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ablethevoice 01-24-2011 06:09 PM

33 years and still working!
Way back in the late 1970's NASA sent up a couple of small planetary probes to do a survey of Jupiter and Saturn. Just as with the Mars rovers, these probes were expected to finish their work and ... well... croak after about 15 or so years but no. A full thirty-three years later, the Voyagers 1 and 2 are still (more or less) functioning and still sending back usable data. If only computer companies could make a home PC with the same build quality...:bored:

The primary issue with the Voyagers is not the computers or the instruments, its their power supplies. They get their power from a special device called a RTG (Radioisotope Thermoelectric Generator); a form of toned-down nuclear reactor. These little beasts can produce a steady stream of power for decades with no refueling - a very appealing characteristic when designing space probes meant to delve into the cold darkness of the outer solar system where sunlight is too dim to make solar panels economically viable. As an example, sunlight on Pluto is about 1/5000 as bright as on earth (about as bright as the moon at first quarter phase) so in order to get the amount of power the 3 RTGs the New Horizons is carrying from solar cells, the NH would have to be carrying about 100 acres of solar panels... an unwieldy setup to say the least!

Besides the Voyager probes, all other outer solar system probes have (or are still) getting their power from RTGs. The Pioneers 10 & 11, the Cassini probe still exploring the Saturn system, the New Horizons mission to Pluto, the (now decommissioned) Galileo mission to Jupiter and others all use these little nuclear batteries.

Now, 33 years after launch, the Voyager craft's RTGs are still producing power but only about 1/6th or so of what they were back in the prime of the mission and that is why the little guys are "more or less" still functioning. The craft's energy hog instruments can no longer function with the power that is left so they were shut down in order for the lower-demand systems to continue working. How much longer will the Voyagers operate? No one knows. I'd say, though, that us taxpayers really got their money's worth out of machines that are still sending back data after 33 years of continuous operation!

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