The ISC Blog

Voyager 1 and the Depths of Interstellar Space

The world is preparing to send humans to Mars.  This will probably be the most technologically challenging undertaking the world has ever known.  Yes, we have been to the moon, but those trip were a breeze compared to what we are about to undertake: the Moon is a mere 240,000 miles from Earth, whereas Mars is 1000 times that distance away – a whopping 240 million miles.  That means that if you were to make a scale model of the solar system, and placed the Earth and the moon one foot apart from each other, you would have to place Mars over three football fields away!

While it only took the Apollo astronauts a few days to reach the moon, experts are predicting that it will take astronauts six months to reach the dusty plains of Mars.  Only a handful of individuals have spent that much time in space, which is why Russian cosmonauts spent 520 days isolated in a mock-up spaceship, and why astronaut Scott Kelly spent a year aboard the International Space Station.  These experiments were designed to test the effects of long term space flight and isolation on the body and mind.

Indeed, 240 million miles is a long way away.

The distance between here and Mars, though, pales in comparison to the distance between here and the farthest man-made objects from Earth.  Since the 1950’s, the United States and the rest of the world have been launching probes to land on or fly by everything from the sun to Pluto and beyond.  While these probes do not carry humans, launching them into space has been a major undertaking, nonetheless.

A few of these space probes have made big news recently.  The New Horizons probe, for example, just flew past Pluto and took our first ever high-resolution photographs of the dwarf planet.  Last year, the European Space Agency launched the satellite Rosetta.  This satellite dropped off the rover Philae, which became was the first man-made object to ever land on a comet.  Furthermore, in the history of NASA, we have built four probes that have come near to or have escaped the solar system: Pioneer 10, Pioneer 11, Voyager 1, and Voyager 2.  The most successful and most fascinating of these deep space probes by far is Voyager 1.

 

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A photograph of Jupiter’s Great Red Spot, taken from Voyager 1.

 

Voyager 1 was launched on September 5th, 1977, and today, it is the farthest man-made object from our planet Earth – it is 11 and a half billion miles away.  Remember Mars’ distance from Earth, a ghastly 240 million miles?  Well, Pluto is 4.5 billion miles away, but even Pluto does not match the geographical prowess of Voyager 1.  If we brought back our scale model of the solar system, where the moon is one foot away from Earth and Mars is three football fields away, Pluto would be a distant three and a half miles away, and Voyager would be floating over eight and a half miles away!

In other words, the distance between Earth and Voyager 1 is over two times the distance between Earth and Pluto!

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Volcano and sulfur-rich lava flows on Jupiter’s moon Io.

Voyager wasn’t supposed to make it this far, however.  Astronomers are surprised and amazed not only that Voyager 1 has passed into the outer reaches of space, but that it is still sending signals back to us on Earth.  The Voyager 1 mission, which started in 1977, was only supposed to last 5 years.  Its purpose was to study Jupiter and Saturn and their moons and then to get lost in space.

The initial findings from Voyager 1 taught us a lot about what we know about Jupiter, Saturn, and their moons, and it also took some pretty sweet closeups of the two planets.  For instance, from data collected by Voyager 1, we learned that Jupiter’s moon Io has volcanic activity. This was the first evidence of volcanic activity anywhere but on Earth.  If you are curious, Io’s volcanoes do not spew the same kind of lava that we find here on Earth, though.  Io’s volcanoes spew sulfur.

Astonishingly, after Voyager passed Saturn, the probe kept ticking, and 38 years later, it is still sending us information about out the outer reaches of the solar system.

In fact, after years of studying what makes up the edge of the solar system, astronomers have confirmed that Voyager 1 finally escaped the solar system in 2012, 35 years after it left Earth.  This made Voyager 1 the only man-made object to ever reach interstellar space, or the space between stars.

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A false-color image of Saturn’s B and C rings and their ringlets.

What will Voyager 1 pass by next?  When it was launched, NASA did not aim Voyager 1 at any stars in particular, but in 40,000 years, Voyager will fly by the star Gliese 445, which is 17.6 light years, or 103 trillion miles, away.  That’s 103,000,000,000,000 miles.  And by fly by, I mean it will pass within 1.7 light years, or 10 trillion miles, of the star. That’s 10,000,000,000,000 miles.  Admittedly, that’s not very close, but it’s the best we will do for a while.  Besides, Voyager’s instruments will be long dead by then, so really it’ll only serve as an unusual space rock to whoever finds it.

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The cover to the gold record on Voyager 1. Click here to learn more about what the symbols mean.

Despite the slim chances of Voyager 1 ever coming close to finding other intelligent life, NASA prepared for such an occasion anyway.

On Voyager 1, engineers at the Jet Propulsion Laboratory (where a lot of NASA’s machinery is built) affixed a record on its side that contains sounds and images of life on Earth.  The record looks like one you’d buy at a store, except it is made from copper and it is coated in gold.  The record was intended to serve as a “time capsule” of sorts, and NASA tasked astronomer Carl Sagan with collecting materials to put on it.  Here is a sampling of what Dr. Sagan chose to represent Earth if the record was ever found by life on planets across the galaxy:

  • Music by Bach, Beethoven and Mozart, Chuck Berry’s Johnny B. Goode, songs from Delta bluesman Blind Willie Johnson and Louis Armstrong, and music samples from all over the world.
  • Greetings in over 50 languages including English, Latin, Dutch, Urdu, Hebrew, and Vietnamese
  • The sound of cars, dogs, rain, volcanos, and many more natural and artificial sounds from Earth
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The record put together by Carl Sagan.
    • Pictures of people, places, and thing on earth, pictures of the other planets, mathematical equations, and chemistry and biological diagrams.

The cover on the record has instructions on how to play it, as well as a map of where our solar system is.

Will an alien species find Voyager 1?  Will they be advanced and intelligent enough to find the record and play it?  Probably not.  But it doesn’t hurt to wonder.  While we are still trying to figure out how to send people to Mars, Voyager 1 will keep floating through outer space, serving as a message of peace from the people of Earth to whoever is around to listen.

Ben Marcus is a recent graduate of the University of Chicago, where he received his Ph.D. in neurobiology. He is a co-editor of the ISC blog and a moderator of Ask A Scientist. You can follow Ben on Twitter @bmarcus128.

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