( CNN ) -- Hurtling across the Milky Way like an eternal explorer -- the Voyager 1 spacecraft continues to nonchalantly reveal the mysteries of the solar system to a captivated Earthbound audience . Active volcanoes , methane rain , icy geysers and intricate details about Saturn 's rings -- the list of revelations attributed to the mission reads like fantastical sci-fi novel but it has revolutionized planetary astronomy . Thirty-seven years after it launched , Voyager 1 is still out in the vast expanse of space , periodically relaying new data back home . But in 2013 , NASA made the groundbreaking announcement that Voyager 1 had left the heliosphere -- a magnetic boundary `` bubble , '' if you will , which scientists use to explain the separation of our solar system from the rest of the galaxy . `` That means Voyager has traveled outside the bubble of our sun , '' explains Voyager project manager Suzy Dodd . `` The data Voyager 1 sends us now is data from other stars and from super nova eruptions and the remnant of stars that have exploded over the course of history . '' It 's an incredible achievement for a probe built for an initial five-year mission . But now , not for the first time since the extraordinary statement , doubts have been cast on whether the craft has actually made the historic crossing . While measurements allowed NASA to feel confident enough to confirm Voyager 1 had entered interstellar space , two University of Michigan scientists who have worked on the Voyager missions remain skeptical . `` This controversy will continue until it is resolved by measurements , '' said George Gloeckler , a University of Michigan professor of atmospheric , oceanic and space sciences , and lead author of a new study , in an American Geophysical Union press release . SEE : Moon maps through the ages . To that end , Gloeckler and fellow University of Michigan professor and study co-author Len Fisk , predict that when Voyager does cross the threshold into interstellar space , the probe will identify a reversal in the magnetic field , which will be relayed back to scientists on Earth , conclusively determining the spacecraft 's location . They expect this magnetic field shift to occur in the next two years , and if it does n't , this would confirm that Voyager 1 has already left the heliosphere . But while we may not know the exact location of Voyager 1 , we do know that it 's one of the most successful spacecraft of all time . 'The little spacecraft that could ' Launched individually in the summer of 1977 , Voyager was a twin-spacecraft primary mission developed by NASA to explore Jupiter and Saturn and their larger moons . Following successful completion of the Voyager mission 's primary objectives , a rare planetary alignment offered up remarkable opportunities for the two craft to continue space exploration . `` Voyager took advantage of alignment of the outer planets , which are Jupiter , Saturn , Uranus and Neptune , to be able to go by all four of those planets in a 12-year period . That alignment of planets only happens every 176 years , '' says Dodd -- who has described Voyager 1 as `` the little spacecraft that could . '' So in 1980 the Voyager mission was officially extended and renamed the Interstellar mission . The probes were now participating in an exploratory odyssey to the farthest reaches of the heliosphere ... and beyond . Through remote-control reprogramming -- a technological advancement unavailable at launch -- using Saturn 's gravitational field , the Voyager 1 probe was fired like a slingshot on a trajectory that would take it onwards into interstellar space . Meanwhile Voyager 2 was redirected onto a new flight path , taking in the sights of Neptune and Uranus , before it will eventually follow its counterpart out of the heliosphere . To this day , it remains the only man-made object to have visited Neptune and Uranus . Not bad for vintage technology that has just 70 kilobytes of memory on board ; a 16 gigabyte iPhone 5 has more than 240,000 times that amount . Voyager 1 is now so far from Earth that commands take more than 17 hours to reach it . But it will be a little while before the spacecraft will encounter any more planets . `` It is going to take us 40,000 years to come within three light years of the next nearest sun or the next nearest star , '' says Dodd . `` And that is a long , long time . '' SEE : Moon maps through the ages . SEE : Best selfies ... from space . WATCH : Stunning solar flares .
Launched in 1977 , Voyager 1 was part of a twin - spacecraft mission on a multi - planet tour . A rare planetary alignment let the spacecraft travel past Jupiter , Saturn , Uranus , Neptune . The two spacecraft have provided unparalleled insight into our solar system . NASA announced Voyager 1 had left orbit last year , but some dispute that .