The shocking satellite imagery of the destruction in the northeastern Nigerian town of Baga and nearby villages earlier this month provided graphic evidence of the extent of the crimes by the Islamist extremist group Boko Haram when they stormed in.
The images released by Human Rights Watch (HRW) and Amnesty International on 15 January, which show clear signs of arson, ended a growing debate on media coverage of remote conflict zones. It turned the spotlight back to the fact that something terrible had happened in Baga, and hundreds, if not as many as 2,000 people, may have died.
“It’s the power of the image,” Nigerian human rights lawyer Clement Nwankwo told IRIN. “The reason people questioned whether 2,000 people were killed was because that level of brutality was unimaginable. But the images validate that claim, the number of fatalities could be in that vicinity.”
Satellite imagery is increasingly being used by human rights organisations to fact check claims that otherwise would be difficult to verify. It provides an additional dimension of evidence for investigators that can be both immediate, or long-term – compiling a sequential series to spot patterns of environmental degradation, for example.
The imagery can also reveal more than was expected. HRW is currently investigating potential human rights incidents in Nigeria that were previously unknown.
Satellites cannot be intimidated or threatened, and their images are a digital record that enables retrospective analysis. But they are just one tool in a campaigner’s kitbag, and they have limitations. There is continuing judicial mistrust over the admissibility of the data in courts as computer-generated images can be manipulated, require subjective interpretation by experts, and may not necessarily demonstrate causality.
US former secretary of state Colin Powell’s presentation to the UN Security Council on Iraq’s weapons of mass destruction is one of the more notorious examples of misinformation – including the loaded suggestion that the view from space was superior to that of the UN weapons inspectors touring the facilities.
Josh Lyons is HRW’s remote sensing analyst. He worked on the Baga imagery, and says collaborating with investigators on the ground – matching testimony and local knowledge to what is observable in the satellite data - is key to the accuracy and credibility of his assessments.
There are a number of increasingly sophisticated commercial satellites available at relatively low cost that are democratizing use. In the case of Baga, Lyons looked up online what imagery of the town was available on the specified days, paid the European company Airbus just US $350 (thanks to HRW’s NGO discount), and had the package of images in his computer within 2 hours. If he had ordered bespoke coverage, tasking the satellite to photograph a specific area, that would have cost between $400 and $1,380 depending how rapidly it was needed.
“The barrier is not necessarily price, but the sufficient software and expertise to interpret the imagery,” Lyons told IRIN. To get around that problem, non-profit organisations like the American Association for the Advancement of Science provide human rights groups with analytical support. Amnesty International used the satellite firm DigitalGlobe to interpret their Baga images.
Computer software, with complicated algorithms and change detection models are usually needed to process and manage large numbers of satellite images. They can come in different spectral bands, including near-infrared – good for monitoring changes in vegetation health - as well as detecting evidence of fire damage, as in the case of Baga. New satellite systems use shortwave infrared to pierce clouds and dense smoke to reveal objects that would be hidden in traditional imagery – with resolutions as high as 31 centimeters per pixel.
What can you see?
Making sense of what your computer displays is the hard part. Fire, for example, leaves tell-tale signs: roofs are burnt away with load-bearing walls left intact; air strikes produce big impact craters; the size of an artillery round can be measured, and therefore the weapon that fired it determined; displaced earth is a different colour, and can indicate something buried beneath.
But what may look like classic damage signatures can be misleading under certain circumstances, and alternatives need to be painstakingly eliminated. Conflating events due to a lack of sufficient sequential time series data is another problem. “It’s also very common that your mind’s eye becomes attuned to a particular type of damage, and you can miss other details,” said Lyons, who worked with the UN on remote sensing on Myanmar and Sri Lanka.
GPS, Google Earth and the George Clooney-funded Satellite Sentinel Project (SSP), were steps in the evolving revolution in human rights monitoring. Now new micro satellite constellations such as Planet Labs and Skybox, which will provide constant real-time observation of the planet, are touted by some as a way to not just document but also deter rights abuse.
The SSP is going beyond “traditional” human rights monitoring, widening its focus to investigate how, in the project’s words, “those committing mass atrocities are funding their activities and where they are hiding stolen assets”.
Greg Hittelman, communications director of the Enough Project, which partners with SSP, believes remote sensing is among a range of technologies that can be used to “help prevent atrocities and human rights abuse, to escalate global awareness, bring accountability to perpetrators, and provide justice for victims”.
But Lyons is less optimistic. “I don’t believe it has that magical capability. When IS [Islamic State] posts video of its latest beheading, or the Syrian government uses barrel bombs – in effect war criminal selfies – the message is clear. They do not believe they will be held to account.”
|How To Spy For The Good Guys|
|- Check: To see if others have already tasked commercial imagery of your area of interest. Determine the date and time sequence you are interested in and the resolution required.|
|- Order: The US firm DigitalGlobe has multiple satellites and its images are the most detailed, but the European Airbus company’s are less expensive and easier to order with a user-friendly online system.|
|- Gather: As much ground-based evidence as possible – photos, testimonies, GPS references. Work with colleagues to cross-check information and investigate the initial observations.|
|- Analyze: This can be outsourced. Accuracy is essential. Beware dangerously easy mistakes - post-harvest waste burning can look like impact craters under certain conditions.|
|- Verify: Do your evaluation again and again to avoid tunnel vision. When the evidence is indisputable, launch your advocacy plan.|
|Sourcing includes How to Use Satellites to Document Human Rights Violations|