A new signal from humanity's most distant spacecraft could be the key to restoring it.
On March 1, engineers sent a command up to Voyager 1—more than 15 billion miles (24 billion kilometers) away from Earth—to "gently prompt" one of the spacecraft's computers to try different sequences in its software package.
But Voyager 1 responded to the March 1 troubleshooting command with something different from what engineers have seen since this issue first appeared on November 14.
"The new signal was still not in the format used by Voyager 1 when the FDS is working properly, so the team wasn’t initially sure what to make of it," NASA said in an update Wednesday. "But an engineer with the agency’s Deep Space Network ... was able to decode the new signal and found that it contains a readout of the entire FDS memory."
Now, engineers are meticulously comparing each bit of code from the FDS memory readout to the memory readout Voyager 1 sent back to Earth before the issue arose in November. This, they hope, will allow them to find the root of the problem. But it will probably take weeks or months for the Voyager team to take the next step. They don't want to cause more harm.
"Using that information to devise a potential solution and attempt to put it into action will take time," NASA said.
The fact that we are even able to still communicate with it, that it is still sending us data, and that this is even a thing just blows me away. I can’t imagine anything I’ve ever worked on lasting this long. 
What I find insane is that scientists actually do firmware upgrades to rovers like Curiosity. Imagine the stakes of doing firmware upgrades on a device on another planet that you can't communicate with in real time.
I'm amazed that they can do anything like that with a computer built in the early 70s that's been subjected to the conditions of deep space for half a century.
In some ways it kinda helps, the larger physical structures of the older computer hardware make it naturally more resistant to cosmic radiation than new stuff. New stuff just needs more shielding though, so not a huge deal.
But a big part of it staying viable for this long is that it was designed in a way that made it possible. Alot of forethought went into making sure it would last as long as possible. While they didn't expect it to for sure last this long, they did at least want to make sure the reason it didn't wasn't because they didn't plan for the possibility. There was a decent element of luck too, as there were more unknowns back then about what it was going to be subjected to on its journey.
The whole way the onboard computer functions was optimized for remote repair though, because of course the plan was to never see it again, and they knew it was going to need to be repaired alot despite. So at any point in it's "thought process" it is waiting to be interrupted by a call from earth telling it to stop all that and basically dump the entire contents of it's operating memory. And can recieve an entire rewrite of it too, with built-in checks to make sure it recieved it right before starting to operate from it again. Luckily an entire rewrite of everything it can possibly hold is 70kb. So despite the distance and chance of failure, it's still not that bad of an ordeal.
It never occurred to me until now to wonder how Voyager knows it's picking up a signal from NASA. Theoretically, if some bad actors had the means to get it beyond the heliosphere, could a rogue signal be sent to make Voyager brick itself?
I mean I would imagine if someone got their hands on the deep space network in order to have the broadcast power thats a possibility, they would also need to know whatever checksum is sent to Voyager as I would imagine it checks data intergrity before attempting an update
That's why they have a "digital twin" that they can use to simulate their actions. They used to have entire replicas of the probes on the ground they could test against, but a virtual one is much cheaper, and you don't need to physically be there to use it.
I assume they've also engineered them so that if there's a failure in a primary system, it falls back to a more basic recovery system. NASA engineers are pretty thorough in planning for failure scenarios.
Like how they fucked up with the antenna on Voyager 2 last year. They eventually sent a correction signal out, but even if they hadn't been able to, they are set to autonomously reorient the antenna back to Earth every so often, as a failsafe against that very error.
Right? I get stressed out doing that to my router