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Arcsec star simulator for nanosatellite attitude testing

Client: Arcsec · Sector: Space

Arcsec logo on a starry sky with a spiral galaxy

Arcsec is a high-tech spin-off of KU Leuven with sixteen employees. The company develops attitude control systems for small satellites, known as nanosatellites. These systems let a satellite work out for itself how it is oriented in space by recognizing the stars it sees. They are used in both academic and industrial space missions.

A system like that has to be validated very precisely, and the real night sky is not a practical place to do it. Arcsec was therefore looking for a way to test its systems realistically on Earth, and that is how they ended up with us.

The challenge

Building a test setup that convincingly reproduces the night sky turned out to be no small task. The Arcsec team is strong in space R&D, but had no experience building this kind of simulator. Developing it in-house would also have pulled R&D capacity away from their core activities, with the risk of delays and higher costs.

The simulator had to meet three requirements:

  • the image had to be visually realistic;
  • it had to run smoothly on limited embedded hardware;
  • operating it had to be simple and intuitive.

Without such a test platform, validation phases would take longer and Arcsec would not be able to verify the reliability of its systems under realistic conditions. So the company looked for an external partner to build the simulator.

The result

Arcsec now has a realistic, compact and reliable test setup for its optical attitude control systems. The simulator displays realistic star patterns, so Arcsec can validate the performance of the satellite software on Earth, long before a satellite is launched. And because we built the simulator, Arcsec’s R&D team could stay focused on its own systems.

What we built

The star simulator: a web application controls the rendering in C++ and SDL2, which shows the night sky on a display for the satellite's sensor CONTROL Web application Runs on the device itself In the browser STAR SIMULATOR Compact, closed enclosure Rendering C++ and SDL2 Electronics board with high-resolution display stars ARCSEC Attitude system Recognizes the stars and derives its orientation
Figure 1. The night sky on a screen.The simulator shows the image the satellite would see in space. Arcsec's attitude system looks at that screen as if it were looking at the real stars.

Hardware in a closed enclosure

The simulator consists of a compact electronics board with enough computing power, connected to a high-resolution display. We designed the whole thing into a compact, closed enclosure.

Rendering in C++ and SDL2

The star images are rendered in C++ with SDL2, so they appear smoothly and sharply on the display even on the limited embedded hardware. The display shows exactly the image the satellite will see in space, and the attitude system can orient itself on it.

A web application for control

For operating the simulator we developed a lightweight web application that runs on the device itself. Users control the simulator through a simple, user-friendly interface.

How we worked together

We worked closely with Arcsec’s R&D team. We started by translating their technical requirements into a feasible architecture, and then built, tested and optimized in short cycles. Working that close to the team meant we could adjust quickly and contribute ideas on both the approach and the execution.

This allowed us to deliver, in a technically demanding environment, a combination of hardware and software that met all of Arcsec’s functional requirements. Taking on the web application for control as well was an extra advantage for Arcsec: they got the complete simulator from a single partner.

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