A positioning receiver designed by researchers at ETH Zürich and based on four u-blox receiver modules is now in orbit onboard an Astrocast nanosatellite.
For a few seconds, everyone watching the live stream at the SwissTech Convention Center (EPFL) held their breath as the SpaceX Falcon 9 rocket of Spaceflight SSO-A: SmallSat Express mission took off towards low Earth orbit from Space Launch Complex 4E (SLC-4E) at Vandenberg Air Force Base in California, USA. The rocket’s payload included a CubeSat nanosatellite designed by Astrocast, a prototype to test the 64-satellite constellation the Swiss company intends to seed into orbit to provide a global communication satellite network for remote IoT and M2M applications.
Among the many prototypes onboard the nanosatellite was a world premiere: a small, relatively low-cost GNSS receiver board. Based on four u‑blox NEO-M8T GNSS modules with experimental firmware, the board was designed by a team of researchers from ETH Zurich’s Institute of Geodesy and Photogrammetry, led by Professor Markus Rothacher.
Tailored specifically to extraterrestrial operation, the board weighs in at under 100 grams, costs less than US$ 1000, and cuts power consumption compared to standard space-compliant GNSS receivers, typically with a price tag of hundreds of thousands of US$ – by a factor of 20.
As down here on earth, GNSS has become an indispensable tool in space missions. Earth observation missions, for example, depend on accurate information of the satellite’s position when data is sensed remotely. Accurate timing information is equally important. The receiver board by Rothacher’s team was designed with these objectives in mind.
Once it is circling the earth at around 575 km altitude, experiencing a sunrise roughly every 100 minutes, the GNSS receiver board will be used to determine the nanosatellite’s precise orbit in real-time. Determining the precise altitude in real-time is particularly relevant when the nanosatellite uses its propulsion system to move to new orbits.
Combining four GNSS modules on a single board offers two main advantages. For one, they can be connected to two antennas, each looking into different directions. Additionally, it offers a level of redundancy: should one GNSS receiver fail, another will be there to replace it.
In addition to being the GNSS receiver with the lowest power consumption flying in space, the board will also be the first to track all of the major GNSS constellations in parallel. If everything goes according to plan, it will remain operational for at least 24 months, gathering valuable data, expertise, and paving the way for exciting new satellite-based applications.
This is the first time for one of our modules to enter orbit, and it’s hard not to get caught up in the excitement surrounding the launch. Not only will the mission offer insight into the positioning accuracy we can expect when in orbit, it will also be an opportunity to test the longevity of our standard hardware in a vastly different real-world environment, where near-zero pressure and the constant bombardment by charged particles carried by cosmic and solar winds. On top of that, the modules will be subject to extreme temperatures and extreme vibrations and accelerations during the launch phase.
For a few months, we expect the experiment to deliver valuable insights into the quality and reliability of our products, until the harsh space environment takes its toll on our hardware, which was designed for the more benign conditions here on earth.
Contributing to academic research projects like this one feeds our curiosity and exposes products to new environments. At least just as importantly, it gives tomorrow’s engineers a chance to work with our hardware, whether they use them to monitor glaciers or landslides, shoot into the sky in a student rocket contest, or embed them into airplanes or drones for real-time positioning. And, finally, who doesn’t dream of building something and shooting it into orbit?
 ETH Globe 3/2018, Geodesy, Intelligent positioning for low-cost nanosatellites