Sensor network on board of ISS secures air quality
Initially the tiny sensor network module was intended to be operational at ISS for just six weeks – the battery limited its lifetime. Instead, the measurement campaign lasted almost ten weeks, from New Year’s Eve 2014 through March 12, 2015. The WiseNet module utilised the infrastructure of the Magvector/MFX magnetic field experiment, also developed by the DLR. The experiment includes a network of four sensors the size of a matchbox each, measuring temperature, air humidity and light intensity at various locations across the ISS Columbus module. Besides collecting the measurement data, the system also generates a statistical overview over the quality of the radio network. In addition, the data are transmitted to the ground stations. Now do they exhibit certain patterns? "The evaluation of the data over a period of ten weeks shows one pattern: everything is in the green", said ADS project manager Hans-Jörg Bestermöller. "The temperature is pretty exact 24 degrees celsius, air humidity is 45% and the pressure is around 1002 hectopascal". Only on January 3, the system reported a deviation of all three parameters – humidity and pressure increased sharply while at the same time the temperature dropped significantly. "We now have to find out what was the reason," says Bestermöller.
The WiseNet sensors thus can warn and protect the ISS crew of possible threats. An exception was the ammonia gas alarm issued at the space station on January 14. Though it turned out that it was just was the result of a computer malfunction and that no real hazard existed, the idea for a potential next generation of WiseNet sensors include a gas sensing system. Multiple sensors distributed across the station could enable the crew to quickly find and fix potential gas leaks. In addition, the WiseNet developers mull the idea of equipping the system with energy harvesting mechanisms. Then the battery would no longer determine the lifetime of the sensors.
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