Reliable and powerful computers play a major role in space travel: for example, computer systems in satellites enable challenging Earth observation missions. The German Aerospace Center (DLR) is developing a new computing architecture that aims to give the so-called Onboard Computers (OBC) more power and also enable them to repair themselves.
Distributed heterogeneous OBCs are being developed in the ScosA Flight Experience Project (Onboard Scalable Computing for Space Avionics). You have different computing nodes connected as a network.
The general challenge to satellite computer systems is that cosmic rays can disrupt computers. “When a radioactive particle flies through memory, it may turn a zero into one there,” explains project manager Daniel Lüdtke of the DLR Institute for Software Technology in Braunschweig. Ultimately, the system can fail or give incorrect results. Therefore, radiation-resistant treatments are available for space travel. However, it is expensive and has little computing power. On the other hand, processors, such as those used in smartphones, are very powerful and also cheaper. However, they are more susceptible to cosmic radiation. ScOSA brings both types of processors together into one system.
Test run on the OPS-SAT test platform in low Earth orbit
The program recognizes errors and failures and takes control of the computer. “Programs that run on a faulty processor are automatically passed on to other processors across the network,” says Daniel Lüdtke. Meanwhile, the satellite continues to operate. The program then restarts the processor and integrates it back into the system.
An experiment on the European Space Agency’s OPS-SAT satellite showed this to work. “The 30 x 10 x 10 centimeter small satellite with an experimental computer has been in low Earth orbit since the end of 2019. Dave Evans, OPS-SAT Project Manager at ESA, explains that OPS-SAT is available to researchers as a full-featured open platform.
DLR scientists have successfully installed and tested the ScOSA software on an OPS-SAT with ESA. For this purpose, the satellite created, processed and evaluated Earth observation images with artificial intelligence. Then the satellite sends only usable images to a ground station. “High-resolution sensors and increasingly complex algorithms require more and more computing power,” Daniel Ludtek summarizes the software and hardware requirements. A larger, commercially available ScOSA system consisting of radioactive processors will soon be tested on the DLR’s CubeSat: the small satellite is expected to be launched into orbit at the end of next year.
Software development for space missions
The Onboard Software Systems group of the DLR Institute of Software Technology is involved in a number of national and international space missions. The central research topic is the development of bug-tolerant programs and so-called resilient programs that can react to bugs and failures. The ScOSA Flight Experiment Project is a DLR research project involving the Institute of Software Technology, the DLR Institute for Space Systems, the DLR Institute for Optical Sensor Systems, DLR Spaceflight Operations and Astronaut Training.
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