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Space Science

Voyager Probes Give Us ET's View 166

Posted by samzenpus
from the a-different-look dept.
astroengine writes "For the first time, scientists have been able to measure a type of radiation streaming out from the Milky Way that in other galaxies has been linked to the birthplaces of young, hot stars. There was no way to make our own galaxy's measurement of the radiation, known as Lyman-alpha, until the Voyager probes were about 40 times as far away from the sun as Earth — any closer and the solar system's own emissions drowned out the fainter glow from the galaxy."
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Voyager Probes Give Us ET's View

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  • by Anonymous Coward on Friday December 02, 2011 @03:03AM (#38235132)

    Pictures of young, hot, stars?! Count me in!

    • by Framboise (521772)

      These stars are known to be strong in X.

    • by Anonymous Coward on Friday December 02, 2011 @09:09AM (#38236256)
      As with most hot young stars, they do tend to cool quickly and their waistline expands as they run out of good, hot material. Eventually they can either have a big blowup or become small, not so hot, older stars when they begin using different materials.

      Damn. That sounded better in my head but the metaphor got a bit muddled. But, think stars, hydrogen, red giants, helium, novas, etc...
    • All stars pictured here are at least 18 years or older.

    • You just have to be careful. Looking at photos of young, hot stars under 180 million years old can get you in trouble.

  • So Cool... (Score:5, Insightful)

    by steevven1 (1045978) on Friday December 02, 2011 @03:06AM (#38235138) Homepage
    Voyager has to be the coolest space probe ever. It's been operating for 34 years straight and is LEAVING OUR GALAXY, still receiving commands from Earth and still transmitting data back. If that's not marvelous, I don't know what is. Anyone interested should read: http://en.wikipedia.org/wiki/Voyager_1 [wikipedia.org]
    • Re:So Cool... (Score:4, Insightful)

      by steevven1 (1045978) on Friday December 02, 2011 @03:09AM (#38235146) Homepage
      Correction: solar system, not galaxy. D'oh!
      • by deroby (568773)

        Patience my friend, one day it might actually leave our Galaxy =)

        • Re:So Cool... (Score:5, Informative)

          by agentgonzo (1026204) on Friday December 02, 2011 @06:13AM (#38235682)
          Unfortunately not. Milky way's escape velocity is approx 525km/s (wikipedia) and voyager and our solar system are moving at approx 18km/s (Monty Python Song [youtube.com]). Unless it happens to get flung out of the galaxy by the impending collision with Andromeda in 3-5 billion years it's not going to be leaving the Milky way anytime soon. It'll just float around in the vicinity of the solar system and go around the Milky way.
          • by deroby (568773)

            Ah, I was not aware of that. My bad.
            I simply assumed it would take a (ridiculous) amount of time but hadn't considered the required escape velocity of the Milky Way, nor the fact that the probe is just coasting...

            Damn, you DO learn something on /. now and then, I'll have to adapt my signature some day =)

          • by Mojo66 (1131579)
            Not true. While its current velocity is too low to escape our galaxy, this can change quickly (in terms of the cosmic time scale) should the probe have a close encounter with a planet or star. This is known as swing-by and was actually used to accelarate the Voyager probes out of the solar system.
            • by tgd (2822)

              I would assume one (and by one, I mean not me!) could calculate the distance it would have to pass away from a typical stellar center of gravity, and figure out if it could actually get a 20x increase in speed without its approach to that center of gravity being within the star.

              That'd tell you if it was possible short of passing by something exotic like a neutron star. (And presumably one could calculate how close it would have to pass to even something that dense to get that kind of acceleration, and if th

              • by Mojo66 (1131579)
                I agree that the odds for an encounter that would propel the probe to galactic exit velocity or more, are very low. However, the time and space scales we're talking about are so big that agentgonzo's seemingly conclusive statement shouldn't be left uncommented.
                • by tgd (2822)

                  I guess my point is, in theory its possible to calculate if it is actually possible. He may be correct (although accidentally).

                  If the type of encounter that Voyager could actually survived added little enough speed, and the time between those encounters are long enough, and the odds of surviving non-ideal encounters is low enough, presumably you could calculate the time it would take to build up that kind of speed *even in that one in quintillion chance*, and compare that time to the time the galaxy will ac

                  • by HiThere (15173)

                    Well, sorry, but we CAN'T calculate how long the galaxy will be around. At least not if you are willing to still consider it "the galaxy" after it merges with Andromeda. That depends on the rate of increase of dark energy, which we don't even have any good ideas about. (Or if we do, I haven't heard of them.)

                    I sort of doubt that dark energy is increasing rapidly enough that the Andromeda-Milky Way super-galaxy will disintegrate, but I haven't heard any REAL reason to doubt it. It's clear that eventually

            • True, but that would be more or less a chance encounter. Right now, it is going at 17.26 km/s. I don't know offhand if it is headed anywhere in the general vicinity of Alpha Centauri, the nearest star to us and the closest gravity boost Voyager could get. For the sake of argument, let's say it is. Alpha Centauri is about 4.24 light years away from us or about 4 × 10^13 km. At its current speed, it would take about 73,437 years for the Voyager probe to reach Alpha Centauri. In 73,000+ years, we wen

              • by Sigmon (323109)

                Kinda makes you wonder if there might be more of our space probes coasting through the cosmos... put up there by a long forgotten civilizations that collapsed.

          • by HiThere (15173)

            It could still leave out galaxy, eventually, via a gravity slingshot. I'll admit it's quite unlikely (and I'm not even sure how unlikely) but it's possible.

            P.S.: I haven't calculated things out, but this might require that it be near a supernova explosion, in which case while the mass might leave out galaxy, it might not be fair to call it Voyager. But I suspect a pair of close binary neutron stars could give it enough velocity without even noticing.

    • Re:So Cool... (Score:5, Interesting)

      by QuoteMstr (55051) <dan.colascione@gmail.com> on Friday December 02, 2011 @04:27AM (#38235354)

      The Voyager computers are awesome [nasa.gov] too. How many other 18-bit word [nasa.gov] systems are actively maintained [space.com] today?

      I'd love to see the source code, though I'm sure it's terribly boring.

    • by Anonymous Coward on Friday December 02, 2011 @06:31AM (#38235734)

      Meanwhile my smartphone will be lucky to survive 34 months, and is only able to receive commands from Earth if I hold it out of an upstairs window...

      Out of interest, are there many computers down here on the planet that have been operating constantly for 34 years?

      • Out of interest, are there many computers down here on the planet that have been operating constantly for 34 years?

        I'm sure there are embedded and industrial control systems that have been running that long, if only though sheer dumb luck. It would need reliable power, but there's a lot of that around. The computers that run security alarm systems come to mind. Most of them will have had something happen by now, but I bet someone's gotten lucky. Same for industrial control systems which have battery backup and run a continuous process.

        Telecom would be another. The older digital telco switches are basically big comp

    • by mcgrew (92797) *

      Voyager has to be the coolest space probe ever.

      Yes, literally as well as figuratively. Pretty damned cold out there past the Kupier belt!

  • by guruevi (827432) <(eb.ebucgnikoms) (ta) (ive)> on Friday December 02, 2011 @03:22AM (#38235180) Homepage

    You never know when such research will pay off. The US and EU is scrapping programs now while China, India and a few others try to get into space, you can bet that a lot of cool research will be coming from that side of the globe in the next 30 years.

    Imagine if we could launch a probe now with what we have available. We could cheaply launch 10's of much faster probes with incrementally better sensors for the price of the voyager program (~$3B in today's dollars).

    • by Brett Buck (811747) on Friday December 02, 2011 @03:27AM (#38235200)

      We could cheaply launch 10's of much faster probes with incrementally better sensors for the price of the voyager program (~$3B in today's dollars).

                I am not sure why you say that. The costs of space technology haven't changed much at all relative to the rate of inflation, and there haven't been any important breakthroughs in launchers. The only thing consequentially different is computer capability, but a faster/more complex computer would just as likely be a liability as a bonus. Software design techniques, if anything, have gone rapidly backwards for this sort of application since the late 70s/early 80s.

      • I'd say that the hardware for collecting data has substantially improved with time too (imaging sensors, etc.). Not to mention storage capacity, and I'm sure there is plenty of other stuff I can't think of right now, even if launching technology hasn't changed much. There could definitely be huge benefits.
        • Those same advantages have tended to reduce reliability and robustness, particularly robustness to radiation damage.

          • by amRadioHed (463061) on Friday December 02, 2011 @05:45AM (#38235580)

            They wouldn't be using state of the art chips, but even the old radiation hardened chips needed for space travel would be an big improvement over 30 year old technology.

            Probably the biggest improvement would be in propulsion. Isn't this the exact sort of mission the new ion propulsion systems would be perfect for?

            • Re: (Score:2, Interesting)

              by Anonymous Coward

              My understanding is that the noise from radiation only became a significant problem with newer chips running at lower voltages. The radiation shielding is a better solution for better systems, but ironically the old technology wasn't good enough to have this problem. Older logic systems (eg TTL but possibly not in this case) were designed for noisier, less stable circuits in general and radiation in space just happened to be just the sort of interferance it could tolerate.

      • by Kjella (173770) on Friday December 02, 2011 @03:51AM (#38235270) Homepage

        Software design techniques, if anything, have gone rapidly backwards for this sort of application since the late 70s/early 80s.

        I'd say the Mars rovers are a good counterexample of that, they're "new" and have been operating for many, many years now. Particularly when it comes to data compression the current probes have a huge leg up on the old ones. That said, yeah computers can't rewrite physics and launching anything into space is still quite expensive and they don't really go faster from it either.

        • by Anonymous Coward on Friday December 02, 2011 @04:53AM (#38235422)

          If we build the probe from neutrinos we could possibly launch it faster than light. And get the results a few years ago.
          If we had known to listen to them, that is.

          • by peragrin (659227)

            nope you want the communication system using neutrino's. that way only the results get sent back.

            Of course even if the neutrino experiment is true, it only means a an hour or two shaved off the 16 hours it takes to get the data at the ranges in question.

            • by mcgrew (92797) *

              nope you want the communication system using neutrino's.

              Using the neutrino's WHAT? Finish the sentence!

      • by Tastecicles (1153671) on Friday December 02, 2011 @05:26AM (#38235524)

        Oh [nasa.gov], I don't know... electrostatic ion propulsion is already proven to be more efficient than ordinary chemical propulsion (once you get out of the gravity well).

        As long as you have fuel, you'll keep accelerating, albeit at a very small rate. It might take ten or twenty years, but I reckon that if an ESI probe was launched tomorrow it'd overtake Voyager and still have propellant to go faster.

        The bonus is with computer technology; that while it's gotten thousands of times faster in practically every respect, it's also gotten a lot smaller [intel.com] - a non-hardened computer package these days weighs no more than 3lb [wikipedia.org], with terrestrial ruggedised coming in at little more [toughbook.eu]. The advantage of this is obvious: with the single biggest non-fuel component of the spacecraft now the size of a paperback, you have far less mass to push.

        Of course, you don't need a screen or a keyboard in deep space, so cut the weight in half and you've got something a smidge lighter than the several hundred pounds of GE custom machine that went up with Voyager, that has its own battery, that pulls about ten Watts rather than over a hundred, that uses solid state storage, and in most cases can automagically govern its own power load (this would be why the later Shuttle missions used self-contained laptops rather than a room full of mathematicians and radio that meant data moved at the speed of speech) - I've metered my netbook off the line and found it runs on between 3-35W, averaging 11, including the screen on minimum brightness.

        That said, you do need to protect the computer against hard radiation. That will obviously push the weight up, but not so much as to make it unmanageable. A couple or three pounds of lead and a steel cage to protect against EMI/RFI I think is all that is needed. The major part of the probe is then going to be propulsion systems and fuel, and the science package.

        • by necro81 (917438)

          As long as you have fuel, you'll keep accelerating, albeit at a very small rate. It might take ten or twenty years, but I reckon that if an ESI probe was launched tomorrow it'd overtake Voyager and still have propellant to go faster.

          All well and good, but how do you power it for a deep-space mission? Ion propulsion systems require 1000W - 10,000W of electrical input. You might be able to manage that at the beginning of the trip with solar panels, but solar incidence falls with the square of distance: at

          • by Tastecicles (1153671) on Friday December 02, 2011 @10:03AM (#38236516)

            ESI is the way (as I said, sans gravity well effects), generation of electrical power is somebody else's problem. As you've pointed out, solar is useless as a source for deep space probes; self contained generation of power is the only option, and right now all we have is RTG. This is what ion engines have used in every practical application so far (examples that spring to mind are SERT I and II, and DS1) and until something better comes along, it'll continue to be a sink for RTGs in deep space exploration. As to your claim that there are no RTGs available: I could build a crude but functional one in about five minutes (if I had a pellet of [insert name of suitable isotope here]), and it's not as if we're short of radioisotopes suited for the task. The problem lies in a particular nation state unilaterally and unjustifiably denying any other from possessing any quantity of refined radioisotopes for any reason other than the manufacture of smoke alarms. That nation state continues to throw RTGs all over the Arctic in the name of science and monitoring the military movements of others without the need to lay thousands of miles of power lines, and there is far more than the Apollo 13 RTG sitting at the bottom of the ocean - the Atlantic passive SOSUS net buoys are all RTG powered (there is very little sunlight three miles underwater).

        • by Muad'Dave (255648) on Friday December 02, 2011 @09:20AM (#38236292) Homepage

          A couple or three pounds of lead and a steel cage to protect against EMI/RFI I think is all that is needed.

          At the high gamma energies found in space, lead is no better than aluminum as a gamma shield [wikipedia.org], and both are pretty anemic. 1 cm of either will attenuate high energy gamma rays by only about 50-70%.

          • by dmatos (232892) on Friday December 02, 2011 @01:37PM (#38239886)

            This is indeed correct. Radiation hard electronics are created at the microchip layout and design level, rather than with external shielding. It requires an understanding of the damage that occurs from ionizing radiation and high-energy particles, and implementing device layouts that are tolerant of that damage.

            Let me give you a little hint: current generation designs with tiny FETs and low voltage drivers cannot operate for very long when the gate Vts start to shift.

        • I'm as big a fan of the smaller, faster, cheaper paradigm as anyone but there is one thing about ALL these space probes that CAN'T be miniaturized.

          It's the communications subsystem, most notably the antenna. I'm pretty sure that it can't be miniaturized due to the laws of physics dictating aperture and gain etc. (Unfortunately, I am not an physicist :( Also, ever since the Galileo probe antenna DISASTER (I call getting much less than one-hundredth the bandwidth a disaster) caused by the fact that the ant

          • by rubycodez (864176)
            higher frequencies use smaller antennae and also smaller dish diameter. There are also fractal antenna designs that work at all frequencies independent of its size. A laser or maser wouldn't need antenna at all, just resonant cavity with material undergoing stimulated emission and a focusing element.
      • by khallow (566160) on Friday December 02, 2011 @05:40AM (#38235562)

        The costs of space technology haven't changed much at all relative to the rate of inflation

        When you get away from government projects and missions you find an interesting thing. They've gone down in absolute dollars. It's not rare to find private analogues which cost an order of magnitude or more less than the government counterpart.

        For example, prior to the early 80s, there was no commercial space flight of any sort. When it first opened up with offerings from Arianespace, Boeing, and Lockheed, prices were on the order of $20k per kg (to low Earth orbit or "LEO"), a bit better than the Space Shuttle. Now there's perhaps a dozen private space launch providers, some offering flight costs well under $10k per kg. So we've gone from $20k per kg in 80s dollars to under $10k per kg in today's dollars. And if SpaceX delivers, we'll be hitting $5k per kg (in today's dollars), perhaps less. The Russians have a good chance of meeting that price point as well.

        It'll never be a Moore's Law thing, but we are seeing a remarkable long term decline in launch costs over a few decades. So no breakthrough in launch technology (with the exception of the creation of commercial space flight in the 80s and the possible exception of SpaceX now) yet we still manage to drop prices considerably even before adjusting for inflation.

        Second, there are great economies of scale in launching tens of probes. For example, R&D is divided up over a large number of probes. There are learning curve effects from building tens of probes and part costs will go down. Now maybe building a Voyager-level vehicle wouldn't be as cheap as the original poster claimed, but I bet $3 billion can buy a lot of interstellar probes, just the same. Especially, if one cuts out the slick tools that Voyager used for its planet flybys, but which weren't used for the interstellar portion of the mission (such as the imaging cameras).

        • by Talderas (1212466)

          So we've gone from $20k per kg in 80s dollars to under $10k per kg in today's dollars. And if SpaceX delivers, we'll be hitting $5k per kg (in today's dollars), perhaps less.

          Convert for inflation..
          $20k 1980 dollars = $52k current
          $20k 1982 dollars = $45k current
          $20k 1985 dollars = $40k current
          $20k 1987 dollars = $38k current
          $20k 1989 dollars = $35k current

          So at best, you're talking about around a 70-80% decrease in cost. SpaceX's cost would be about 85-90% lower than the 1980s.

        • by mcgrew (92797) *

          I think it's an unwarranted assumption that prices have gone down because government isn't doing it. I paid $600 for a 25 inch TV in 1976, you can get a flat screen hi res one that size for 1/5th that much today. An IBM-PC was four or five thousand dollars, and government never made TVs or computers.

          More likely the costs have gone down because of advances in science and technology, just like with computers and TVs.

      • by stephanruby (542433) on Friday December 02, 2011 @06:16AM (#38235690)

        The only thing consequentially different is computer capability, but a faster/more complex computer would just as likely be a liability as a bonus. Software design techniques, if anything, have gone rapidly backwards for this sort of application since the late 70s/early 80s.

        Thankfully, some of our/your assumptions about space technology are currently being proven wrong. For instance, take the Nexus One. NASA has been testing it to see if it could make cheaper smaller satellites with it, and its performance in that regard has been completely outstanding.

        Granted, it hasn't survived 30 years in space yet, only time will tell on that one.

        But it can survive in all kinds of extreme temperatures, all kinds of G forces, and it works perfectly well in a vacuum. And it's so small to begin with, the extra hardware it needs to power it, recharge it, move it, etc, doesn't have to be that big to begin with.

        During one of its space test, the Nexus One was even strapped to the tip of a rocket and the rocket accidentally crashed back into the desert leaving a large crater, but the phone only got a cracked screen and was still fully functional otherwise.

        And this is probably something that's not unique to that phone, or to Android, in particular. Consumer-grade devices, because they've been designed to survive actual consumers and sometimes even little kids, have come a long way in terms of reliability.

        And granted, a Nexus One will still have bugs that would normally be intolerable in the older type of computers designed for space, but it has enough computing power to be reprogrammed remotely and compensate for most bugs that are found after the fact. And since they take much less space and weight, and are much cheaper to launch. You can launch half a dozen for a fraction of the cost it used to launch an older type of satellite, thus building a type of redundancy that we just couldn't afford to have with the older kind.

        So if anything needs to improve, it's probably not our technology, but our mindset. We have good technology. That technology may not be perfect, but it should be more than good enough for unmanned space exploration at least. And it's grand time we start using it for that purpose.

        • by tibit (1762298)

          But it can survive in all kinds of extreme temperatures, all kinds of G forces, and it works perfectly well in a vacuum. And it's so small to begin with, the extra hardware it needs to power it, recharge it, move it, etc, doesn't have to be that big to begin.

          Sorry, that's engineering fantasy. No, a phone not designed for it will not survive "all kinds of extreme temperatures", "all kinds of G forces", etc. You'd have to test it -- you know, environmental chambers, shakers, etc. Without such tests any assumptions are pure fantasy. We don't know how it works in vacuum, because it hasn't really been in vacuum, only in atmosphere that's survivable to humans with supplemental oxygen. There's plenty of components that I'd expect will experience problems in vacuum si

    • by JasterBobaMereel (1102861) on Friday December 02, 2011 @05:15AM (#38235478)

      Launched today they would not do much .... they relied on a chance alignment of the planets that allowed them to use gravitational slingshots to get there in a reasonable time, tour most of the planets, and leave the solar system ... next time this will happen is around 2150 ...

    • by Kagura (843695)

      You never know when such research will pay off. The US and EU is scrapping programs now while China, India and a few others try to get into space, you can bet that a lot of cool research will be coming from that side of the globe in the next 30 years.

      Imagine if we could launch a probe now with what we have available. We could cheaply launch 10's of much faster probes with incrementally better sensors for the price of the voyager program (~$3B in today's dollars).

      As a side related note, I have heard nothing about New Horizons' after-rendezvous plans other than a possible second Kuiper belt flyby, but I'll bet you a million bucks that they've over-engineered this probe to later provide the kind of science that 1970s' Voyager is doing for us still today.

    • by necro81 (917438)

      We could cheaply launch 10's of much faster probes with incrementally better sensors for the price of the voyager program (~$3B in today's dollars)

      you are off in your reckoning. We could perhaps launch a handful of small craft, but certainly not 10's. And although technology has progressed, the speed with which we can travel in the solar system hasn't changed much.

      For comparison, the New Horizons [wikipedia.org] mission to Pluto has an expected lifetime cost of about $650 million - and that is a very modest probe.

  • Impressive (Score:5, Insightful)

    by PortaDiFerro (1719902) on Friday December 02, 2011 @03:22AM (#38235182)
    That must be one of the most successful space exploration projects so far, too bad it's running out of juice!
    • Re:Impressive (Score:5, Interesting)

      by niktemadur (793971) on Friday December 02, 2011 @05:26AM (#38235522)

      The distance at which the Voyagers are still collecting and transmitting useful data back to Earth, is mind boggling.
      Over a light day away! [nasa.gov]

      Back in 1989, when Voyager 2 flew past Neptune, the JPL command center was probably dismantled and refitted for the next glamor project, while the long final phase of the Voyager mission was relocated to a much tinier space, probably the basement, with a couple of old-school, hardcore Voyager geeks down there, living on Doritos, pizza and Usenet, a rickety AC rattling and slowly dripping water over a puddle, unfixed for months because the Maintenance Department is constantly needed up at Voyager's old stomping ground, kept immaculate for the Galileo probe people, or Cassini, or the Mars Rovers, whatever the Flavor Of The Lustrum [wikipedia.org] was / is.

      Nice and quiet down there among the rusted ceiling pipes and aged Crays, though. They didn't bother nobody, nobody bothered them. Beer could be smuggled to work and no one would notice, everybody upstairs would be swooning over Neil DeGrasse Tyson filming a segment on Pluto and the Horizons mission. Only time anybody saw the strange Voyager geeks, was when they went up to the ground floor vending machines, as the supply guy always forgot to restock the one in the JPL basement, forgot there was one in the basement.

      Little did anybody know (except for these guys) that the Voyagers were like an aging boxer with one good fight left in them, very low bitrate coupled with an ultra-weak signal perhaps, but with still one final, grand potential payoff - a peek at the outside, which may end up being the longest lasting legacy of all.

      Look at it now bitches, it's on the other side of the heliopause!

      • Re:Impressive (Score:4, Informative)

        by Kjella (173770) on Friday December 02, 2011 @07:53AM (#38235958) Homepage

        The distance at which the Voyagers are still collecting and transmitting useful data back to Earth, is mind boggling. Over a light day away!

        Uh? 120 AU is only 0.7 light days. And if that's far depends on perspective, it's 0.05% of the way to the closest star. Somehow the Mars rovers have been a lot more visual in saying that yes, we can do interplanetary with their cameras. The Voyager probes are more of a reminder that interstellar is a completely different ballgame. Thirty three years and 18 billion kilometers out yet it's still gotten nowhere in interstellar terms. Though it's fun to see them still operational and still doing science...

        • Uh? 120 AU is only 0.7 light days..

          You are correct, the JPL page I linked to states the "Roundtrip Light Time From The Sun" for both V'gers (Voyager 1 - 33:13:28, Voyager 2 - 27:05:23 as of writing this). Somehow the Round in Roundtrip just whizzed by me. Anyway, both Voyagers are over half a light day away.

        • Funny (giving up mod points to reply...) When I saw that 0.05%, I thought of it just the other way - to me it meant that we could launch a probe now that would arrive at the nearest star in ONLY 200 * 33 = 6600 years, using old-for-us technology. And that made me think that with a bit of thought and effort, maybe we could reduce that by an order of magnitude. And that was on the outer edge of something that the nations of earth might actually think was worth trying.

          200 years would be better, of course. I

  • by steevven1 (1045978) on Friday December 02, 2011 @03:29AM (#38235206) Homepage
    It receives commands from Earth, and it's 34 years old. What's to keep enemies of the United States from sending it bad instructions, or from collecting all data it sends back to us? I realize that Voyager isn't of any military importance, but I guess this is more of a hypothetical question. Does it use some type of encryption? Is that encryption still unbreakable today? The keys haven't been compromised after all this time? Just curious.
    • Re: (Score:3, Insightful)

      by Anonymous Coward

      > What's to keep enemies of the United States from sending it bad instructions, or from collecting all data it sends back to us?

      The fact that they are so far away that talking or listening to the Voyagers _REQUIRES_ a POINTABLE satellite dish 70 fucking meters in diameter. Only three that big exist in the world, and guess who owns them?

      http://voyager.jpl.nasa.gov/news/profiles_dsn.html

      • by Framboise (521772) on Friday December 02, 2011 @04:41AM (#38235390)

        In the linked article I didn't find that "only three" such antennae exist. The deep space network made of three big antennae is able to follow and control Voyager without interruption, but other isolated and big antennae exist and might be used to perturb the spacecrafts, probably with slight modifications.

        Germany has a 100 m radiotelescope (Effelsberg), UK a 76m one (Jodrell Bank), Australia a 64 m one (Parkes), and China builds a 300m equivalent one, FAST, to be ready in 2013 (http://en.wikipedia.org/wiki/Five_hundred_meter_Aperture_Spherical_Telescope).

           

        • by Tastecicles (1153671) on Friday December 02, 2011 @06:04AM (#38235640)

          It's not just single large antennae that can be used to detect signals from Voyager.

          The VLA uses technology developed in Britain (actually, a quirk of physics) to use several small antennae to simulate one large antenna. You can do the same, using similar frequencies to those used for the Voyager downlink (2.3GHz), a few lengths of coaxial cable, some one and a half inch nails, and four feet of marine ply.

          1. Set two nails in the ply a set distance apart, call this distance D. You'll need this.
          2. Connect each nail to its own demodulator (AKA receiver), then connect the receivers to a phase correlator.
          3. Set the phase correlator to cycle the sinD differential between the two signals.
          4. Take the output to a computer for decoding.

          It is possible to do the phase correlation on the computer, or simply use the computer to record the signals from each receiver (forgetting about the phase correlator altogether) and combine them later. If you're dealing with streaming data (like you would be if using WiFi) you'll need a phase correlator* or set sinD as close to zero as you can get it (by setting the nails in the case of WiFi at multiples of 1.21"/30.734mm apart - as far apart as you can get them).

          *There is a way around this, but it also requires precise angle measurement. If you know which direction your signal is coming from, you can point your interferometer toward it (the elements set exactly perpendicular to the signal source so they receive the signal in precise phase alignment). It helps if the interferometer is mounted on a common axis as this does away with the need for a phase correlator.

          An improvement on this extremely simple design is the use of "cantennas" or other narrow-field antenna, which develops a narrow but high gain cone for the receiving antenna, making life a bit easier for finding the transmitter. If you want to get ambitious, the VLA uses 27 antennas, a 21+21+21km 3-way rail baseline, and several supercomputers.

          • I'd love to know more about this! Always wanted to know how they connect multiple receivers together. Not just for low frequency em, but things like light etc... Do you know of any DIY projects that did something like this? Would make some nice Friday reading over here :)

            I wonder if anyone wrote any OSS software to do the above. It would be cool!

            • easiest way to play with (recorded) signals is to use stereo audio waveforms in something like Audacity: take each channel (representing the signal recorded from each receiver) and subtract one from other (destructive interferometry), add them together (constructive interferometry), phase shift (same as signal correlation) then subtract or add... there are all sorts of ways to get all sorts of effects from three filters which come with the software: add, subtract, phase, and you can hear the results practic

            • by Muad'Dave (255648)

              http://en.wikipedia.org/wiki/Beamforming [wikipedia.org]
              http://en.wikipedia.org/wiki/Phased_array [wikipedia.org]
              On a slightly different scale: http://www.km5kg.com/array.htm [km5kg.com]

              If you're interested in modern radio techniques, I suggest getting a decent book on Digital Signal Processing [wikipedia.org] and software-defined radio. The things that can be accomplished with software are amazing!

          • Um, no. (Score:4, Interesting)

            by dtmos (447842) * on Friday December 02, 2011 @08:27AM (#38236080)

            You're confusing antenna angular resolution with antenna effective area. The problem with reception of the Voyager probes isn't being able to discern them among other relevant signals. The problem is that the signals are so weak that they need an antenna with large area just to collect enough energy per bit to reliably overcome noise generated in the receiving system. Until you do this, you can't get a signal strong enough for your correlator to work on -- all you'll get out of the correlator is noise, because that's all that's going in to the correlator from your receivers.

            Ergo, the 70m dishes.

            • I don't have a 70m dish to hand. I do, however, have an array of 9 Cantennas, which I use on a motorised axis to wardrive from home. I've picked wifi signals from several miles away - wifi uses weak signals which usually have an effective range of less than one eighth of a mile and even less when you factor in the bleed from surrounding devices such as Bluetooth and microwave ovens. It's not the size of the dish, it's the number you have, and the more you have the higher the SNR (providing you have the elem

              • by dtmos (447842) *

                By moving from one to nine antennas, you'll get an effective area improvement of at most 9, or 8 dB, but most of the improvement you're seeing is, in fact, the phenomenon you describe -- you're creating a phased array that rejects signals from undesired transmitters in the ISM band, in order to receive the desired signal.

                The problem in receiving the Voyager probes, however, is not this problem. The Voyager problem is that one doesn't have enough incoming signal to manipulate at all -- when received by even

          • by rimcrazy (146022) on Friday December 02, 2011 @09:48AM (#38236416)

            Not that anyone is probably interested but I worked in the group that made the radios that are in Voyager. I just missed working on those specific models but I worked on the next generation following those use on Voyager. Working there (Motorola GED) I worked close with NASA and was in the loop on all the programs, past and current that we were working on with NASA. What is really remarkable here is both Voyager probes have "failed" receivers on them. There was a problem with the capacitors that were used for the input loop bandwidth filters. These failed in such a manner as to cause the acquisition loop bandwidth to be a very narrow band instead of the intended wide band. NASA was able to recover using these radios by basically making an empirical model of each of the spacecraft. They did this when the spacecraft were relatively close to the earth and they could blast them with wideband signals to ensure acquisition. What they did with the model was to identify exactly how the on board xtals in the radio aged or varied with power and temp and then threw in compensation for age and doppler. With all of this data then then had a model that told them on such and such a date, the correct xmit frequency to use to put the carrier in the middle of the narrow band filter is X. They would dial it in, send it out and everything still worked. Actually a very clever fix for what would have been a disaster.

            • by adri (173121)

              .. why isn't this in wikipedia somewhere? Was this ever published?

              • by rubycodez (864176)
                most human knowledge is not on the internet. Most electronics component and design knowledge of the 1960s and 1970s is not on the internet (I was alive at the time, there are references I wish I could retrieve, but the only possible store of such is technical libraries usually at colleges and universities)
              • by rimcrazy (146022)

                There are probably only a very small number of people that know about this. Certainly the group of people I worked with at Motorola and the NASA engineers and techs associated with the program. Since NASA was able to come up with a fix to make everything work, I would guess it's probably not something they would want to publicize in general but I've always thought this was a very ingenious solution. The truth be known, there are probably stories like this on just about every mission they ever did. Stuff

          • by ckaminski (82854)
            Now TRANSMIT a phased signal that will still be detectable at 120 AU from earth with that setup.
      • by tibit (1762298)

        It doesn't need to be a pointable dish in the physical sense. You can do a flat phased array. Heck, a competent RF engineer living in a U.S. suburb could probably assemble one if he/she pooled up the backyards with a couple of neighbors.

    • by ETEQ (519425) on Friday December 02, 2011 @04:02AM (#38235294)

      I don't think it's encrypted, but I think the methods of encoding the transmissions are incredibly arcane and the formats for the data are nothing even approaching standard (standards for such things didn't exist back then). Probably more important is that the only radio receivers in the entire world that are capable of detecting its signal are run by NASA...

      • by Zoxed (676559)

        I work in ground based space systems, and can confirm it is tough enough to write the code for a modern satellite *with the documentation* :-0

    • Your is the strangest of mindsets. "Enemies of the United States" ? "Collecting all data it sends back to us" ? This is about science, dude. Cool down. The moment is not close for the US to militarily occupy outer space. ( It will have gone bankrupt before that time ).
      • by rubycodez (864176)
        it's not just funding that is an obstacle of our total occupation of all space, no matter how many people we send, they quickly get spread out too thin to do any effective occupying. Even if every U.S. person occupies 1,000 cubic light-years, we would then need 39 billion people to occupy the Milky Way. Clear we need a much higher level of unprotected sex among the fertile portion of our populace if we are to ever achieve the goal.
    • by necro81 (917438)
      at this point the limiting factor would be the fact that you need fantastically sensitive radio equipment to communicate with Voyager. At this point, only NASA's Deep Space Network can manage it. The Voyager transmitters are only about 20 W, and by the time it reaches Earth 10-12 hours later is down to about 10^-18 W (about -150 dB). You need large radio dish antennae and uniquely sensitive equipment to be able to receive that. On the transmit side, I've seen the number 20 kW bandied about, again with v
    • by Tim C (15259)
      I don't know about the protection from rogue commands (it may simply be impractical or impossible for any other agency to transmit to them now), but as for the data collection question - who cares if someone else does receive the data? It in no way prevents NASA from also receiving it.
    • by tibit (1762298)

      Whoever modded the parent flamebait is an idiot. Please post to undo the moderation. It's an insightful question that needs to be seriously considered.

      I don't think there's any encryption involved. I presume that all of the telemetry and command uplink coding at several levels (modulation, error correction coding, data coding, framing/packetizing, etc) could be reverse engineered fairly quickly. But the problem is that what goes over the air is still useless until you have most of the details of the spacecr

  • by agentgonzo (1026204) on Friday December 02, 2011 @06:24AM (#38235722)
    Last I heard, the voyagers are about 100-110 AUs from the sun. Is the summary incorrect or do you only need to be 40 AUs from the sun to make these measurments? In which case, why is it news now and not in the 80s/90s when they reached this distance?
    • by Shadowmist (57488) on Friday December 02, 2011 @07:51AM (#38235952)

      Last I heard, the voyagers are about 100-110 AUs from the sun. Is the summary incorrect or do you only need to be 40 AUs from the sun to make these measurments? In which case, why is it news now and not in the 80s/90s when they reached this distance?

      Presumably because it's only recently that they discovered techniques to make these observations with the remaining equipment on board. Voyager is now making measurements it was never designed to. Keep in mind that the engineers who built these ships did not expect them to last as long as they did, nor that we would still be able to get useful signal strength from them at this point. Also remember that with the twin factors of half life decay and thermocouple degradation, they're only getting about half the power from the RTG's that they used to, so some equipment has had to have been permanently turned off.

    • by Kjella (173770)

      Not just the summary, but the article is probably horribly wrong. The new measurements are almost certainly related to the probes approaching the edge of the heliosphere [wikipedia.org], but the journalist didn't have a clue and confused it with the distance to Pluto - which is about 40 AU.

  • A surprisingly large part of me feels good that those amazing spacecraft are so far away, nearing the depths of interstellar space and will continue on for as near as makes no difference to forever. An even larger part of me regrets that I won't be around to see the day when they make contact with another civilisation.
    • In other news, a partial image was just received from Voyager 2 which has DHS worried [wikimedia.org]. Contact with the probe has not been reestablished.

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