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Basically, what the title asks. To my understanding, New Horizons is currently the fastest spacecraft that's moving away from the Sun, with arguably only Helios-A and Helios-B possibly faster still, but in an elliptical orbit around the Sun, so they won't make it out of the heliosphere.

So I'm curious, when will New Horizons traverse larger distance from the Sun than the Voyager 1 will in that time, and at approximately what distance?

I'm not entirely sure this can yet be calculated with any precision, since we don't know which Kuiper belt object will be selected for New Horizons visit after its Pluto flyby (or do we?), so feel free to make broad assumptions in your calculations.

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up vote 35 down vote accepted

New Horizons will never overtake Voyager 1.

Although New Horizons is currently faster than any other man-made object, it won't be by the time it reaches the outer corners of the solar system.

From the John Hopkins University/Applied Physics Laboratory New Horizons page:

Though New Horizons will also reach 100 AU, it will never pass Voyager 1, because Voyager was boosted by multiple gravity assists that make its speed faster than New Horizons will travel. Voyager 1 is escaping the solar system at 17 kilometers per second. When New Horizons reaches that same distance 32 years from now, propelled by a single planetary swingby, it will be moving about 13 kilometers per second.

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So New Horizons doesn't get any speed boost from slingshooting past Pluto? Or is the plan to even reduce relative velocity to assume orbit in the Kuiper belt? –  TildalWave Jan 28 at 11:54
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Pluto is gravitationally tiny and won't have any significant influence on New Horizons' orbit. Perhaps a tiny correction but I wouldn't think so. New Horizons won't go into orbit anywhere. I don't know if they plan to use any fuel to slow down at all (but I could look it up). I wouldn't think so. –  gerrit Jan 28 at 12:09
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Here's a nice graph of Voyager 2's speed, and the difference made by the gravitational assists:
Voyager speed graph
You can see that the probe slowed down between assists. New Horizons would follow a similar graph, but with fewer assists its speed will end up below Voyager 2's, as @gerrit said.

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Thanks, yes, I understand that there's gravitational influence on the probes even at those distances, of course, but I didn't find any directly comparable data on their velocities at more or less same distances without any gravitational assist maneuvers later changing it. Actually, I still can't find it to directly compare New Horizons and Voyager 1. There is data for Voyager 1 and 2 though, of which Voyager 1 was/is faster than what the graph for Voyager 2 from Wikipedia that you're attaching is showing. –  TildalWave Jan 28 at 13:17
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The delta-V from the Sun's influence is the same for any probe (and proportional to $1/r^2$) , so you'd only need to know the probe's initial speed, and the delta-V gain from planetary gravitational assists to calculate the current speed of various probes. –  Hobbes Jan 28 at 14:13
    
Well, their velocity past any gravity assist slingshots, since they didn't follow same trajectory, yes. And that's what I couldn't find. I found velocities for Voyager 1 & 2 on the same date, from which I could calculate their velocities relative to the Sun at any distance to it once they're out of region of significant gravitational perturbations of the gas giants, but I just didn't find any such numbers for New Horizons. But I'll take those calculations from M. Buckley on New Horizons page. Thanks to both. :) –  TildalWave Jan 28 at 14:34
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It's interesting that the Neptune fly-by resulted in gravity braking - not an assist. –  EtherDragon Jan 28 at 22:48
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To get a Triton flyby, a high-priority science objective, Voyager 2 had to go over the North pole of Neptune. That resulted in a net reduction in heliocentric energy. –  Mark Adler Mar 25 at 1:22
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