The science of satellite navigation and how it can be fooled or "spoofed", a new system to pinpoint a person within a building to within a metre, and how GPS signals can probe and track volcanic dust clouds. Plus, news of what nuclear bomb tests have revealed about the brain, why volcanoes might cause Parkinsonism, HPV and oral cancer and why we comfort-eat high fat foods when we get depressed...
As well as the primary GPS application of providing geographic location, GPS can be used in a secondary application of providing an accurate time reference. This is used in modern cellular phone networks to synchronise multiple transmitters covering overlapping areas to within 1 microsecond.
GPS is commonly used to lock SPGs (Sync Pulse Generators - the device used to lock all of the equipment in television facilities together) for accurate timecode.
Some GPS applications can be spoofed. There was a discussion of this on a recent CBC podcast called "Spark"