NASA's Project Scientist Faces Painful Choices as Voyager Mission Nears Its End(gizmodo.com)
gizmodo.com
NASA's Project Scientist Faces Painful Choices as Voyager Mission Nears Its End
https://gizmodo.com/keeping-voyager-alive-nasas-project-scientist-faces-painful-choices-as-the-iconic-mission-nears-its-end-2000580634
39 comments
> We're teaching 2020s engineers to understand machine code written before MS-DOS existed
It has three on-board computers. Two of them (the CCS and AACS) are 18-bit word-oriented machines with 4096 words of memory – so in 8 bit bytes thats 9KB of RAM. Although 18-bit machines were reasonably common in the 1960s and 1970s (especially the DEC PDP-7 which was the birthplace of both UNIX and MUMPS, its predecessor the PDP-4 and its successors the PDP-9 and PDP-15), you'd never encounter them nowadays except in retrocomputing or ultra-legacy systems like this. The other one (FDS) is a 16-bit word oriented machine with 8198 words of memory – so a bit less esoteric, although the 16-bit systems most people would be familiar with (e.g. the Intel 8086/8088 used by MS-DOS) are byte-oriented not word-oriented. So yeah, even for people used to doing assembly programming, might take a bit of time to get your head around it.
Both computer architectures are NASA custom, not industry standard – although they were reused from the Viking Mars landers, so weren't a brand new thing to NASA at the time. Rather than a single chip CPU, their CPUs were built out of a large number of 7400 series TTL ICs – so essentially early third generation computers (small scale integration, SSI, became available in mid-1960s), as opposed to fourth generation computers (1970s, with LSI/VLSI, transistor counts on integrated circuits had become high enough that the whole CPU could fit on a whole microprocessor).
(There is this widely repeated legend that the Voyagers used RCA 1802 CPUs, but that appears to be mixing up Viking/Voyager which used NASA custom CPU architectures, with the Galileo probe launched in 1989, which used RCA 1802 CPUs for its main computer, plus Itek ATAC CPUs for the attitude control computers. The ATACs were also used by some US naval aircraft – and whereas the Voyager was all assembler, the Galileo ATAC CPUs were programmed using HAL/S, the same language used for the Space Shuttle flight software.)
It has three on-board computers. Two of them (the CCS and AACS) are 18-bit word-oriented machines with 4096 words of memory – so in 8 bit bytes thats 9KB of RAM. Although 18-bit machines were reasonably common in the 1960s and 1970s (especially the DEC PDP-7 which was the birthplace of both UNIX and MUMPS, its predecessor the PDP-4 and its successors the PDP-9 and PDP-15), you'd never encounter them nowadays except in retrocomputing or ultra-legacy systems like this. The other one (FDS) is a 16-bit word oriented machine with 8198 words of memory – so a bit less esoteric, although the 16-bit systems most people would be familiar with (e.g. the Intel 8086/8088 used by MS-DOS) are byte-oriented not word-oriented. So yeah, even for people used to doing assembly programming, might take a bit of time to get your head around it.
Both computer architectures are NASA custom, not industry standard – although they were reused from the Viking Mars landers, so weren't a brand new thing to NASA at the time. Rather than a single chip CPU, their CPUs were built out of a large number of 7400 series TTL ICs – so essentially early third generation computers (small scale integration, SSI, became available in mid-1960s), as opposed to fourth generation computers (1970s, with LSI/VLSI, transistor counts on integrated circuits had become high enough that the whole CPU could fit on a whole microprocessor).
(There is this widely repeated legend that the Voyagers used RCA 1802 CPUs, but that appears to be mixing up Viking/Voyager which used NASA custom CPU architectures, with the Galileo probe launched in 1989, which used RCA 1802 CPUs for its main computer, plus Itek ATAC CPUs for the attitude control computers. The ATACs were also used by some US naval aircraft – and whereas the Voyager was all assembler, the Galileo ATAC CPUs were programmed using HAL/S, the same language used for the Space Shuttle flight software.)
> although they were reused from the Viking Mars landers
Correction: the 18-bit computers used on the Voyagers were reused from the Viking orbiters. The Viking landers used a different computer architecture, the Honeywell HDC 402, which used a 24-bit word, and was not reused by Voyager
Correction: the 18-bit computers used on the Voyagers were reused from the Viking orbiters. The Viking landers used a different computer architecture, the Honeywell HDC 402, which used a 24-bit word, and was not reused by Voyager
Great comment. This mentality is what makes great engineers and thinkers.
Every time this topic comes up on HN, I always like to remind readers about the following:
One of my favorite facts ever is that Voyager 1 contains something called the Voyager Golden Record [1]. It has the following quote written:
This is a present from a small, distant world, a token of our sounds, our science, our images, our music, our thoughts and our feelings. We are attempting to survive our time so we may live into yours.
I get chills every time I think about this.
[1] https://en.wikipedia.org/wiki/Voyager_Golden_Record
One of my favorite facts ever is that Voyager 1 contains something called the Voyager Golden Record [1]. It has the following quote written:
This is a present from a small, distant world, a token of our sounds, our science, our images, our music, our thoughts and our feelings. We are attempting to survive our time so we may live into yours.
I get chills every time I think about this.
[1] https://en.wikipedia.org/wiki/Voyager_Golden_Record
I thought it was interesting to share the full quote. It’s a fascinating read.
>An official statement by President Jimmy Carter was included as images (positions 117, 118). It reads, in part:
This Voyager spacecraft was constructed by the United States of America. We are a community of 240 million human beings among the more than 4 billion who inhabit the planet Earth. We human beings are still divided into nation states, but these states are rapidly becoming a global civilization. We cast this message into the cosmos…
It is likely to survive a billion years into our future, when our civilization is profoundly altered and the surface of the Earth may be vastly changed. Of the 200 billion stars in the Milky Way galaxy, some – perhaps many – may have inhabited planets and space faring civilizations.
If one such civilization intercepts Voyager and can understand these recorded contents, here is our message: This is a present from a small distant world, a token of our sounds, our science, our images, our music, our thoughts, and our feelings. We are attempting to survive our time so we may live into yours. We hope some day, having solved the problems we face, to join a community of galactic civilizations. This record represents our hope and our determination and our goodwill in a vast and awesome universe.
>An official statement by President Jimmy Carter was included as images (positions 117, 118). It reads, in part:
This Voyager spacecraft was constructed by the United States of America. We are a community of 240 million human beings among the more than 4 billion who inhabit the planet Earth. We human beings are still divided into nation states, but these states are rapidly becoming a global civilization. We cast this message into the cosmos…
It is likely to survive a billion years into our future, when our civilization is profoundly altered and the surface of the Earth may be vastly changed. Of the 200 billion stars in the Milky Way galaxy, some – perhaps many – may have inhabited planets and space faring civilizations.
If one such civilization intercepts Voyager and can understand these recorded contents, here is our message: This is a present from a small distant world, a token of our sounds, our science, our images, our music, our thoughts, and our feelings. We are attempting to survive our time so we may live into yours. We hope some day, having solved the problems we face, to join a community of galactic civilizations. This record represents our hope and our determination and our goodwill in a vast and awesome universe.
The Golden Records [1] seem like astonishing, singular undertakings to me. Like the Svalbard seed bank, or the LHC, or the Prado. Their existence inspires me because they remind me of what we're capable of.
The book Murmours of Earth by Carl Sagan, Frank Drake, and Ann Druyan is an interesting commentary on the ideas and choices behind the production of the Golden Records. Published in 1978, but there are copies available from the usual aources.
[1] https://en.wikipedia.org/wiki/Voyager_Golden_Record
The book Murmours of Earth by Carl Sagan, Frank Drake, and Ann Druyan is an interesting commentary on the ideas and choices behind the production of the Golden Records. Published in 1978, but there are copies available from the usual aources.
[1] https://en.wikipedia.org/wiki/Voyager_Golden_Record
Genuine question: what is so great about the Golden Record?
I understand the Svalbard seed bank. That can come very handy in a bad situation. May we never need it. I have visited the LHC and it is seriously impressive. Works in the Prado are amazing.
But the Golden Record feel just like someone made a mixtape and then chucked it far away. The music on it of course is great. But will anyone ever find it? And even if anyone ever finds it, will they have the anatomy to listen to it? If we received a similar record could we do anything with it?
For example the recorded greatings. A few sentences in many languages. There is something there. Presumably an interested alien could use it kind of like a Rosetta Stone to learn the structure of our languages. But for that to realistically work they would need a lot more recording in each language and the speakers should be saying the same thing!
Similarly the “brain recording”. An hour long recording, “compressed” somehow and then bandwidth gated so it can be etched into a disk. How is that supposed to contain any usefull information? It is like you want to transmit the content of a book, so you take a blurry underexposed image of the book’s spine as it is reflected in a foggy mirror. Even if the aliens are brilliant there is not much they can do with that “brain recording”.
The whole thing is so vibes based, but on the rational level it doesn’t add up to much.
I understand the Svalbard seed bank. That can come very handy in a bad situation. May we never need it. I have visited the LHC and it is seriously impressive. Works in the Prado are amazing.
But the Golden Record feel just like someone made a mixtape and then chucked it far away. The music on it of course is great. But will anyone ever find it? And even if anyone ever finds it, will they have the anatomy to listen to it? If we received a similar record could we do anything with it?
For example the recorded greatings. A few sentences in many languages. There is something there. Presumably an interested alien could use it kind of like a Rosetta Stone to learn the structure of our languages. But for that to realistically work they would need a lot more recording in each language and the speakers should be saying the same thing!
Similarly the “brain recording”. An hour long recording, “compressed” somehow and then bandwidth gated so it can be etched into a disk. How is that supposed to contain any usefull information? It is like you want to transmit the content of a book, so you take a blurry underexposed image of the book’s spine as it is reflected in a foggy mirror. Even if the aliens are brilliant there is not much they can do with that “brain recording”.
The whole thing is so vibes based, but on the rational level it doesn’t add up to much.
Your skepticism about the Golden Record is understandable, but its value goes beyond mere practicality—it's a powerful symbol of humanity's hopes, dreams, and curiosity.
Sure, the odds of another civilization discovering and fully decoding it are slim. But the Record was never simply meant as a practical tool, like the Svalbard seed bank or the LHC. Instead, it's an intentional gesture of optimism, an attempt to capture and communicate the essence of who we are at this unique moment in our history.
Importantly, the Golden Record was carefully designed using universal scientific principles—binary notation, hydrogen atom properties, and pulsar maps—ensuring that any intelligent civilization might realistically decode it. The instructions etched onto its cover rely on fundamental concepts universally understandable across the cosmos.
The greetings, music, and even brainwave recordings aren't strict instructions but rather snapshots showcasing humanity’s diversity, creativity, and complexity. Even partial understanding by an advanced civilization would provide profound insights into human emotion, ingenuity, and our deep desire for connection.
In the end, the Golden Record is NOT just about practical outcomes; it's about reflecting humanity’s best qualities back to ourselves and inspiring us to strive toward the ideals we've shared with the universe.
Sure, the odds of another civilization discovering and fully decoding it are slim. But the Record was never simply meant as a practical tool, like the Svalbard seed bank or the LHC. Instead, it's an intentional gesture of optimism, an attempt to capture and communicate the essence of who we are at this unique moment in our history.
Importantly, the Golden Record was carefully designed using universal scientific principles—binary notation, hydrogen atom properties, and pulsar maps—ensuring that any intelligent civilization might realistically decode it. The instructions etched onto its cover rely on fundamental concepts universally understandable across the cosmos.
The greetings, music, and even brainwave recordings aren't strict instructions but rather snapshots showcasing humanity’s diversity, creativity, and complexity. Even partial understanding by an advanced civilization would provide profound insights into human emotion, ingenuity, and our deep desire for connection.
In the end, the Golden Record is NOT just about practical outcomes; it's about reflecting humanity’s best qualities back to ourselves and inspiring us to strive toward the ideals we've shared with the universe.
> Importantly, the Golden Record was carefully designed using universal scientific principles—binary notation, hydrogen atom properties, and pulsar maps—ensuring that any intelligent civilization might realistically decode it. The instructions etched onto its cover rely on fundamental concepts universally understandable across the cosmos.
You're describing the Pioneer Plaque, not the Golden Record: https://en.m.wikipedia.org/wiki/Pioneer_plaque
You're describing the Pioneer Plaque, not the Golden Record: https://en.m.wikipedia.org/wiki/Pioneer_plaque
Both the Golden Record and the Pioneer Plaque were carefully crafted with universality in mind, drawing on fundamental scientific principles understandable by any intelligent civilization. They both shared many similarities. [1][2]
https://upload.wikimedia.org/wikipedia/commons/thumb/e/ed/Vo...
[2] https://en.wikipedia.org/wiki/Voyager_Golden_Record
> Some images contain indications of chemical composition. All measures used on the pictures are defined in the first few images using physical references that are likely to be consistent anywhere in the universe.
> The pulsar map and hydrogen molecule diagram are shared in common with the Pioneer plaque.
https://upload.wikimedia.org/wikipedia/commons/thumb/e/ed/Vo...
[2] https://en.wikipedia.org/wiki/Voyager_Golden_Record
I always imagine it being the only thing left of humanity one day to show we even existed.
Like, some aliens will play it and feel an experience like the TNG episode "The Inner Light."
Like, some aliens will play it and feel an experience like the TNG episode "The Inner Light."
[deleted]
In my very first Astronomy class, just a few years after voyager, I did a report on that record, based on a cartoon: "Send more Chuck Berry."
It is an extraordinary piece of work of human history: THank you Astronomer Carl Sagan, Linda Salzman Sagan, Frank Drake, Ann Druyan, Jon Lomberg, and others.
It is an extraordinary piece of work of human history: THank you Astronomer Carl Sagan, Linda Salzman Sagan, Frank Drake, Ann Druyan, Jon Lomberg, and others.
Voyagers are the greatest technical achievement of human kind. Keeping in the space a piece of hardware run by a computer with power of today's car keys, in the hostile environment, outside freaking solar system is something that is the most amazing thing we have witnessed so far.
Kudos to all the people who made it happen and kept going this project, we owe them, as a humanity, really a lot.
Voyagers will keep flying across Milky Way, maybe they will last longer the the Earth itself, as the witnesses of our civilization.
Kudos to all the people who made it happen and kept going this project, we owe them, as a humanity, really a lot.
Voyagers will keep flying across Milky Way, maybe they will last longer the the Earth itself, as the witnesses of our civilization.
> Voyagers will keep flying across Milky Way, maybe they will last longer the the Earth itself
Will they? Good thing I am tired and going to sleep right now, you almost nerd-sniped me. What will happen on the scale of millions to billions of years? Will it collide with something? Will it be slowly eroded by particles? Will it lose material by outgasing?
Will they? Good thing I am tired and going to sleep right now, you almost nerd-sniped me. What will happen on the scale of millions to billions of years? Will it collide with something? Will it be slowly eroded by particles? Will it lose material by outgasing?
If I understand correctly, dust particles with a size of 0.1 microns are estimated to survive against sputtering or collisions with other grains for ~ 10^8 years. This suggests the spacecraft could survive trillions of years before substantial erosion, or more if the rate of supernovas in the galaxy declines with age.
A competing process over the very long term is repeated close encounters with stars and stellar remnants. This tends to add kinetic energy to lighter objects. So, one would expect the spacecraft to gradually acquire more kinetic energy by random close encounters and eventually be ejected from the galaxy.
A competing process over the very long term is repeated close encounters with stars and stellar remnants. This tends to add kinetic energy to lighter objects. So, one would expect the spacecraft to gradually acquire more kinetic energy by random close encounters and eventually be ejected from the galaxy.
> silica
For anyone else curious, it's from the hydrazine tank's rubber diaphragm. Tubes inside the thrusters, which direct fuel to the catalyst beds, had openings taken from 250 um diameter down to 35 um.[1]
The 28" spherical tank[2] has a rubber hemisphere to separate hydrazine from pressurant (He? N?). The diaphragm is EDPM that's teflon and silica filled.[3] The silica particles are for (tensile?) strengthening. It has a leaching issue (discussed in [2] page17).
PSI was a small SoCal company. Derivative tank used for Shuttle APU. Same material used since 1975.
[1] a story https://www.jpl.nasa.gov/news/voyager-1-team-accomplishes-tr... [2] nice paper https://scholar.google.com/scholar?q=review+and+history+of+p... [3] meh, color pic Low cost derivative tanks... https://scholar.google.com/scholar?q=AIAA+99-2831
For anyone else curious, it's from the hydrazine tank's rubber diaphragm. Tubes inside the thrusters, which direct fuel to the catalyst beds, had openings taken from 250 um diameter down to 35 um.[1]
The 28" spherical tank[2] has a rubber hemisphere to separate hydrazine from pressurant (He? N?). The diaphragm is EDPM that's teflon and silica filled.[3] The silica particles are for (tensile?) strengthening. It has a leaching issue (discussed in [2] page17).
PSI was a small SoCal company. Derivative tank used for Shuttle APU. Same material used since 1975.
[1] a story https://www.jpl.nasa.gov/news/voyager-1-team-accomplishes-tr... [2] nice paper https://scholar.google.com/scholar?q=review+and+history+of+p... [3] meh, color pic Low cost derivative tanks... https://scholar.google.com/scholar?q=AIAA+99-2831
Obligatory trailer for the "It's Quieter in the Twilight" documentary, about the team of engineers riding out the end of the Voyager program:
https://www.youtube.com/watch?v=8vJT8AW0wYw
https://www.youtube.com/watch?v=8vJT8AW0wYw
Seconded. I found it both technically interesting and also moving.
Sad to see EOL coming up, but too bad NASA's budget has been cut so back over the years.
We just had a smaller planetary alignment a few months ago. Would have been nice if NASA had the budget to send out a more robust craft a few years ago. But I guess science no longer means anything to the US. Especially now.
Maybe China will take up the mantle, I heard they are about to send out a rather long term interesting craft, but I forgot the details.
We just had a smaller planetary alignment a few months ago. Would have been nice if NASA had the budget to send out a more robust craft a few years ago. But I guess science no longer means anything to the US. Especially now.
Maybe China will take up the mantle, I heard they are about to send out a rather long term interesting craft, but I forgot the details.
NASA’s budget is larger today adjusted for inflation than during the Voyager program. https://images.app.goo.gl/qai42hiZ8RMtfViw6
People usually measure this as percentage of GDP, not absolute dollars.
Why would I measure it that way? What matters is the capacity of NASA's ability to do things, based on its funding.
You can argue that an outfit like NASA should get more or less funding, but it should be based on what you want them to be able to do, not some arbitrary measure like a percentage of GDP.
You can argue that an outfit like NASA should get more or less funding, but it should be based on what you want them to be able to do, not some arbitrary measure like a percentage of GDP.
No they don’t. Why would a budget scale with GDP?
A couple of reasons. One is that NASA is an arm of the United State's advanced research, and if you want to get compounding returns there the goal is that you allocate a proportion of your spending there rather than a fixed value, because every year some of that research will drive gains to your GDP. Another is that the services that NASA provides gradually expands as it provides more things to society: I expect that alongside space exploration there is an increasing budget allocated to dealing with civilian spaceflight. So if you keep the budget constant then you are necessarily prioritizing some things over others, which means a net decrease to specific programs.
Of course, none of this means it should be pegged at a specific fraction of the GDP, it's just a helpful metric to compare against when we look at overall spending. I expect its budget to fluctuate naturally as our needs from it change, and there are certainly programs that have fixed budgets (or even need less money as time goes on) that we should still be looking at. But in general the spending for things like NASA should gradually increase because of its goals.
Of course, none of this means it should be pegged at a specific fraction of the GDP, it's just a helpful metric to compare against when we look at overall spending. I expect its budget to fluctuate naturally as our needs from it change, and there are certainly programs that have fixed budgets (or even need less money as time goes on) that we should still be looking at. But in general the spending for things like NASA should gradually increase because of its goals.
I agree with that. But that’s different than saying “NASA's budget has been cut so back over the years.” The military budget has been shrinking as a share of GDP since the 1980s as well. It would be odd to say the military budget had been cut back though.
You're too smart to make that comparison. 1980s we were in the middle of a VERY strong cold was with the USSR. Every American agrees that military focused has decreased since then, while scientific focus/interest/value has increased.
Arguably it makes more sense for military budget to reference GDP since military capability is relative to that of one’s adversaries. If their capability has increased, then so must ours to achieve a net zero difference. And their capability is proportional to their spending ability with everything else kept equal.
While you seem to imply NASA is wasting money how many legacy projects did that Voyager era budget have to support? Oh yeah, close to zero. When a company implements an ERP system, a HR system, etc. the IT budget tends to increase to more than before.
How many weather satellites did NASA operate during the Voyager program verses now?
How many Landsats like Landsat 8 and 9 now https://www.earthdata.nasa.gov/data/projects/hls
Anything like GRACE and GRACE-FO?
Perseverance rover? https://phys.org/news/2025-04-perseverance-rover-witnesses-m...
Were Mars Reconnaissance Orbiter (MRO) and Mars Atmosphere and Volatile EvolutioN (MAVEN) missions ongoing?
Anything like the Juno project around Jupiter?
Complex projects like OSIRIS-REx?
Telescopes matching the ongoing requirements of James Webb Space Telescope?
Were there Psyche style missions ongoing? https://www.jpl.nasa.gov/missions/psyche/
How many weather satellites did NASA operate during the Voyager program verses now?
How many Landsats like Landsat 8 and 9 now https://www.earthdata.nasa.gov/data/projects/hls
Anything like GRACE and GRACE-FO?
Perseverance rover? https://phys.org/news/2025-04-perseverance-rover-witnesses-m...
Were Mars Reconnaissance Orbiter (MRO) and Mars Atmosphere and Volatile EvolutioN (MAVEN) missions ongoing?
Anything like the Juno project around Jupiter?
Complex projects like OSIRIS-REx?
Telescopes matching the ongoing requirements of James Webb Space Telescope?
Were there Psyche style missions ongoing? https://www.jpl.nasa.gov/missions/psyche/
I’m not implying any of that. I’m simply pointing out that when you tell people “budget for X was cut” they think that means absolute terms, or inflation adjusted. They don’t think that you mean that it wasn’t growing fast enough relative to some perceived needs.
A visual alignment like the one you mention wouldn’t have been useful for spacecraft to get to the planets more easily.
An alignment in the scale of the one that enabled the Voyager flybys of the outer planets won’t happen until sometime in the 23rd century.
An alignment in the scale of the one that enabled the Voyager flybys of the outer planets won’t happen until sometime in the 23rd century.
> An alignment in the scale of the one that enabled the Voyager flybys of the outer planets won’t happen until sometime in the 23rd century.
Only if you're particularly concerned with using a single probe to visit all of them. Jupiter provides the main boost and launch windows from jupiter to anywhere come by every decade.
Only if you're particularly concerned with using a single probe to visit all of them. Jupiter provides the main boost and launch windows from jupiter to anywhere come by every decade.
Parent did mention a single craft. Of course NASA can’t even afford that these days so it’s all moot anyway.
Ah, I did not know it was just visual. I thought it was odd and too quick for another alignment :)
Thanks
Thanks
It's stunning to think how well these missions have done and what we've learnt. I'd love to see new missions aimed at much greater longevity with more modern instruments. I wonder how long one could make the mission? 100 years? 200? Would new generators reduce the power loss to less than 4W/year, or would it just need more/much bigger ones?
The power loss is due to the fact that the power source is plutonium. Which decays over time. So, your lump of plutonium contains less and less plutonium over time, and thus generates less power. A more modern generator doesn't really change this basic fact; the power source would still likely be plutonium, and would have the same issue. But yes, you could send up a larger lump of plutonium so that your power budget started out larger and would remain adequate for a longer time.
IIRC the output has decayed faster than that, due to degradation of the solid state generators.
The most striking part isn't the technical achievement of keeping 1970s hardware alive for half a century. It's the human infrastructure behind it - the institutional knowledge passed through generations of engineers like some ancient priesthood maintaining a temple.
Think about it: We're teaching 2020s engineers to understand machine code written before MS-DOS existed, working with 50 year old documentation on yellowing paper, and bringing retirees back to decipher systems they built when Nixon was president.
Our space exploration legacy is being maintained by the engineering equivalent of oral history. This is why we need consistent funding for these long-term missions - the value isn't just in the data, but in maintaining the unbroken chain of knowledge transfer that makes missions like this possible.
The sticky notes on diagrams trying to revive a silent probe 15 billion miles away just broke me. This is humanity at its finest.