Finnish start-up Iceye says it is the first company to use a small satellite equipped with synthetic-aperture radar technology to create an image with a ground resolution of less than one meter.
Iceye has published an image showing a container terminal in the Nigerian port of Port Harcourt. A resolution of half a meter has been achieved. Such resolution is normally only available for larger, more powerful satellites. However, Iceye has achieved this with the company’s three satellites launched, each weighing less than 100kg and the size of a suitcase. For comparison, the Finnish company has also posted an optical image of the same port container terminal, which was taken with the Copernicus Sentinel-2 satellite. That is an observation satellite of the ESA that weighs 1140 kg.
The Finnish company uses synthetic-aperture radar technology on its current three satellites. That makes it possible to take pictures at any time, both at night and during the day and clouds or rain are not an obstacle. In Sar technology, the synthetic-aperture part represents the concept of moving the sar instruments to map a specific area with radio waves. This differs from the situation where a very large instrument maps an area only once. To obtain the movement, sar instruments are often placed on satellites or aircraft.
The technology, as it were, synthetically increases the size of the antenna by increasing the azimuth resolution. The Doppler effect plays a role in this. The distance between the satellite’s radar antenna and the various reflection points on the Earth’s surface is measured and then processed into images that can be read and recognized. Thus, the resolution is increased by combining many images of the moving satellite. Smooth surfaces do not reflect radio waves back to the antenna and therefore appear black on sar images. This makes ships at sea clearly visible, for example, but also small objects can be displayed well, according to Iceeye.
The Iceye-X2 satellite launched on December 3 with a Falcon 9 rocket from SpaceX.
Iceye plans to have a total of five satellites in space later this year. In January 2018, the very first satellite went up and numbers two and three followed last month. Two more are to be launched later this year, Iceye co-founder Pekka Laurila told Ars Technica. Earlier, the company indicated through the CEO that it wants to have a network of eighteen satellites in the air by 2020. CEO Rafal Modrzewski told CNBC in December last year that it was necessary to launch at least eight satellites in 2019 to meet the target of 18 satellites by 2020. Because Laurila is now talking about launching five satellites for the whole of 2019, that originally desired goal will not be achieved within the set time frame.
According to Modrzewski, once six satellites are in orbit, Iceye can set up a commercial service that makes it possible to take two images of exactly the same place on Earth within 24 hours. As a result, even very small changes or deviations are visible. The CEO said in December that there were no satellites yet that could guarantee such a “global 24-hour repeat service.”
The first image from the Iceye-X2 satellite showing the Spanish Aralar and Aizkorri-Aratz Natural Parks. This photo was taken on December 7, 2018. Here the resolution is still 3x3m.