This weekend, NASA's historic Voyager spacecrafts celebrate their 40th year in space. The missions have given humanity many awe-inspiring discoveries in those four decades, and Voyager 1 and 2 have inspired infinite further initiatives or related works, too (such as a great new documentary debuting this week). To celebrate the occasion, we're resurfacing this appreciation from 2012 that details another thing Voyager forever inspired: our science editor.

August 20, 1977 turned out to be a before-and-after moment for me—and probably a lot of other people as well. None of us knew it at the time, though, since the launch of Voyager 2 (followed a few weeks later by Voyager 1) wasn't obviously a big deal to most people. In fact, I wouldn't fully appreciate the change until sometime in 1980.

To understand why, a bit of history is in order. NASA had been sending probes to other planets, like the Mariner and Pioneer series, since the 1960s. However, even the best technology of the time was pretty limited in terms of what it could do remotely. And for most of that time, they were badly overshadowed by manned exploration, first the Apollo missions and Skylab, and later the planning for the space shuttle. In fact, even as the Voyagers flew past Jupiter, I seem to recall more attention being paid to the impending de-orbit of Skylab, which scattered charred pieces of itself over Australia later that year.

But for me, everything changed with the arrival of the January issue of National Geographic early the next year. Its picture, of an erupting volcano on Jupiter's moon Io, was simply stunning. The contents continued to amaze. Supersonic winds in Jupiter's atmosphere. Stunning photos of the Great Red Spot. Water ice reshaping the surface of Europa. I can't even begin to imagine how many times I reread the issue.

Further issues of the sort came as the Voyagers passed the other outer planets, but the Jupiter issue was the one that truly fulfilled the before-and-after promise held by the Voyagers' launch.

Reimagining science

I had always had an interest in science, going back to things like a childhood addiction to all things dinosaur and a love of PBS specials. But like most other kids, I had been operating under the distorted picture of science presented by the typical school textbooks at the time: make a hypothesis, do some direct tests, and draw a conclusion. The Voyagers turned all that upside-down.

Whoever wrote National Geographic's coverage brilliantly captured the fact that scientists sometimes do things just to see what's out there, rather than being driven by a specific hypothesis. And, quite often, they're actually surprised by what they find. Europa being nearly crater free? None of our previous planetary visits had suggested anything like that was going to be likely. Active volcanoes on a moon? That wasn't on the mission list.

In fact, the discovery of Io's volcanoes showed that serendipity played a part in science. If the narrative was right, they weren't even found during the observations that were directed at the moon. Instead, a camera simply meant to pick out stars for navigation purposes happened to capture an eruption while trying to get a fix on a nearby star.

It also became clear that the whole idea of science being all about direct tests needed a bit of revision. The Voyagers did have cameras and spectrometers that told us about the composition of various things they observed. But they also had magnetometers, that simply registered what was going on in their immediate environment. It was clear those readings could be plugged into models that told us something about the environment as a whole and, more broadly, what was going on at Jupiter and its moons to generate that environment.

And those models weren't static things that you tested, then either accepted or discarded. Tidal forces were quickly pinpointed as providing the heat that made Jupiter's inner moons such dynamic places, but the details were revised, argued over, and left with a fair degree of uncertainty attached. Other data was described even as it was made clear that there was no consensus about what could possibly explain it.

You can tell how much of an impression this made on me based on the fact that I still remember all of this over 30 years later.

Reimagining the Universe

But like the best of science, the Voyagers didn't just change their corner of science; they changed how we view the world.

It may be hard to imagine it now, but I had grown up at a time when we believed that the Earth was the only host of active volcanoes in the Solar System, and all of the bodies we'd explored had been so hostile that life wasn't a realistic option. Now, we regularly talk about the active geology of places like Io and Titan, and consider the relative prospects for life on various moons. The Voyagers completely changed the way we talk about the Solar System and, in the process, our place in it.

I don't think it's an exaggeration to say that the Voyagers have also shaped how we view the rapidly expanding catalog of planets outside our solar system as well. Rather than viewing them through the lens of Mars' barrenness or the hellish conditions of Mercury and Venus, the Voyagers made it possible to envision other worlds as part of a cacophony of different environments, including some we have not seen in our own Solar System. In fact, it wouldn't surprise me if the Voyagers didn't help inspire some people to look for planets elsewhere in the first place.

Now, over 30 years on, the Voyagers' greatest discoveries are part of the background of how I view science and the Universe. But they continue to amaze for one other reason: their longevity. NASA builds its hardware to survive incredibly harsh environments, so provided nothing goes badly wrong, it has become common for missions to still be going long after their expected finish. Even so, 35 years of operation and data sent back from the border of the space between the stars is just a staggering testament to the Voyagers' engineering.

They will probably never change the world again, but it's somehow nice to think that their scientific career has continued to span the entirety of one they helped inspire: mine.