In the late '70s, NASA launched the Voyager 1 spacecraft on an epic mission of exploration through the outer solar system.
But, despite massively increasing our understanding of our solar system, the Voyager 1 spacecraft's journey isn't over just yet.
That intrepid traveler is still beaming back information from the outer reaches of the solar system…or it was, until recently.
No, it hasn't stopped working. It's finally left the solar system.
Clipping along at nearly 11 miles per second, Voyager 1 has been measuring solar wind (charged particles that the sun routinely spews out in all directions) for years. Despite being more than 30 years old, scientists are still making use of new data beamed back from the spacecraft. In this case, we've discovered that there is, in fact, a detectable boundary between interstellar space and the solar system. The environmental influence of the sun – detectable as hydrogen and helium – drops dramatically and suddenly, and the prevailing “currents” of particles are more in line with what we'd expect in deep space.
Scientists have been waiting for this for a while.
Last year, Voyager 1 entered the heliopause, which is generally considered to be the boundary zone between interstellar space and the solar system, but they weren't exactly sure how long the transition would take.
This is the first time that any manmade object has left the solar system – Voyager 1 is also moving at a higher velocity than any other manmade object. And just to give you an idea of the distance travelled here: Moving at a speed of 38,610 mph, it took 30 years to reach the edge of the solar system, 11 billion miles away.
It takes light from the sun 17 hours to travel that far. To make you feel even smaller, it will take another 40,000 years moving at that speed to reach a nearby star.
Voyager 2, the twin of the Voyager 1 spacecraft, is still alive and well and is also headed out of the solar system – it's somewhat closer to the sun than Voyager 1, despite being launched first. Voyager 1 is traveling more quickly due to “slingshot” maneuvers it undertook near Saturn.
Unfortunately, Voyager 1's nuclear power supply will run down around 2020, bringing its mission to an end – but we've certainly gotten our money's worth.
Until then, Voyager 1 will continue to return data, and both Voyager 1 and its sister spacecraft, Voyager 2, maintain active Twitter accounts for anyone interested in following their missions. Voyager 1's Twitter account can be found @NASAVoyager, and Voyager 2's Tweets can be seen @NASAVoyager2.
-Nick DeLorenzo is director of interactive and new media for The Times Leader. E-mail him at email@example.com.