Man-made objects launched by the United States in 1977 are about to leave our solar system to begin an infinite journey through interstellar space.
Back when Voyagers One and Two were launched, mission planners at the Jet Propulsion Laboratory calculated that the probes would last five years. It would not be the first time scientists would drastically underestimate the staying power of an American space machine.
Very soon, the twin spacecraft (NASA opted for redundancy to ensure the success of the mission) will emerge from the sun’s magnetosphere, sometimes referred to as the “heliospheric bubble” that divides the solar and stellar winds, and become the first spacecraft to leave our solar system to explore the Milky Way. Each carries a gold-plated copper disk containing, among other data, greetings in 55 Earth languages.
It appears the only thing that can silence the Voyagers, whose signal strength in messages back to Earth is now measured in femtowatts, is the depletion of their plutonium power sources. That isn’t expected to happen until around 2020, meaning the craft will actually be traveling through the extreme foreground of deep space seen in all those spectacular Hubble Telescope images.
The Voyagers are hardly the only planetary probes that have far exceeded their expected lifetimes. The spunky Mars rover named Opportunity recently resumed operations after surviving its eighth Martian winter. Opportunity and its stalled mate Spirit landed on Mars in January 2004 and were expected to operate for perhaps a few months.
Both the Voyager and Mars rover programs illustrate the remarkable reliability of space electronics and the genius of the system engineers who in many cases used off-the-shelf systems, such as real-time operating systems, to design these magnificent machines. Their ingenuity stands as one of the foremost achievements of the electronics age.