- DLR is developing distributed and heterogeneous on-board computers for future space missions.
- Combination of radiation-resistant and commercially available processors that monitor each other and redistribute tasks in the event of an error.
- Successful experiment with Earth observation data on an ESA test satellite.
- Focus: space travel, earth observation, technology
Reliable and powerful computers play a central role in space travel: computer systems in satellites, for example, enable demanding earth observation missions. The German Aerospace Center (DLR) is developing a new computer architecture that is intended to give the so-called on-board computers (OBC) more power and also enable them to repair themselves. Distributed heterogeneous OBCs are being developed in the ScOSA (Scalable On-Board Computing for Space Avionics) flight experiment project. You have different computing nodes connected as a network.
A general challenge for computer systems in satellites is that cosmic rays can disrupt the computers. “When a radiation particle flies through a memory, it might turn a zero into a one there,” explains project manager Daniel Lüdtke from the DLR Institute for Software Technology in Braunschweig . Ultimately, the system can even fail or deliver incorrect results. Radiation-resistant processors are therefore available for space travel. However, these are very expensive and have little computing power. On the other hand, processors, such as those used for smartphones, are very powerful and also cheaper. However, they are much more susceptible to cosmic radiation. ScOSA brings both processor types together in one system.
Test run on the test platform OPS-SAT in low earth orbit
The software recognizes errors and failures and controls the computer. “Programs running on a faulty processor are automatically transferred to other processors via the network,” says Daniel Lüdtke. Meanwhile, the satellite continues to work. The software then restarts the processor and integrates it back into the system.
An experiment on the satellite has now shown that this works OPS-SAT of the European Space Agency ESA shown. “The 30 x 10 x 10 centimeter small satellite with an experimental computer has been in low-Earth orbit since the end of 2019. OPS-SAT is available to researchers as a full-featured open platform,” explains Dave Evans, ESA’s OPS-SAT Project Manager.
The DLR scientists installed and successfully tested the ScOSA software on OPS-SAT together with ESA. For this purpose, the satellite created earth observation images, processed and evaluated them with artificial intelligence. The satellite then transmits only the usable images to a ground station. “Increasingly higher resolution sensors and complex algorithms require more and more computing power,” Daniel Lüdtke summarizes the requirements for software and hardware. A larger ScOSA system consisting of radiation-resistant and commercially available processors will soon be tested on DLR’s own CubeSat: the small satellite is expected to be launched into orbit at the end of next year.
Development of software for space missions
The Onboard Software Systems Group from the DLR Institute of Software Technology participates in a number of national and international space missions. A central research topic is the development of error-tolerant and so-called resilient software that can react to errors and failures. The ScOSA flight experiment project is a DLR research project in which the Institute for Software Technology , the DLR Institutes for Space Systems and Optical Sensor Systems as well as DLR Space Operations and Astronaut Training are involved.