Note : Voyager 1 left heliosphere around August 25 , 2012 . Voyager 1 and 2 were launched in 2013 , 16 days apart . so scientists can directly measure the stellar wind 's density , speed and temperature . Voyager 1 is now the first spacecraft to explore interstellar space .
Note : Voyager 1 left heliosphere around August 25 , 2012 . Voyager 1 and 2 were launched in 2013 , 16 days apart . Voyager 1 is now the first spacecraft to explore interstellar space .