On this day in 1980, the NASA space probe Voyager 1 made its closest approach to Saturn. Of course, close is a relative term; in this case, the spacecraft was 40,000 miles from the top of the gas giants cloud layer. But it gave scientists their best opportunity to study the planets most famous feature: its spectacular rings. Voyager 1s images reveal seven main rings, each named with a letter of the alphabet and made up of thousands of strands held in formation by the gravitational pull of the planet and its dozens of moons. The rings are made of ice particles — some as big as a car — and bits of debris from broken up moons, comets, and asteroids. Voyager 1 also discovered the shepherd moons: Prometheus and Pandora, small moons that interact with Saturns F ring and keep it separate from the other rings. Voyager 1 was launched in 1977, sent out into the solar system to explore Jupiter and Saturn along with its twin, Voyager 2. Both probes carry a greeting to any sentient life forms that they may encounter, in the form of a gold-plated record. The information on the record was selected and compiled by a committee chaired by Carl Sagan; it includes spoken greetings in 55 languages, a selection of music from different eras and cultures, and a variety of images and sound recordings from nature, including a baby crying, ocean waves, and whale song. President Jimmy Carter said: This is a present from a small, distant world, a token of our sounds, our science, our images, our music, our thoughts and our feelings. We are attempting to survive our time so we may live into yours. We hope someday, having solved the problems we face, to join a community of galactic civilizations. This record represents our hope and our determination, and our good will in a vast and awesome universe. The original plan was for Voyager 1 to explore Saturns moon Titan, and then continue on to other moons and planets. But the gravity of Titan spun the probe off into an unexpected direction and put it on a path for deep space. Scientists debated whether to correct Voyagers trajectory and send it past Pluto, or let it continue on. The latter course promised more interesting data, and less risk, so they opted not to interfere. According to NASA, 11,000 workyears have been devoted to the Voyager project from its inception in 1972 until its encounter with Neptune in 1988; that sounds like a lot, but its only about one-third the effort that went into building the Great Pyramid of Giza. The cost for the mission works out to about eight cents per U.S. resident per year. The probes are fuel-efficient too, getting about 30,000 miles to the gallon of rocket fuel; they use the gravity of the planets theyre studying to slingshot them along to their next destination. On Valentines Day, 1990, Voyager 1 was in a position to take whats come to be known as a family portrait of our solar system. The series of photographs captures six of the planets; Mercury and Mars were caught in the glare of the Sun, and Pluto was too small and dim to show up. These were the last pictures that Voyager 1 took; the cameras were shut down afterward to conserve power. In August 2012, Voyager 1 left the solar system and entered interstellar space. Its now the most distant human-made object in space — almost 19 billion kilometers as of October 2013 — and it continues to send back data, via the Deep Space Network, to highly sensitive equipment here on Earth. Voyager is so far away that the signal it sends back takes 17 hours to reach us, and is 20 billion times weaker than a digital watch. Its expected to be able to continue its mission until about 2025, when its generators will no longer be able to provide sufficient power.
Posted on: Tue, 12 Nov 2013 16:42:15 +0000
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