Badgers spend a lot of time underground, which make it difficult for biologists and zoologists to track their whereabouts and activities. GPS, for example, doesn’t work well underground or in enclosed areas. But about five years ago, University of Oxford researchers Andrew Markham and Niki Trigoni solved that problem by inventing a wireless tracking system that can work underground. Their system is clever, but they didn’t do it alone. Like many other scientists, they turned to open source to avoid having to rebuild fundamental components from scratch. One building block they used is an open source operating system called Contiki.