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Gifts for all occasions in the Galleria! Subscribe to the "What is the Deal?" mailing list. November 9, 2003 What is the Deal with Voyager I? By Jan A. Larson  The
Voyager spacecraft, Voyager I and Voyager II, launched from Earth in
1977, are wonders of science. Voyager I is now over eight billion
miles from Earth, or 90 times the distance from the Earth to the sun,
traveling at over 38,000 miles per hour relative to the sun. It
take nearly 25 minutes for signals from Voyager I traveling at the
speed of light to reach Earth. [1]Voyager I is the most distant human-made object in space and carries a gold-plated copper disk that contains images and sounds from Earth. These disks were attached to both Voyagers in the unlikely event that either spacecraft will be discovered by an advanced extra-terrestrial civilization. A Saturday Night Live spoof some years ago reported that the disk had been discovered in space and a request to "send more Chuck Berry" had been received. NASA announced last week that Voyager I was approaching the "termination shock," the point at which the velocity of the solar wind slows from supersonic velocity of approximately one million miles per hour to subsonic velocity of approximately 250,000 miles per hour. The solar wind consists of particles that flow outward from the sun. The termination shock is the region at which the solar wind first encounters the "interstellar medium," or the "stuff" that occupies the space between the stars. The termination shock is not a hard boundary and two teams currently disagree as to whether Voyager I has actually passed the boundary. Beyond the termination shock is the heliopause, the outer boundary of the sun's magnetic field and solar wind. It is estimated that it will take another 10 to 20 years before Voyager I reaches the heliopause and enters inter-stellar space. The Voyager spacecraft operate on approximately 400 watts of power, or roughly one fourth of the power used in the average residential home in the United States and it is estimated that both spacecraft have sufficient power to continue operating until 2020 or beyond. It is simply mind-boggling that these machines could continue to operate in the harsh environment of space for over 26 years and barring something unforeseen, may continue to operate for another 15 to 20 years until their fuel runs out. Even more mind-boggling is the fact that technology allows scientists to communicate with these devices at such incredible distances. Needless to say, scientists aren't using cell phones to call the Voyagers. But the most incredible aspect of the Voyager missions is that long after our days on Earth are done, after the extinction of mankind and yes, after the Earth itself is but a distant memory, the Voyagers will fly on carrying the message that mankind was here. To all of those that made the Voyager missions possible - a job well done. [1] http://voyager.jpl.nasa.gov/mission/weekly-reports/2003-09-12.html -- Send feedback to the author. The "What is the Deal?" column will appears weekly on the Pie of Knowledge website. Guest submissions are welcome and encouraged. To submit an article to "What is the Deal?" click here. To subscribe to the "What is the Deal?" mailing list and receive early notification when a new column is available, click here. The Pie of Knowledge will never, ever divulge email addresses to any third party for any reason unless so ordered by a court of law. Contributions to the Pie of Knowledge are greatly appreciated. 
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