Learning from declassified U.S. satellite imagery

From the desk of Philipp Barthelme

In October 2021 I started a PhD to study the long-term impacts of the Vietnam War on the environment and local community livelihoods in Southeast Asia. I had come across the project proposal, advertised by the Centre for Satellite Data in Environmental Science (SENSE), one year earlier, and it sparked my interest. Not because I knew much about satellite data or the Vietnam War at the time, but because a few weeks earlier I had come across a map showing the bombing missions of the Vietnam War. It was one of those “Did you know…” moments that you can’t help but share with the people around you. 

Did you know that the U.S. dropped more bombs on Laos during the American Secret War in Laos than on Japan and Germany combined during the entire World War II?

Did you know that more than 20% of the land in Vietnam, Lao PDR and Cambodia are estimated to remain contaminated by unexploded ordnance (UXO) today?

Did you know that 50 years after the end of the war people are still dying from UXO every year?

Early during my PhD I came across the declassified KH-9 satellite imagery and downloaded an image showing parts of Quang Tri province, Vietnam in 1973. My first reaction was surprise. The image was incredibly detailed. To give some context, the only satellite imagery from that time I had known about was the Landsat 1 imagery with a resolution of about 80m. In comparison, the KH-9 images had a resolution of 0.6-1.2m, not far off from what we can see on Google Maps today. It would take more than 25 years, until 1999, before the first commercial satellite mission (IKONOS) achieved a comparable resolution.

KH-9 image D3C1205-100113A010_c showing parts of Quang Tri province, Vietnam in 1973. The image is available as part of the Declassified Satellite Imagery – 3 collection courtesy of the U.S. Geological Survey.

My second reaction was disbelief. I knew more facts about the war by now but I didn’t know what they meant. Looking at the destruction visible in the KH-9 image it started to dawn on me. It took a moment for me to understand that all the white circles I was looking at were in fact bomb craters, tens of thousands of bomb craters.

Zoomed in view of KH-9 image D3C1205-100113A010_c showing a large number of bomb craters.

I have since spent countless hours zooming in and out of KH-9 images, a habit I expect to keep up for the remainder of my PhD. Unfortunately, looking at old images alone isn’t quite enough these days to get a PhD. So I started working on machine learning methods to automatically detect the bomb craters in the KH-9 imagery. Although the presence of bomb craters means that the corresponding bombs exploded, any unexploded bombs from the same bomb strike are likely to be located nearby. My hope was therefore that the imagery and derived bomb crater locations would be useful for non-technical survey and residual risk management in Southeast Asia.

I realized that, in order to create anything useful, I needed to understand more about mine action in Southeast Asia. With the help of the Conflict and Environment Observatory (CEOBS), who have been supporting my PhD, I started reaching out to people. Finally, in autumn 2023, I was able to visit Vietnam and Lao PDR to present my research on the bomb crater detection, which is now also available online. I had great conversations and learned a lot from the people I met and I hope to work together with them in the future. 

Now, back in Edinburgh, I can’t help but wonder if maybe, almost 50 years after the end of the war, there isn’t anything new I can contribute. Then I think about the journey of that first KH-9 image of Quang Tri I had looked at about two years ago. I keep thinking about the U.S. analyst who looked at that same image in 1973 before it disappeared into an archive for almost 50 years when someone pulled out the now declassified film roll, scanned the image and put it online. I think about all the other KH-9 images, all the other declassified documents in the archives and all the documents that remain classified until today. I think about all the people in Southeast Asia that still can’t move on from the war, as much as they would like to. And I can’t help but wonder if maybe, almost 50 years after the end of the war, there is still more I can do to contribute. Maybe, at the very least, I can ask someone did you know…?