Still Transmitting
Voyager 1 is approximately 24 billion kilometers from Earth. Voyager 2 is about 20 billion kilometers away. both were launched in 1977. both are still transmitting. the signals take more than 22 hours to reach us at the speed of light. and yet, every day, the Deep Space Network receives data from both probes.
this is remarkable for reasons that go beyond the obvious. the probes were designed for a five-year mission. they've been operating for nearly fifty years. the hardware running them — the computers, the power systems, the transmitters — was designed and built in the early 1970s. the engineering decisions that outlast their context are rarely this visible, but Voyager makes them impossible to ignore.
The Anomalies
in 2023, Voyager 1 started sending garbled data. the science and engineering data was corrupted — readable, but wrong. the team at JPL spent months diagnosing the problem from 24 billion kilometers away, with a 45-hour round-trip communication delay. they eventually traced it to a single corrupted memory chip in the flight data system computer.
the fix required reprogramming the probe to route around the damaged chip — essentially rewriting the software of a 46-year-old spacecraft using a programming language that almost nobody still knows, transmitted across interstellar space, with no ability to test the fix before deploying it. the challenge of maintaining legacy systems doesn't get more extreme than this.
Why They're Still Talking
the Voyager probes are powered by radioisotope thermoelectric generators — RTGs — that convert heat from the decay of plutonium-238 into electricity. the RTGs are losing about 4 watts of power per year. the probes currently have enough power to operate a few instruments each. by the early 2030s, they'll have to start shutting down instruments entirely. by the mid-2030s, they may not have enough power to transmit at all.
but they're still talking now. the longevity of well-engineered systems is the real story here. the Voyager probes were built to last five years and have lasted fifty. the engineers who built them are mostly retired or dead. the probes are still out there, still sending data, still doing science in a region of space no human-made object had ever reached before.
What This Means
I think about Voyager when I'm making decisions about software architecture. not because spacecraft engineering translates directly to software — it doesn't — but because the question is the same: what are you building, and how long do you expect it to last? the Voyager engineers built for five years and got fifty. that's not luck. that's margin. they built in more margin than they thought they needed, and the margin is what's still transmitting.