Voyager At 40: Humanity's Eternal Message In A Bottle | Answers With Joe

The Voyager probes launched in 1977, but the idea for their mission was conceived 13 years earlier, in 1964.

Gary Flandro, an aerospace engineer working at NASA’s Jet Propulsion Laboratory, was tasked with finding ways of exploring the outer gas giants.

While proposing different possible trajectories that could come up over the next 20 years, he noticed a rare alignment of the outer planets that was going to occur in the late 1970s.

All four outer gas giants would line up in such a way that a single probe could slingshot past all four of them. This was a once every 175-year phenomena.

So he created the Planetary Grand Tour - a plan to visit all four gas giants in one shot.

Both probes lifted off in 1977, with Voyager 2 actually launching before Voyager 1, on August twentieth and September fifth, respectively.

But they were named in the order of when they would reach the planets, and Voyager 1 would be traveling faster.

Voyager 1 reached Jupiter on March 5, 1979, and Voyager 2 followed a few months later on July 9.

Together, they discovered that Jupiter has a ring system and found active volcanos on Io, the first active volcano outside planet Earth ever discovered.

They took detailed photos of the Great Red Spot and the clouds in the Jovian atmosphere, studied the cracks in the ice around Europa and took the first pictures of Ganymede.

They also took detailed measurements of Jupiter’s gravitational field and the radiation it carries.

Saturn

Voyager 1 reached Saturn in November of 1980 and Voyager two followed in August of 1981.

And this is where they parted ways.

Mission scientists were extremely interested in studying the moon Titan after Pioneer 11 photographed a dense atmosphere and organic compounds.

But in order to get a close look at Titan, it required a polar trajectory around Saturn, which means it would be slingshotted up and out of the elliptical plane. Making it impossible to continue on to the other planets.

So Voyager 1 took one for the team and made Saturn the end of its planetary run. It passed 6400 kilometers behind Titan and studied the temperature and composition of its atmosphere.

And then, after a close fly-by of Saturn, the gravity assist propelled Voyager 1 up and out of the elliptical plane faster than any other manmade object in history.

Voyager 2 had some fireworks of its own when it snapped the Pale Blue Dot photo on request from Carl Sagan.

This now iconic photo, taken as Voyager sped away from Saturn, shows Earth as a tiny point of light in the sky, or as Sagan said, a mote of dust suspended in a sunbeam.

Voyager 2 continued on to Uranus in January of 1986, and on to Neptune in January 1989. To this day, it is the only spacecraft that has visited either of these planets.

At Neptune, Voyager 2 took a 30 degree turn south and continues to provide information about the sun’s magnetic field and the solar wind.

In the north, Voyager 1’s enormous speed shot it further away from the sun than Pioneer 10, making it the furthest manmade object ever.

And in 2012, NASA announced that Voyager 1 had officially entered the heliopause, the area where the sun’s solar wind meets the cosmic rays of interstellar space.

Making it the first spacecraft to leave the solar system.

There are only 5 spacecraft so far that will eventually leave the solar system, Voyager 1, Voyager 2, Pioneer 10 and 11, and the New Horizons spacecraft, and Voyager 1 is traveling faster than all of them. So unless we invent an interstellar warp drive, it will always be the furthest thing we have ever sent anywhere. Ever.