For the last 37 years now, folks have been gathering in Utah every August to talk about satellites. Last week, some of us headed out to join them at Utah State University (USU) and attended this year’s Small Satellite Conference.
Over the last decade or so the definition of what a ‘small satellite’ is has ballooned beyond the original cubesat design specification to embrace satellites of 50 or 100 kg or more. Today a ‘smallsat’ is defined far more by its cost, and sometimes the technologies used, than the size and shape of the box that goes into orbit; and over the next few years the number of small satellites in orbit is going to rise exponentially.
With multiple companies — like SpaceX, Amazon, and OneWeb — planning Low Earth Orbit (LEO) communications networks, and others — like Planet Labs — building constellations of Earth Observation satellites, thousands of smaller satellites are going to get boosted into orbit throughout the next decade.
Taking Raspberry Pi into orbit
Small satellite builders are using a lot more off-the-shelf technology than the old-school aerospace companies. While that inevitably means more on-orbit failures, the cost of production of a small satellite is so much lower than a traditionally sized payload that it’s actually an acceptable trade-off. Off-the-shelf technology also means that the barriers to entry to building a satellite are considerably lower, and development times are correspondingly shorter.
Which is where we come in. There has been Raspberry Pi hardware in orbit since at least 2015, when two space-hardened Raspberry Pi B+ computers, equipped with environmental sensors and a Camera Module used for Earth observation, were sent to the ISS as part of ESA’s AstroPi programme.
AstroPi doing Earth observation onboard the International Space Station
However the first satellite, at least as far as we know, to be built entirely around a Raspberry Pi was launched just last year. A 1U CubeSat built by students from USU, the GASPACS satellite was a “Get Away Special.” It operated on orbit for 117 days, from deployment from the ISS in late January 2022 until its reentry later that year.
Intended as a technology demonstration mission, the satellite tested deployment of a metre-long inflatable boom for passive attitude stabilisation. A Raspberry Pi Zero was used as the satellite’s flight computer, while a Raspberry Pi Camera Module was used to take pictures of the boom deployment.
It was a real privilege to meet with the GASPACS team on their home turf, to have played a small part in getting them into orbit, and to hear more about their next satellite, GASRATS, while we were at SmallSat.
Whither the weather?
While some of us were out in Utah, our Maker in Residence Toby got left behind at Pi Towers, so he started looking skyward for inspiration for his next tutorial. But, looking up during a British summer inevitably means you get rained on. Fortunately, that was the inspiration he needed. Because it turns out don’t have to go to Utah, or LEO, to start working with satellites. It was time to build a Raspberry Pi-powered satellite ground station!
Toby set to work making a suitable antenna from a combination of plumbing materials in the form of copper and plastic piping, some 3D-printed parts, a Raspberry Pi 4 model B and a cheap USB Software Defined Radio (SDR). Keen readers will notice that this is the exact same low-cost SDR Toby used previously to build our own Raspberry Pi flight tracker.
The new tutorial covers everything you need to know about making your own antenna. You’ll get step-by-step instructions and free STL files for making the 3D printed parts. As well as adding strength to the antenna, these 3D printed parts will hold the conductors in the right position and orientation to make assembly much more straightforward than some of the other builds we’ve seen.
We walk you through the set-up process for your Raspberry Pi once your antenna build is done, then how to install the open source software called raspberry-noaa-v2. With the SDR on our Raspberry Pi, we’re able to decode signals from orbiting weather satellites and make images of the weather.
After installing the software and setting up the antenna outside, we’ll show you how to get some usable data using the webserver now running on your Raspberry Pi.
The community of experienced engineers, radio operators, and tinkerers that contributed to the success of the open source raspberry-noaa-v2 software did a great job of making the setup of your weather station as easy as possible. The software shows you all the relevant satellite positions overhead and sets your system to record signals whenever a satellite passes over your location.
The results are impressive. You’ll see various representations of data depicting different aspects of current weather conditions. For example, the following image shows cloud cover with enhanced emphasis on rainfall shown in bright green and yellow:
Where this is an image based on just temperature:
While Toby’s tutorial focuses on receiving data from weather satellites, the principles apply to other satellite types, like cubesats. A weather satellite ground station is not just a standalone project, but could be the start of a journey into space.
To infinity and beyond
It turns out that the GASPACS team aren’t alone in using Raspberry Pi on orbit. We’ll be talking more about some of the Raspberry Pi news we uncovered at this year’s SmallSat (there was a lot) over the coming months, as we’re given permission to talk more about some of those projects.
To build on our expanding flight heritage we’re currently looking into formal vacuum and radiation testing for our Raspberry Pi boards and cameras to better support people using our hardware in space, so if you’re building your satellites or your ground stations around our hardware we want to hear from you.
Because it turns out Jeff Bezos’ now infamous statement that “there’s not that much interesting about cubesats” has turned out to be the twenty-first century’s “nobody needs more than 640kb.”
