NASA is planning to extend the life of the Voyager 1 spacecraft until 2025 by shutting off the heating system to save power. Voyager 1 was launched on Sept. 5, 1977, about two weeks after Voyager 2 in what was originally planned to be a five-year mission to study Jupiter and Saturn.

The spectrometer, which collects and returns data, aboard Voyager 1 was built to withstand temperatures as low as minus 35 degrees Celsius (minus 31 degrees Fahrenheit), The heater nearest the spectrometer was actually shut off 17 years ago and other heaters in the spacecraft kept the temperature around minus 56 degrees Celsius (minus 69 degrees Fahrenheit.) Scientists believe the termperature inside Voyager 1 will read minus 79 degrees Celsius (or minus 110 degrees Fahrenheit), since that's as low as the thermometer will indicate.

In this gallery, originally posted in 2007, we'll look at some of the more fascinating discoveries of Voyager 1 and Voyager 2.

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