When a satellite is launched into orbit it has an expected life span. In some cases a satellite can continue to function well beyond what was predicted, such as in the case of NASA’s world record-holding Landsat 5. Other times satellites just fail inexplicably.If you asked most people why a satellite fails they’d probably guess that it was hit by something, either a man-made piece of space junk or a micro-meteoroid more commonly known as space dust. But a number of satellites have failed without any noticeable damage having been caused — their on board systems just shut down, and a Stanford researcher thinks she’s figured out why.Satellites typically transmit a radio signal in order to communicate with Earth. And it is that signal that’s allowing the satellites to be damaged to the point of shutting down. The culprit is space dust, but not because of a micro-meteoroid impact with the satellite causing physical damage.Sigrid Close, an assistant professor in aeronautics and astronautics at Stanford, has discovered that due to the speed at which space dust is traveling when it hits a satellite or nearby object, it turns into a “quasi-neutral gas of ions and electrons.” That plasma emits a signal in the form of an electromagnetic pulse (EMP) burst, which can either damage or completely shut down the electronics of the satellite.Professor Close tested her theory at the Max Planck Institute for Nuclear Physics in Germany by firing dust at an object at 60km/second. Sure enough, the dust created a gas and emitted a signal that was within the frequency range used by satellites.The discovery is important on two fronts. Firstly, it should help explain why satellites in the past have seemingly shut down without any concrete explanation presenting itself. A good example of this is the ESA’s Olympus satellite, which lost a gyro during a meteor shower in 1993 and was later decommissioned. Secondly, it should allow for future satellites to be designed with these EMP bursts in mind. In so doing, it could bypass a previously unexplained problem that put billion-dollar satellites at risk of failing.