10 ms·
Voyager 1 hears the hush of interstellar plasma
- acidburnNSA 6y agoIt's pretty wild that this probe, launched 44 years ago (1977) and now well beyond the solar system, can still take novel measurements and transmit information back. At that range, our sun looks roughly like any other star. The nuclear radioisotopic thermal generator really is an incredible power source for this kind of application. Some info on the current design here [1]. [1] https://mars.nasa.gov/internal_resources/788/ https://mars.nasa.gov/internal_resources/788/
- niceairport 6y agoCurious as to how long does it take for the transmission to reach earth. Where can I learn that?
- dweekly 6y ago21h https://voyager.jpl.nasa.gov/mission/status/ https://voyager.jpl.nasa.gov/mission/status/
- niceairport 6y agoI can't say I'm surprised, but it's still pretty crazy to think about that it took us 44 years to get an object to a place it takes light less than 24 hours to get to. It feels both pretty far and also not far at all at the same time.
- kzrdude 6y agoI think new horizons is much faster, and will catch up. Still the same order of magnitude though
- jonas21 6y agoWikipedia disagrees: > Provided Voyager 1 does not collide with anything and is not retrieved, the New Horizons space probe will never pass it, despite being launched from Earth at a higher speed than either Voyager spacecraft. The Voyager spacecraft benefited from multiple planetary flybys to increase their heliocentric velocities, whereas New Horizons received only a single such boost, from its Jupiter flyby. As of 2018, New Horizons is traveling at about 14 km/s, 3 km/s slower than Voyager 1, and is still slowing down.
- kzrdude 6y agoOh, cool
- wartijn_ 6y agoNot according to this stack exchange answer[0]. It quotes a page from John Hopkins University, although that source page doesn't seem to exist anymore. > Though New Horizons will also reach 100 AU, it will never pass Voyager 1, because Voyager was boosted by multiple gravity assists that make its speed faster than New Horizons will travel. Voyager 1 is escaping the solar system at 17 kilometers per second. When New Horizons reaches that same distance 32 years from now, propelled by a single planetary swingby, it will be moving about 13 kilometers per second [0] https://space.stackexchange.com/questions/3520/when-will-new-horizons-overtake-voyager-1-in-distance-from-the-sun#3521 https://space.stackexchange.com/questions/3520/when-will-new...
- amatecha 6y agoYeah, I had this reaction of like "yeah, only 21 hours? that's not too long"… Then it occurred to me, it's 21 hours at the _speed of light_, something we generally consider effectively "instant" here on Earth. Pretty fascinating stuff. I'm really happy to hear we're still getting transmissions back from Voyager 1 - from nearly 23 billion kilometers away, for that matter! Also really interesting is the Voyager FAQ, even from the first question (about whether the cameras could be turned back on). "Mission managers removed the software from both spacecraft that controls the camera. The computers on the ground that understand the software and analyze the images do not exist anymore." https://voyager.jpl.nasa.gov/frequently-asked-questions/ https://voyager.jpl.nasa.gov/frequently-asked-questions/
- wongarsu 6y ago> something we generally consider effectively "instant" We are in one of the very few professions where the speed of light is considered annoyingly slow. Just three days ago there was a thread of people lamenting that the closest Hetzner datacenter is about 50 light-milliseconds away
- pflanze 6y agoI don't know enough to say, but it wouldn't surprise me if our speed of thinking (and perhaps also time in general) is indirectly tied to the speed of light; meaning, if the speed of light were faster, we'd be thinking faster, and thus the round trip speed to Hetzner would appear just as annoying. I'll be happy to be corrected.
- Chris2048 6y agoGiven the distances involved, here's lightspeed travel from the sun: https://digg.com/video/light-speed-solar-system-travel https://digg.com/video/light-speed-solar-system-travel
- kevbin 6y agoThanks for the that link. I just spent an hour in the Eyes on the Solar System web app and listening to Carl Sagan wax poetic about our Voyagers: https://www.youtube.com/watch?v=H92iCnecYGQ https://www.youtube.com/watch?v=H92iCnecYGQ "…and far from home, untouched by these remote events, the Voyagers, bearing the memories of a world that is no more, will fly on."—C. Sagan
- celias 6y agoThe one-way light times are at the bottom of https://voyager.jpl.nasa.gov https://voyager.jpl.nasa.gov roughly 17.5 hours for Voyager2 and 21 hours for Voyager 1
- holoduke 6y agoJust About 1200 times longer and it approached the same distance as our nearest star at 4 ly
- wongarsu 6y agoIf we started pursuing nuclear pulse propulsion we could have our first probe arrive in the next star system in a hundred years or so, and eventually get the travel time closer to 40 years.
- techrat 6y agoIf? Theoretical is still theoretical. We have no functioning propulsion that can exceed what the probes are currently travelling at.
- wongarsu 6y agoAt least for something like Project Orion, all the individual components are either verified in prototypes or proven technology. We have existing stockpiles of nuclear bombs. Propelling a craft by exploding something behind it is demonstrated in smaller prototypes with TNT. We know how to do radiation shielding, we know how to do shock absorbers. Or course combining technologies in a new way comes with lots of engineering challenges, but it's a smaller leap in technology than e.g. the first moon landing.
- dweekly 6y agoThe energy density of nuclear batteries is astounding. Per the linked spec sheet, at 2.8W/kg and 17y mission duration, that's about 417,000Wh/kg. By comparison a lithium ion battery has 250Wh/kg.
- acidburnNSA 6y agoNuclear fission reactors are even crazier. With breeding you get 22,500,000,000 Wh/kg. Good old E=MC^2.
- dheera 6y agoTechnically all batteries are E=mc^2, it's just that nuclear fission converts more of the mass, but still, not all of it. Lithium batteries do get ever so slightly heavier when charged, but it's basically undetectable.
- kuprel 6y agoHow do lithium ion batteries convert mass to energy?
- dheera 6y agoThe principle of E=mc^2 is of mass-energy equivalence. Any form of stored energy has mass, including the binding energy between atoms in a molecule, and lithium ions convert those chemical bonds to electric currents when a load is applied. The mass associated with those chemical bonds is miniscule compared to the protons, electrons, and neutrons, but it is not zero.
- ben_w 6y agoAll (confined?) energy is equivalent to mass, even when that mass isn’t in the form of elections and quarks.
- samplatt 6y agoThere's a really good joke about Ferengi political situations here, but I'm no economist.
- asaddhamani 6y agoIt’s now 22 Billion km away from Earth. Amazing.
- geenew 6y agoOne of the few times you can use the unit ‘terametres’. 22Tm. Or, 22 terametres from Terra.
- tablespoon 6y ago> It's pretty wild that this probe, launched 44 years ago (1977) and now well beyond the solar system, can still take novel measurements and transmit information back. Through (according to Wikipedia) the party might end in just a few years: https://en.wikipedia.org/wiki/Voyager_1 https://en.wikipedia.org/wiki/Voyager_1: > Voyager 1's extended mission is expected to continue until about 2025, when its radioisotope thermoelectric generators (RTGs) will no longer supply enough electric power to operate its scientific instruments.
- The_rationalist 6y agoWhat about voyager 2 lifetime ? Humanity hasn't sent any probe having an extra-solar system target since 1977?? If so, this is extremely sad and distant space exploration will die and 50 years will be lost. I attribute this mediocrity to the anti nuclear/RTG lobby at NASA
- csunbird 6y agoWe haven’t sent another probe, not because of anti nuclear lobby, but because of there was an unique event of planets being nearly on a line around 1970, which allowed NASA to plot a series of gravity assists, instead of one or two, that allowed gaining immense amount of free velocity. Sun’s gravity well is so immense that escaping it requires a very, very large amount of energy. I am not sure if it could be done with conventional rockets with current technology, without multiple gravity assists. Edit: As the child comment says, it seems to be possible with current technology. It is very exciting!
- teraflop 6y ago> I am not sure if it could be done with conventional rockets with current technology, without multiple gravity assists. Yes, it can. New Horizons is escaping the solar system only a little bit slower than the Voyager probes, and it was already on an escape trajectory before its single Jupiter gravity assist.
- 6y ago
- mjgs 6y agoIts so cool that the entire solar system has a sort of ozone layer (the heliopause), I also really like the diagram that shows how each craft is travelling in different directions. I think we should have a new mission, send out huge amounts of tiny crafts in all directions at the same time, to get a sort of Google street view of our solar system and interstellar space. I bet we could create crafts with modern tech that where tiny and much less expensive that the original pioneer and voyager crafts.
- throwaway3699 6y agoStreet view in space? I think you might be underestimating just how empty the solar system is.
- feintruled 6y agoThe Gaia probe is doing something a little like this to create a full 3D star map. It rotates as it goes and uses parallax to measure the distance and motion between stars exactly. https://en.wikipedia.org/wiki/Gaia_(spacecraft) https://en.wikipedia.org/wiki/Gaia_(spacecraft)
- qwertox 6y agoThanks. Your comment sent me to Wikipedia, where I found this related snippet: > In the year 2000, 23 years after production, the radioactive material inside the RTG had decreased in power by 16.6%, i.e. providing 83.4% of its initial output; starting with a capacity of 470 W, after this length of time it would have a capacity of only 392 W. A related loss of power in the Voyager RTGs is the degrading properties of the bi-metallic thermocouples used to convert thermal energy into electrical energy; the RTGs were working at about 67% of their total original capacity instead of the expected 83.4%. By the beginning of 2001, the power generated by the Voyager RTGs had dropped to 315 W for Voyager 1. There's also a nice picture of one deployed on the moon. The dust on the moon's surface looks spectacular in that picture. https://en.wikipedia.org/wiki/Radioisotope_thermoelectric_generator https://en.wikipedia.org/wiki/Radioisotope_thermoelectric_ge...
- tutfbhuf 6y agoHow much Watt do they have now 20 years later in 2021?
- chias 6y agoI can give you half an answer and speculation on the other half. Given that radioisotopes decay with a halflife pattern, I would expect that you'd see a 16.6% drop in capacity every 23 years. So something like: 1977: 100% (470 W) 2000: 83.4% (392 W) 2023: 69.6% (327 W) To get a full answer, you'd need to know how the thermocouples degrade. Under the (completely unsubstantiated) assumption that they degrade linearly, that's about a 20% efficiency degradation per 23 years: 1977: 100% isotope * 100% coupling efficiency -> 470 W (100% of capacity) 2000: 83.4% isotope * 80% coupling efficiency -> 314 W (67% of capacity) 2023: 69.6% isotope * 60% coupling efficiency -> 196 W (41% of capacity) I suspect the thermocouple efficiency degradation is very much non-linear -- or rather, I have no reason to actually expect it to be linear -- so the second half of the above is a total SWAG, but maybe gives you a rough idea :)
- st_goliath 6y ago> There's also a nice picture of one deployed on the moon. That was also one of the many issues that cropped up during Apollo 13. They too had an RTG on board that was supposed to stay on the moon[1]. According to the book "Lost Moon" by Lovell and Kluger, a potential explosion of the Saturn V during launch was accounted/planned for, but the RTG "coming home" together with the LEM wasn't. IMO the book was a bit hazy on how that situation was addressed exactly, but according to Wikipedia that RTG is currently resting somewhere deep in the Pacific[2]. Also an interesting read on that topic is the SNAP program itself that developed the technology in the first place, even shot entire mini-nuclear-reactors into earth orbit[3] and resulted in some stereotypical 1960s nuclear safety shenanigans/mishaps during testing[4][5]. [1] https://en.wikipedia.org/wiki/Apollo_13#Experiments_and_scientific_objectives https://en.wikipedia.org/wiki/Apollo_13#Experiments_and_scie... [2] https://en.wikipedia.org/wiki/Apollo_13#Reentry_and_splashdown https://en.wikipedia.org/wiki/Apollo_13#Reentry_and_splashdo... [3] https://en.wikipedia.org/wiki/Systems_for_Nuclear_Auxiliary_Power https://en.wikipedia.org/wiki/Systems_for_Nuclear_Auxiliary_... [4] https://en.wikipedia.org/wiki/SNAP-10A#Safety https://en.wikipedia.org/wiki/SNAP-10A#Safety [5] https://en.wikipedia.org/wiki/Systems_for_Nuclear_Auxiliary_Power#SNAP-9 https://en.wikipedia.org/wiki/Systems_for_Nuclear_Auxiliary_...
- windy_willow 6y agoI am so impresses that this device is still actually able to do so much after so long... I really hope that the current space probes and rovers do just as well if not better.
- f6v 6y agoI wonder why don’t we send more probes like that in every direction by dozens?
- throwaway894345 6y agoI was thinking it would be interesting to send a stream of them out in one direction (or many streams) with the idea that they could serve as a relay/mesh network, allowing us to communicate with the probes (and vice versa) for longer. Not sure how valuable that would be scientifically.
- dredmorbius 6y agoThere's not much, in every direction, for a long ways. It makes more sense, generally, to send probes to where things (planets, moons, dwarf planets, asteroids, comets) are, that we can reach in reasonable time (years, possibly a decade or more for outer targets). "Every direction" just takes you to deep space. And that's not going to be particularly illuminating, though a few such probes (say, a high- or low-solar plane one) might be interesting.
- f6v 6y agoOort cloud is still not confirmed, right? I get that it might be incredibly sparse, but isn't there anything to study there?
- dredmorbius 6y agoOort is (mostly) in the solar plane AFAIU, and there's every reason to use gravity assist to get there. I don't know that any specific objects are known, and getting into an Oort-observing orbit might be challenging. Otherwise, yesm it's sparse and arbitrary flybys would likely miss anything interesting. Spraying random probes in all directions makes lttle sense. Voyager 1 won't reach the Oort Cloud, if it in fact exists, for another three centuries.
- Beldin 6y ago
- divbzero 6y agoIt’s also wild to compare: – how far Voyager 1 has already traveled ~150 AU or ~0.002 ly [1] – how much farther it could go in 40,000 years ~1,000,000 AU or ~17 ly [2] [3] – the visible diameter of our Milky Way ~6,000,000,000 AU or ~100,000 ly [4] [1]: https://voyager.jpl.nasa.gov/mission/status/ https://voyager.jpl.nasa.gov/mission/status/ [2]: https://voyager.jpl.nasa.gov/mission/interstellar-mission/ https://voyager.jpl.nasa.gov/mission/interstellar-mission/ [3]: https://en.wikipedia.org/wiki/Gliese_445 https://en.wikipedia.org/wiki/Gliese_445 [4]: https://en.wikipedia.org/wiki/Milky_Way https://en.wikipedia.org/wiki/Milky_Way
- ssheth 6y agoOne of the most important parts of the Voyager is apparently a little motor that rotates every 192 seconds to take 360 degree readings of the sky. Each rotation is called a "step" in their lingo .. they built it to run a few thousand steps (or about 4-5 years). And that little motor has now run over 5 _million_ steps over 48 years... and is still running. More at https://www.nature.com/news/2008/080702/full/454024a.html https://www.nature.com/news/2008/080702/full/454024a.html
- tablespoon 6y ago> One of our chief goals was to apply the power of signal processing to search for weaker signals in the PWS data, which maybe, just maybe, were hiding between and behind the bright plasma oscillation events that had already been discovered. So this doesn't mean that Voyager 1 has entered a new region with different characteristics, just that they've used signal processing to tease a little bit more out of the existing data.
- artpop 6y agoAliens.
- kuu 6y agoRelated: https://xkcd.com/1189/ https://xkcd.com/1189/
- ilamont 6y agoWhat are MAG rolls cited in video?
- senbarryobama 6y agoSoon Voyager will be another planets Ouamuamua
- 1970-01-01 6y ago>Who knows what discoveries still lie ahead of it? Its very likely this is the last one. The craft is simply running out of power and the instruments will be forced to shutdown in a few years. The current deep space network will lose its already extremely faint signal in about a decade.
- pwned1 6y agoAs a ham radio enthusiast I find this sort of article fascinating, from the actual frequencies detected to the fact that even Voyager suffers from RFI. :)
- wolverine876 6y ago> While I was busy learning the undergraduate physics curriculum, Voyager 1 was treading through the interstellar medium and revealing in stark detail how interstellar plasma and the solar wind collide and interact across a boundary layer called the heliopause, where they engage in a massive pressure-balancing act that shields our heliosphere from the great beyond. I thought Voyager 1 was out in interstellar space for awhile now, beyond the heliopause, heliosphere, etc. ? I'll also note, > Almost 11 years ago, Voyager 1 crossed an unprecedented boundary: it became the first human-made object to enter interstellar space. I was just a high-school student at the time, oblivious to the milestone ... That's no excuse! :)
- gumby 6y agoI find this tremendously thrilling, and not just for the exciting discoveries about the environment of the outer solar system. Somehow human spaceflight seems dull to me while I just can't get enough of the cool and crucial work these robots are doing on our behalf. Never send a human to do a robot's job, I suppose.
- robofanatic 6y agoAre there any such probs sent in recent years with latest technology on it?
- 3pt14159 6y agoWell there is New Horizons[0], which launched in 2006 and is now beyond Pluto. But in terms of coolness, I really like The Parker Solar Probe[1] which is going closer and closer to the sun with a massive heat shield and at eye watering speeds. By 2025 it will be going 690,000 km/h (430,000 mph), or 0.064% of the speed of light. [0] https://en.wikipedia.org/wiki/New_Horizons https://en.wikipedia.org/wiki/New_Horizons [1] https://en.wikipedia.org/wiki/Parker_Solar_Probe https://en.wikipedia.org/wiki/Parker_Solar_Probe
- RedOrGreen 6y agoI came to this thread a bit too late, but if you're interested in the actual signal that Stella found, take a look at the spectrum vs time on the NASA release [1] - third plot on the page, with a convenient slider that lets you flip back and forth to see the previously known plasma oscillation events and the newly discovered continuous signal. Notice the huge change in scale! [1] https://www.nasa.gov/feature/goddard/2021/as-nasa-s-voyager-1-surveys-interstellar-space-its-density-measurements-are-making-waves https://www.nasa.gov/feature/goddard/2021/as-nasa-s-voyager-...