\" \" Voyager, the interstellar traveler NASA/JPL-CaltechIn 1977, Voyager 2 launched from Earth to carry out an unprecedented mission to the outer solar system. Mission controllers were alerted to Voyager 2 entering interstellar space in November when its instruments detected a dramatic change in the space particles surrounding the spacecraft. In 2012, Voyager 1 also detected a steep decline in solar wind particle counts, signifying that it was the first of the pair to reach interstellar space. \"There is still a lot to learn about the region of interstellar space immediately beyond the heliopause,\" said Ed Stone in the accompanying NASA/JPL press release. For example, NASA's Interstellar Boundary Explorer (IBEX) that is in Earth orbit is observing the interface between the heliosphere and interstellar space and trying to help astrophysicists understand how the interstellar medium interacts with the heliosphere as our solar system travels through interstellar space.