Satellites do much more than to offer us astonishing photographs of space. Some of them, like the European Space Agency’s Sentinel-1 satellites, save lives. This ESA’s mission monitors the Earth day and night: it has witnessed the birth of a gigantic iceberg, helped locating the seismic fault in a Sea earthquake; or monitored glaciers in the Alps to help us understand how landslides work and helping us fight against disasters. It also provides access to remote areas, where we can’t place sensors. And the microwave radar imaging technology on board of Sentinel-1 allows scientists to have a peek of the ground through the clouds, even on the darkest nights.
The Sentinel-1 images not only allow us to have eyes in disasters that occur in remote zones, it gathers a global view of the state of the disaster with a great amount of detail. In its higher definition mode, it provides a 5 meter resolution image. The mission is composed by two satellites, which guarantees a great response speed: at European latitudes it revisits the same area about every three days. This is why this never sleeping sentry is so interesting for our project and why we needed the efforts of our partners from the Remote Sensing Research group of TU Wien. Thanks to them we will be able to incorporate the Sentinel-1 radar images into our system.
All this activity generates up to 3 Terabytes every 24 hours. This is the equivalent of creating 40 high definition movies… each day! Processing all this information can’t be done in a regular laptop. It requires the use of a supercomputer. The Remote Sensing Research group uses a supercomputer—the Vienna Scientific Cluster—to analyse the Sentinel-1 data. Thanks to the computational power of this supercomputer, they are able to compare the latest Sentinel-1 images to all past data, that form a picture of a “normal looking” Earth. This allows them to create change maps that depict flooding, deforestation and other such drastic events.
But surprisingly, this daily amount of new information is not the one thing that poses the heaviest toll for computers. Establishing this “normal looking” Earth picture isn’t as easy as it sounds. Just think on the view you have through a window in your home: it changes a lot from spring through winter and from one year to another. What constitutes normal and what is out of line? To account for changes in the terrain, and the different looks that the Earth offers throughout the year, our colleagues at TU Wien are using the data already obtained by the Sentinel-1 in the past 3 years and the data obtained by the ENVISAT satellite, a past mission that went on between 2002 and 2012. Together, they constitute 1000 TB of images, more than 13000 high resolution movies. That’s certainly a lot of Netflix to catch up, so no wonder that a supercomputer is needed for analysing this huge database automatically.
Only a decade ago, this kind of technology seemed like science fiction. Today, we are integrating satellites, supercomputers and many other cyber-technologies to fight against disasters.