VOYAGER 1

It's official. Voyager 1 has left the solar system. While there will be little immediate benefit from this feat, it does represent a historic milestone of exploration. Voyager 1's achievement is every bit as important as Roald Amundsen's party reaching the South Pole on 14 December 1911, or Edmund Hillary and Tenzing Norgay conquering Everest on 29 May 1953. The difference is that there is no human inside Voyager. With no obvious human, there is no obvious hero to venerate for the achievement. And the army of scientists and engineers who built and shepherded the mission seem too diffuse a collective for adoration. We must therefore celebrate Voyager 1 itself, as being a robotic extension of our senses, carrying our experiments to places that we simply cannot go. The duration of its mission alone is worthy of celebration. Launched in 1977, the same year that Elvis finally left the building, Voyager 1's primary mission was to visit the giant planets Jupiter and Saturn. Its orbit was designed to make a close pass of Saturn's mysterious moon, Titan, but that left the spacecraft coasting through space with no other planets to encounter. In the subsequent decade, sister ship Voyager 2 stole the limelight because of its flyby of Jupiter, Saturn, Uranus and Neptune. Voyager 1 was travelling faster, however, and that extra speed now means it is around 120 times the distance of the Earth from the sun, whereas Voyager 2 is lagging behind at about 100 times. Powered by radioactivity, both are still communicating with Earth. It was realised that sunlight would be far too weak in the outer solar system to drive solar panels. The power is gradually running down, however, as the radioactive fuel decays. The craft are expected to last until around 2020, and that gives plenty of time to collect data about this newly reached realm of nature. The boundary of the solar system is defined by the magnetic field created inside the sun. This bubble of magnetism traps particles and when Voyager passes the boundary, the density of particles will change abruptly. A recent review of the spacecraft data shows that this happened on 25 August 2012, over a year ago. So, according to Nasa Voyager 1 has officially left the solar system. It is difficult to say at the moment what benefit this knowledge will bring to us – just as it was difficult to say what benefit Amundsen's and Hillary's achievement would have on society. But just as certainly, achievements inspire us and drive us on to our own personal goals and therefore cannot be underestimated. Stuart Clark is the author of The Day Without Yesterday (Polygon). Find him on Twitter @DrStuClark Posted by Stuart Clark @DrStuClark Friday 13 September 2013 11.42 BST theguardian.com Jump to comments (28) Print thisShareContact usArticle history Science Nasa · Space More from Across the universe on Science Nasa · Space More blogposts More on this story Voyager 1 leaves solar system Nasa scientists say they believe the spacecraft has now reached interstellar space, beyond the influence of the sun Previous Blog home