South African satellites could soon be in orbit providing almost continuous real-time remote radar sensing of the continent. This would give defence and intelligence services new capabilities to keep an eye on the region and also help in many other tasks such as infrastructure and crop monitoring, as well as disaster management.
The first satellite, which could be used as a demonstrator, might be launched in about 2025, said the government’s technology development house, the Council for Scientific and Industrial Research (CSIR). The CSIR, which is manging the development of the radar systems for the satellites, and its two local private firm partners (SCS Space and Dragonfly Aerospace) also want to use the project to sell remote sensing images, mass produced circuit boards for space radar systems, and satellite structures to global clients.
The South African satellites will use synthetic aperture radar (SAR), which unlike conventional radar, does not require a large moving parabola shaped dish. SAR antennas are placed on flat panels in arrays outside the main body of the satellite and capture imagery as the satellite moves over earth in its orbit. In order to capture images, solid state transistors on the panels emit pulses as they cross the ground. The reflection of these pulses from the earth are recorded and an image is then made.
Helping the project make economic sense is that over the past few years strong competition in the space launch market has lowered the costs of putting satellites into orbit. Due to its advantages over optical imaging, there is fast growing demand for remote sensing radar. Unlike optical sensing, radar can be used during the day and night and can see through all sorts of weather.
A widening number of applications for remote sensing radar has driven the strong growth of this market segment. The technology has been finding new uses as the need for different types of monitoring emerge.
So far the project has been funded by the Department of Science and Innovation, which wants to help develop local technology that can make an economic contribution to the country. Now that the design and engineering of key aspects of the project has been tested by the CSIR, the future of the project will depend on finding additional financing. The partners are talking about funding with various South African government agencies, potential clients who might want their own satellite constellations, and international investors.
The business case for the satellite constellation is that it will be able to provide nearly continuous imagery to African clients in almost real-time, something that is not presently available. It will also greatly reduce the cost of remote sensing radar imagery for bulk government users. The project will potentially be able to generate revenue from the global market from the sale of the imagery, the technology for SAR payloads and the construction of micro-satellite buses – the satellite structure and avionics.
A number of private European and US companies such as Capella Space and ICEYE already have satellites that provide remote sensing radar imagery to customers. Purchasing imagery from private providers is highly expensive and delivery can take time, as there are no satellites that continually orbit the continent with this capability.
With key design, engineering, and testing work now complete, the next stage will be to manufacture the boards for the radar system and the satellites in South Africa. The flat synthetic aperture radar panels that will be mounted to the satellites have been tested in an environment that replicates that in low-earth orbit, and also flown on an unmanned aerial vehicle (UAV).
Unlike most space borne synthetic aperture radars, which operate on the X band wavelengths, SA’s system will use the C-band. The CSIR said that for most uses, this makes little difference, although the X band provides higher resolution. But the C band has advantages in such areas as soil moisture and crop monitoring.
Willie Nel, the CSIR’s Chief Radar Systems Engineer, who leads the technology development on the radar payload project, said many components in C-band systems can be assembled from off the shelf components that are used in the WiFi and cell phone markets, and are a lot less expensive than parts used for X-band systems. Nel said there are also a number of potential customers who want to use C-band technology.
The CSIR’s partners are Stellenbosch based aerospace companies Dragonfly Aerospace and SCS Space. Dragonfly makes the structure and avionics of satellites (buses). SCS provides consulting services for satellite development. A private company, FleetSAR, headed by the managing director of SCS, Sias Mostert, has been established to manage the construction and launch of the FleetSAR constellation of satellites. There are a number of companies such as SpaceX as well as international government agencies which could launch the satellites in packs of three.
“Over the next 15 to 20 years, low-earth orbit observation systems will become a massive business, and SA needs to be in on that action. Otherwise it will be yet another thing we just import, rather than creating an industry that exports and creates jobs,” said Nel.
