39 The Voyager Program-Mid

The Voyager Program FOCUS Question What can the Voyager spacecraft tell us about the outer solar system and beyond?

Messages from Earth Deep in space, two little spacecraft are speeding out of the solar system. Voyager 1 and Voyager 2 travel thousands of kilometers farther from the Sun every hour. Each spacecraft carries a golden record album. On the records are pictures and sounds from Earth, including those of animals, plants, people, and technology. They also include music and greetings from people all over Earth. Scientists hope that someday, intelligent life from another solar system will receive these messages from Earth! Do You Know? One of the greetings on the Golden Record says. "Friends of space, how are you all? Have you eaten yet? Come visit us if you have time."

The Voyager Mission The two Voyager spacecraft were launched into space in the summer of 1977. They were designed to explore the outer planets of the solar system. Because its route to the outer planets was longer, Voyager 2 launched first but it reached Jupiter second. At first, the plan was just to visit Jupiter and Saturn. Later, NASA realized that the spacecraft could also be sent to Uranus and Neptune. These planets had never been visited before. After passing the outer planets, the Voyagers set out on a new mission: to explore the space beyond the planets. Math Moment One astronomical unit (AU) is the distance between Earth and the Sun. If the Voyagers have been flying at 3.5 AU per year, how far have they traveled to date?

The Grand Tour Long before the Voyagers were launched, scientists dreamed of a "grand tour" of the solar system. Study the timeline to learn about some of the Voyager program's top moments. August and September 1977 Voyager 2 and then Voyager 1 launch from Cape Canaveral, Florida On Earth, 150 million km (1 AU) from the Sun March 1979 Voyager 1's closest approach to Jupiter; studies Io (EYE-oh), one of Jupiter's moons discovers active volcanoes 778 million km (5.2 AU) from the Sun July 1979 Voyager 2's closest approach to Jupiter; studies Europa, another one of Jupiter's moons; discovers evidence of water beneath its icy surface 778 million km (5.2 AU) from the Sun November 1980 Voyager 1 flies by Saturn; records images of the planet and its moons 1.4 billion km (9.5 AU) from the Sun

August 1981 Voyager 2 flies by Saturn; studies its atmosphere, rings, temperature, and how it rotates 1.4 billion km (9.5 AU) from the Sun January 1986 Voyager 2 becomes the first and only spacecraft to visit Uranus; comes within 81,500 km of the planet; records thousands of images of planet's atmosphere, rings, and moons 2.9 billion km (19.1 AU) from the Sun August 1989 Voyager 2 becomes the first and only spacecraft to visit Neptune; flies within 5,000 km of the gaseous surface of the planet; discovers several moons orbiting the planet 4.5 billion km (30.1 AU) from the Sun August 2012 Voyager 1 enters interstellar space 18.7 billion km (125 AU) from the Sun

The Laws of Motion in Space The Voyager spacecraft have been traveling through space since they were launched in 1977. Unless they collide with something, they will continue to move deeper into space for thousands of years. And yet, they left Earth with very little fuel How is this possible? Newton's Laws of Motion can explain it. Newton's Third Law explains how Voyager 1 and 2 were launched. This rule of science states that for every action, there is an equal and opposite reaction. In this case, the rockets burned rocket fuel. As the rockets pushed the exhaust out, the exhaust pushed the rockets up into space.