A number of reports are saying that Voyager 1, launched in 1977, has left the solar system. If this simple machine has indeed left the confines of our solar neighborhood, then it's a reason to celebrate like we did in July of 1969 when humans first walked on the moon. We live in a world where people scream and shout at technology just a few months old for being 'too slow' or 'out of date' but, here we are, with a machine that's been operating in one of the harshest environments known to humanity that's been operating well beyond its expected lifespan ... and for two years longer than I've been alive.
How Is It Still Working?
One of the most common questions that I've heard people ask about the two Voyager probes is how they're still working. Very few machines are able to work continuously for as long as these probes have, and solar collectors are not realistically feasible beyond Mars, so where do the two Voyager probes get their energy?
On the right side of the image above, we can see a series of radioisotope generators. This is where the power is generated for the various instruments and radios that are still being used today. As the name implies, this device employs some Plutonium-238 in the form of an oxide to generate heat, and that heat is used to create electricity. It's not a full-fledged nuclear reactor, but it certainly gets the job done. Current estimates expect the Voyager probes to run out of power in another two decades, but this could be off by a year or ten. Lord knows how many times NASA engineers have been overly cautious with their "estimated life" predictions.
Who Cares About This?
People who don't care about the Voyager probes shouldn't be reading this site. Go away.
After the Voyager probes reach interstellar space they'll be surrounded by the some of the coldest temperatures and purest of vacuums in the galaxy. There is very little of anything in the interstellar medium and the nearest star system to our is Alpha Centuari ... which neither Voyager probe is pointed towards. Unfortunately this means that these two intrepid machines will eventually run out of power in a region of absolutely nothing where they will continue to travel at a rate of 10 kilometers per second until they are either pulverized by a rogue asteroid or destroyed by Klingons in search of glory1. Hopefully they will one day be collected and returned to Earth where they can rest in the relative comfort of our atmosphere and be a source of wonder and entertainment for museum visitors.