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Voyager 2 enters interstellar space

The Voyager 2 spacecraft, launched in 1977, has entered interstellar space, becoming the second human spacecraft to achieve this.

Comparing data from different instruments aboard the trailblazing spacecraft, mission scientists determined the probe crossed the outer edge of the heliosphere on Nov. 5. This boundary, called the heliopause, is where the tenuous, hot solar wind meets the cold, dense interstellar medium. Its twin, Voyager 1, crossed this boundary in 2012, but Voyager 2 carries a working instrument that will provide first-of-its-kind observations of the nature of this gateway into interstellar space.

Voyager 2 now is slightly more than 11 billion miles (18 billion kilometers) from Earth. Mission operators still can communicate with Voyager 2 as it enters this new phase of its journey, but information – moving at the speed of light – takes about 16.5 hours to travel from the spacecraft to Earth. By comparison, light traveling from the Sun takes about eight minutes to reach Earth.

When I first wrote about these spacecraft in the 1990s, it was thought that Voyager 2 would probably not exit the solar system until the 2020s, meaning that its nuclear power source might die before that happened. That it has happened now, so much earlier, helps map the size of the heliosphere as well as the pressure that might be placed upon it by the interstellar medium

Genesis cover

On Christmas Eve 1968 three Americans became the first humans to visit another world. What they did to celebrate was unexpected and profound, and will be remembered throughout all human history. Genesis: the Story of Apollo 8, Robert Zimmerman's classic history of humanity's first journey to another world, tells that story, and it is now available as both an ebook and an audiobook, both with a foreword by Valerie Anders and a new introduction by Robert Zimmerman.

The ebook is available everywhere for $5.99 (before discount) at amazon, or direct from my ebook publisher, ebookit. If you buy it from ebookit you don't support the big tech companies and the author gets a bigger cut much sooner.

The audiobook is also available at all these vendors, and is also free with a 30-day trial membership to Audible.

"Not simply about one mission, [Genesis] is also the history of America's quest for the moon... Zimmerman has done a masterful job of tying disparate events together into a solid account of one of America's greatest human triumphs."--San Antonio Express-News


  • Col Beausabre

    By my back of the envelope calculation, Voyager 2 will take another 19 years to reach 1 light-day from Earth. It would be so cool for it to be still transmitting – but I guess Bob’s going to tell me that a sixty year life for the power source is nothing but a dream. Sigh. I wonder if >I’ll < still be operating – I'd be 87 (and jeeze, it was launched when I was a 25 year old 1LT at Ft Lewis…talk about in a previous lifetime !)

    "Space is big….No, BIG…. REALLY, REALLY BIG"

  • wayne

    “MHW-RTG: Multihundred-Watt radioisotope thermoelectric generators.”

    Each RTG had a total weight of 37.7 kg including about 4.5 kg of Pu-238. It uses 24 pressed plutonium-238 oxide spheres and provides enough heat to generate approximately 157 watts of electrical power initially – halving every 87.7 years. Each Voyager spacecraft has 3 RTGs. Collectively, the RTGs supplied each Voyager spacecraft with 470 watts at launch.”

  • Chris

    – is the “REALLY REALLY BIG” in a Trump voice over?

    – the data at your finger tips never ceases to amaze

    The article has a graphic showing the exit points of Voyager 1&2 in general terms being toward the “thinner” part of our heliosphere. In the text they describe a “constant interstellar wind flowing from beyond”. There is a Hubble picture of a young star and it’s “bow wave” in its own interstellar wind.
    This “wind” is intriguing.
    I wonder on the source from “beyond”, the flow and flux of this wind. How would projects such as the (1000?) cube sat mission to the Alpha experience them?

    Space is (Trump voice over) REALLY REALLY BIG!

  • wayne

    I’m just a primate with a keyboard, but thanks! (It could all be double-plus ungood information.)

    So– who knows enough math to figure out how much power is being (theoretically) generated, if we assume 157 watts per RTG, with an 87.7 year 1/2 life?
    Q: What’s the minimum electric required, to keep the radio going?

    Referencing Space:
    Not only is it YUGE….

    “It is very cold, in space…..”
    Khan Noonien Singh

  • m d mill

    FYI… are you aware of the 2017 documentary “The Farthest: Voyager in space”
    available on netflix and youtube.

    An inspiring account of the interplanetary exploration at its amazing best.
    It reminded me of the incredible scientific and technical accomplishment (1971-77) of a nation that was then the greatest in the history of the world.

  • wayne

    Swan Tour dot com:
    Yeah, right, sure you did.

    “More adventures in replying to spam”
    James Veitch

  • Col Beausabre

    “Space is big. Really 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, but that’s just peanuts to space.” Douglas Adams, The Hitchhiker’s Guide to the Galaxy

  • All: Please do not post comment replies to any spam that gets through. Such replies will generate more spam. As soon as I see the spam I mark it as such and it vanishes forever. Just be patient

  • Alex Andrite

    IT is “Really Really Big”.
    This, as so many posts by our Host, is Amazing. Thank you Mr. Z.

    I rather prefer to acknowledge the ‘Bigness’ as a Mystery for us to struggle with, to enjoy, to savor, to marvel at, yes, to explore, which actually is only one of so many other mysteries right here in our very midst.
    “Good Night Moon”.

    “Look to the Heavens …..”

  • wayne

    Pink Floyd

    “All that you touch , all that you see,
    All that you taste, all you feel.
    All that you love, all that you hate,
    All you distrust, all you save.
    All that you give, all that you deal,
    All that you buy, beg, borrow, or steal.
    All you create, all you destroy,
    All that you do, all that you say.
    All that you eat, and everyone you meet,
    All that you slight, and everyone you fight.
    All that is now, all that is gone,
    All that’s to come.
    And everything under the sun is in tune,
    But the sun is eclipsed, by the Moon.”

  • pzatchok

    We have not even flown there yet and we are already leaving garbage out there.

    By gosh we need a new space program to go out and collect those things.

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