Eye in the Sky

By: Grace Chen

Look up at the night sky. The starry heavens inspire a primitive, instinctive fascination in the human mind. In the 21st century, however, the skies are populated with more than just celestial bodies. Many of the glimmering lights we watch in our night sky are satellites – and they are watching you, too.

The earliest satellites were military, emerging in the 1960s after the Second World War as Soviet Russia and the United States competed for dominance over the stratosphere as well as the planet’s surface. The US’s early successes were fueled by the then-classified Corona program, which launched a number of satellites into low orbit for reconnaissance and gathering intelligence. A major development was the Landsat program, which the government used to track and archive images of the Earth’s surface for geological and ecological surveys. Continuously running and updated since 1972, Landsat is today the longest continuous record of remote sensing images.

The basic principle of remote sensing is that electromagnetic radiation reflecting off the surface of the planet is captured by sensors on the satellite as it passes overhead. This remote sensing can be passive, relying on the sun as the source of electromagnetic radiation, as in the case of simple photography a la Google Earth. More sophisticated satellites can also participate in active sensing by emitting sonar, lasers, or radar, which bounce back off the earth’s surface differentially based on the surface’s composition and topography. With the rise of multispectral and hyperspectral imaging, the types of images produced have become increasingly sophisticated. Multispectral sensors can detect 3 to 10 different bands of electromagnetic radiation with a different sensor each, while hyperspectral sensors have even finer resolution and a greater number of bands they can pick up (1).

It is important to remember, however, that the capturing of light is only half the story. The captured light must then be processed in a variety of ways to produce an image – colorized, enhanced, compressed, and so forth to generate a meaningful image or dataset. The power of big data in satellites is growing as technology improves and operational costs drop, with resolution on these images now frequently finer than 1 meter. Yet interpreting the information seen in the image is an art as well as a science.

The ability to see from above with such clarity produces knowledge in unexpected ways. One key application is in environmental protection. The nonprofit Skytruth, for instance, has used consolidated images from satellites to monitor environmental threats such as the BP oil spill and expansion of fracking. One of their more recent ventures is a partnership with Google and Oceana to launch a program called Global Fish Watch, which hopes to help track and capture illegal fishing activiy (2). Pew Charitable Trusts and Satellite Applications Catapult launched a similar project called Project Eyes on Seas in 2015 to spot anomalous ship behavior that might reflect illegal fishing.

Overfishing is a serious threat to the balance of the ocean ecosystem. Stocks of predatory fishes, such as tuna, have fallen precipitously since the 1950s. A recent article in Science has gone so far as to warn that if current fishing rates continue, all of the world’s fisheries will have collapsed by the year 2048. The financial incentives for illegal fishing, however, mean that the number of “pirates” is troublingly high. Many governments, recognizing the impeding crisis, have responded by designating protected marine reserves, or limiting the number of fishing licenses issued. The sheer size of the sea, however, makes it difficult for these laws to be effectively enforced. In the US, for instance, the Pacific Remote Islands National Marine Monument was expanded in 2015 to 490,000 square miles of ocean, an unfathomably large area to patrol by ship or even aircraft. The lofty view of an orbiting satellite therefore presents a unique vantage point from which erratic ship behavior and the boundaries of marine reserves can be monitored.

Satellites can also prevent wrongdoing in a variety of other settings (3). New agencies are popping up under the title “space law,” dedicated to using satellite images in trials. Such images can provide valuable evidence over disputes ranging from property boundaries to vehicle theft to waste disposal (4). Satellite imaging even has the potential to fight human rights abuses on a global scale. The International Criminal Tribunal first admitted the use of satellite images as legal evidence in the Srebenica trials of 1992, which provided evidence of mass genocide and contributed to the eventual conviction. Initiatives like the Signal Program at Harvard Humanitarian Initiative continue to use satellite images to monitor alleged humanitarian crises.

The use of satellite imagery in legal cases faces some difficulty, however. Currently, lawyers can only trawl through archived images from commercial providers in search of relevant data; there is little economic incentive or capacity for third-party providers to store images before a lawsuit begins, so the amount of available data is constrained. Moreover, there are no standards for provenance and auditing to ensure that images are authentic, objective, or accurate. Even if images are produced, their novelty means that judges and juries may not yet be sure how to interpret this evidence in a lawsuit.

Despite its many uses, the recent expansion of satellite technology runs up against a number of difficult challenges. First, laws and markets have not yet fully evolved to accommodate “big data,” including the massive amounts of new information produced by satellites (5). As the number of satellites grows and quantity of images proliferates, there is no clear legal framework defining who should get control of those images or restrictions on how they can be monetized. Questions of data ownership and rights remain largely unresolved. Second, the fields of ecology and criminal justice are still adapting to the new tools provided by this technology. The development of data repositories and new training courses might equip professionals to properly utilize the growing amount of raw data captured by satellite imaging. This data cannot be optimally used until there are more scientists trained with this expertise.

Perhaps the biggest challenge facing expansion of satellite technology is the ethical and privacy concerns. The resolution of many satellites is now reaching a point where individual houses, cars, and even faces can be recognized. This inevitably generates concerns about the possibility of constant monitoring from the skies. Even crime-fighting and environmental protection present ethical problems; traditionally protected rights against unwarranted searches may not hold up in the world of satellite surveillance. The interlinked concerns of ethics, laws, and public opinion must inform the continued development of satellite imaging technology (6).

Grace Chen ‘19 is a freshman in Holworthy Hall.


[1] Durst, S.K. Michigan Technological University. http://www.geo.mtu. edu/rs4hazards/ksdurst/website/ lectures/RemoteSensing.pdf (accessed March 2, 2016).

[2] Gunther, M. To catch a fishing thief, SkyTruth uses data from the air, land and sea. The Guardian, Nov. 24, 2015. http://www.theguardian. com/sustainable-business/2015/ nov/24/fishing-thief-skytruth-data-software-maps-illegal#sthash. FuUW3UI0.dpuf (accessed March 2, 2016).

[3] Monks, K. Spy satellites fighting crime from space. CNN, Aug. 12, 2014. http://www.cnn. com/2014/08/11/tech/innovation/ spy-satellites-fighting-crime-from-space/ (accessed March 2, 2016).

[4]Marks, P. World’s first space detective agency launched. New Scientist, Oct 8, 2014. https:// http://www.newscientist.com/article/ mg22429902-900-worlds-first-space-detective-agency-launched/ (accessed March 2, 2016).

[5] Pettorelli N, Safi K, Turner W. Philosophical Transactions of the Royal Society B: Biological Sciences. 2014, 369

[6] Chun, S. A., Vijayalakshm, A. Data and Application Security. 2002, 233-244.

Categories: Spring 2016

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