As of this writing, the Cassini spacecraft is no more. After 13 very fruitful years of exploring the Saturn system, Cassini finally crashed into the ringed planet on Sept. 15, 2017. With Cassini’s planned crash and burn into Saturn, humanity now has one less robotic emissary in space.
However, some of our remaining space probes are still sending us a treasure trove of scientific data. Two of them, the twin space probes Voyager 1 and Voyager 2, have been in the depths of space for more than 40 years now. (They were launched a little bit more than 40 years ago. Voyager 1 was launched on Sept. 5, 1977. Voyager 2 was launched 16 days before Voyager 1.)
Boasting the title of being the farthest human-made objects from Earth, the Voyager space probes are pushing the boundaries of humanity’s reach in the universe. Like Cassini, they too will run out of fuel some day. In the meantime, the scientific achievements that were made through them, and even the ones that are yet to be made, are worth celebrating. So let’s revisit the highlights of what the Voyager space probes have taught us about our place in the universe.
The main objective of the Voyager space probes was to explore the outer Solar System.
To accomplish the exploration of the outer Solar System, Voyager 2 flew by Jupiter, Saturn, Uranus, and Neptune. As it did this, it also took photographs and measurements of the moons of the outer planets.
To this day, Voyager 2 is the only spacecraft to have explored the so-called ice giant planets Uranus and Neptune. Since no other missions are slated to go to those planets in the coming years, pictures of them and their moons taken by Voyager 2 are the only ones we will see for many years to come. Those achievements alone make for quite a legacy for the Voyager missions.
However, the legacy of the Voyager space probes extends far beyond this. For example, the Voyagers essentially served as the reconnaissance missions for the next generation of outer Solar System missions, namely Galileo, Juno, and Cassini.
Galileo and Juno are space missions to study Jupiter. A big part of their missions is to investigate not only Jupiter, but also its moons. In particular, two moons stand out—Ganymede and Europa. Those moons stand out because they hold the possibility of harboring life. We now know that both moons hide seas of liquid water underneath their icy outer surface. We know this because of the Voyager space probes.
Cassini, on the other hand, was a mission to study Saturn and its moons. As with the Jupiter system, two of Saturns moons are of particular interest—Titan and Enceladus. Like Ganymede and Europa, we find them interesting because they might harbor life.
In many ways, Enceladus is very similar to the icy moons of Jupiter. Titan, on the other hand, is entirely different. For one, instead of having liquid water, Titan has lakes of liquid methane on its surface!
As with the two potentially life-bearing moons of Jupiter, Saturn’s moons were brought to the spotlight thanks to the Voyager space probes.
Titan, in particular, was the reason why Voyager 1 was not able to visit Uranus. Instead of spending the space probe’s remaining fuel to go to Uranus as was planned, scientists instead decided to make it fly by Titan. The results of that visit helped pave the way for the Cassini mission.
But the achievements of the Voyagers don’t end there. In fact, what makes the Voyagers so special among all of humanity’s excursions into space is that they are the farthest of them all. In fact, not only is Voyager 1 the farthest human-made object from Earth, it boasts of being the farthest object in the Solar System whose position is known. It is farther out that Pluto and all the other dwarf planets out there that we know of. And yet it still continues to send scientific data from that far out.
It will be hundreds of thousands of years before any of the Voyager space probes reach another star system. Nonetheless, it is a great comfort to know that both space probes contain a mass of information about humanity in the 20th century. The Voyagers are the time capsules for our species, carrying videos and sounds that would represent us to any possible aliens (or future humans) who might bump into them in the distant future.
Aside from being time capsules, the Voyagers are also products of collaboration between our bests minds. That way, they represent the best of humanity to whoever may find them. May they continue to serve as inspiration for us to keep on investing in the future of space exploration.
Pecier Decierdo is resident physicist and astronomer of The Mind Museum.