Anyone got any detailed info on what CPU, software and programming language is used on the Voyager that can support something as "advanced" as OTA software patches?
It was launched in 1977 and since aerospace uses tech older than consumer tech, it probably isn't running anything remotely as advanced as a Z80, 6800 or 6502 which came out only a few years before Voyager was launched.
Any info I found point to a custom 18 bit CPU built out of discrete TTL 7400 series parts which would be period correct, but not much details on how the SW, programming and OTA updates work.
I assume NASA has the full HW-SW stack, compiler, toolchain, version control, plus HW and SW simulators for it so making some of them public would be really cool considering the source code of the moon lander is already public. What do they have to loose?
There's two of them.
They send software updates fairly regularly (including a nearly full rewrite in 1990) and this is a common question. You can find some statements in older reporting on other updates..
It's in some sense not very exciting. Basically, it's an interrupt-driven system and you can, by radio command, invoke handlers that will rewrite some memory holding the program with new contents and hand control back to other routines. Of course with the expected error handling and failover protections in place. NASA got quite good at it during the Mariner missions, which saw the first remote updates for their programmable sequencers, and by the time of Viking and the CCS, it was a routine part of the requirements.
There's tooling written in Fortran (and later partially ported with C) that supports the Earth-based team in preparing the updates.
The patches discussed in the article are actually for a different type of computer in the system, the AACS (Attitude and Articulation Control Subsystem). But it's similar there: There's redundancy (there's two) and you patch memory contents, do a memory read-out to double check and kick things into gear.
Well, neither is the Doom source code for most people, but for others it could be pretty cool to read, especially that the moon lander's source code is already public.
Technically it's like 0.0001% OTA and 99.9999% OTVoS (Over The Void of Space).
Voyager website is awesome
https://voyager.jpl.nasa.gov/mission/timeline/
A very different time, thank goodness for DEI now
https://voyager.jpl.nasa.gov/assets/images/timeline/0003.jpg
or a picture of senior leadership at Google.
plus ça change, plus c’est la même chose
What is it written in? Assembler, surely?
What is the development toolchain like in 2023 for a 70s computer? Do they have an emulator? What happened to the spare development Voyager they had lying around?
https://www.muckrock.com/foi/united-states-of-america-10/voy...
"The spacecrafts’ original control and analysis software was written in Fortran 5 (later ported to Fortran 77). Some of the software is still in Fortran, though other pieces have now been ported to the somewhat more modern C."
"To keep the Voyager 1 and 2 crafts going, NASA's new hire has to know FORTRAN and assembly languages." - https://www.popularmechanics.com/space/a17991/voyager-1-voya...
It is crazy that the government can pay for something and yet the People do not own it.
Under Illinois FOIA, anything done under a contract to the State is FOIA-able as a record of the government body that ordered the work.
The 2013 article was based on an interview with the current (2013) Voyager project manager, who began working on the Voyager project in 1984, a few years after the 1977 launches.
First off, I'm guessing that project manager said "Fortran Five" (while thinking "Fortran V") and the writer wrote down "Fortran 5". The Wikipedia article for Fortran (which also references this Wired article, erroneously I think) says there was only one Fortran 5, introduced by Data General in the late 1970s. Other companies offered Fortran V.
Second, I think the key phrase in the quote is "control and analysis software". To me, this connotes the ground system: mission control and science data analysis. And Fortran was commonly used in ground processing and such code could be ported to Fortran 77 and later C.
The on-board spacecraft flight software would be another matter. Voyagers 1 and 2 were launched in 1977. I can't imagine trusting the flight software to newly introduced Fortran V compilers (or even a pre-release DG Fortran 5 compiler). And then switching compilers to Fortran 77 and then C. Possible, but IMHO, not likely.
I am open to being corrected. Regarding FOIAs, I had not thought of going to that extreme and, as your link to the muckrock request verifies, I had also learned that the papers were the property of Caltech, not NASA. Which is unfortunate as the documents and communications mentioned in the link below promise some fascinating reading just begging to be made available online!
I highly recommend reading "Computers in Spaceflight: The NASA Experience" at https://history.nasa.gov/computers/contents.html . (The author of the history did visit the JPL archives and was able to read a fascinating assortment of documents in hardcopy form.)
Chapter 6, "Distributed Computing On Board Voyager and Galileo" ( https://history.nasa.gov/computers/Ch6-2.html ), describes the Voyager computers in some detail. There were 3 computers:
(1) Command Computer Subsystem (CCS) - command processing/sequencing, etc. This computer was carried over from the Viking missions.
(2) Attitude Control System - used a revamped, beefed up CCS computer.
(3) Flight Data System - telemetry and science data handling/transmission. Because of the high data rates, a new computer was needed. A hardware engineer and a software developer collaborated on the design of the computer. Knowing the timing requirements, they developed the CPU's hardware and instruction set on the fly until the software (a changing mock-up I assume) could meet the requirements. (Some of this I might have read elsewhere.)
As I noted, what a treasure trove their memos and communications from this time would be if they were online!
Also is this correct?
>NASA extended the mission so that Voyager 2 could visit Uranus and Neptune; it is still the only spacecraft ever to have encountered the >ice giants<.
Aren’t they gas giants? I mean they are probably very cold, but usually they are called gas giants.
"Ice giant" seems to be the more modern terminology:
An ice giant is a giant planet composed mainly of elements heavier than hydrogen and helium, such as oxygen, carbon, nitrogen, and sulfur. There are two ice giants in the Solar System: Uranus and Neptune.
In astrophysics and planetary science the term "ice" refers to volatile chemical compounds with freezing points above about 100 K, such as water, ammonia, or methane, with freezing points of 273 K (0°C), 195 K (−78°C), and 91 K (−182°C), respectively (see Volatiles). In the 1990s, it was determined that Uranus and Neptune were a distinct class of giant planet, separate from the other giant planets, Jupiter and Saturn, which are gas giants predominantly composed of hydrogen and helium.
As such, Neptune and Uranus are now referred to as ice giants.
In any case, I understand ice giants to be a subset of gas giants with more specific parameters.
Uranus is for sure.
Right now I think the only dish in the world setup with the correct equipment to signal the Voyagers that is large enough is the Deep Space Network dish in Canberra, Australia.
Voyager’s follow-ups have been missions like Galileo and Cassini, which stayed in orbit around Jupiter and Saturn respectively, allowing more detailed observations with better instruments. It looks like the next priority is Uranus:
- The Jupiter Icy Moons Explorer is a European probe that was launched earlier this year, it'll be studying the moons Europa, Callisto, and Ganymede.
- NASA has Europa Clipper scheduled for launch next year, that'll be taking a close look at Europa.
- NASA also has the Dragonfly mission in the works to explore Saturn's moon Titan using an octocopter, currently planned for launch in 2027.
