by As soldiers and citizens provide information from the front lines and fields of the war in Ukraine – two years old as of February 24, 2024 – in real time, an active community of open source information has been created to keep track of the troops. action, destruction and other aspects of war.
Remote sensing complements this approach, offering a safe way to study inaccessible or dangerous areas. For example, seismologists have recorded the high speed of bombardments and artillery fire around Kyiv during the first few months of the war.
Previously, Teng Wang, a professor at Peking University in China, and I – both Earth scientists – studied illegal nuclear tests in North Korea with satellite data.
Putting our skills to good use again, graduate student Hang Xu and I have analyzed the development of warfare from space. We exclusively used freely accessible open source data to ensure the reproducibility of all our findings, thus guaranteeing transparency and neutrality.
View from above
Sensors on satellites record electromagnetic waves radiated or reflected from the Earth’s surface with wavelengths from hundreds of nanometers to tens of centimeters, enabling semi-continuous monitoring on a global scale, unhindered by political borders and natural obstacles.
Optical images, equivalent to photographs taken from space, help governments, researchers and journalists monitor troop movements on the front and the destruction of equipment and facilities. Although optical images are easily interpreted, they suffer from cloud cover and only work during daylight hours.
To combat these issues, we used radars on board satellites. Spaceborne radar systems beam long-wave electromagnetic waves toward Earth and then record the returning echoes. These waves – about 0.4 to 4 inches (1 to 10 centimeters) – can penetrate the clouds and smoke. Radar interferometry has already proven to be an invaluable tool for monitoring widespread damage from natural disasters.
Radar from space
Free and publicly available radar data for civilian applications is rare – the US is due to launch its first 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 accessible through its data hub.
Two radar images formed over 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 a change in the shape or position of surfaces. Another measure of surface change is the coherence of the reflectance signals – that is, the degree of similarity between two different images when neighboring pixels at the same location in the two images are compared. Great coherence means little change and therefore the preservation of a building or other structure. On the other hand, loss of coherence in a battlefield context involves damage or destruction of a building or structure.
The Sentinel-1 radar’s spatial resolution of 66 feet (20 meters) over a range of 255 miles (410 kilometers) combined with 12-day updates makes its radar data ideal for urban warfare monitoring. Previous research efforts have used satellite radar data to assess 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 highlighted highly damaged areas by comparing pre- and post-war radar coherence, within the areas classified as artificial surfaces by the European Space Agency’s WorldCover 2021 dataset. Using this approach, we first analyzed the battle of Bakhmut, one of the longest and bloodiest of the war, which began on October 8, 2022, and ended with the Russian victory on May 20, 2023.
When Hang Xu showed Teng Wang and me the data he had processed, we were confused. We saw a checkerboard pattern across the city. We quickly realized the horror of the situation. The only thing that survived the year-long battle was the city’s road network. All the buildings partially or completely collapsed due to the continuous bombing.
We then looked at the battles of Rubizhne, Siievierodonetsk and Lysychansk which began in April 2022 and ended with a Russian victory on July 2, 2022. The relatively lower destruction of Lysychansk is explained by the rapid encirclement of the city to the south instead. of continuous frontal attacks, as in Bakhmut. The radar data reveals destruction away from the front line within cities, showing the full extent of the destruction.
Annihilation in focus
Remotely sensed imagery offers ways to safely monitor the impact of armed conflicts, especially as high-intensity wars increase in urban environments. Open access satellite instruments complement other forms of open source information by offering unfettered access to high-resolution, unbiased information that can help people understand the real impact of war on the ground.
The picture is clear: The real story is the war of destruction.
This article is republished from The Conversation, a non-profit, independent news organization that brings you facts and analysis to help you make sense of our complex world.
It was written by Sylvain Barbot, USC Dornsife College of Letters, Arts and Sciences.
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Sylvain Barbot receives funding from the National Science Foundation.
