Published in Imaging Notes (USA)

September/October issue, 2000

Posted at



Eyes in the Sky:

In Service of Humanity?




By Bjørn Willum,

freelance journalist specializing in international conflicts, including remote sensing

Copenhagen, Denmark




The U.S. Ambassador had a few photos in her diplomatic bag. At first glance, the photos-depicting a field where a large hole was being dug with an excavator and oblong objects neatly lying next to the hole-were of little interest to the diplomatic corps. It was Aug. 9, 1995, and the U.N. Security Council was reconvening at its New York headquarters to debate the crisis in the Balkans.

Examining the photos more closely, however, revealed that this wasn't just a dump in the countryside. In fact, the hole was a mass grave and the oblong objects were human bodies awaiting burial at two farms near the Bosnian town of Srebrenica, where 7,000 Muslim men were reported missing shortly before the photos were taken by a Pentagon U-2 spy plane.

The photos caused great upheavel in the council, as well as in the media, and justified a much harder stance by Western governments toward the nationalist leadership of the Bosnian Serbs. But the Srebrenica photos also proved that overhead imagery could be used by human rights groups to combat large-scale crimes against civilians.

Last year, another instructive project for human rights groups was carried out involving, among others, the U.N. High Commisioner for Refugees (UNHCR), whose staff used aerial imagery to assess damage to villages after Serbian ethnic cleansing in Kosovo. The imagery allowed analysts to assess housing conditions simply by counting how many houses lacked roofs, which usually collapse if a house is burned or otherwise destroyed (Figure 1).

Of course, some houses could be severely damaged inside despite an intact roof, but the imagery provided a good foundation for estimating available housing, says Jean-Yves Bouchardy from UNHCR's Geographical Information Unit, which participated in the assessment project. "The information on the damage of villages was essential to plan the return of refugees [and] the shelter needs for the coming winter," he says (Figure 2).

Even though the imagery was provided free of charge by various U.S. defense institutions, 1-meter commercial satellite imagery could have done the job as well, and for rapid damage assessment, it might even have been cost effective to purchase the imagery, according to Bouchardy. "If we have to send a team of experts to access all the villages, it would be far more costly and sometimes impossible. The imagery was very useful because some of the areas were still under fighting or there were land mines," he says.

Human rights groups often face the same problems that Bouchardy's team encountered: Access to scenes of heinous crimes is usually cumbersome and dangerous. With the help of satellite imagery, analysts could substantiate or refute news reports of systematic destruction of villages. While it would be dangerous for a non-governmental organization (NGO) to fly a spy plane over warring territories to look for mass graves, very high-resolution commercial satellite imagery could, without risk, provide data to much the same effect.

Because turned soil is a different shade of gray than undisturbed soil on satellite imagery, comparing two images taken at different times allows analysts to detect holes dug in the interim, provided the holes cover more than a few square meters of ground and aren't covered by forest.

However, whether the objective is counting destroyed buildings or looking for mass graves, satellite imagery is a complementary tool and can't provide all the answers. First, according to Bouchardy, you must know where and when to look; you need to know that something has happened. Next, supplementary information must establish whether houses lack roofs due to ongoing construction work, an earthquake, suppressive campaigns or something else.

Likewise, turned soil doesn't necessarily reveal a mass grave. Rather it may indicate a dump or newly plowed field. Even if human bodies were lying next to a grave when a satellite passed over, human bodies would be extremely difficult to detect in a 1-meter resolution image. But used with news reports or witness accounts, satellite imagery can help substantiate allegations of atrocities and help policymakers apply pressure on reluctant external governments to intervene diplomatically or militarily.

Satellite imagery also can be used effectively by U.N. International Criminal Tribunals endeavoring to bring the masterminds of crimes against humanity to justice. Instead of rushing around to check every field in a country, prosecutors could use satellite imagery to point out a small number of suspected sites to investigate.

Using satellite imagery to track refugee movements is another useful application for human rights groups, because refugee flows often result from systematic violence. In addition, the ability to keep a public eye on refugees contributes to their safety. However, the task of tracking refugees is hampered by the fact that it's extremely difficult to track humans with even the best commercial satellite imagery available today, unless, for instance, the background has an exceptionally contrasting effect.

Therefore, to locate refugees it's necessary once again to look at circumstantial evidence. The presence and number of refugees can be inferred by identifying larger objects, such as tents and large campfires in unusual places or cars in unfamiliar convoys.

Even so, efforts to combat human rights abuses will be greatly hampered by very slow delivery times.

Although Space Imaging's (Thornton, Colo.) IKONOS satellite can provide commercial 1-meter resolution imagery to customers within 24 hours, this is clearly the exception. Some imagery takes longer to obtain because of cloud cover and other factors-a long time in a world where events occur quickly and one human rights violation is usually followed by another.

Another problem for human rights groups is imagery cost, especially considering that NGOs often need at least a dozen images for proper assessment. So why not rely on the U.S. government-who gave imagery away for free on Srebrenica in 1995 and during the Kosovo campaign last year-whose equipment is far superior to that of commercial providers?

"There's a highly selective process of releasing pictures in the Pentagon," says Susan Osnos, associate director of Human Rights Watch (New York). Osnos points out that the Srebrenica images were released long after the victims were dead and buried and following a major internal squabble in the administration. Further, NGOs have not conducted proper testing to assess the utility of using commercial satellite imagery as a complementary tool to monitor human rights abuses. The reason, according to Osnos, is that even large organizations such as the Human Rights Watch don't have large enough budgets to buy test imagery on a large scale.

The technology exists for greater information-gathering capabilities by human rights groups. However, an atmosphere of cooperation must exist between image providers (commercial and government) and NGOs to promote better monitoring of human rights violations.

Captions Figure 1. Overhead images such as this can help human rights groups monitor human rights violations. The arrow points to one of many damaged houses. This possibly degraded U.S. military image is comparable to 1-meter resolution commercial imagery. Credit NATO

Figure 2. This damage-assessment map summarizes UNHCR findings regarding housing conditions in Kosovo after Serbian ethnic cleansing campaigns. Credit UNHCR Geographical Information Unit