Sometime around 2 a.m. Pacific time on November 18, Voyager 1 will cross a line that exists only on our charts. That's the moment mission project scientist Linda Spilker gave Planetary Radio for the spacecraft reaching one light-day from Earth, about 16 billion miles out. In practical terms, a probe launched in 1977 will be so far away that The Register notes a command takes a full 24 hours to arrive and another 24 for the response to come home.
It's a lovely number, and it will get the headlines. My argument is that the more interesting story sits beside it. Distance isn't really what Voyager is good at, because anything thrown hard enough will travel. What deserves the attention is that the thing still answers, and it does so because of a quiet craft: fixing machines that no human will ever touch again.
So here are three repairs, picked because each one worked around a different limit. One is a broken part, one a capability running out, and one a power supply that won't stretch. They aren't all from the same mission. They do share a habit of mind.
The chip nobody could replace
The best-known repair is Voyager 1's own. On November 14, 2023, the spacecraft stopped sending readable data, although controllers could tell it was still receiving their commands. By March, teams at NASA's Jet Propulsion Laboratory had found the culprit, a single malfunctioning chip.
Nobody could go out and swap it. The fix had to fit the tight memory of a 46-year-old computer system. "So we had to reprogram what was in that memory, move it to a different location, link everything back together and send everything up in a patch," Spilker told the ABC. It's the sort of job you'd give a careful librarian, carried out more than 24 billion kilometres from the shelves, with each message taking about 22.5 hours to reach the spacecraft.
It worked. Space.com reported that Voyager 1 sent intelligible data on April 20, 2024, from only two of its four science instruments, and that the other two were back about two months later. Slow, yes, but I can't think of many pieces of 46-year-old technology that would survive that kind of surgery, and fewer still where the surgeon waits nearly two days to find out whether the patient is alive.
The telescope that learned to limp
Hubble's problem was simpler and less forgiving. It has six gyroscopes, all replaced on the final servicing mission in 2009, and it normally needs three. Spaceflight Now's William Harwood reported in June 2024 that one of the survivors had been taken offline, leaving two healthy units.
NASA's answer was to stop asking for three. From mid-2024 the plan was to work on one gyro and hold the other in reserve. The price is real: scheduling efficiency drops by about 12 percent, less of the sky is visible at any given moment, and the telescope can't lock onto anything closer than the orbit of Mars. Project manager Patrick Crouse put the odds of keeping at least one gyro running through 2035 at better than 70 percent.
I like this one because it isn't a triumph. It's an honest trade. Somebody looked at a machine losing a capability and worked out which jobs it could give up to keep doing the rest.
The power bill that keeps coming
Back on Voyager, the newest repair is barely a repair at all. Controllers have just finished a procedure nicknamed the "Big Bang", The Register reports, turning off onboard devices and switching to lower-power alternatives. It was done on Voyager 2 first, then on Voyager 1 six weeks later in September, and the outlet says it should buy a few more years and put off further instrument shutdowns.
Nothing was broken. The team simply went looking for a little more life, which is about as Voyager as it gets.
What a two-day wait does to a fix
Then, on October 18, the Deep Space Network couldn't find Voyager 1's signal. There was nothing on the next attempt on October 19 either. On October 20 it came back. So far, it seems a group of thrusters went offline and their backups were turned on, which The Register says could mean the onboard computers detected a problem and put the spacecraft in a safe mode. "This is the first time we've seen the spacecraft do something like this, but we are also at a point in the mission where we have to expect the unexpected," mission manager Kareem Badaruddin said.
Every repair above depended on a conversation, and that conversation keeps stretching. At one light-day, you can't poke at a fault and watch what happens. Each question has to be chosen as if it's your only one for the week.
Project manager Suzanne Dodd has already told The Register how this ends: "We're just going to one day not hear the signal from the DSN, and we're going to rush around and make sure that it's not something on the ground." That's the line I'd keep in mind on November 18. The light-day will be marked as a measure of how far we've gone. For the people keeping Voyager alive, it's closer to a measure of how slowly they'll now have to think. The line itself doesn't matter much. The fact that someone is still on the other end of it, working out the next careful question, matters a great deal.
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