Recalculating the distance to interstellar space

Jun 15, 2011 by Jia-Rui C. Cook
This artist's concept shows 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. After more than 33 years of travel, the two Voyager spacecraft will soon reach interstellar space, which is the space between stars. Image Credit: NASA/JPL-Caltech

(PhysOrg.com) -- Scientists analyzing recent data from NASA's Voyager and Cassini spacecraft have calculated that Voyager 1 could cross over into the frontier of interstellar space at any time and much earlier than previously thought. The findings are detailed in this week's issue of the journal Nature.

Data from Voyager's low-energy charged particle instrument, first reported in December 2010, have indicated that the outward speed of the charged particles streaming from the sun has slowed to zero. The stagnation of this solar wind has continued through at least February 2011, marking a thick, previously unpredicted "" at the edge of our solar system.

"There is one time we are going to cross that frontier, and this is the first sign it is upon us," said Tom Krimigis, prinicipal investigator for Voyager's low-energy charged particle instrument and Cassini's instrument, based at the Johns Hopkins University Applied Physics Laboratory in Laurel, Md.

Krimigis and colleagues combined the new Voyager data with previously unpublished measurements from the ion and neutral camera on Cassini's magnetospheric imaging instrument. The Cassini instrument collects data on streaming into our solar system from the outside.

The analysis indicates that the boundary between interstellar space and the bubble of charged particles the sun blows around itself is likely between 10 and 14 billion miles (16 to 23 kilometers) from the sun, with a best estimate of approximately 11 billion miles (18 billion kilometers). Since Voyager 1 is already nearly 11 billion miles (18 billion kilometers) out, it could cross into at any time.

"These calculations show we're getting close, but how close? That's what we don't know, but Voyager 1 speeds outward a billion miles every three years, so we may not have long to wait," said Ed Stone, Voyager project scientist, based at the California Institute of Technology in Pasadena.

Scientists intend to keep analyzing the Voyager 1 data, looking for confirmation. They will also be studying the Voyager 2 data, but Voyager 2 is not as close to the edge of the solar system as . Voyager 2 is about 9 billion miles (14 billion kilometers) away from the sun.

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stndspec
5 / 5 (8) Jun 15, 2011
it's one thing to get radio signals past that threshold, but to really have a physical device of human making traveling beyond our native system is just... neat!
OdieNewton
5 / 5 (2) Jun 15, 2011
This is what NASA was created to do. We're finally taking a good look at something that we've only ever been able to hypothesize about. And usually we find out we were at least half way wrong.
Wulfgar
5 / 5 (9) Jun 15, 2011
Soon the Voyagers will smash into the solid walls of our holographic prison, and this farce will end!! Ha ha ha!!!

Spielberg, call me...

abhishekbt
5 / 5 (1) Jun 16, 2011
@stndspec: Right said. It
abhishekbt
5 / 5 (2) Jun 16, 2011
@stndspec: Rightly said. And considering that this was planned and designed with the technology in 1977, we should be really proud! I seriously doubt another man made object will cross the boundaries of the Solar System at least in our life time.
SCVGoodToGo
5 / 5 (3) Jun 16, 2011
@abhish; I don't know how old you are, but New Horizons should achieve Voyager 1's current position by 2038.
Inco
5 / 5 (2) Jun 16, 2011
"is likely between 10 and 14 billion miles (16 to 23 kilometers) from the sun"
I think they lack a few zeros in the kilometers translation.
Peteri
5 / 5 (1) Jun 16, 2011
This begs the question: Was it by good fortune, or instead by good planning on NASA's part, that both Voyager's post-planetary encounter trajectories took them in the direction of the closest portions of the heliopause and bowshock? I suspect good planning, but does anyone actually know if this is the case?
eachus
not rated yet Jun 16, 2011
This begs the question: Was it by good fortune, or instead by good planning on NASA's part, that both Voyager's post-planetary encounter trajectories took them in the direction of the closest portions of the heliopause and bowshock? I suspect good planning, but does anyone actually know if this is the case?


Good luck. The "Grand Tour" path that visited all the large outer planets occurs about every 168 years (a bit longer than Neptune takes for one rotation around the sun). So even if the Voyager missions had waited for the next launch window in the 22nd century, they would leave the solar system in about the same direction.

GSwift7
5 / 5 (1) Jun 16, 2011
I suspect good planning, but does anyone actually know if this is the case?


The "Grand Tour" path that visited all the large outer planets occurs about every 168 years (a bit longer than Neptune takes for one rotation around the sun).


Voyager 1 only visited Jupiter and Saturn. Voyager 2 also went near Uranus and Neptune. Here's a graphic from wiki:

http://en.wikiped...Path.jpg

This also:

even the faster (at launch) New Horizons probe will not pass it, since the final speed of New Horizons (after maneuvering within the solar system) will be less than the current speed of Voyager 1.


So new horizons will never pass V1. Either they both eventually smash into the 'celestial sphere' or voyager remains the farthest manmade object forever. It would take a radically different engine to surpass it at this point.
xavier78
5 / 5 (2) Jun 17, 2011
So new horizons will never pass V1. Either they both eventually smash into the 'celestial sphere' or voyager remains the farthest manmade object forever. It would take a radically different engine to surpass it at this point.


Forever? The exact same engine, made .001% more efficient, and launched a thousand years from now, would surpass it.
OdieNewton
not rated yet Jun 19, 2011
I agree, I mean thinking on the astronomical scale it seems like the newer object would have a reasonably large amount of time to catch up... i.e. forever...
GSwift7
not rated yet Jun 21, 2011
Yeah, I meant in relation to what we have already in the pipe. Of course there will be future missions designed specifically to go beyond our solar system. However, it is possible that even on a very long time scale, we will not send an object on a free trajectory into the void. If we design a probe specifically to visit the Centauri system, for example, then that probe would reach Centauri and stop there. Is there a reason we would want to just send something out into nowhere again? Voyager 1 is really hauling ass. We'd have to actually plan hard for a mission with a faster velocity. It got big boosts from gravity on its way out. Eventually I'm sure we'll build something like a fusion drive but that's likely to be a very long time. Even then, I can't imagine sending something out without a set destination again like Voyager.