From the Edge

Ed Stone
by Ed Stone
Voyager Project Scientist

Winds of charged particles race outwards from the sun at 300,000 miles per hour. They are so faint that, here on the outer edge of the solar system, they would be undetectable if it were not for the very sensitive instruments carried by spacecraft.

From this distant, dark void, the sun is 100 times farther away than it is from Earth. Even so, our star is a million times brighter than Sirius, the brightest star seen from Earth. All around is a near-perfect vacuum, with only the most capable of instruments able to detect an ambient magnetic field that is 200,000 times weaker than the field back on Earth. To top off the loneliness factor, nothing from Earth has ever journeyed this far from home.

This remote zone is the domain now for Voyager 1 and 2.After 31 years of exploration, the twin spacecraft are the elder statesmen of space exploration, robotic envoys in the most distant reaches of our solar system. Voyager 1 is now 107 times farther from the sun than Earth is; Voyager 2 is 87 times farther. It takes about 15 hours for a signal leaving Earth to reach Voyager 1. (By contrast, it takes a little more than 20 minutes for a signal to go to Mars, even when the red planet is farthest from Earth.)

This artist’s rendering depicts NASAs Voyager 2 spacecraft as it studies the outer limits of the heliosphere - a magnetic ‘bubble’ around the solar system that is created by the solar wind.

The twin spacecraft do not rest on the laurels of their discoveries at Jupiter, Saturn, Uranus and Neptune - the planets they flew by between 1977 and 1989. In fact, their findings at our solar system’s edge are changing scientists’ theories about what happens “way out there” and how interstellar space affects our solar system.

The Voyagers have shown that the heliosphere - the sun’s protective bubble surrounding our solar system — is not smooth and symmetric, as was originally thought. The robotic team discovered that this bubble is being pushed in and deformed by the pressure from the interstellar magnetic field outside our solar system. Another surprise came when the spacecraft passed an important milestone near the edge of the solar system, called the termination shock. The energy released from the sudden slowing of the sun’s supersonic wind had an unexpected outcome - it was absorbed not by the wind itself, but by ionized atoms that had come from outside our solar system. And inevitably, as theories are shattered in the wind, more questions arise. There are cosmic rays we know come from this distant region, for example, but their origin is yet to be found and explained.

After all this time, Voyager’s discoveries continue to do what they have always done - take us to new places we have never been, and shed light on the how our solar system interacts and interconnects with the surrounding regions of the Milky Way.

Both Voyagers have enough power to run until 2025. Voyager 1 will probably cross into interstellar space by about 2015. At that moment, Voyager 1 will become Earth’s first interstellar spacecraft, leaving the sun behind as it enters the interstellar wind produced by the supernova explosions of other stars.

Until their final transmissions — hopefully many years in the future — the Voyagers still have a long way to go and lots to tell us.

    13 Responses to “From the Edge”

  1. Dave Lingard (England) Says:
    September 23rd, 2008 at 1:01 pm

    Voyager 1 & 2 continue to amaze me long may they continue and thanks for keeping us all updated Dr Stone

  2. Derek Says:
    September 23rd, 2008 at 9:03 pm

    This is a very nicely written article, but of course you probably wouldn’t care what my critique is on the verbiage of an article. But that’s irrelevant anyways. The main point of my reply to express my sincere longing for the feasible proposition of a new interstellar spacecraft. There have been several but none have come to fruition as far as I can tell. I think the reason for this is that there is little will and also not very interesting or feasible designs to begin with.

    I’d love to see a Kuiper-belt or beyond region observatory whose sole purpose is to study the dynamics of the solar system. Let’s put a one to two and a half meter observatory (or what about a James Webb Space Telescope, 6.5 meter clone) out to the an orbit maybe seventy or eighty AU from Sol. We could use visible, ultraviolet and infrared observations of our inner solar system. Wouldn’t it be nice to have a constant “family portrait’ like that from the Voyager 1 spacecraft?

    We could also have magnetometers and whatever other instruments to accompany the study of the solar wind and the outer solar system environment in general. Of course the only problem is the cost. Of course being able to maintain such a telescope would be virtually impossible and having it survive the long trip to the outer solar system and the several years of operation we’d require would be challenging. It would need far more redundant systems (extra gryoscopes, twice as many batteries as needed, extra transponders for communication, Ka-band, X-band, and heck even S-band). Anyways, such a mission is unlikely, but one can always wish.

  3. Frank Costello Says:
    September 27th, 2008 at 7:47 am

    Voyager 1 and 2 have been at ‘the edge’ of half my life as an amatuer astronomer so it is good to hear the latest about their progress. I do wonder though if in the early days you noticed anything like the anomalies reported by John D Anderson and others in their paper ‘Anomalous orbital-energy changes observed during spacecraft fly-bys of Earth’, Physical Review Letters, vol 100. Their findings when aplied to, say, the now much longer signal time from Earth to both Voyagers compared to the data from Galileo, Cassini, Rosetta or Messenger, could have a bearingon what Anderson refers to as ‘a pressing need to investigate such fly-by anomalies’. As current investigations appear to have stalled through lack of ideas may I suggest that, apart from passing on any relevant data you may have, you also point them towards a new model called Tempo Field Theory which promises many new lines for enquiry. Such is the way in which I would feel that I had done my small bit for science.

  4. Mike Green Says:
    September 29th, 2008 at 3:08 pm

    Great Article! There are plenty of us out here in internet land who have loyally followed the Voyagers since launch. We love these articles and we love the information on the Voyager website. Please keep it coming!

  5. Marion Williams Says:
    October 3rd, 2008 at 4:24 am

    All I can say is wow!! We really got it right with these two spacecraft. I enjoy coming to JPL’s web page for some quiet time and reflection. (I linked here from there)

  6. Ahmed Says:
    October 13th, 2008 at 11:06 am

    This is just amazing! All mankind should be proud of these of the Voyagers; the greatest voyagers in history.

    Also, working until 2025 is good. There’s still plenty of time for the spacecrafts to continue to amaze.

  7. Paul Filmer Says:
    October 23rd, 2008 at 12:48 pm

    I have followed the science from V1 & 2 since the first planetary encounters, and now enjoy the VIM phase. However, I am also interested in the engineering data, and have been disappointed by the lack of updates on the Mission Operations Status Reports pages - the last one dates from May 30. Has this suffered a budget cut?

  8. Dewey Chapman Says:
    December 11th, 2008 at 9:31 pm

    Where is the center of our universe ? Iwas told a few years ago by some om some person @ JPL >that there was no center as all galaxies were traveling away from each other.. This was before blogs , and I thought the person was full of IT .Since this was e-mail ,and I thought the answer wrong I left it ne til’ now .

    There are galaxies that have already collided and shredded each other to reform .
    as time goes on .

    Andromeda our nearset galaxy will collide with us soon , soon being to consider the life of our universe .

    Sinse cosmologists and others can’t agree on the # of dimensions or how many strings it takes to make a dimension , I don’t know to whom I should apply blame for complicating things so badly ,

    Happy Holidays,./.,./.,,../Dewey Chapman

  9. watch Green Zone online Says:
    March 9th, 2010 at 3:57 pm

    seriously, this blog is nice . I think im gonna stick around and read a few of your posts. Yours sincerely

  10. john Says:
    June 8th, 2010 at 3:10 pm

    Where can I find more info on this post? Perfect Just what I was looking for.

    JPL Media Relations responds:

    You can find more information on the heliosphere, here:

    For recent updates on the Voyager mission, visit:

  11. javier hume Says:
    July 24th, 2010 at 11:48 pm

    Allowing Raptor four winged jets: 2 Sided magnet wings that are magnetically pushed away from each other one smaller wing on each side and one larger wing just below smaller wing and magnetically pushing against each other to lesson vibration. For higher speeds performance from magnetic wing barrier.

  12. J.Madson Says:
    March 22nd, 2011 at 3:00 pm

    Howdy….Hello…..I am pleased to say hello to Professor Stone in my lifetime. Thank You for the wonderful work you have done, and are continuing.

  13. J.Madson Says:
    March 22nd, 2011 at 3:21 pm

    One day humanity will have a new style of spacecraft. It will be based upon Newtons’ apple and Einsteins’ mass. The apple will fall off of the earth to another place, being attracted to that place. It is pro gravity, not anti. It will travel very fast.

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