Large-scale flooding caused by heavy rains in Germany and devastating landslides in the popular Japanese tourist resort of Atami are just two examples of an increasing number of natural disasters being caused by changes in the world’s climate. In response, the use of satellites, especially Synthetic Aperture Radar (SAR) satellites, is being looked at as a way of helping to minimize the damage caused by such disasters, and to save as many lives as possible.
SAR satellites emit microwaves aimed at observation targets and receive radio waves that bounced back from these targets. By creating images from the received data, it is possible to develop a detailed image of ground surface at any hour of the day or night, under any weather conditions, something which is not possible with conventional optical satellites.
Previously, a limited number of satellites meant disaster sites could only be observed once every few weeks, which also meant the unit price of the imaging data itself was high. But an expansion in the number of satellites in orbit and a big reduction in their size is enabling an increase in coverage and a reduction in costs.
Miniaturization reduces cost
The high levels of power consumed by satellites has made miniaturization difficult. However, owing to recent technological innovations and developments, satellites can now be manufactured to weigh as little as 100kg (conventional SAR satellites weigh between 1,000 and 2,000 kgs). These smaller satellites can then be grouped into constellations, systems which operate multiple satellites in cooperation with each other, which helps to provide more frequent coverage of incidents and disasters.
With these technological innovations, many private start-ups have been founded and are participating in space development and creating constellations. This was originally, a very costly process. These innovations have the potential to help develop countermeasures in the event of an environmental disaster.
SAR constellations and disaster relief efforts
In the event of a natural disaster, it is of utmost importance to accurately understand the current situation of the affected area so appropriate decisions can be made to minimize damage. Currently, information comes in through various information routes such as ground sensors and social media. However, information about areas that cannot be easily accessed is fragmented and often fails to provide important information.
The situation in a wide area is normally analyzed by using data from airplanes and drones, after any adverse weather has cleared up and when it is safe to fly again. But the construction of small SAR satellite constellations will enable wide-area observations of most areas on the planet, once every few hours and regardless of weather conditions and time of day. Central and local governments will be able to grasp the situation at disaster-stricken areas in real-time with dramatically improved imaging frequency. This will enable the authorities to take appropriate initial actions and prioritize relief activities. In the private sector, insurance companies can receive real-time data on the inundation range and inundation depth of disaster areas, leading to faster payment of insurance claims to victims. Furthermore, data can be acquired at fixed points for a long time after a disaster which will provide vital data for understanding causes and for planning preventative measures in the future.
The small SAR satellite business is still in its early phase. However, it is expected to be used not only for disaster countermeasures but also in various other fields in the future. We can see the world they could not see before. By having the ability to make frequent observations (once every few hours), we’re able to make data-driven decisions that were previously based on personal rules. SAR satellites have great potential, and we expect to see them become invaluable to operations in a variety of situations and across a range of industries.