering data and transmitting it back to Europe. Eventually it finished its mission and plummeted into the atmosphere, where it burned up.
Scientists kept studying the remote sensing data it had collected, though. In 2018, researchers from Kiel University in Germany combined the information from GOCE with data from a different satellite to digitally strip the ice from Antarctica and peer beneath. In the bedrock they found remnants of ancient continents beneath Antarctica, reports Live Science. East Antarctica’s crust has a very old mix of features called cratons, cores of continents that came before Antarctica. They also found orogens, crumpled-up regions where ancient continents would have rammed together and created mountains.
“This observation leads back to the break-up of the supercontinent Gondwana and the link of Antarctica to the surrounding continents,” the study’s leader Jörg Ebbing told Live Science.
Illegal Fishing Boats
High crimes run rampant on the high seas. Up to one in five fish sold in the world is caught illegally, according to Pew research. Large-scale illegal fishing damages ecosystems and depletes fish stocks and is linked to arms and wildlife smuggling, drug trafficking, human rights abuses and slavery. A patchwork of fishing policies, lax enforcement and the impossibility of policing the open ocean only exacerbates, reports Pew. How to combat it? The answer lies in satellite technology.
Some satellites are equipped with receivers that receive radio signals from a ship’s Automatic Identification System, or AIS. The signal is analogous to a plane’s air traffic control data and contains information about the ship’s identity, position, course and speed. They’re automatically generated and sent every two to 180 seconds from vessels more than 120 feet long as a way to prevent collisions and allows authorities to monitor vessel activities.
Researchers around the word are beginning to analyze this and other data to piece together the otherwise unseen happenings in commercial fishing. One project, Global Fishing Watch, a nonprofit launched in 2016 and funded by Oceana, Google and SkyTruth, leverages satellite data and machine learning to track, visualize and share data about global fishing activity in near-real time and for free. To date, the platform has tracked approximately 65,000 commercial fishing vessels globally, an effort that has improved transparency and enforcement.
Migrating Animals
In the United States, big game species such as deer, elk, antelope, mountain goats and wild sheep draw lucrative amounts of hunting revenue to local economies. But human development, increased road traffic and expanded oil and gas drilling is adversely impacting wildlife. In Wyoming, for instance, mule deer herds have declined by 40% over 15 years in regions where oil and gas extraction has boomed, reports the Center for American Progress. Not only do shrinking herds reduce biodiversity, but they negatively impact Western state economies, where hunters and outdoor enthusiasts spend hundreds of billions of dollars
Recently Wyoming, Utah, Colorado, Oregon and New Mexico have begun ramping up funding and research efforts to study animal migration in an effort to improve wildlife management and conservation. Most scientists have turned to GPS collars and satellite tracking technology. Advancements in the technology have made it possible to not only accurately locate animals but do so every hour, reports Smithsonian. Scientists can reprogram a collar remotely, too, setting up so-called “geo-fences” that send out a notification if a group of animals leaves a predetermined border.
Although studies have found that migration patterns change, species have unique pathways and timing. The majority of herds travel to the same summer ranges and return to the same winter ranges, year after year, reports Smithsonian. Knowing those routes can help conservation efforts. Research from the University of Wyoming, for instance, found that 4,000 to 5,000 pronghorn used a migration route that passed through the small town of Pinedale, Wyoming, situated in a valley between two large peaks. Preventing the development of private land there was critical to keeping the herds flowing through unimpeded.
Another study from the University of Wyoming that used GPS collars on mule deer found that the animals “have a cognitive map of their migration routes and seasonal ranges, which helps them navigate tens to hundreds of miles between seasonal ranges,” assistant professor, Jerod Merkle said in a press statement. “Because landscape memory so strongly underlies mule deer migratory behavior, the loss of a migratory population also will destroy the herd’s collective mental map of how to move within a landscape, making it very difficult to restore lost migration routes,” the researchers say.
The view of Earth from miles above is expanding our understanding of the world and our place on it. And although there are more than 700 Earth observing satellites circling the globe, more are coming online. According to MarketWatch, the global commercial satellite imaging market is expected to grow more than 10% by 2023. It’s only a matter of time before other hidden mysteries are laid bare.
