A corrupted chip has been blamed for the ageing spacecraft's recent woes. This prevented Voyager's computers from accessing a vital segment of software code used to package information for transmission to Earth.
For a period of time, engineers could get no sense whatsoever out of Voyager, even though they could tell the spacecraft was still receiving their commands and otherwise operating normally. The issue was resolved by shifting the affected code to different locations in the memory of the probe's computers.
Voyager-1 departed Earth on 5 September 1977, a few days after its sister spacecraft, Voyager-2. The pair's primary objective was to survey the planets Jupiter, Saturn, Uranus and Neptune - a task they completed in 1989.
They were then steered towards deep space, in the general direction of our galaxy's centre. Their power comes from radioisotope thermoelectric generators (RTGs), which convert heat from decaying plutonium into electricity. The continual decay process means the generators produce slightly less power each year.
How much longer the Voyagers can continue is uncertain, but engineers have until now always come up with strategies to eke out a few extra years of operations. Voyager-2 is a little behind its twin and moving slightly slower.
It's just over 20 billion km (13 billion miles) from Earth. Even though both are travelling at over 15 km per second (9 miles/s), they would not approach another star for tens of thousands of years.
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