Voyager 1 is Awake and Communicating!

This past Saturday, April 20, Voyager 1 updated ground control about its health status with a coherent message for the first time in 5 months. While she still isn't fully operational and sending science data back to Earth, Voyager 1 is now returning usable information about the health and operating status of its onboard systems. 

If you're a regular reader, you'll recall that back in November, Voyager suddenly started acting like something was seriously wrong. I likened it to the probe having had a stroke, although that's too anthropomorphic. The probe seemed to take commands and respond, it still kept its position and kept the data link back to Earth running, it's just that the replies it sent back were more like incoherent ramblings. Something about its uncle having been eaten by cannibals before the mission started. No, sorry. I made that up. 

In the months since that first post on December 12, we've gotten a few updates. The last things we heard were in mid-March, that they had run a memory "poke" and had a pretty good idea of what the problem was. 

This memory dump revealed to scientists and engineers that the "glitch" is the result of a corrupted code contained on a single chip representing around 3% of the FDS memory. The loss of this code rendered Voyager 1's science and engineering data unusable.

With a light travel time of 22-1/2 hours, it takes a couple of days to do an experiment, so it's a good practice, perhaps even more than usual, to be pretty darn sure it's going to work. The software was sent to Voyager over the Deep Space Network on Thursday, the 18th. On Saturday, several dozen scientists and engineers gathered in a conference room at the Jet Propulsion Laboratory, or connected virtually, to wait for a new signal from Voyager 1.

“In the minutes leading up to when we were going to see a signal, you could have heard a pin drop in the room," said Linda Spilker, project scientist for NASA's two Voyager spacecraft at JPL. "It was quiet. People were looking very serious. They were looking at their computer screens. Each of the subsystem (engineers) had pages up that they were looking at, to watch as they would be populated."

And then the celebrations began.

After receiving data about the health and status of Voyager 1 for the first time in five months, members of the Voyager flight team celebrate in a conference room at NASA’s Jet Propulsion Laboratory on April 20. Credit: NASA/JPL-Caltech

Of course, with the Voyagers being over 22 hours away at the speed of light, and it having taken them 46 years to get that far away, nobody's going out to Voyager 1 to replace a memory chip. No single section of the memory is large enough to hold this code entirely. The team can slice it into sections and store the slices separately. There are more details, as always, which come down to essentially recreating a storage system and ensuring that will work. Redesigning the computer on the fly. As it approaches its 50th birthday in 2027. And "document, document, document" what you've done - like every space job.

One of the first references I found to this story started out with a line that I think I'll finish with. I can't find the article but it was something like, "the miracle workers at the JPL have done it again." Well done, everyone. Well done, and good luck with the work left to be done.