6 ms·

NASA's Project Scientist Faces Painful Choices as Voyager Mission Nears Its End

114 points by rntn 2y ago

jmclnx 2y ago
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.
- loloquwowndueo 2y ago
  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.
  - Dylan16807 2y ago
    > 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.
    - loloquwowndueo 2y ago
      Parent did mention a single craft. Of course NASA can’t even afford that these days so it’s all moot anyway.
  - jmclnx 2y ago
    Ah, I did not know it was just visual. I thought it was odd and too quick for another alignment :) Thanks
- rayiner 2y ago
  NASA’s budget is larger today adjusted for inflation than during the Voyager program. https://images.app.goo.gl/qai42hiZ8RMtfViw6 https://images.app.goo.gl/qai42hiZ8RMtfViw6
  - saagarjha 2y ago
    People usually measure this as percentage of GDP, not absolute dollars.
    - rayiner 2y ago
      No they don’t. Why would a budget scale with GDP?
      - saagarjha 2y ago
        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.
        rayiner 2y ago
        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.
davidwritesbugs 2y ago
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?
- Bud 2y ago
  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.
  - pfdietz 2y ago
    IIRC the output has decayed faster than that, due to degradation of the solid state generators.
jahlove 2y ago
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
- andyjohnson0 2y ago
  Seconded. I found it both technically interesting and also moving.
gcp123 2y ago
I've been following Voyager since the late 70s when my dad (who worked at Ames) would bring home printouts of the Jupiter images. This interview captures something profound about these missions that non-space folks often miss. 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.
- chneu 2y ago
  Great comment. This mentality is what makes great engineers and thinkers.
- skissane 2y ago
  > 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.)
gzer0 2y ago
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 https://en.wikipedia.org/wiki/Voyager_Golden_Record
- andyjohnson0 2y ago
  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 https://en.wikipedia.org/wiki/Voyager_Golden_Record
  - heavymetalpoizn 2y ago
    [dead]
  - krisoft 2y ago
    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.
piokoch 2y ago
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.
- GuB-42 2y ago
  > 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?
  - pfdietz 2y ago
    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.
mncharity 2y ago
> 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-tricky-thruster-swap/ https://www.jpl.nasa.gov/news/voyager-1-team-accomplishes-tr... [2] nice paper https://scholar.google.com/scholar?q=review+and+history+of+psi+elastomeric+diaphragm+tanks 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 https://scholar.google.com/scholar?q=AIAA+99-2831

114 points by rntn 2y ago

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.

loloquwowndueo 2y ago
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.
- Dylan16807 2y ago
  > 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.
  - loloquwowndueo 2y ago
    Parent did mention a single craft. Of course NASA can’t even afford that these days so it’s all moot anyway.
- jmclnx 2y ago
  Ah, I did not know it was just visual. I thought it was odd and too quick for another alignment :) Thanks
rayiner 2y ago
NASA’s budget is larger today adjusted for inflation than during the Voyager program. https://images.app.goo.gl/qai42hiZ8RMtfViw6 https://images.app.goo.gl/qai42hiZ8RMtfViw6
- saagarjha 2y ago
  People usually measure this as percentage of GDP, not absolute dollars.
  - rayiner 2y ago
    No they don’t. Why would a budget scale with GDP?
    - saagarjha 2y ago
      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.
      - rayiner 2y ago
        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.

davidwritesbugs 2y ago

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?

Bud 2y ago
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.
- pfdietz 2y ago
  IIRC the output has decayed faster than that, due to degradation of the solid state generators.

jahlove 2y ago

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

andyjohnson0 2y ago
Seconded. I found it both technically interesting and also moving.

gcp123 2y ago

I've been following Voyager since the late 70s when my dad (who worked at Ames) would bring home printouts of the Jupiter images. This interview captures something profound about these missions that non-space folks often miss. 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.

chneu 2y ago
Great comment. This mentality is what makes great engineers and thinkers.
skissane 2y ago
> 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.)

gzer0 2y ago

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 https://en.wikipedia.org/wiki/Voyager_Golden_Record

andyjohnson0 2y ago
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 https://en.wikipedia.org/wiki/Voyager_Golden_Record
- heavymetalpoizn 2y ago
  [dead]
- krisoft 2y ago
  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.

piokoch 2y ago

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.

GuB-42 2y ago
> 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?
- pfdietz 2y ago
  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.

mncharity 2y ago

> 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-tricky-thruster-swap/ https://www.jpl.nasa.gov/news/voyager-1-team-accomplishes-tr... [2] nice paper https://scholar.google.com/scholar?q=review+and+history+of+psi+elastomeric+diaphragm+tanks 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 https://scholar.google.com/scholar?q=AIAA+99-2831