In 1977, NASA’s Voyager 1 and 2 spacecraft began their pioneering journey across the Solar System to visit the giant outer planets. Now, the Voyagers are hurtling through unexplored territory on their road trip beyond our Solar System. Along the way, they are measuring the interstellar medium, the mysterious environment between stars that is filled with the debris from long-dead stars. Voyager 1 became the most distant spacecraft from Earth in 1998, and no other spacecraft launched, to date, has a chance of catching it. (Credit: NASA, ESA, and G. Bacon)

Voyager 1 has left the Solar System. Will we ever overtake it?

In all of human history, only 5 spacecraft had the right trajectory to exit the Solar System. Will they ever catch Voyager 1?

Exiting the Solar System isn’t easy.

The Voyager spacecraft, illustrated here, are two of the five spacecraft currently on trajectories that will take them out of the Solar System. Both spacecraft actually left the heliosphere behind and entered interstellar space in the 2010s, and will, when Voyager 2 passes Pioneer 10 in 2023, become the two most distant spacecraft from Earth for the foreseeable future. (Credit: NASA/JPL-Caltech)

You must escape the Earth’s and Sun’s combined gravitational pulls.

Although the Earth exerts a substantial gravitational pull, requiring that an object at its surface travel at ~11 km/s to escape our planet’s gravitational pull, the Sun’s gravitational influence dominates the Solar System. From Earth’s orbital location, an object would need to reach a speed of 42 km/s to escape from the Solar System entirely. In all of human history, only five (six, if you’re generous) spacecraft have met those criteria. (Credit: T. Pyle/Caltech/MIT/LIGO Lab)

Of all the spacecraft ever launched, only five are on Solar System-departing trajectories.

There are five spacecraft presently either on their way out of the Solar System or that have already left it. From 1973–1998, Pioneer 10 was the most distant spacecraft from the Sun, but in 1998, Voyager 1 caught and passed it. In the future, Voyager 2 will pass it as well, and eventually New Horizons will pass Pioneer 11 and later Pioneer 10 as well. (Credit: NASA/Johns Hopkins APL/Southwest Research Institute)

The first, Pioneer 10, was launched a half-century ago.

The Pioneer 10 mission was launched with a number of instruments, and one of its science goals was to become the first spacecraft to visit and take data from Jupiter. Some of the first images of Jupiter from in situ are shown at right, showcasing a total solar eclipse shadow on Jupiter’s right side. (Credits: Rick Giudice (L); NASA/Pioneer (R))

Humanity’s first spacecraft to encounter Jupiter, that gravitational assist accelerated it beyond escape velocity.