Open-source data reveals destruction in Ukraine war after 2 years as seen from space

An active open-source intelligence community has emerged to monitor troop activity, destruction, and other developments in the ongoing war in Ukraine, which has been ongoing for two years as of February 24, 2024. Soldiers and citizens on the front lines and in affected areas are providing real-time information to contribute to this effort.

Remote sensing complements this approach, providing a safe way to survey hard-to-reach or dangerous areas. For example, seismologists have documented the rapid pace of bombing and artillery fire around Kiev during the first months of the war.

In the past, Professor Teng Wang of Peking University in China and I – both Earth scientists – used satellite data to investigate illegal nuclear tests in North Korea.

We are putting our know-how to use again and together with graduate student Hang Xu, we have analyzed the development of the war from space. We exclusively used open source, freely available data to ensure that all our findings are replicable, ensuring transparency and impartiality.

View from above

Satellite sensors record electromagnetic waves emitted or reflected from the earth’s surface, the wavelengths of which vary from hundreds of nanometers to tens of centimeters, which enables semi-continuous monitoring on a global scale without political borders and natural obstacles.

The optical images, equivalent to photographs taken from space, help governments, researchers and journalists monitor troop movements on the frontlines and the destruction of equipment and facilities. Although optical images are easy to interpret, they suffer from cloud cover and only work in daylight.

To solve these problems, we used probes on satellites. Space-based radar systems beam long-wavelength electromagnetic waves toward Earth and then record the returning echoes. These waves—about 0.4 to 4 inches (1 to 10 centimeters)—can penetrate clouds and smoke. Radar interferometry has already proven to be an invaluable tool for monitoring widespread damage caused by natural disasters.

Radar from space

Free and publicly available radar data for civilian applications is rare – the US is scheduled to launch its first radar in March 2024 – but the European Space Agency has made such data available since the early 1990s. Data from the European Space Agency’s Sentinel-1 satellite radar is freely available through their data center.

Two radar images formed in the same area can be used to detect changes in structures and other surfaces. Interferometry measures the difference in travel time between two radar signals, which is a measure of the change in shape or position of surfaces. Another measure of surface change is the coherence of the reflected signals – that is, the degree of similarity between two different images when comparing neighboring pixels at the same location in two images.

High consistency means little change and thus the preservation of the building or other structure. On the other hand, loss of coherence in the context of a battlefield means damage or destruction of a building or structure.

The Sentinel-1 radar’s 66-foot (20-meter) spatial resolution over a 255-mile (410-kilometer) range, combined with 12-day updates, makes its radar data ideal for monitoring urban warfare.

Previous studies have used satellite radar data to assess the damage in Kyiv and Mariupol. We used the data to analyze the evolution of damage to cities over time during several long battles.

The measure of destruction

We marked highly damaged areas by comparing prewar and postwar radar coherence in areas classified as artificial surfaces in the European Space Agency’s WorldCover 2021 dataset. With this approach, we first analyze the Battle of Bahmut, one of the longest and bloodiest of the war, which began on October 8, 2022 and ended with a Russian victory on May 20, 2023.

When Hang Xu showed Teng Wang and me the data he processed, we were puzzled. We saw a checkerboard pattern all over the city. We quickly realized the horror of the situation. The only thing that remained after a year of fighting was the city’s road network. All the buildings had partially or completely collapsed due to the constant shelling.

After this, we looked at the battles of Rubizhne, Sievierodonetsk and Lysytsansk, which began in April 2022 and ended with a Russian victory on July 2, 2022. The relatively lesser destruction of Lysytsansk is instead explained by the rapid encirclement of the city from continuous frontal attacks from the south, as happened in Bakhmut. Radar data reveals destruction far from the front line within cities, showing the full extent of the devastation.

Destruction in focus

Remote sensing images provide the means to safely monitor the effects of armed conflicts, especially when wars escalate in urban environments. Open access satellite tools complement other open source intelligence services by providing unfettered access to high-resolution, unbiased data that can help people understand the true impact of war on the ground.