More than 30 years after it was launched, NASA’s Voyager 1 probe is preparing to become the first manmade object to reach interstellar space. The probe has recently entered the so-called ‘stagnation zone’ 11bn miles from the sun, and should hit interstellar space well before its batteries run out in the year 2020.
The stagnation zone is the area where the sun’s solar winds become less evident and other forces from outside start to enter. Voyager 1 is still capable of communicating with Earth and NASA is expecting to learn a great deal about this zone over the next couple of years.
NASA will not be exactly sure when Voyager 1 enters interstellar space, because it’s not known precisely what the telltale signs might be. It’s expected that there will be a change in the magnetic field direction, and that interstellar wind will prove to be slower, colder and denser than solar wind.