If during the planning and construction of the Voyager missions they knew what we know now, what changes to the missions would have been most helpful in augmenting the science obtained?
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8$\begingroup$ I guess "what we know now" only refers to knowledge about the solar system and not about technology? $\endgroup$– asdfexCommented Feb 4, 2023 at 16:59
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8$\begingroup$ Well if we knew then what we know now we could get Voyager to investigate different things altogether. $\endgroup$– DKNguyenCommented Feb 4, 2023 at 20:53
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1$\begingroup$ Does "We know moon 19##P## exists, so we can schedule multiple pictures of it at best illumination and/or closest approach instead of discovering it months or years later in images of something else." count? Heck, Shoemaker-Levy 9 might have already been orbiting Jupiter during the Voyager flybys. $\endgroup$– notovnyCommented Feb 4, 2023 at 21:24
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1$\begingroup$ As it stands this question looks like idea-generation, without a clear focus. Every answer provides a different aspect, but no single answer can objectively be the "right" answer. Without a clear format this seems no good fit for the Q&A format of stack exchange. $\endgroup$– FalcoCommented Feb 6, 2023 at 10:18
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$\begingroup$ Are you asking about changes to the spacecraft or changes to the mission? The missions took advantage of a once in a century (if not longer) alignment, but there were other options. The spacecraft themselves were designed using what we would now call stone age devices (the stone age of computing and sensors). Which are you asking about, the mission designs or the spacecraft designs? $\endgroup$– David HammenCommented Feb 6, 2023 at 14:40
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3 Answers
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Knowing what we know now about Titan's thick and resistant-to-surface-photography atmosphere, choosing a Pluto flyby for Voyager 1 over a Titan flyby would perhaps have given more exciting results. Voyager 1 had the capability of flying by either but not both of these, as going by Titan gave the wrong exit angle from the Saturn system to subsequently fly by Pluto.
Instead, we had to wait until 2015 to get a closer look at Kuiper belt objects with new Horizons.
answered Feb 4, 2023 at 12:41
SE - stop firing the good guysSE - stop firing the good guys
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A simpler question is what wouldn't have changed. The answer to that is simple: The power source, and possibly propulsion. We still use pretty much the same radioisotope thermoelectric generators (invented in 1954) that powered the Voyager spacecraft to this day. Whether the Voyager spacecraft would have used the same kind of propulsion that it did use is perhaps debatable. I suspect they would not have used the propulsion systems used on Voyager if they had a choice of modern alternatives.
Cameras have improved a lot. If the designers of the Voyager spacecraft had the choice of using the camera technology of today versus what they had then it would be an easy choice. They would have chosen the camera technology of today.
The biggest improvement since the Voyager era is in computation and data storage. Computing systems, even the lousy ones that deep space missions tend to use / are forced to use, have changed by multiple orders of magnitude since the Voyager era. For example, the computers on the Voyager spacecraft had 32K words of memory. I'm amazed they did so much with so little memory.
The New Horizons spacecraft, which had a considerably lower budget than did the Voyagers, took advantage of those huge improvements in computing and data recording technologies. Computation and data recording were extremely limited in the Voyager era. Those wonderful images of Pluto from New Horizons simply would not have been possible using Voyager era technology. The New Horizons spacecraft took its sweet time (well over a year) to transmit those recorded wonderful images back to Earth. The Voyager spacecraft didn't have that ability.
answered Feb 5, 2023 at 12:35
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6$\begingroup$ Two big advantages in modern computer technology are they are significantly more power efficient, and we have made significant advances in error correcting codes for sending signals over noisy channels. The combination of these factors would allow the Voyager spacecraft to extend the missions even further, as the RTG power level dropped, and the spacecraft get further from earth. $\endgroup$ Commented Feb 5, 2023 at 20:31
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5$\begingroup$ Data recording for sure. I think Voyager had a tape recorder. $\endgroup$ Commented Feb 5, 2023 at 22:09
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2$\begingroup$ I've heard that during mission planning, it wasn't even 100% given that Voyager would carry a computer at all. It took some convincing to reach that decision (Source: personal communication with someone who was on the science team). $\endgroup$– gerritCommented Feb 6, 2023 at 11:09
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4$\begingroup$ @gerrit This gets into the tricky question of what makes a computational / sequencing device a "computer". Designers of device drivers to this day oftentimes object to the devices they design being called "computers." While those drivers typically don't have a
main()or an operating system, those device drivers / sequencers are still "computers" in my mind, and more importantly, are "computers" in the minds of many others. $\endgroup$ Commented Feb 6, 2023 at 14:00 -
2$\begingroup$ I would think that the power source would have been designed to last longer if anyone had any clue that the power supply would be the limiting factor for mission duration. $\endgroup$– supercatCommented Feb 6, 2023 at 23:48
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I think the simplest answer with no "back to the future" aspects would be that what we know now is that the Voyagers are still alive an kicking and providing new science!
Thus they might have considered finding a way to include the mass and heat of a second RTG somehow to double their available electrical power and warmth in the 2020's and 2030s.
This is not at all trivial task and I'm not saying they'd be able to do this; those RTGs were heavy and of course produced a lot of heat, so it would be a significant design challenge for the spacecraft and the payload considerations during launch.
They might also look into adding more of the small radioisotope heaters for some instruments.
In the end they might instead say "nah, if this works there'll be plenty of funding for a second round of Voyagers in a decade, let's just get these out there for now.
Further reading:
- Which wears out faster on RTGs; the R's or the TG's? (the radioisotopes or the thermocouples)
- Why did Voyager have to shunt unused electrical power and radiate as heat?
- How cold are the Voyagers now? Colder than LOX? Colder than SOX?
- Did any of Voyagers' receivers' front ends take advantage of the "cold of space" to lower noise? (communications or radio/plasma science receivers)
- How long will communication with the Voyager probes continue?
- How would the Voyagers be tracked after the RTGS runs out of fuel?
- Is Voyager 2 capable of proving the existence of Oort cloud?
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5$\begingroup$ Perhaps swapping some of that 238Pu for 241Am would be nice? 5x the half life, 1/5 the power. $\endgroup$ Commented Feb 5, 2023 at 21:03
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3$\begingroup$ @SE-stopfiringthegoodguys or just swap the 238Pu for 5x 241Am? Your idea puts my answer to shame, except that maybe they didn't know how to make and purify that much Am241 in the early 1970's (or have the right equipment) in time to prove the technology before committing? Maybe "Why didn't Voyager have Am241?" would be a great new question! $\endgroup$– uhohCommented Feb 5, 2023 at 21:11
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1$\begingroup$ @SE-stopfiringthegoodguys You want to use a mix of 238Pu and 241Am or to replace 238Pu with 241Am? Replacing is 5x the half life, 1/5 the power and 5x the mass of the nuclear material. Total weight of the RTG would be much less than 5x. $\endgroup$– UweCommented Feb 6, 2023 at 8:12
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2$\begingroup$ @Uwe Only like 10% of the RTG mass is the nuclear part. $\endgroup$ Commented Feb 6, 2023 at 8:46
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$\begingroup$ @SE-stopfiringthegoodguys, half-life isn't the limiting factor for RTGs. The limiting factor is radiation-caused damage to the thermocouples. $\endgroup$– MarkCommented Feb 7, 2023 at 4:35