Since Russia began the invasion of Ukraine last week, the Twitter OSINT community, open-source investigators, and analysts, have been in full gear and many working around the clock. Volunteers and professionals (often both simultaneously) are verifying bits of information, tracking casualties and lost equipment, and geolocation airstrikes. I have participated in this Twitterverse myself but also spent an equal amount of time learning others and their methods. In a time when publicly available, high resolution, frequently updated, satellite imagery is non-existent for those on a budget, people have resorted to other remote sensing methods, namely radar or more specifically, Synthetic-Aperture Radar (SAR).
SAR imagery does not rely on the reflection of light from the earth’s surface to create detailed imagery, like other satellite imagery, meaning it can create images both night and day, clear sky or cloudy. In very basic terms, instead of using light as a source, it creates its own energy, sends that out, and records the energy that is reflected back at it from the Earth’s surface. For example, below you can see ships waiting to pass Port Said and the Suez Canal from Sentinel-1’s SAR.
Besides the ability to create images both during the day and night, there are several advantages and applicabilities of SAR imagery. Firstly, the frequency of imagery. You can find updated imagery of nearly every corner of the world every couple of days from the Sentinal-1 satellite. You can access these for free on several platforms, but Sentinel Hub is a good place to get started. You can use the Sentinel-1 imagery to monitor maritime traffic, track illegal fishing, oil spills and pollution, winds, ice sheets, and much, much more. However, in the last couple of weeks OSINT people have been using SAR imagery to closely monitor troop movements in and around Ukraine. @coreymaps on Twitter created a tool to monitor the 40-mile long convoy headed for Kyiv. Below is imagery taken by Capella Space.
If you are wondering, like I once did, how to read SAR imagery then here is a short tutorial I found helpful – or at least explains the very basics. If you know of any great investigations using SAR imagery or any other remote sensing technique, please feel free to send them to the email found here.