Voyager 1 Breaking Through the Borders of the Solar System

After almost 35 years traveling at over 35,000 mph, the venerable (and still operational!) Voyager 1 spacecraft is truly breaking through to the other side, crossing the outermost boundaries of our solar system into interstellar space — over 11 billion miles from home.

Data received from Voyager 1 — a trip that currently takes the information 16 hours and 38 minutes to make — reveal steadily increasing levels of cosmic radiation, indicating that the spacecraft is leaving the relatively protected bubble of the Sun’s influence and venturing into the wild and wooly space beyond.

From the JPL press release:

“The laws of physics say that someday Voyager will become the first human-made object to enter interstellar space, but we still do not know exactly when that someday will be,” said Ed Stone, Voyager project scientist at the California Institute of Technology in Pasadena. “The latest data indicate that we are clearly in a new region where things are changing more quickly. It is very exciting. We are approaching the solar system’s frontier.”

The data making the 16-hour-38 minute, 11.1-billion-mile (17.8-billion-kilometer), journey from Voyager 1 to antennas of NASA’s Deep Space Network on Earth detail the number of charged particles measured by the two High Energy telescopes aboard the 34-year-old spacecraft. These energetic particles were generated when stars in our cosmic neighborhood went supernova.

“From January 2009 to January 2012, there had been a gradual increase of about 25 percent in the amount of galactic cosmic rays Voyager was encountering,” said Stone. “More recently, we have seen very rapid escalation in that part of the energy spectrum. Beginning on May 7, the cosmic ray hits have increased five percent in a week and nine percent in a month.”

This marked increase is one of a triad of data sets which need to make significant swings of the needle to indicate a new era in space exploration. The second important measure from the spacecraft’s two telescopes is the intensity of energetic particles generated inside the heliosphere, the bubble of charged particles the sun blows around itself. While there has been a slow decline in the measurements of these energetic particles, they have not dropped off precipitously, which could be expected when Voyager breaks through the solar boundary.

“When the Voyagers launched in 1977, the space age was all of 20 years old. Many of us on the team dreamed of reaching interstellar space, but we really had no way of knowing how long a journey it would be — or if these two vehicles that we invested so much time and energy in would operate long enough to reach it.”

– Ed Stone, Voyager project scientist, Caltech

Read more on the JPL site here.

Addition: Check out the accompanying video from Science@NASA below:

Top image: Artist’s concept showing NASA’s two Voyager spacecraft exploring a turbulent region of space known as the heliosheath, the outer shell of the bubble of charged particles around our sun. Credit: NASA/JPL-Caltech. Secondary image: Artist’s concept of NASA’s Voyager spacecraft. Credit: NASA/JPL-Caltech.


26 Replies to “Voyager 1 Breaking Through the Borders of the Solar System”

  1. I have little experience in physics, but I got to thinking…. big trouble, that will lead to the following stupid question. Is Voyager traveling away from our sun in the same direction the sun is traveling in its orbit around the center of the Milky Way? I looked up that the sun’s orbit of travel is at 486,000 MPH and if Voyager was traveling in the same direction at only 35,000 MPH wouldnt we pass it up as it traveled in space? And if we are like inside a ballon that travels around the center of the Milky Way, then would Voyager bounce back inside the balloon when it breached the outer layer?

    1. The number 35.000mph is meant relative to the sun’s motion. So, no, we won’t catch up.

      Secondly, we are inside a “bubble” but not inside something like a balloon. There is no solid wall defining the solar system. The boundary is defined as the distance from the sun, where the solar wind (particles emitted by the sun) are slowed down significantly, because they collide with energetic particles from outside the solar system.

    2. To take Dr Flimmer’s statements one step further, motion is not relative to space. Motion is always relative to other objects. There is nothing in space that is some absolute fixed point, and one can set up the origin of a coordinate system anywhere going at any speed less than the speed of light.

  2. Fly, little bird, fly.

    It is a disparate set of scales. If effectively interplanetary space is one lightday out, while the Oort cloud of cometary satellites may stretch halfway to the next star or ~ 2 lightyears out, we have gravitationally influenced satellites ~ 500 times as far out as the EM sphere of influence.

    Illustrating that magnetism, being a dipole field, goes as r^-3, while monopole gravity goes as r^-2. Or in other words, however charged you are, gravity gets you in the end.

    1. Well at least Dr. Sagan is traveling on the “Golden Disc” on board Voyager.

  3. I wonder if the illustration is accurate regarding the idea that our solar system has a bow shock. If there is a bow shock it means that the solar system is orbiting galaxy at some speed which is relatively higher than the rest of the surrounding gas. But should not the gas also orbit the galaxy at approximately the same speed? Also if the solar system is really traveling at a speed higher than the surrounding environment, should not that impart a small but persistent drag on the solar system causing it to reduce the orbiting speed and fall towards the center of the galaxy?

    1. The bow-shock indeed implies a drag.
      However, the drag is many-many-many orders of magnitude to small to cause any important difference on the solarsystem over the duration of the universe to date.

    2. Magnus is right that there is no real breaking effect of our flight through the surrounding medium. The densities are just way too low (we are talking here of only a few particles per ccm, compared to 10^23 particles per ccm in our atmosphere!).
      However, even the bow shock has been called into question recently, after some new results from the IBEX mission. It seems that there is no bow shock at all, so our move through the interstellar medium is even gentler than normally assumed.

      1. I did some calculations and if we assume that we have a constant speed of ~90000km/h through the interstellar medium, the density of it is ~10^-24 g/cm3, the weight of solar system ~2*10^30kg then we would need “only” 486 trillion years to come to a full stop due to a drag imparted by the interstellar medium. No risk of that happening soon 🙂

    3. As indicated by Dr Flimmer and as you indicated below the medium out there is very close to being a vacuum. The Voyager spacecrafts have a detector on board which measures the energy of incident particles of gas in the very thin medium of only a few atoms or ions per cubic centimeter.. What has happened is the energy and flux of these particles has changed in a way commensurate with a model of a heliosphere. So this is consistent with saying the spacecraft has in the way of Elvis “left the building.”

    4. Now you got me thinking – what if some very unprobable initial conditions would result in a star system orbiting galaxy core in highly elliptical orbit. Would we see a bow shock in the direction of its motion in periapsis as it falls towards the galaxy core and then, few million years later, bow shock in the other direction as it would move slower than the rest of galaxy in its apoapsis?

  4. The illustration shows our heliosphere as having a tail. But if we are subjected to interstellar radiation should that not be pushing on our heliosphere equally in all directions ? Hence “sphere”

    1. No, because we move relative to the surrounding interstellar medium. It might be less pronounced than implied in the drawing, but at least a slight elongation should be there.

    2. THere is more radiation coming from the direction of the centre of the galaxy. Therefore our tail will point outward as opposed to the direction from which we came around our galactic orbit.

  5. Break free little one oh tiny mote, oh infinitesimal spark of energy drifting on solar winds travel now the trackless voids, ride the unseen currents through cold chasms of space … break free, and see,.. forever

  6. This is one of the best, ongoing astronomy stories of all time!
    My regret is that we haven’t been sending out similar probes to the Voyageurs at regular intervals, in all different directions to get a better sense of the nature of our heliosphere. We are currently trying to learn so much from so little data. I would love it if our solar system were flush with these little spacecrafts. We would learn so much.

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