According to an article posted on Space.com, one of mankind’s robotic emissaries is about to depart our Solar System. Voyager 1 has travelled nearly 11 billion miles since its Cape Canaveral lift-off back on September 5, 1977 and is now sniffing like an inquisitive dog at a fence, looking for a way to cross the boundary into interstellar space.
Built by the Jet Propulsion Laboratory (JPL) and designed to explore the outer gas giants of our solar neighborhood, Voyager 1 looked over its shoulder on the way out to take the first-ever photograph of the Earth and Moon together, before finally saying “See ya!” to its planet of origin.
Voyager 1 and its sister ship Voyager 2, launched about two weeks earlier, completed their primary missions to explore Jupiter and Saturn in flawless fashion, each reaching the imposing Jupiter in 1979 and flying by her famously-ringed sister Saturn two years later. While Voyager 1’s path led it out towards the cosmos without further interruption, JPL scientists realized they could wring some more science out of Voyager 2.
Boy did they! Voyager 2 craft completed the “Grand Tour” of the outer Solar System, checking off planetary pit stops as if it was on some sort of interplanetary motorcycle rally: Jupiter in 1979, Saturn in 1981, Uranus -- stop giggling -- in 1986, and finally sweeping by the last planet we now recognize as a planet – sorry, Pluto fans – Neptune in 1989.
And what pictures these two ships snapped along the way! We knew about Jupiter’s Great Red Spot, but Voyager 2 provided close-ups of that vast, angry, centuries-long cauldron of a storm like we’d never seen before. Neptune’s Great Dark Spot was a surprise -- all we knew about Uranus and Neptune before Voyager 2 were that they were both probably sorta bluish -- but she gave us a look at that too. And speaking of surprises, we never expected anything like the incredibly intricate ring structures Voyager 2 revealed around Saturn, not to mention the fact that we didn’t even know Jupiter, Uranus and Neptune even had rings! Until Voyager 2, that is.
Nearly lost in all that planetary excitement was what these two ships revealed about the many moons around all these worlds. The Voyager spaceships transformed what had previously been 49 anonymous dots, blurry blips of light next to their gigantic parent planets, into achingly intriguing worlds worthy of more exploration and discovery in their own right.
When the Galileo spacecraft launched in 1989, the folks at NASA and JPL designed much of its mission to follow up on the tantalizing morsels the Voyager craft had exposed during their scouts a few years prior. We may yet find life on Mars, but after Voyager 2’s reconnaissance and Galileo’s detailed exploration, the smart money now predicts that if there is other life in our Solar System, we’ll find it swimming in the salty sub-surface seas beneath the icy crust of Jupiter’s moon Europa.
If you don’t believe me, just watch the movie 2010.
But, the laws of the universe being the laws of the universe and all, both Voyager spacecraft were destined for one-way trips into the cosmos. Their primary and secondary missions more than accomplished, both Voyager spaceships have continued to coast “out there” ever since, heading in different directions, following different trajectories.
They aren’t, actually, the first spacecraft to soar past the orbital boundary of the most distant planet in the Solar System. That honor goes to two earlier spacecraft. Pioneer 10, launched in 1972, and Pioneer 11, launched in 1973, were the first ships to escape the Sun’s gravitational pull, but they weren’t the fastest. On February 17, 1998, Voyager 1, perhaps jealous of all the press her sister ship had received a decade or so earlier, overtook Pioneer 10 to become the most distant human artifact in space.
At that point it would have been easy to let the Voyagers go; to simply say “thank you” and bid them fond adieus as they sped off into the depths of interstellar space at 38,000 mph. However, the science geeks who had already cajoled so much out of the intrepid robots realized they had an opportunity to squeeze yet one more mission out of their twin charges. Thus was born the Voyager Interstellar Mission.
Both Voyagers had been cruising uneventfully through the Heliosphere, a region of space still-dominated by the Sun’s solar plasma and solar magnetic fields that extends out about three times as far as the orbit of the planetoid Pluto. More recently, they reached the choppy outskirts of the Heliosphere, a region known as the Heliosheath that indicates the growing influence of the interstellar wind. It’s as if the Voyagers were boats heading out of the calm, protected cove of the Solar System into the windswept whitecaps of an intergalactic open lake.
Scientists know that at some point, a boundary called the Heliopause exists at the edge of the Heliosheath. This boundary marks the edge of the Solar System and the beginning of true, interstellar space.
They know this boundary exists, they just don’t know exactly where it is. Recently, however, NASA’s scientists reported that Voyager 1 has entered a previously unknown “transition zone” where the outwardly blowing solar wind is clocking speeds at near zero. They speculate that the craft has discovered an area where the even more powerful interstellar wind turns aside the solar wind like a blocking hand deflects water from a garden hose.
Scientists expected it would take another few years for Voyager 1 to cross the Heliopause into interstellar space. With this discovery, they wonder if, in fact, she’s closer than they realized. Like suddenly-alert sentries detecting unexpected movement, scientists are now keeping close watch over the telemetry that takes 16 hours at the speed of light to reach their computer consoles from the rugged craft out in the cosmos via NASA’s Deep Space Network. They estimate that anytime between, well, now, and sometime in the next five years, Voyager 1 will become mankind’s first emissary to the stars. Voyager 2 will eventually follow.
As they head out, each ship carries with it a 12-inch gold-plated copper disc carrying mathematical and graphic descriptions of who we are and where we are in the intergalactic neighborhood. It contains recorded greetings in 55 different languages, 115 photographs and numerous sounds of our world, and musical samples from different time periods and cultures.
Before the mission began, there was considerable debate about including our location on the disc for fears that such intel might provide any potentially hostile alien race that recovered either craft a veritable homing beacon right back to our world. In the end, however, the committee responsible for selecting the materials, chaired by the late great astronomer Carl Sagan, convinced the skeptics to include their digital “We Are Here!” sign, probably because they figured that any race that recovered Voyager and discovered the photographs of leisure suit-wearing human beings would be laughing too hard to consider invading us.
So, Voyager 1 and 2 speed onward and outward, carrying their gold-plated mementos of humanity, soon to cross the threshold of the Solar System and head into the depths of interstellar space. Each has enough battery power and guidance fuel to last until about 2020, after which they will soar on silently into the cold, dark depths of deep space.
And the universe is a big place. The next rendezvous for either craft will occur when Voyager 1 cruises into the neighborhood of the star AC+79 3888 in the constellation Camelopardalis, coming within 1.6 light years, or 9.3 trillion miles, in about 40,000 years. The wait for Voyager 2 is even longer. It will take the Grand Tour veteran some 296,000 years to wander within 4.3 light years, or 25 trillion miles, of Sirius.
Which makes me wonder. What will our world be like then? What will our species have evolved into if, in fact, we’re still around at all? Will we still be exploring the universe from Earth, or will we be out in it by then?
And will there still be any evidence left that we ever wore leisure suits and danced to disco music?
