Voyager 1 Riding on a Magnetic Highway Out of the Solar System

Artist concept of NASA’s Voyager 1 spacecraft exploring a new region in our solar system called the “magnetic highway.” Credit: NASA/JPL-Caltech

The Voyager 1 spacecraft has not left the solar system, as was speculated earlier this year, but has now entered a new region at the edge of the solar system that scientists didn’t even know was there. It appears to be a “highway” of magnetic particles, shepherding Voyager 1 out into interstellar space.

“When you’ve gone where nothing has gone before, you expect to make new discoveries,” said Arik Posner, Voyager Program Scientist at a press briefing today.

“This is really another exciting step in the Voyager journey of exploration,” said Project Scientist Ed Stone. “Voyager’s discovered a new region of the heliosphere that we had not realized was there. It’s a magnetic highway where the magnetic field of the Sun is connected to the outside. So it’s like a highway, letting particles in and out.”

This artist’s concept shows plasma flows around NASA’s Voyager 1 spacecraft as it approaches interstellar space. Image credit: NASA/JPL-Caltech/JHUAPL

The heliosphere is a huge bubble of charged particles, and previously the Sun’s lower-energy charged particles have dominated. Now, Voyager 1 is in a region where it is surrounded almost entirely from cosmic rays from outside our solar system,as the lower-energy particles appear to be zooming out and higher-energy particles from outside are streaming in.

The first indication that something new was happening was on July 28 of this year when the level of lower-energy particles originating from inside our Solar System dropped by half. However, in three days, the levels had recovered to near their previous levels. But then the bottom dropped out at the end of August.

The two Voyager spacecraft have been heading outward since their launches 16 days apart in 1977. Voyager 1 is now near the edge of the solar system, and Voyager 2 is not far behind. Scientists feel this new region at the far reaches of our solar system is the final area the spacecraft has to cross before reaching interstellar space.

The Voyager team infers this region is still inside our solar bubble because the direction of the magnetic field lines has not changed. The direction of these magnetic field lines is predicted to change when Voyager breaks through to interstellar space.

“We believe this is the last leg of our journey to interstellar space,” Stone said. “Our best guess is it’s likely just a few months to a couple years away. The new region isn’t what we expected, but we’ve come to expect the unexpected from Voyager.”

Since December 2004, when Voyager 1 crossed a point in space called the termination shock, the spacecraft has been exploring the heliosphere’s outer layer, called the heliosheath. In this region, the stream of charged particles from the Sun, known as the solar wind, abruptly slowed down from supersonic speeds and became turbulent. Voyager 1’s environment was consistent for about five and a half years. The spacecraft then detected that the outward speed of the solar wind slowed to zero.

The intensity of the magnetic field also began to increase at that time.

“If we had only looked at the particle data alone, we would have said well, we’re out, goodbye solar system,” said Stamatios Krimigis, principal investigator for Voyager’s low-energy charged particle instrument. “We need to look at what all the instruments are telling us, because nature is very imaginative, and Lucy pulled out the football again.”

That’s because the magnetic field direction has not yet changed to the expected north-south orientation of interstellar space.

“We’re quite confident that there’s really no reason to believe we’re outside the heliosphere,” said Leonard Burlaga, with the Voyager magnetometer team. “There’s no evidence that we have entered the interstellar magnetic field. We are in a magnetic region unlike any we’ve been in before — about 10 times more intense than before the termination shock. The magnetic field data turned out to be the key to pinpointing when we crossed the termination shock. And we expect these data will tell us when we first reach interstellar space.”

As for the future of the spacecraft, which are powered by plutonium 238, they each lose about 4 watts of power a year and by 2020, the science team will have to start turning off instruments in order to conserve power. By 2025, there will probably not be enough power for any of the instruments to run, but there will be enough power to “ping” the spacecraft and have it answer. But by that time, they should be well out of the solar system. However, the spacecraft likely won’t encounter much, as it would take about 40,000 years for one of the Voyagers to reach another star system.

Voyager 1 is the most distant human-made object, about 18 billion kilometers (11 billion miles) away from the Sun. The signal from Voyager 1 takes approximately 17 hours to travel to Earth. Voyager 2, the longest continuously operated spacecraft, is about 15 billion kilometers (9 billion miles) away from our Sun. While Voyager 2 has seen changes similar to those seen by Voyager 1, the changes are much more gradual. Scientists do not think Voyager 2 has reached the magnetic highway.

Sources: Press briefing, JPL

25 Replies to “Voyager 1 Riding on a Magnetic Highway Out of the Solar System”

  1. Sad to think that after 2025, we won’t be able to “see” through their eyes anymore. Yet amazing that our modest technology of ’77 is still telling us wonderful things today. Go V’ger!

  2. That thing is built like a brickhouse, I think I’ve had eleven cars since 1977. How much mil-spec equipment from that era can still be used? Freakish.

  3. Voyager rocks! Hoping we still get its ping long after I’m retired, just so we know it hasn’t been assimilated by the Borg…

  4. Fitting, that the the spectacularly successful Voyager saga of man’s early off-World explorations, through the frontier of outer-world Giants (having beamed back exciting progress reports that struck humanity with awe and wonder), should end their epic journeys in the majestic realm of Interstellar Space. From hailing distance of last farewells to Earth-port of launching, mankind’s Home-world Sun will then be lost amid the radiant glory of surrounding Constellations.

    Ah, what a view from their decks looking astern, as they travel the cosmic winds off into the unknown: a once vast sprawling world community of familiar landscapes, now light hours away. One of several points of light on horizon plane, huge of Life-import, lost in the distant cold-light of its beneficent Star.

    On “final leg”, they will fall silent, passed away into Galactic darkness. But as nuclear power fades, their soaring legacy will live on as beckon of the human spirit, and inspiration of its creative will to explore and discover, to learn and understand.

  5. As I stated before, “the edge of the Solar System” depends on the definition.
    To my definition, the edge of the Solar System starts at the end of the Oort Region. This means, we (may be some others) need to wait for some time for Voyagers to reach there…
    It is obvious that the signals will be weak (or stopped) enough to detect them before even nearing to inner edge of the Oort…
    “The Magnetic Highway” may be new discovery; but, the “Gravitational Highway” is not; isn’t it !
    Thanks to Voyager Team, anyway…

    1. The problem with the ‘gravitational highway’ is… where would you define the end-point of the sun’s gravitational influence?

      Arguably, even the Oort Cloud isn’t the furthest extent of the Sun’s gravitational reach, as the entire galaxy is entwined in a gravity-governed dance.

      At least the Sun’s particle-based emissions offer more clarity – providing the heliosphere doesn’t flux quite so dramatically as Earth’s magnetosphere!

      1. If we’re being pedantic (like me) every atom in the universe is being pulled by every other atom in the universe, right?. But still it is expanding, which is what I can’t understand!

      2. Nowt wrong with being pedantic – just so long as your atoms continue heading away from mine 😉

      3. Thanks for your comment..Personally; my Solar System extends to Oort region. Gravitational influence baundry seems more acceptable to me… Yuksel

        Subject: [universetoday] Re: Voyager 1 Riding on a Magnetic Highway Out of the Solar System

      4. No problem – I’m not asking you to abandon any beliefs 😉

        From a practical viewpoint though, the Voyager probes are not equipped to (at least directly) measure the sun’s declining gravitation field / influence, so electro-magnetic particles and fields are all the data we have to work with from the long running Voyager experiment.

        Whichever viewpoint you have of the solar system’s boundary, this is still really fascinating science and sadly something we may not see repeated (e.g. for more detailed study with a wider range of detectors) within the life-times of most readers here.

    1. If you run water in an empty sink you see the water form of sort of zone of flow that ends where the water is starting to accumulate. In a nutshell that boundary region is what the Voyagers are passing through. Of course this boundary region is much more complicated than the water flow analogue. However, at that boundary region the solar magnetic field accumulates and ceases to occur further out. Charged particles coming from the rest of the universe, cosmic rays, are deflected by the Lorentz force of the solar magnetic field. What is being measured is a change in the flux of these charged particles as voyager passes through this region.

      The Voyager spacecraft are really old (old in a digital sense) technology. Interestingly it means they are rather hard against such radiation. Those old transistors and early integrated circuits are a lot more robust against radiation than modern electronics.


      1. There are a lot of tricks to harden modern electronics, from special processes and constructions to picking the high quality grades. (Well testing ICs correlates to long lifetime and robust operation, due to the statistical nature of its production processes.)

        But you can also install Faraday cages (against EM) with ion particle or ionization radiation stoppage power. IIRC the Jupiter crafts use thick titanium plates.

        So relatively easy but costly in terms of demanding heavier launchers and/or more gravity assists so longer mission times.

        If you one day need _really_ hardened electronics, you could try to use micromechanic methods to sculpt miniature vacuum tubes. Then you need radiation flows that creates potentials and currents that overwhelms the ionizing voltages or working currents, or do mesoscale mechanical damage! You see the proposals repeated constantly, but it is always too costly.

  6. “The first indication that something new was happening was on July 28 of
    this year when the level of lower-energy particles originating from
    inside our Solar System dropped by half. However, in three days, the
    levels had recovered to near their previous levels. But then the bottom
    dropped out at the end of August.”

    My assumption is that the “bubble” of the edge of the solar system is not static but undulates. Voyager probably passed it, then it overtook Voyager, then Voyager got out of its reach.

    1. Lucille “Lucy” van Pelt is a fictional character in the syndicated comic strip Peanuts, written and drawn by Charles Schulz. …

      Lucy is a crabby and cynical eight-year-old girl, and often bullies the other characters in the strip, particularly Linus and Charlie Brown. …

      Perhaps Lucy’s most famous gimmick in her long existence as a character is the one in which she pulls the football away from Charlie Brown right as he is about to kick it.

  7. hey im a follower of universe today many years now, i enjoy the comments debates and ideas theories to bounce our thoughts off each others i never registered as rarely do i have time with work family etc am currently injured but voyager gives me such hope! its fascinating its so far out and kudos to nasa and any involved in launching it what a success it has been and yet it still flies on!

  8. one problem with astronomy / cosmology ive had over years is what is actualy scientific based knowledge of what we do actualy know with evidence. i read all my older brothers space books from 70s 80s but was horrified disapointed to years later findout alot of the information was speculative and not proven yet or worse weak theories ! what is the truth so far on voyager etc?

  9. How auspicious that the crafts will last about as long as is needed to say farewell to the system, on their star trek!

    “Magnetic highway” may be an ill chosen term if not the particles like the gravity highways of interplanetary travel easily go distances. Loosely these flows are more akin to jet streams at the boundary of the troposphere.

  10. Here’s hoping Voyagers 1 & 2 continue to function long beyond the heliopause and reveal yet more surprises about space weather, way out there… where I guess you could say, “the sun don’t shine (very much)!”

    On second thoughts, that makes it sound like a trip across the UK !!!

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