Bench Talk

When I think of the International Space Station (ISS), I think of smiling astronauts giving TV interviews while floating weightless in some sort of tube. Meanwhile, the rest of us wonder "what exactly are they doing up there"? Well, it should come as no surprise to you that the Internet of Things (IoT) has finally reached space. Thankfully, it's not connected to the space station's refrigerator. Instead the astronauts are testing a re-entry technology called an Exo-Brake. The Exo-Brake is similar to a parachute, but it is designed to operate both in low-pressure atmospheres and light payloads – for example, sending a small spacecraft from the ISS into a safe re-entry to Earth. Whereas a regular parachute would have too much drag for this situation, an Exo-Brake is perfect for small payloads.

So, when the ISS needs to send a few small samples back to Earth, instead of taking a ride on the next spacecraft, a small vehicle the size of a refrigerator can be separated from the ISS, sent into a re-entry trajectory, and the Exo-Brake deployed. Got it?

So NASA launched Black Brant IX, whose mission was to hunt down Jason Bourne and bring him back to.. no, wait, wrong mission. The Black Brant IX is a small rocket whose mission was to barely touch the tip of space, then release a payload for the Exo-Brake to bring safely back to Earth. The Black Brant series of research rockets are low-altitude vehicles designed for simple, automated scientific experiments.

To do this properly, data had to be collected. NASA is filled with engineers, and us engineers love collecting data. So after a number of wireless options were considered, the protocol finally settled upon was ZigBee.

It was decided that the most effective way to do this was to use the XBee-Pro ZigBee modules from Digi International. One XBee ZigBee module sensed temperature and pressure in the nose cone of the rocket, another sensed 3-axis acceleration and deceleration of the payload, and a third took temperature and pressure readings of the surface of the Exo-Brake. The ZigBee wireless mesh network formed by these three XBee modules made its way to a fourth XBee module in the payload itself, which was connected to an Arduino Mega 2560 board with an Iridium satellite communications module.

The Arduino board sent data back to Earth by – get this – an email. How do I sign up for that distribution list?

A parachute is an example of something that you can’t just run wires to, so a wireless network was the answer. This was the first ZigBee network in space. This, to me, is exciting – we now have commercial-grade semiconductors robust enough to send into space. Of course, all kinds of tests were done on Digi’s parts such as vacuum tolerance and extreme temperature sensing. But it brings to me a sense of how, what was once my hobby, then my passion, and now my occupation, has been made accessable by anyone. Any of us can put our fingerprints on components that can be easily ordered online, and know that these are now the same components that are being used in space.

Find out how YOU can help the ISS with your designs! Check out our ISS Design Challenge for a chance to have your project 3-D printed... IN SPAAAAAAAAAACE!