On 22 April Voyager 2 went wrong. Since their launch in 1977, the Voyager twins have provided a non-stop 24/7 stream of data telemetry to the mission scientists at NASA’s Jet Propulsion Laboratory. But on the day of the fault, that stream of information suddenly became scrambled and unreadable. Quick diagnostics showed that the probe was still working as designed, was still receiving and obeying instructions and still collecting data and transmitting it to Earth. It was only one specific step – where the data was encoded into a stream that can easily be transmitted and decoded – that had gone wrong. Dwell on that for a minute – can you think of one single complex electronic device in your life that has continued to operate without powering down for 33 years before developing a single fault? Then consider the incredibly harsh radioactive environment in which the probes operate!
Mission engineers have now identified the fault. It seems a cosmic ray (super energetic subatomic particle blasted out from some primeval star billions of years ago. Space is full of them.) managed to blast through the radiation shielding and collided with one single bit of memory on Voyager’s on-board computer. The value of that bit flipped from ‘0’ to ‘1’, which was enough to corrupt the software in that region of memory. Tomorrow (19 May), a new program will be uploaded to correct the error. It all sounds so routine until you realise that Voyager 2 is running a 33 year old computer system with no option to replace spares, that’s almost fourteen BILLION kilometres away and is moving away from us at a speed of seventeen kilometres every second. I thought I’d worked a few miracles in my days as a support tech, but this is pretty hard act to follow!