Spare a thought for Voyager 2.

The spacecraft, which has been in operation for just over 32 years reached a humbling milestone this week; 20 years since the closest approach to Neptune. On August 25th, 1989 it came within 5000 km of the big, blue gas giant, taking spectacularly beautiful ‘close-ups’ that Adams, Galle and Le Verrier could only have dreamt of (see pictures after the jump). Just 5 hours later, it made its closest approach to Triton, Neptune’s largest moon, which is spiraling in slowly to its eventual demise.

Voyager 2 is so far the only probe to have visited Neptune (and Uranus) completing the reconnaissance of our Solar System’s main planets. I was only three years old at the time, but thanks to the achievements of the Voyager programme, I grew up with books containing a complete set of stunning photographs and they inspired me no end. Every time I look through my old books, I remember not to take this for granted. Most of the planets’ discoverers lived long before they were seen up close and it is only through the hard work of many scientists and engineers that in the time I live, we have landed probes on alien worlds (Huygens on Titan, 2005), we’ll soon be exploring dwarf planets (Dawn to Ceres, New Horizons to Pluto) and we’re continuously discovering other Solar Systems of all flavours. I can’t help but wonder how exploration will have improved hundreds of years after I’m gone, and how the distant planets being discovered today might also be seen in close up.

Voyager 2, true to its name, continues to sail into the limitless blackness, carrying with it evidence of an intelligence with a thirst for discovery. And it’s not alone. Its twin, Voyager 1, has also crossed the termination shock and entered the Sun’s heliosheath. Despite being launched over two weeks after 2, 1 has travelled further than any other man-made object and the only probes to compete with the Voyagers are Pioneer 10 and 11, both now dead. The Voyagers on the other hand, are very much alive, still transmitting back valuable data since officially becoming interstellar missions. They’re expected to survive for a further 15 years as well! How’s that for engineering?

They’re only machines, but they’re the loneliest machines ever built and we are in debt to them. They have seen much more of the Universe than we delicate organisms could have managed and without complaint, they shared and continue to share their experiences with us. So spare a thought for Voyager 2 and the others. If robots ever learn to have heroes, it’s a safe bet that these probes will be near the top of the list.