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Voyage to the Stars

September 5, 2012

Today is the 35th anniversary of the launch of the Voyager I, one of two Voyager spacecraft comprising the Voyager Mission — arguably one of the truly great achievements of the NASA space mission program.

Voyager I was launched on September 5, 1977, second after Voyager II, which was sent out  16 days earlier on August 20, 1977. After over a decade of firsts in imaging planets and moons of our Solar System, the Voyager spacecrafts are collectively the longest-running (a title held by Voyager II) missions, and the most distant human-made machines (Voyager I is about 11 billion miles from Earth, exceeding Voyager II by about 2 billion miles — which, by astronomical standards, is not too far behind).

Artist's rendering of Voyager

Artist’s rendering of one of the identical Voyager spacecraft. (NASA/JPL)

The year of the Voyager launch — 1977 — was a time when the most sophisticated computer equipment included 8,000-word computer memory banks and 8-track tape recorders. They were were the first fully automated spacecraft, and were the state-of-the-art. What’s amazing is where they are now — at the frontier of the Solar System, still sending Earth data of what lies in the great beyond.

Before careening toward interstellar space in 1989, Voyager revolutionized our view of the Solar System as they beamed back amazing photographic data of our Solar System, in particular the systems of Jupiter, Saturn, Uranus and Neptune. Their data brought about a new view of the Solar System, rich in moons, volcanoes, atmospheres, storms and rings. Click here for a gallery of Voyager photos.

Jupiter's great red spot

Jupiter’s great red spot imaged by the Voyager mission (credit: NASA/JPL)

Saturn imaged by Voyager

View of Saturn, rings and moons imaged by Voyager (Credit: NASA/JPL)

“Pale Blue Dot” : Voyager I’s final image is perhaps its most thought-provoking. This image came to be known as the “Pale Blue Dot”, and was simply a fuzzy picture of the Earth taken in 1990 as part of a larger “Solar System portrait”. Taken at at a record distance of about 6 billion km (3.7 billion miles) at the request of astronomer Carl Sagan, this image contrasted the glorious displays of our giant planets, instead showing the Earth as a tiny, single pixel within a vast expanse of space.

Pale Blue Dot

This narrow-angle color image of the Earth, dubbed ‘Pale Blue Dot’, is a part of the first ever ‘portrait’ of the solar system taken by Voyager 1. The spacecraft acquired a total of 60 frames for a mosaic of the solar system from a distance of more than 4 billion miles from Earth. From Voyager’s great distance Earth is a mere point of light, less than the size of a picture element even in the narrow-angle camera. Coincidentally, Earth lies right in the center of one of the scattered light rays resulting from taking the image so close to the sun. This blown-up image of the Earth was taken through three color filters — violet, blue and green — and recombined to produce the color image. The background features in the image are artifacts resulting from the magnification. (Credit: NASA/JPL)

The title of the photograph was used by Dr. Sagan for his 1994 book, Pale Blue Dot: A Vision of the Human Future in Space, in which he pointed out that “all of human history has happened on that tiny pixel (shown here inside a blue circle), which is our only home” (speech at Cornell University, October 13, 1994.)

Click here to listen to Dr. Sagan’s famous “Pale Blue Dot” speech.

Bursting the Solar System Bubble

The Voyager spacecraft travel at roughly one million miles per day, and are fast approaching a region called the heliosphere, the outer reaches of the Sun’s influence. Using data that take over 16 hours to make the 11-billion mile journey through space, scientists believe that, very soon (from days to a few years from now), Voyager I will pass through the heliosphere of our Solar System, into interstellar space.

At the point of passing out of our Solar System, scientists hope to learn the true size of the heliosphere, as estimates currently range from 11 billion to 14 billion miles across. Increases in cosmic rays hitting the spacecraft signal to scientists that Voyager I is likely to approach the edge of the heliosphere sooner rather than later.

Once Voyager passes through, scientists should obtain data on cosmic ray bombardment beyond the heliosphere, and the strength and direction of the magnetic field abutting the Solar System edge.

Artist's rendering of Voyager location

Artist’s rendering of Voyager location in the “heliosheath” — the outermost layer of the heliosphere where the solar wind is slowed by the pressure of interstellar gas. Both spacecraft are still sending scientific information about their surroundings through the Deep Space Network (Credit: NASA/JPL).

Is anyone out there? 

While we do not have yet any sign from another technologically-advanced, intelligent civilization, NASA scientists seized the opportunity presented by the ambitious Voyager itinerary to place some “Earthling” messages on-board, should some beings find the spacecraft in the years beyond.

The Golden Record: Both Voyager spacecraft carry a phonograph record – -a 12-inch gold-plated copper disk containing sounds and images selected to portray the diversity of life and culture on Earth, selected for NASA by a committee chaired by Carl Sagan of Cornell University. Dr. Sagan and his colleagues assembled 115 images and a variety of natural sounds, along with musical selections from different cultures and eras, and greetings in fifty-five Earth-spoken languages.

As the Voyager missions travel farther and farther from Earth, we can look forward to data sent back to our planet (at least until an optimistically prospective end in the year 2025) from distances beyond which humanity may never go.

Cover of the Golden Record

Cover of the Golden Record, sent on the Voyager Spacecraft into interstellar space, should any intelligent beings be contacted (Credit: NASA/JPL)

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