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How satellite mapping technology is revolutionizing the way we see Earth

When researchers from the British Antarctic Survey (BAS) published a study last year on its discovery of 11 new colonies of emperor penguins, they acknowledged an unusual source of assistance – students at Stirling High School in Scotland. Inspired by a David Attenborough program on the plight of the iconic bird, the teens and their teacher used satellite mapping imagery from the European Space Agency’s Copernicus Sentinel-2, developed an algorithm, and found traces of unknown and unconfirmed colonies. They then passed on their findings to the BAS.

The notion that schoolkids are as capable of accessing Earth Observation data as scientists and government ministers is an indication of how satellite technology has revolutionized scientific research across the globe, and especially of the environment.

Satellites “change everything,” says Nathalie Pettorelli, a senior research fellow at the Zoological Society of London and author of the book Satellite Remote Sensing and the Management of Natural Resources. Monitoring extraordinarily large territories, providing access through visibility to remote areas, and boosting transparency of countries’ environmental standards are some of the benefits she cites. “They provide you with the opportunity to monitor the Earth globally and monitor aspects of biodiversity that were very much neglected before.”

The student built CubeSat Radio Frequency Tag Satellite (RFTSat) is deployed from the International Space Station using a deployment system called SlingShot. NASA
The student built CubeSat Radio Frequency Tag Satellite (RFTSat) is deployed from the International Space Station using a deployment system called SlingShot. NASA

But it’s not just biodiversity that satellites are aiding. Ever since the National Aeronautics and Space Administration (NASA) together with the United States Geological Survey launched the world’s first Landsat satellite in 1972, a continual stream of data on everything from deforestation to glacier retreat to weather patterns has been recorded and archived, providing an incredibly valuable picture of long-term change to scientists, land managers, policy-makers and many others. Today, a veritable constellation of satellites of all shapes and sizes, both public and private, constantly orbit and monitor what’s happening on Earth, deepening and extending that pool of knowledge.

“When you talk about NASA, many people know only about things like our Mars expedition,” says Sachidananda Babu, who is in charge of its Sustainable Land Imaging Technology (SLI-T) program, “but they don’t realize how much effort we spend on preserving our own planet, Earth.”

Experiments in orbit

Over the decades since its first launch, Landsat and other civil satellites have proven useful to ecologists with their ability to monitor plant health, land cover and water, he says. For example, “the Thermal Infrared Sensor (TIRS) on Landsat measures evapotranspiration, and western states’ water management of the Colorado River depends heavily on this measurement.”

Babu and his colleagues are now in the process of developing a new tool, which they hope to have ready soon, for identifying potential forest fires. “The tool will take data from satellite measurements and calculate moisture index,” he says, “which can estimate the chances of forest or bush fires. Is fire due to lack of moisture? Or hot air that’s in that area? So that’s a very advanced thing that’s going on right now.”  

A chart mapping the Landsat 9 mission development and lifecycle. NASA Landsat
A chart mapping the Landsat 9 mission development and lifecycle. NASA Landsat

This September will see the launch of Landsat 9, which is, says Babu, “mostly identical to Landsat 8 in shape, size, and weight, and it uses the same hardware. But we refined it a little bit.” By sending down 14-bit image data instead of 12-bit, he says, “you have a more dynamic range of data, and that means you can see even smaller changes on the ground, which enhances the quality of the data.”

As program manager of NASA’s In-space Validation of Earth Science Technologies (InVEST), Babu also works in the relatively new field of CubeSats. A new, low-cost pathway to research, these can, he explains, provide trial runs for new technologies in space. So far, these have included compact instruments to measure evapotranspiration and radio occultation measurements that can measure root zone soil moisture.

“CubeSats are the best way to try out whether that technology is really useful,” he says. “To do that, we put that one specific part of the technology on a satellite and fly it. We see if it works well, then we can infuse the technology into a bigger program.”

Two scientists with a small swarm of CubeSats capable of collecting and transferring scientific data. NASA Ames Research Center
Two scientists with a small swarm of CubeSats capable of collecting and transferring scientific data. NASA Ames Research Center

Providing higher resolution imagery than civil satellites, the pint-sized CubeSat – at anywhere from 10 to 240 square centimeters in size – is also used for commercial and educational purposes, and for scientific research. Educational institutions and non-profits in the U.S. can send their CubeSats into space using rockets, belonging to NASA or private companies such as Virgin Orbit, SpaceX or Rocket Labs, the latter of which includes a ‘Book My Launch’ tab on its webpage. They can also be launched directly from the International Space Station on a Cygnus orbiter.

More than a hundred CubeSats have already been selected and taken into space as part of NASA’s Educational Launch of Nanosatellites (ELaNa) Missions, and Babu credits their success to fostering close working relationships with the principal investigators of the selected proposals. “What we do is take personal interest and mentor the team,” he says. “Calibrated and traceable measurements are required for any impactful science measurements looking at minute changes.”

Making data digestible

But with such complex data – and so much of it – available, how can the people who need it make sense of it all? Enter initiatives like Digital Earth Africa (DEA), a unique platform that democratizes the capacity to process and analyze satellite data.

A successful pilot study involving five African countries proved that better use of Earth Observation data had significant benefits for decision making, national statistics, resource management and innovation on the African continent, says DEA’s managing director Adam Lewis. DEA also created the Africa–based leadership team that produced the vision, mission and principles the initiative, which is funded by the Helmsley Charitable Trust and the Australian government.

A Sentinel-2 image of Madagascar's Betsiboka Estuary. Digital Earth Africa
A Sentinel-2 image of Madagascar’s Betsiboka Estuary. Digital Earth Africa

The platform’s sources of information are the time series data produced by civil satellites, especially the Landsat series and Sentinel-1 and Sentinel-2 constellations. “These are underexploited because the satellites have advanced so quickly that people are unable to keep up with the ‘big data’ they produce, says Lewis. “So there is immense untapped potential.”

DEA is overcoming those difficulties by doing some of the heavy lifting for the data users, providing the data in an analysis-ready form, accessible in the cloud, and with the open data cube as a processing system – what DEA calls “decision-ready data.”

“What we are striving for with our approach is information that is close enough to a decision-maker’s problem that they can see how they can engage with the products,” says Lewis. “Telling a decision-maker that you’ve got satellite data can be pretty abstract for them. It’s not their job to know how relevant that is. But if we can say we are mapping the surface water of Africa through time, how it has changed, and are updating it, then they can identify and link it into their decision-making process.”

To use his example, observations that map surface water can show where water has been seen in the past, says Lewis. “The fact that it hasn’t been seen in certain places for 10 or 15 years doesn’t mean it’s not going to come back and be there again. There are patterns, and we can use the patterns of the past to understand the future.”

Founded just two years ago, DEA has, over the past year, made food security another priority by developing a crop map area product. “We can produce the sort of information on crops that Earth observation can give, like, how green is the countryside? How green is it compared to a normal year? Is that an indicator of drought? Now, in a particular country or region, an agronomist or a company might say, that’s an indication that farmers in this area should be planting at this point, or not planting. That,” he adds, “then gets communicated to those farmers in ways that make sense.”

From high above to down below

Platforms like DEA with its training material and mapping and analysis tools are already proving useful to ecosystem scientists. “Wetlands can be monitored,” says Lewis. “Forest can be monitored. We can look at land degradation. All these things can be done.”

A Landsat 8 image of the Tanezrouft Basin in Algeria. Lacking vegetation and water, the Basin is one of the most desolate parts of the Sahara Desert. USGS Earth as Art 4
A Landsat 8 image of the Tanezrouft Basin in Algeria. Lacking vegetation and water, the Basin is one of the most desolate parts of the Sahara Desert. USGS Earth as Art 4

At the moment, DEA is not using data from CubeSats because their data is not free and open, and they don’t give universal and automatic daily coverage. But DEA is starting to explore how CubeSat data can nonetheless still be effectively used alongside that of other satellites. “It is quite possible for a country to bring in high resolution data from a CubeSat…and to use the data in conjunction with those lower-resolution earth observing satellites that the USGS and Copernicus run. It is a really interesting area.”

For Pettorelli, it is nonetheless crucial that access to earth monitoring tools remains open and free. “You can really see the boom in science as Landsat opened its archive for free,” she points out.

“There’s an important message behind that, which is, the more we show that this is transformational, the more it becomes really important to protect those resources so we can continue to do what we do on the long term and monitor, for example, the effectiveness of various actions. Because they not only give you access to remote places on the earth, they allow you to look at things over a long time,” she says. “So it’s hugely important to continue to protect that, for humanity as a whole.”