Viewing: Pi’s in Space!

Pi’s in Space!

Last night two Raspberry Pi computers were launched into space on board the Cygnus spacecraft which will rendezvous with the International Space Station on 19th December.  These "Astro Pi's" are standard model B+ Raspberry Pi's but have been augmented with extra sensors and are each inside a special flight case.    

When British ESA astronaut Tim Peake arrives at the Space Station he'll be using the Astro Pi's and their sensors to run experiments.  But while all the other computers on board the ISS have been programmed by professional scientists and software engineers, most of the code on the Astro Pi's was written by UK school students (read more about the programs here).

clairepisquareLast week I got the chance to visit Raspberry Pi headquarters in Cambridge and meet some of the Astro Pi team.  The photo above shows the Astro Pi displaying the flag of the country the ISS was currently travelling above.  Here's a short video of it in action:  

I also got to try out the "Crew Detector" program (working title: "How Sweaty is my Astronaut?").  This works by detecting changes in humidity in the environment – when the astronauts are exercising, for example.  It then scrolls a message across asking if anyone's there and, if the astronauts press a button to confirm, it will trigger the camera enabling them to take a "space-selfie". (Being more lazy than the average astronaut I just triggered it by breathing on it a couple of times).

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The most surprising thing about the Astro Pi was that the back of the flight case looks like a giant heat-sink: this turned out to be because it is a giant heat-sink.  Because there's no gravity on the ISS heat won't be carried away by the heated air rising when cooler air sinks – as it is on Earth.  This means that even the tiny amount of heat the Pi produces could lead to the flight case heating up to over the maximum 45  degrees Celcius allowed on the ISS.

As well as the giant heat sink, the Astro Pi's circuitry has been coated in a protective layer of varnish.  This is because the solder joints may suffer from a phenomenon known as "tin whiskers" where fine strands of tin start to grow out of the surface of the metal.  If these break off – particularly on the ISS where they can then float about – they can cause short circuits.

Thanks to Helen and Dave at Raspberry Pi for letting me come in and see behind the scenes! You can follow the adventures of Tim Peake and the Astro Pi's over here.  Best wishes from CoderDojo Scotland for the mission!

Claire Quigley
CoderDojo Scotland

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