In 2015, The Raspberry Pi Foundation built two space-hardened Raspberry Pi units, or Astro Pis, to run student code on board the International Space Station (ISS).
Astro Pi upgrades
Each school year we run an Astro Pi challenge to find the next generation of space scientists to program them. After the students have their code run in space, any output files are downloaded to ground and returned to them for analysis.
That download process was originally accomplished by an astronaut shutting down the Astro Pi, moving its micro SD card to a crew laptop and copying over the files manually. This used about 20 minutes of precious crew time.
Last year, we passed the qualification to allow the Astro Pi computers to be connected to the Local Area Network (LAN) on board the ISS. This allows us to remotely access them from the ground, upload student code and download the results without having to involve the crew.
This year, we have been preparing a new payload to upgrade the operational capabilities of the Astro Pi units.
The payload consists of the following items:
- 2 × USB WiFi dongles
- 5 × optical filters
- 4 × 32GB micro SD cards
Before anyone asks – no, we’re not going outside into the vacuum of space!
USB WiFi dongle
Currently both Astro Pi units are located in the European Columbus module. They’re even visible on Google Street View (pan down and right)! You can see that we’ve created a bit of a bird’s nest of wires behind them.
The decision to add WiFi capability is partly to clean up the cabling situation, but mainly so that the Astro Pi units can be deployed in ISS locations other than the Columbus module, where we won’t have access to an Ethernet switch.
The Raspberry Pi used in the Astro Pi flight units is the B+ (released in 2014), which does not have any built in wireless connectivity, so we need to use a USB dongle. This particular D-Link dongle was recommended by the European Space Agency (ESA) because a number of other payloads are already using it.
Plans have been made for one of the Astro Pi units to be deployed on an Earth-facing window, to allow Earth-observation student experiments. This is where WiFi connectivity will be required to maintain LAN access for ground control.
With Earth-observation experiments in mind, we are also sending some flexible film optical filters. These are made from the same material as the blue square which is shipped with the Pi NoIR camera module, as noted in this post from when the product was launched. You can find the data sheet here.
To permit the filter to be easily attached to the Astro Pi unit, the film is laser-cut to friction-fit onto the 12 inner heatsink pins on the base, so that the camera aperture is covered.
32GB micro SD cards
A consequence of running Earth observation experiments is a dramatic increase in the amount of disk space needed. To avoid a high frequency of commanding windows to download imagery to ground, we’re also flying some larger 32GB micro SD cards to replace the current 8GB cards.
This particular type of micro SD card is X-ray proof, waterproof, and resistant to magnetism and heat. Operationally speaking there is no difference, other than the additional available disk space.
The micro SD cards will be flown with a security-hardened version of Raspbian pre-installed.
We have several crew activities planned for when this payload arrives on the ISS. These include the installation of the upgrade items on both Astro Pi units; moving one of the units from Columbus to an earth-facing window (possibly in Node 2); and then moving it back a few weeks later.
Currently it is expected that these activities will be carried out by German ESA astronaut Alexander Gerst who launches to the ISS next year (and will also be the ISS commander for Expedition 57).
We are targeting a January 2018 launch date for the payload. The exact launch vehicle is yet to be determined, but it could be SpaceX CRS 14. We will update you closer to the time.
If you have any questions about this payload, how an item works, or why that specific model was chosen, please post them in the comments below, and we’ll try to answer them.