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Night Vision: The Voyager Missions

Posted January 28, 2019 - by Robert Bigelow

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In the summer of 1965, calculations revealed that once every 176 years it is possible to launch a single spacecraft from Earth and visit all four outer planets. Fortunately, that opportunity had not already happened, but would occur a decade in the future. Planning soon began for a space mission to explore the outer solar system.

Scientists decided to send two spacecraft, later named Voyager 1 and Voyager 2. Both would fly by Jupiter and Saturn. A top priority was a close inspection of Saturn’s largest moon Titan, the only moon in the solar system with an atmosphere. But a close flyby of Titan would send the spacecraft in a direction away from the path that would take it on to the next planet.

Both spacecraft launched in 1977. Voyager 1 would reach Saturn first. If it accomplished the goals for Titan exploration, then Voyager 2 would be sent on to Uranus and Neptune. Voyager 1 was successful and Voyager 2 completed its grand tour of all four outer planets when it flew by Neptune 30 years ago.

More recently, these twin robots have gone where no spacecraft has gone before. Each has entered interstellar space. Voyager 1 entered interstellar space on August 25, 2012 and Voyager 2, just months ago, on November 5, 2018.

Voyager 1 Leaving the Solar System
An artist's rendition of Voyager 1 entering interstellar space on August 25, 2012. Voyager 2 followed on November 5, 2018. They are the first spacecraft to leave the solar system. V'Ger, here we come! (Image credit: NASA/JPL-Caltech)



What is interstellar space? The Sun emits light in all directions. It also emits a stream of protons, electrons, and atoms at very high speeds called the solar wind. It also has a magnetic field that extends far into space. Where the influence of both the Sun’s magnetic field and solar wind ends, interstellar space begins.

Voyager 1, currently four times farther from the Sun than Pluto, is the most distant human made object. At that distance it takes 20 hours for a radio signal from the spacecraft to reach Earth.

Join us for Night Vision on Thursday, January 31 at 6:45 p.m. for a brief tour of the night sky and a discussion of the Voyager missions to the outer solar system and beyond. Tickets are just $2.00 per person for the public, and free for members of Clark Planetarium. Get your tickets now.