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Space NASA

Interstellar Space Even Weirder Than Expected, NASA Probe Reveals (nationalgeographic.com) 152

New submitter paralumina01 shares a report from National Geographic: In the blackness of space billions of miles from home, NASA's Voyager 2 marked a milestone of exploration, becoming just the second spacecraft ever to enter interstellar space in November 2018. Now, a day before the anniversary of that celestial exit, scientists have revealed what Voyager 2 saw as it crossed the threshold -- and it's giving humans new insight into some of the big mysteries of our solar system. The findings, spread across five studies published today in Nature Astronomy, mark the first time that a spacecraft has directly sampled the electrically charged hazes, or plasmas, that fill both interstellar space and the solar system's farthest outskirts. It's another first for the spacecraft, which was launched in 1977 and performed the first -- and only -- flybys of the ice giant planets Uranus and Neptune.
[...]
For the first time, researchers could see that as an object gets within 140 million miles of the heliopause, the plasma surrounding it slows, heats up, and gets more dense. And on the other side of the boundary, the interstellar medium is at least 54,000 degrees Fahrenheit, which is hotter than expected. In addition, Voyager 2 confirmed that the heliopause is one leaky border -- and the leaks go both ways. Before Voyager 1 passed through the heliopause, it zoomed through tendrils of interstellar particles that had punched into the heliopause like tree roots through rock. Voyager 2, however, saw a trickle of low-energy particles that extended more than a hundred million miles beyond the heliopause. Another mystery appeared as Voyager 1 came within 800 million miles of the heliopause, where it entered a limbo-like area in which the outbound solar wind slowed to a crawl. Before it crossed the heliopause, Voyager 2 saw the solar wind form an altogether different kind of layer that, oddly, was nearly the same width as the stagnant one seen by Voyager 1.

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Interstellar Space Even Weirder Than Expected, NASA Probe Reveals

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  • by Calydor ( 739835 ) on Tuesday November 05, 2019 @02:16AM (#59382288)

    Did I miss some kind of memo where space isn't actually cold but burning hot?

    • Re:54,000 degrees? (Score:5, Informative)

      by war4peace ( 1628283 ) on Tuesday November 05, 2019 @02:32AM (#59382304)

      I was confused by this as well, until I realized they were talking about the plasma within the space, not space itself.

      • Re:54,000 degrees? (Score:5, Informative)

        by rioki ( 1328185 ) on Tuesday November 05, 2019 @05:16AM (#59382536) Homepage

        The temperature of the interstellar medium is it's temperature, there is no difference temperature for "space". The questions is at the astounding low density, does it matter that there are a few high energy particles. Same is with space craft, especially maned ones, have more of a problem of overheating. Thermodynamic become counter intuitive when operating in a near vacuum.

        • Re: 54,000 degrees? (Score:4, Interesting)

          by JoeRobe ( 207552 ) on Tuesday November 05, 2019 @07:02AM (#59382682) Homepage

          I suspect that at the densities of gas/plasma in the ISM that any spacecraft can radiatively shed the extra heat.

        • Re:54,000 degrees? (Score:4, Insightful)

          by drinkypoo ( 153816 ) <drink@hyperlogos.org> on Tuesday November 05, 2019 @10:20AM (#59383278) Homepage Journal

          I'd say the question is whether it makes any sense to talk about the temperature of space at all, and I'd also say that the answer is no. In space you'd have to talk about the amount of heat energy per unit of volume, which could then be meaningfully compared to something with which the reader is familiar.

        • >

          No, there are TWO temperatures for space: That of the matter, and that of the electromagnetic radiation. Equilibrating with just the matter (an not generating additional heat internally) would make an objet approach the high temperature quoted in TFA. Equilibrating only with the light would approach the black body temperature - somewhere above 2.7 kelvin, how much depending on how close you are to local light sources like stars and planets.

          The matter may be very hot, but it's thin. Unless your inters

    • by Gabest ( 852807 )
      Looks like the Sun and its radiation, as it moves through space, collides with particles that are not moving, relative to it. I wonder why the probes were sent in that direction and not sideways or to the tail.
      • Re:54,000 degrees? (Score:5, Interesting)

        by wierd_w ( 1375923 ) on Tuesday November 05, 2019 @02:55AM (#59382348)

        The trajectory of the probes is the result of their "Grand Tour" itinerary. EG-- they were sent to rendezvous with the gas giant planets, at their orbital locations, calculated on launch day.

        Exploring the heliopause/heliosheath was a secondary mission that the probes were tasked with after completing the grand-tour. As such, their exit trajectories were not planned for such a mission; they are the consequence of what the probe's inherited after their final interactions during the grand-tour.

        Given the data that they have collected at different parts of that region, there is a scientific desire to get more data sources. Sadly, the only energy sources suitable for such a mission are RTGs, and those need radioactive materials that are difficult to source these days, and politically difficult to launch, because "OMG, what if it lands in my back yard!" and other nonsense.

        I hope the scientists can get what they need, but I have my reservations on their getting it.

        • Re:54,000 degrees? (Score:5, Interesting)

          by blindseer ( 891256 ) <blindseer@noSPAm.earthlink.net> on Tuesday November 05, 2019 @04:17AM (#59382448)

          I hope the scientists can get what they need, but I have my reservations on their getting it.

          As I recall NASA has acquired funds and permission to build a reactor that can produce the Pu-238 they will need for future missions. After NASA lost some very valuable probes to being in the shade too long, too long for the solar panels and batteries to keep everything running, they had a new urgency for RTG materials.

          I have confidence that NASA will get their RTGs now.

          Exploring the heliopause/heliosheath was a secondary mission that the probes were tasked with after completing the grand-tour. As such, their exit trajectories were not planned for such a mission; they are the consequence of what the probe's inherited after their final interactions during the grand-tour.

          It would be interesting if we could have a mission headed to another star. Let's get a probe that can take the fast path to a planet or two on it's way to examine the interstellar material and maybe after a few decades give us some up close and personal photos of other stars and perhaps some exoplanets. We learned a lot from probes launched decades ago and how to make them last a long time. We should start thinking about century scale long missions. The vastness of space is lost on people but if humanity is going to explore space then we need to think of missions that we will not live long enough to see to the end. Long enough that our grandchildren will not see the end. Hopefully this will provide information to aid humanity for millennia.

          • Re:54,000 degrees? (Score:5, Informative)

            by close_wait ( 697035 ) on Tuesday November 05, 2019 @08:14AM (#59382794)
            At their current velocities, New Horizons and Voyager 1 would take around 70,000 years to reach the nearest star, had they been heading that way. Also, we currently struggle to receive data from those probes using a 70m receiver dish. To receive data when the probe has reached alpha centauri or similar would need a dish approx 180,000m in diameter, all other things being equal.
            • Yep, I made the mistake of not taking into account the vastness of space while also complaining of others not taking into account the vastness of space.

              I will hold to some hope of a small probe being constructed soon that could be launched to a near(-ish) star that could reach a speed high enough to get us something in the time frame of decades or centuries, and not millennia.

              Perhaps we can launch something that will return to us, negating the need for the large dish. Perhaps we will find a means to constr

              • by Ol Olsoc ( 1175323 ) on Tuesday November 05, 2019 @10:07AM (#59383232)

                Yep, I made the mistake of not taking into account the vastness of space while also complaining of others not taking into account the vastness of space.

                That sounds pretty half-vast to me.......

              • by PPH ( 736903 )

                "Space is big. You just won't believe how vastly, hugely, mind-bogglingly big it is. I mean, you may think it's a long way down the road to the chemist's, but that's just peanuts to space."

                --Douglas Adams

              • It wonder if takes more resources to return to us than to broadcast a strong signal from several light-years away. It's weighing a big broadcasting module versus a big return engine system. Could laser broadcasting make it viable that far out, since a narrower signal needs less total energy (in theory)?

                But a returning mission would probably mean the probe could slow down enough to get a better look at the target system's planets etc. Something going say 10% of the speed of light when it gets to the target

            • To receive data when the probe has reached alpha centauri or similar would need a dish approx 180,000m in diameter, all other things being equal.

              What if we launched a probe along the same path every year and used them as repeaters? Use solar sail tech to create large foil receivers. Put most of your mass budget into the transmitter.

              • What if we launched a probe along the same path every year and used them as repeaters? Use solar sail tech to create large foil receivers. Put most of your mass budget into the transmitter.

                If the Earth stood still that would be a fine idea. Oh, and since we don't want to spend the absolutely silly amount of propellant required to boost a probe directly out of the solar system, we also need at least one of the gas giants to stand still. Any of them will do. Pick one. (Pick Jupiter. It always gets you the best boost.)

                And then watch as the Sun leaves us behind.

                Ok, so you can launch from the same spot in Earth's orbit around the Sun each year, and despite Sol's rather ridiculously high prope

          • by kbahey ( 102895 )

            It would be interesting if we could have a mission headed to another star. Let's get a probe that can take the fast path to a planet or two on it's way to examine the interstellar material and maybe after a few decades give us some up close and personal photos of other stars and perhaps some exoplanets. We learned a lot from probes launched decades ago and how to make them last a long time. We should start thinking about century scale long missions. The vastness of space is lost on people but if humanity is

      • Good luck colliding with something that's not moving relative to you...
    • Re:54,000 degrees? (Score:5, Informative)

      by mike.mondy ( 524326 ) on Tuesday November 05, 2019 @02:42AM (#59382320)

      Did I miss some kind of memo where space isn't actually cold but burning hot?

      High temperature but extremely low heat.

      The summary mentions "54,000 degrees Fahrenheit", but doesn't mention that the density of the interstellar medium is so low that it's orders of magnitude less than what you could get with a high quality laboratory vacuum chamber. IOW, there's *almost* no ions or molecules in the less than perfect vacuum, but the ones that exist do have a decent amount of energy.

    • by hcs_$reboot ( 1536101 ) on Tuesday November 05, 2019 @02:46AM (#59382330)
      It's F. Convert it to C and it's much lower.
    • Modern journalism uses such flowery and filler language that the message suffers. Plus, I suspect that the author didn't elaborate because he didn't understand what it meant, either.

      Space is 'cold,' as there is very little total energy (relatively), but there are high energy particles zapping about. It's just that your body would be emitting much more energy via blackbody radiation than you'd be receiving, and there wouldn't be enough high energy particles to keep the balance.

      Temperature actually seems
    • Re:54,000 degrees? (Score:5, Informative)

      by Sique ( 173459 ) on Tuesday November 05, 2019 @06:06AM (#59382592) Homepage
      Yes, you missed the very definition of "temperature".

      Temperature is the average kinetic energy of particles, more exactly: T = 2/3 E_kin/k_B with k_B being the Boltzmann constant. In this case, we are talking about interestellar plasma and its temperature (e.g. its average kinetic energy per particle).

      What you are probably meaning is the cosmic background radiation, whose spectrum is thermal (e.g. has the frequency distribution of a thermal radiator), and is equal to the radation a black body would radiate at a temperature of 2.7 K.

      • by Calydor ( 739835 )

        Right, because that is how people not in the field always use the word 'temperature'.

      • by Luckyo ( 1726890 )

        The problem here is visible in your own post. It's a norm to post such numbers in Kelvin, which gives an immediate indication of what is being talked about.

        Here they are posted in Fahrenheit, which is very unusual. Whether the goal was deception or just the fact that clickbait expert in question didn't know the subject matter is up to debate.

        • Here they are posted in Fahrenheit

          So subtract 459.67 (or don't bother, because it's below the apparent significance of the quoted value) and multiply by 5/9.

    • That is nothing, in outer space temperature is a Fahrenheit thing! And I've heard distance units are inches and feet too!

    • Imagine a single atom in space. What is its temperature? The answer is we don't know from a single atom. If we had lots of atoms and they were all moving in random directions, then the atoms would have a temperature. If they were all moving in the same direction then they would have zero temperature, but the would have a temperature.

      Temperature is a property of things in steady equilibrium with other things. In space, there are lots of atoms which are too spaced out to be interacting very much. There are

    • All this means is the hot atoms or plasma have a non-directional average kinetic energy equivalent the energy kT where K is 54,000. THen There's a couple of things to understand about 54,000 degrees. First is, why doesn't the space craft simply overheat. The answer is that the density of the hot atoms is so low that it doesn't transfer a lot of heat, and also the rate of heat transfer may be low since the hot atoms bounce off easily. THe second thing to ask is will equilbrium temperature of the craft m

    • Did I miss some kind of memo where space isn't actually cold but burning hot?

      Been known for some time. Particles are very hot, but there are so few in that level of vacuum.

    • by urusan ( 1755332 )

      If you put your hand inside the cavity of an oven, letting the 400F/200C air wash over your hand, it will simply feel a little warm despite that temperature being more than 4 times hotter than the ambient air temperature that your hand was in thermoequilibrium with, and 400F/200C being a lethally hot air temperature (of course, if you let your hand stay in this hot air long enough it would eventually bake, but that would take a while).

      On the other hand, if you touch the solid metal surface of the same hot o

  • by account_deleted ( 4530225 ) on Tuesday November 05, 2019 @02:25AM (#59382298)
    Comment removed based on user account deletion
  • I'm always kind of hoping that Outside is kind of like Vernor Vinge's Zones of Thought [wikipedia.org], where everything changes once you start moving away from the galactic core.

  • by RyanFenton ( 230700 ) on Tuesday November 05, 2019 @03:34AM (#59382418)

    But the whole space between solar systems wouldn't be like 54,000 degrees or something. Just those faint ribbons of plasma - which given their density, wouldn't be a major threat to pass through or anything for any spaceworthy craft.

    The reason those bits of plasma can remain so hot is because there is literally nowhere for the heat (rattling atoms) to go. There's not even enough gravity or solar winds out there to strip the stray atoms that get flung out... so they swing back in time and don't add up to terribly much entropy over time.

    That's actually a common problem with any potential space engineering - space doesn't let you radiate heat very easy like you can in an atmosphere. All that 'cold space' doesn't actually translate to much actual material cooling since there's nothing contacting you to leech off the heat.

    Even if you designed a ship that could move without on-board propulsion, both keeping warm and preventing overheating would still be big strains on resource usage if we wanted to transport even partially viable living things with some recent-ish technologies.

    But they wouldn't fry from that plasma - so at least there's that!

    Ryan Fenton

    • Whole idea of "cold space" is nonsense. What its actual temperature is is irrelevant since it's nearly perfect thermal insulator. Vacuum of space is a lot purer than that found in a consumer grade vacuum flask. So basically everything you have in space is automatically put into a thermos and is in danger of overheating rather than freezing over.
      • Sort of, but not exactly. In a thermos, you have a vacuum layer for insulation, a reflective material to turn back thermal radiation, and then room temperature materials that make their own heat radiation. In space, you have the same excellent thermal insulator of the vacuum, but then you have empty space. So if you manage to radiate away your heat it won't come back to you. You do however get the unattenuated heat from the sun, which can be an enormous amount or almost nothing, depending on your distance f
        • There is lots of confusion about radiative heat transfer in all the replies. Conductive heat transfer is proportional to the temperature difference whereas radiative heat transfer occurs in proportion to the absolute temperature to the fourth power. This makes radiative transfer extremely weak up to temperatures over what humans handle, then it becomes so dominant it's about the only important form of heat transfer at high temperatures. This is why thermos don't have a problem with radiating heat, but st
    • There is in fact a way to leech heat off in space. You can radiate heat via actual radiation, ie via black body emission. It's what all spacecraft use to shed heat, since once you're far from the sun the solar photon flux hitting the spacecraft is minimal (so radiation goes one way, away from spacecraft). If you look up black body equations you'll notice that it's not a small amount of power either, and goes by T^4. For example, the human body radiates about 100 W. When you're surrounded by other radiato

      • More importantly, conductive transfer is proportional to temperature difference so radiative, because of the small Boltzmann constant, is negligible until the ^4 term blows up then it's many orders of magnitude more than conducive. Conductive dominates at low temperatures (when conduction occurs) and radiative at high temperatures.
  • Fahrenheit (Score:5, Funny)

    by zmooc ( 33175 ) <zmooc@zmooc.DEGASnet minus painter> on Tuesday November 05, 2019 @03:56AM (#59382426) Homepage

    (...) the interstellar medium is at least 54,000 degrees Fahrenheit, which is hotter than expected (...)

    The real surprise here is not so much that it is so hot out there but that temperatures measured in Fahrenheit were encountered, which up to now had only been known to exist in the United States and its perimeter.

    • I count as a surprise that measurement devices keep working accurately after 40 years of hard radiation.

    • by dkone ( 457398 )

      Do you realize the irony of your insult? Fahrenheit, Celsius, Kelvin and ALL the other units of measure that mankind has come up with are only known to exist on this tiny spec of real estate we call Earth. What happens when we meet an advanced civilization that uses base 42? Please keep in mind how much your insult is diminished in the context of you making it against the Country that launched the probe that was able to send back the data.

      • If we encounter aliens that use base 42, it will be all the proof I need that Douglas Adams was, in fact, an interstellar hitchhiker and his novels a documentary.
      • by WallyL ( 4154209 )

        Alas, but they only know it as base )0. What's it to you?!

    • Because, like the moon, it belongs to whomever got there first until someone can tear it from them.

    • Thanks to forward-thinking Americans of the ‘70s, we can, today, say that Fahrenheit is being used far and away more than Celsius.

    • by sfcat ( 872532 )

      The real surprise here is not so much that it is so hot out there but that temperatures measured in Fahrenheit were encountered, which up to now had only been known to exist in the United States and its perimeter.

      So, in the US we do use a mix of F and C. For science we use C and for weather we use F. It is pretty dumb for the "journalist" in this case to use F in a scientific context and even American scientists would be confused by that. See for air temperature (what we use F for) its easier to just say, "it will be in the 70's" today or it "high in the 50's today" and you only need to remember 1 digit. When you express human scale temperatures like air temp, its actually easier to do that in F than C. In C, y

  • Units issues aside, does any know how they're measuring temperature? In general, what are the ways to measure temperatures of a very sparse gas/plasma at crazy high temperatures? Is there something other than spectral, or is that what the Voyager spacecraft are using?

Top Ten Things Overheard At The ANSI C Draft Committee Meetings: (10) Sorry, but that's too useful.

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