To me, the physics of the situation makes this all the more impressive.
Voyager has a 23 watt radio. That’s about 10x as much power as a cell phone’s radio, but it’s still small. Voyager is so far away it takes 22.5 hours for the signal to get to earth traveling at light speed. This is a radio beam, not a laser, but it’s extraordinarily tight beam for a radio, with the focus only 0.5 degrees wide, but that means it’s still 1000x wider than the earth when it arrives. It’s being received by some of the biggest antennas ever made, but they’re still only 70m wide, so each one only receives a tiny fraction of the power the power transmitted. So, they’re decoding a signal that’s 10^-18 watts.
So, not only are you debugging a system created half a century ago without being able to see or touch it, you’re doing it with a 2-day delay to see what your changes do, and using the most absurdly powerful radios just to send signals.
The computer side of things is also even more impressive than this makes it sound. A memory chip failed. On Earth, you’d probably try to figure that out by physically looking at the hardware, and then probing it with a multimeter or an oscilloscope or something. They couldn’t do that. They had to debug it by watching the program as it ran and as it tried to use this faulty memory chip and failed in interesting ways. They could interact with it, but only on a 2 day delay. They also had to know that any wrong move and the little control they had over it could fail and it would be fully dead.
So, a malfunctioning computer that you can only interact with at 40 bits per second, that takes 2 full days between every send and receive, that has flaky hardware and was designed more than 50 years ago.
FlatFootFox@lemmy.world 1 year ago
I still cannot believe NASA managed to re-establish a connection with Voyager 1.
That scene from The Martian where JPL had a hardware copy of Pathfinder on Earth? That’s not apocryphal. NASA keeps a lot of engineering models around for a variety of purposes including this sort of hardware troubleshooting.
It’s a practice they started after Voyager. They shot that patch off into space based off of old documentation, blueprints, and internal memos.
nxdefiant@startrek.website 1 year ago
Imagine scrolling back in the Slack chat 50 years to find that one thing someone said about how the chip bypass worked.
xantoxis@lemmy.world 1 year ago
Imagine any internet company lasting 50 years.
ricecake@sh.itjust.works 1 year ago
To add to the metal, the blueprints include the blueprints for the processor.
hackaday.com/2024/05/…/the-computers-of-voyager/
They don’t use a microprocessor like anything today would, but a pile of chips that provide things like logic gates and counters. A grown up version of gigatron.io
That means “written in assembly” means “written in a bespoke assembly dialect that we maybe didn’t document very well, or the hardware it ran on, which was also bespoke”.
Karyoplasma@discuss.tchncs.de 1 year ago
They also released the source code of the Apollo 11 guidance computer. So if you want to fly to the moon, here is one part of how to do it.
BearOfaTime@lemm.ee 1 year ago
I realize the Voyager project may not be super well funded today (how is it funded, just general NASA funds now?), just wondering what they have hardware-wise (or ever had). Certainly the Voyager system had to have precursors (versions)?
Or do they have a simulator of it today - we’re talking about early 70’s hardware, should be fairly straightforward to replicate in software? Perhaps some independent geeks have done this for fun? (I’ve read of some old hardware such as 8088 being replicated in software because some geeks just like doing things like that).
I have no idea how NASA functions with old projects like this, and I’m surely not saying I have better ideas - they’ve probably thought of a million more ways to validate what they’re doing.
PriorityMotif@lemmy.world 1 year ago
FlatFootFox@lemmy.world 1 year ago
The Hard Fork podcast had a pretty good episode recently where they interviewed one of the engineers on the project. They’d troubleshooted the spacecraft enough in the past that they weren’t starting from square one, but it still sounded pretty difficult.
SpaceNoodle@lemmy.world 1 year ago
They apparently didn’t have an emulator. The first thing I’d have done when working on a solution would have been to build one, but they seem to have pulled it off without.
Qli@lemmy.world 1 year ago
There is an fascinating documentary about the team that sends the commands to Voyager 1 and 2 called It’s Quieter in the Twilight
Baggie@lemmy.zip 1 year ago
100% they’ve got an emulator, they’ve had dedicated test environments since the moon landing for emulating disaster recovery scenarios since the moon landings, they’ve likely got at least one functioning hardware replica and very likely can spin up a hardware emulation as a virtual machine at will.
Source: I made this up, but I have a good understanding of systems admin and have a interest in space stuff so I’m pretty confident they would have this stuff at bare minimum