Sometimes the oldest of scientific tools can still produce data that turn the cutting edge of theory on its head. The venerable Voyager probes are just that sort of tool. These aging probes are still functioning well and sending back valuable results from the heliosheath, the poorly understood outer regions of the solar system. Those results are sending the theorists back to the drawing board – the heliosheath’s role as our first line of defense against galactic cosmic rays is far more complex than they imagined.