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Space Science

Voyager 1 Crosses The Termination Shock 420

Posted by Hemos
from the going-gentle-into-that-good-night dept.
SubstormGuy writes "In a scientific session at the AGU meeting in New Orleans this morning, Dr. Ed Stone presented clear evidence that Voyager 1 crossed the termination shock last December. The scientists in the room applauded when the announcement was made."
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Voyager 1 Crosses The Termination Shock

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  • by Anonymous Coward on Wednesday May 25, 2005 @01:04AM (#12631466)
    It absolutely will not stop, ever, until you are dead.
  • The wikipedia entry claims that The Voyager I spacecraft is believed to have passed termination shock in February 2003.

    I'd do it, but my wiki privileges have been revoked temporarily. I can't imagine why.
  • by professorhojo (686761) * on Wednesday May 25, 2005 @01:06AM (#12631479)
    ...voyager fans, unsure what "termination shock" exactly means, start raising donations "just in case".
  • Fixed article link (Score:5, Insightful)

    by darkpurpleblob (180550) * on Wednesday May 25, 2005 @01:07AM (#12631485)

    The first link doesn't go anywhere useful. This link [agu.org] brings up the correct results for the session. You can also view the session details [agu.org].

  • by uptownguy (215934) <UptownGuyEmail@gmail.com> on Wednesday May 25, 2005 @01:08AM (#12631494)
    I am shocked I say -- SHOCKED -- to hear this news.

    And excited.

    The geek in me is excited about 2005. Methane oceans, rovers on Mars and private spaceflight? There's a lot that's scary going on in the world today. But when it comes to SPACEFLIGHT -- 2005 is shaping up to be a banner year!

    Kudos to the Voyager team!
  • While it's there, I'll send it a message to have a look around... I think that's where I left my sunglasses.
  • Woohooo! (Score:4, Interesting)

    by Fjornir (516960) on Wednesday May 25, 2005 @01:09AM (#12631499)
    Worlds grow old and suns grow cold
    And death we never can doubt.
    Time's cold wind, wailing down the past,
    Reminds us that all flesh is grass
    And history's lamps blow out.

    But the Eagle has landed; tell your children when.
    Time won't drive us down to dust again.

    Cycles turn while the far stars burn,
    And people and planets age.
    Life's crown passes to younger lands,
    Time brushes dust of hope from his hands
    And turns another page.

    But the Eagle has landed; tell your children when.
    Time won't drive us down to dust again.

    But we who feel the weight of the wheel
    When winter falls over our world
    Can hope for tomorrow and raise our eyes
    To a silver moon in the opened skies
    And a single flag unfurled.

    But the Eagle has landed; tell your children when.
    Time won't drive us down to dust again.

    We know well what Life can tell:
    If you would not perish, then grow.
    And today our fragile flesh and steel
    Have laid our hands on a vaster wheel
    With all of the stars to know

    That the Eagle has landed; tell your children when.
    Time won't drive us down to dust again.

    From all who tried out of history's tide,
    Salute for the team that won.
    And the old Earth smiles at her children's reach,
    The wave that carried us up the beach
    To reach for the shining sun.

    For the Eagle has landed; tell your children when.
    Time won't drive us down to dust again.

    (c) 1975 - Leslie Fish
  • details (Score:3, Interesting)

    by rhennigan (833589) on Wednesday May 25, 2005 @01:11AM (#12631513)
    Anyone care to give a better explanation of termination shock? How hot does it get there? Can the sensors onboard obtain more information of this phenomenon? The wikipedia article doesn't go into too much detail.
    • Re:details (Score:5, Informative)

      by downsize (551098) * on Wednesday May 25, 2005 @01:25AM (#12631574) Homepage Journal
      if NASA does not terminate the project [washingtonpost.com] to favor Bush's push to put humans on Mars, the Voyager 1 has enough power to last another 15 years (2020). in that case, they should be able to retain enough data to calculate what is going on in the heliosheath [wikipedia.org] and beyond. I don't think 'hot' is used to describe a location that is 7 billion miles from the sun :-} .. but they should be able to calculate a close temperature based on the distance and magnetic fields among many other factoring (IANAS)
      • Re:details (Score:5, Interesting)

        by FireFury03 (653718) <slashdot@CHEETAHnexusuk.org minus cat> on Wednesday May 25, 2005 @07:31AM (#12632882) Homepage
        I don't think 'hot' is used to describe a location that is 7 billion miles from the sun

        Actually, "hot" (or temperature) is really describing the energy of the particles in the area. Inside the solar system, the solar wind is moving at pretty high speeds - wikipedia suggests energies of 500 KeV. Using the Boltzmann Constant we get 500,000 x 11,605 = 5.8 billion degrees K (Sounds a lot - can some astrophysacists check my figures please :).

        Once you get to the termination shock, the solar wind is moving at much slower sub-sonic speeds. Not sure what energies we're talking about here but they're going to be a *lot* lower... A bit of googling suggests He energies somewhere around the 5.2 KeV area (5,200 x 11,605 = 60 million degrees K).

        Of course, although the matter may be "hot", there isn't much of it - the low density of matter means that there isn't much "heat" (compare - a cigarette is "hot" (it's gonna burn you) whereas a central heating radiator is not as hot but generates more "heat" (it'll warm your room better than the cigarette because it's total energy output is much greater, even though it's temperature is less)).

        Disclaimer: IANAAP (Astro-Physacist) so the above could be crap, but that is how I understand it.
    • Re:details (Score:5, Informative)

      by helioquake (841463) * on Wednesday May 25, 2005 @01:32AM (#12631607) Journal
      The termination shock is basically where the wind of the sun meets "the wall" -- as known as interstellar medium.

      You know about the solar wind. It's basically a stream of particles flowing out of the Sun's atmosphere at a supersonic speed. The particles would cruise radially out of the Sun and go on and on and on...until it meets a clump of gas associated with semi-primodial stuffs that the Sun and other neighboring stars were made out of. Imagine that the Sun is sitting in a void of space (the emptiness was due to the solar wind sweeping out the material around it).

      Anyway, as the particles in the solar wind nears the wall, the particles in the solar wind begins to "feel" the presence of a wall. It's like a wind hitting a building and twirl near the wall of the building. A similar thing happens here and the sensors on board Voyager can sense the motion of these particles "twirling" around. In this case, these particles are slowing down and that's what Voyager I has detected.

      As for the precise timing? I don't think there is a clear signature of the "termination" point. It might have been in 2003 or in Dec 2004. In the astronomical standpoint, the distinction is, I believe, not so meaningful.

      Phew. That's alot to write. I'd better go to bed now.
      • Re:details (Score:2, Interesting)

        by CroDragn (866826)
        I've noticed several uses of the term "supersonic" in relation to solar wind. Exactly how does this apply? Was under the impression that an atmosphere was a requirement for supersonic speeds.
        • Re:details (Score:4, Informative)

          by helioquake (841463) * on Wednesday May 25, 2005 @02:22AM (#12631780) Journal
          Supersonic means just that -- particles moving faster than the LOCAL speed of sound. It varies slightly at a distance, as you might imagine.

          Don't think too much. Generally speaking there is the presence of a "shock" where a supersonic flow turns into subsonic one. That's why you hear about these words often when talking about heliopause.
  • by bushboy (112290) <lttc@lefthandedmonkeys.org> on Wednesday May 25, 2005 @01:23AM (#12631566) Homepage
    Yep, had no idea what it was (so much for my Space Geek Badge)

    http://en.wikipedia.org/wiki/Termination_shock

    <i>In astronomy, the termination shock is theorised to be a boundary marking one of the outer limits of the sun's influence. It is where the bubble of solar wind particles slows down to below supersonic speed and heats up due to collisions with the galactic interstellar medium. It is believed to be about 100 Astronomical Units from the Sun.

    The termination shock boundary fluctuates in its distance from the sun as a result of fluctuations in solar flare activity i.e. changes in the ejections of gas and dust from the sun.

    The Voyager I spacecraft is believed to have passed termination shock in December 2004.</i>
  • Voyager (Score:2, Informative)

    I have been intermittently following the voyager program with some interest. Much more detail is available at the NASA JPL website, including transcripts of communication efforts with the spacecraft, as well as info about the program and the spacecraft themselves. It's quite the interesting story, given that the program was never expected to continue as long as it has.
  • more info (Score:5, Informative)

    by Ichigo Kurosaki (886802) on Wednesday May 25, 2005 @01:34AM (#12631613)
    the bbc http://news.bbc.co.uk/1/hi/sci/tech/4576623.stm [bbc.co.uk] has some more info on this. You should know that they are not 100% it has crossed the termintation shock. "Some researchers thought the probe had arrived at the shock; others thought it still had some way to go. Now, at the 2005 Joint Assembly meeting organised by the American Geophysical Union, space scientists say they are confident - and agreed - that Voyager has gone beyond the termination shock and is flirting with deep space. Predicting the location of the termination shock was hard, the researchers say, because the precise conditions in interstellar space are unknown. Also, changes in the speed and pressure of the solar wind cause the termination shock to expand, contract and ripple. The most persuasive evidence that Voyager 1 has crossed the termination shock is its measurement of a sudden increase in the strength of the magnetic field carried by the solar wind, combined with an inferred decrease in its speed. This happens whenever the solar wind slows down."
    • So when it actually passes out of the solar system that meands that the interstellar winds will start slowing it down once its fuel runs out, and eventually will push it back into the solar system? The picture makes it look as if the interstellar wind blows orthogonally to the solar system at the direction voyager is exiting, which presumably means that once its fuel runs out then it will get blown back into the solar system and get stuck in the boundary somewhere.
      • I'm an idiot, ignore the previous post. I really need to stop posting at 3am.
      • Re:more info (Score:2, Informative)

        The Voyage wont accually be traped because it is primarily using inertia to propel it self. If you think back to Newtonian physics in order to stop the voyager you would either need a pulling or a pushing force that is greater then the force of the moving object. Since it has breached the termination shock the gravity from the solar system is not suffiecient to prevent it from leaving. And the solar winds do not present enough drag (D=Cd*A * .5 * r * V^2) on the frontal area of the craft to sufficently stop
        • Right, but according to the diagram there is wind in deep space also. Thus given long enough the probe should either come to a stop and start going backwards, or continue going forward while changing direction more and more.
          • Re:more info (Score:5, Informative)

            by khallow (566160) on Wednesday May 25, 2005 @06:13AM (#12632459)
            Right, but according to the diagram there is wind in deep space also. Thus given long enough the probe should either come to a stop and start going backwards, or continue going forward while changing direction more and more.

            Given enough time. Interstellar space is incredibly empty. The pressure of interstellar gas (outside of the somewhat more dense nebula) is on the order of 10^13 times [wikipedia.org] less than Earth's atmosphere and since most interstellar gas is hydrogen or helium (both which are significantly lighter than the main ingredients of Earth's atmosphere), the drag of this medium is incredibly small.

          • Re:more info (Score:3, Informative)

            by MindStalker (22827)
            Everything being equal wind from stars in all directions will equalise themselves and should provide zero force in any direction. And I believe the probe is above terminal velocity to leave the system.
  • Funny (Score:5, Funny)

    by ndansmith (582590) on Wednesday May 25, 2005 @01:38AM (#12631629)
    I am totally depressed by my inability to make a Star Trek: The Motion Picture joke.
  • by mjsottile77 (867906) on Wednesday May 25, 2005 @01:39AM (#12631632)
    Is anyone else frustrated when you hear wonderful science like this being done, yet see that probes like this are slated to have their funding cut (http://www.spacedaily.com/news/voyager1-05a.html [spacedaily.com]) ? For some reason, $4.2 million / year to operate them (ie, listen) seems unbelievably cheap for such a unique resource - not only are there only TWO probes out there (voyager 1 and 2), but to get others out to replace them would cost a whole ton more. ...In addition to having to wait another 20 or so years to get there.
    Science just doesn't work when politics gets involved... :(
    • by NathanBFH (558218) on Wednesday May 25, 2005 @02:06AM (#12631723)

      Science just doesn't work when politics gets involved... :(

      On the other hand, science like this would never be funded with out politics. There's only a limited amount of money out there to fund endevours like this, and someone has to decide how to divy that money up. So who gets the money? Well you have to create a policy to decide where appropriate funds.... and now you've entered the relm of politics. Whether it's decided by elected senators on the floor of Congress or by a tribunal of society's leading scientists: scarcity leads to a policy of allocation which leads to politics. Can't avoid it.

      • On the other hand, science like this would never be funded with out politics. There's only a limited amount of money out there to fund endevours like this, and someone has to decide how to divy that money up.

        Gee, someone has to decide how to spend my money? Who should that be? How about me? Seriously, it always astounds me when people make arguments about public funding that would reveal their absurdity if made about any other expenditure. "There's only a limited amount of money for breakfast cereal
        • The previous poster wasn't saying that it should all be publically funded. He was saying that if there is public funding, then there will be politics involved in handing out the money. He doesn't say exactly how much is involved, but he implicity acknowledges that public funding has a limit.

          The original poster complained that currently the US government wasn't spending the "small" sum of $4.2 million on the project. This is the guy that needs to have some help with explaining how to do this without publ
    • I agree with the sentiment, but remember that interstellar space is, almost by definition, the most boring place in the universe.
  • but doesn't Voyager do so as well? Is it subsonic by now too? It's rather impossible it had its engines on all the time (or even most of the time) or that it moved faster than Solar Wind at any time.
    Same laws of physics should apply I think?

    Another question, "solar sail" related - it seems it's the distance where any Solar Sail based starship would slow down to subsonic speeds - and it would stop by heliopause?
    • Except the solar wind slows down due to it 'running in to' interstellar particles. Larger objects are less affected by these subatomic particles, and can keep much more of their momentum.

      Likewise, a solar sail isn't like a nautical sail. Once the momentum has been imparted, you need to apply energy to SLOW it down. On a sailboat, when the wind stops, the friction with the water slows you down. In interstellar space, when you don't have any solar 'wind' to power you, you just keep going...

      I also have a
      • Likewise, a solar sail isn't like a nautical sail. Once the momentum has been imparted, you need to apply energy to SLOW it down. On a sailboat, when the wind stops, the friction with the water slows you down. In interstellar space, when you don't have any solar 'wind' to power you, you just keep going...
        except you need to discard the sail, or it would create the "friction" against particles that have already slowed down :)

        I wouldn't be so hostile towards "subsonic", it's about speed, not about sound itse
      • A gas floating around in space has a speed of sound associated with it, which is the speed a disturbance propagates through the gas (due to the gas molecules bumping into each other down the line). This is the same way a sound wave propagates through the atmosphere. The medium that the sound waves travel in is the gas itself.

        You get a shock wave when you have a bunch of matter traveling at supersonic speeds that then at some point slow to subsonic speeds. That is what is going on here.

    • the change in mag-flux is small, enough to slow down ionic particles, but not enough to seriously affect a massive and low-charge probe or ship. so kinda no.

      also, the heliopause and termination shock is a very small effect. its a big deal to the solar wind, but to any uncharged object bigger than a small rock its near unnoticable.
  • by astromog (866411) on Wednesday May 25, 2005 @01:47AM (#12631660)
    For those who want to know what a termination shock looks like: Clicky. [nasa.gov]
  • ..before it finds the machine planet, and begins the long journey home.
  • ... the termination shock boundary passed by Voyager 1? This would depend on the (decrease od) speed of the solar wind and thus (decreased) solar activity some time in the past.
  • This really makes me (Score:5, Interesting)

    by el_womble (779715) on Wednesday May 25, 2005 @02:55AM (#12631875) Homepage
    envious of Americans. We 'foriegners' give you guys A LOT of crap over wars, the environment, religion, guns etc (not that the British have a leg to stand on... we forget our history way too quickly), but the fact is that we don't have the balls to do anything like this anymore. Creating an object that can travel out of the Solar System is HUGE. It is an achievement that should stand out as a moment in history that we can be truely proud of: no-one got killed, you're not doing it for greed or wealth - its a pure scientific achievement.
    • by Strontium-90 (799337) on Wednesday May 25, 2005 @04:12AM (#12632116)
      On behalf of my fellow Americans, whether they like it or not, I'd just like to say thanks for your comment. Not that I had anything to do with Voyager or any other sattelites up there. In spite of some of the bad things we've done, I'm proud of my country (as I'm sure you are of yours), and I'm glad to see someone who doesn't judge all Americans based on a subset of our population.

      Just like all countries, we do good things and we do bad things. We have good politicians and we have bad politicians. We have good people and we have bad people. So, thanks again for your levelheadedness, in all seriousness, I really do appreciate it.
    • by alistair (31390) <alistair@hot[ ]p.com ['lda' in gap]> on Wednesday May 25, 2005 @04:34AM (#12632171)
      Fully agreed, it is nice to see someone articulate this so clearly on Slashdot. All countries contain a wide range of contradictory trends in their societies but the space program stands as a lasting achievment for all of mankind and one we have to thank the US for pouring so much of it's investment into.

      The nearest we have in Europe is the European Space Agency [esa.int]. Now celebrating thirty years this has run some major programs and developed some excellent lauchers. Although it has a European Branding, my impression is that almost half the funding and most of the political drive has come from France, with very little in the way of contribution from the UK. If you ever get the chance and find yourself in South West France, check out the excellent Cité de l'Espace [cite-espace.com] museum near Toulouse. This is easily Europe's finest space museum with a wide range of information on space exploration and the European Space Program, inclding two Skylabs to walk through and a full size Ariane 5 rocket which dominates the skyline as you approach.

  • --> What happens when you get caught browsing slashdot.
  • boundaries (Score:3, Interesting)

    by MarsDude (74832) on Wednesday May 25, 2005 @03:54AM (#12632070) Homepage
    From wikipedia : "In astronomy, the termination shock is theorised to be a boundary marking one of the outer limits of the sun's influence."

    How many outer limits does the sun have and what are they ?
  • Now that's space! (Score:3, Interesting)

    by master_p (608214) on Wednesday May 25, 2005 @04:38AM (#12632178)
    It is very irritating (for us geeks!) to say that humans have started space exploration. We have been raised on Star Trek and Star Wars...we can't accept having gone a few hundred kilometers up in the sky as "space". If we could take a trip to the place Voyager now is, then we can say that we have started exploring space. Until that day, we can't say anything. Here is an analogy with sea exploration: would we say that we have explored the Atlantic ocean, if the European explorers of the 15th century have just put their feet in a local lake? we wouldn't. Then how can we talk about "space age" and "space exploration"?
  • by justins (80659) on Wednesday May 25, 2005 @07:48AM (#12633001) Homepage Journal
    They don't really KNOW that that it crossed that TERMINATION SHOCK thingamajigger. The termination shock isn't mentioned EVEN ONCE in the bible, new OR old testament.

    OMG cut NASA's funding!
    • by Anonymous Coward on Wednesday May 25, 2005 @08:58AM (#12633681)
      They don't really KNOW that that it crossed that TERMINATION SHOCK thingamajigger. The termination shock isn't mentioned EVEN ONCE in the bible, new OR old testament.

      Ha, you don't have a very good translation do you?

      It says right here after, "Thou shalt not pop-off around the corner for a pint," that, "Thou shalt enjoy thine termination shock so long as thou art not seen to be smug about the business. Thine undergarments must be clean at the time of the shocking of the termination. Thusly, shalt the word of the Snazzites be proven unworthy of the jigsaw-mongerer. And all will be well in Geziphalohn."

      See? Plain as day.
  • I've always wondered how we get these pictures of the milky way. Anybody have a clue?
  • by schnitzi (243781) on Wednesday May 25, 2005 @06:54PM (#12640138) Homepage
    ...how many here still haven't gotten through the termination shock of Star Trek Voyager?

"'Tis true, 'tis pity, and pity 'tis 'tis true." -- Poloniouius, in Willie the Shake's _Hamlet, Prince of Darkness_

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