What these guys did… moving software around in memory
would be routine locally, but to diagnose and workaround a dud memory chip at that distance is an amazing achievement.
I wonder what language they used?
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I just kind of skimmed an article on that earlier today, but that is pretty amazing. Maybe they have a replica to test with back here on Earth to test with. Or a simulator at least.
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They would have to be able to debug locally. No room for error when they install at that distance.
I found out what software is used
"The original software for the Voyager probes was written using Fortran 5 then ported to Fortran 77, and today there is some porting in C. "
Not sure what they upload… probably a binary. They would not compile it in Voyager.
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They did it without a local test bed!
“Newer NASA missions have hardware and software simulators on the ground, where engineers can test new procedures to make sure they do no harm when they uplink commands to the real spacecraft. Due to its age, Voyager doesn’t have any ground simulators, and much of the mission’s original design documentation remains in paper form and hasn’t been digitized.”
This came from here
Can you imagine doing that on paper and having to get it right first try?
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It’s like watching Apollo 13 and when Jim Lovell asks for them to check his math, they whip out their slide rules and go at it.
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Talk about wait time or being on hold.
“Given Voyager 1’s immense distance from Earth, it takes a radio signal about 22.5 hours to reach the probe, and another 22.5 hours for a response signal from the spacecraft to reach Earth.”
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This is really cool, Neville! Thank you for sharing!
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So 45 hours for a ping. … that is latency (with a capital L)
What is the baud rate?
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Don’t know how accurate this is but I found this;
“Voyager data is returned to earth in real time at 160 bits per second and recorded plasma science data is sent several times a year at 2.8 kbps. Uplinked commands are sent to the spacecraft at 16 bps.”
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So they uploaded code at 16bps… it could have taken days to upload that fix.
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If it did take days, where did they send it from? Before the transmission was done the Earth would have rotated with Voyager being out of view. It must have been from someplace in orbit or maybe from multiple ground stations.
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Of course when the spacecraft was lunched and in almost perfect condition, the data transmission rate was much, much better. Doing a little more reading I found this about the data rate.
“The data rate for the Voyager Interstellar Mission is much reduced from its planetary encounters. The maximum data rate at Jupiter was 115,200 bps.”
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The people on the mission team have truly achieved a monumental success! After reading all the posts and replies here, I’ve learned just how huge it really was! They not only fixed Vouager1 from the greatest distance of any man-made object, they did it without any ground-based simulator, so, if they made any mistakes, they wouldn’t have known about it until about 2 days after the upload, that is, if they got any response at all. This may have been the most daunting operation ever attempted by any mission/IT team, ever! Those people should be very proud of their achievement! I know I am!
Ernie
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NASA has a history of programming achievements, including the famous Margaret Hamilton
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Then perhaps I over-stated the achievement, but it is one of the most significant I’ve learned about,
Ernie
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I dont think you overstated.
Programming that without a test bed is an awesome achievement
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Well said. That’s what I was trying to say 
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If you get a chance you may want to watch the movie ‘Hidden Figures’. I really enjoyed it.
The movie tagline is about 3 “African-American female mathematicians that served as the brains behind one of the greatest operations in U.S. history. Based on the unbelievably true life stories of three of these women, known as “human computers””.
Back then they called a person who performed mathematical calculations a computer.
The move is “loosely based on the 2016 non-fiction book of the same name by Margot Lee Shetterly”.
This was before computers were used. One of the women was Katherine Johnson.
Two NASA facilities have been named in her honor,
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The achievements of the NASA engineers correcting the Voyager systems are awesome as were those of the women who worked at NASA in the early days of space flights as portrayed in Hidden Figures. All these engineers must have spent time thinking through the problems while lacking simulators etc.
I was reminded of problems, trivial in comparison, which I met when working
on vehicle engine management systems. On one vehicle model the starter
was being damaged and this was thought to be due to an interface chip
causing an interrupt leading to starter failure. This happened very rarely in each vehicle but with many thousands of vehicles in use it was an expensive problem. Days were wasted trying to log the fault on a test vehicle without success. The solution was found when an engineer spent time thinking about why and when the interrupt occurred.
Another case was to determine when integer overflow could occur. First thoughts were to use a simulator but the solution was to think about the magnitudes of the numbers involved.
Do others feel that not enough time is spent thinking about problems rather than rushing to simulation etc.
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I was doing the Advent of Code a couple years ago in Python and there was one problem I attempted to solve and couldn’t quite get there. The problem was simple enough and I had an algorithm that would find a solution, but they had created the problem such that you would run out of memory before reaching a solution. I even thought I’d fire up a t3.4xlarge EC2 instance with tons of memory to see if it’d work but had the same issue.
They wanted you to think about the problem and I just didn’t make the leap in my mind to their solution.
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