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Voyager Enters Final Frontier Of Solar System
djellison
post Sep 13 2013, 10:59 PM
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Hopefully, as Voyager 2 has more instruments to bring to bear on the situation - it should help solve some of those problems.
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0101Morpheus
post Sep 14 2013, 12:21 AM
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Are there any estimates when Voyager 2 will cross the heliopause? Considering that now that we know Voyager 1 crossed it a year ago, the boundary was pretty close to the initial estimate.

Considering just how large the heliosphere is, ten years is not that much time. Even if Voyager is in the interstellar medium, it is still in a special region that is being effected by the heliosphere. And because we don't know how large this region is, it is possible that the voyager probes will be spending the rest of their lifetimes in it.
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TheAnt
post Sep 14 2013, 01:12 PM
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As for V2 there's been some suggestions the solar wind & magnetosphere bubble might be lopsided. So it might take a while more, then again, the V1 passage came relatively suddenly without any clear sign beforehand. So the answer is that we simply do not know.
This all due to the fact that most ideas about this region have ended up being incorrect in the last year. (Though IBEX gave a hint some time earlier.)

Now that the solar wind at this distance is so ratified and the magnetic field correspondingly weak that the transition zone were undramatic and hardly noticeable except for the particle count that we payed attention to in Sept 2012 Dilo's post #78
The counter press release in post #104 might look a bit embarrassing for JPL, but it's actually a sign of good science where one is not only supposed to measure 'twice and cut once' but constantly re-measure as the cut is made to make sure everything is correct. smile.gif

Anyhow, you might be correct, Voyager1 might spend the rest of the mission in this region, my long term interest on this matter have had me keep an eye on Voyager and later on Ibex (even before it were launched) for exactly this. Er rather when someone publish a paper on these findings.
There's many things that other people get excited about on the net, in my case it's certain scientific papers. smile.gif
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Mongo
post Jul 9 2014, 02:09 AM
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Sun sends more 'tsunami waves' to Voyager 1

NASA's Voyager 1 spacecraft has experienced a new "tsunami wave" from the sun as it sails through interstellar space. Such waves are what led scientists to the conclusion, in the fall of 2013, that Voyager had indeed left our sun's bubble, entering a new frontier.

"Normally, interstellar space is like a quiet lake," said Ed Stone of the California Institute of Technology in Pasadena, California, the mission's project scientist since 1972. "But when our sun has a burst, it sends a shock wave outward that reaches Voyager about a year later. The wave causes the plasma surrounding the spacecraft to sing."

Data from this newest tsunami wave generated by our sun confirm that Voyager is in interstellar space—a region between the stars filled with a thin soup of charged particles, also known as plasma. The mission has not left the solar system—it has yet to reach a final halo of comets surrounding our sun—but it broke through the wind-blown bubble, or heliosphere, encasing our sun. Voyager is the farthest human-made probe from Earth, and the first to enter the vast sea between stars.

"All is not quiet around Voyager," said Don Gurnett of the University of Iowa, Iowa City, the principal investigator of the plasma wave instrument on Voyager, which collected the definitive evidence that Voyager 1 had left the sun's heliosphere. "We're excited to analyze these new data. So far, we can say that it confirms we are in interstellar space."

Our sun goes through periods of increased activity, where it explosively ejects material from its surface, flinging it outward. These events, called coronal mass ejections, generate shock, or pressure, waves. Three such waves have reached Voyager 1 since it entered interstellar space in 2012. The first was too small to be noticed when it occurred and was only discovered later, but the second was clearly registered by the spacecraft's cosmic ray instrument in March of 2013.

Cosmic rays are energetic charged particles that come from nearby stars in the Milky Way galaxy. The sun's shock waves push these particles around like buoys in a tsunami. Data from the cosmic ray instrument tell researchers that a shock wave from the sun has hit.

Meanwhile, another instrument on Voyager registers the shock waves, too. The plasma wave instrument can detect oscillations of the plasma electrons.

"The tsunami wave rings the plasma like a bell," said Stone. "While the plasma wave instrument lets us measure the frequency of this ringing, the cosmic ray instrument reveals what struck the bell—the shock wave from the sun."

This ringing of the plasma bell is what led to the key evidence showing Voyager had entered interstellar space. Because denser plasma oscillates faster, the team was able to figure out the density of the plasma. In 2013, thanks to the second tsunami wave, the team acquired evidence that Voyager had been flying for more than a year through plasma that was 40 times denser than measured before—a telltale indicator of interstellar space.

Why is it denser out there? The sun's winds blow a bubble around it, pushing out against denser matter from other stars.

Now, the team has new readings from a third wave from the sun, first registered in March of this year. These data show that the density of the plasma is similar to what was measured previously, confirming the spacecraft is in interstellar space. Thanks to our sun's rumblings, Voyager has the opportunity to listen to the singing of interstellar space—an otherwise silent place.
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MarcF
post Jul 24 2014, 02:26 PM
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Is Voyager 1 Really in Interstellar Space? New Test Could Prove It for Good:
http://www.space.com/26628-voyager-1-inter...140724_28353606
It seems that it is still not clear that V1 has indeed entered interstellar space !
Regards,
Marc.
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MarcF
post Dec 16 2014, 07:37 PM
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Some news from our old friend:
http://www.jpl.nasa.gov/news/news.php?feature=4411

The "tsunami wave" that NASA's Voyager 1 spacecraft began experiencing earlier this year is still propagating outward, according to new results. It is the longest-lasting shock wave that researchers have seen in interstellar space.

"Most people would have thought the interstellar medium would have been smooth and quiet. But these shock waves seem to be more common than we thought," said Don Gurnett, professor of physics at the University of Iowa in Iowa City. Gurnett presented the new data Monday, Dec. 15 at the American Geophysical Union meeting in San Francisco.
...

Mysterious things happening outside the heliosphere. Can't wait to have Voyager 2 outside too.
Regards,
Marc.
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TheAnt
post Dec 24 2014, 09:25 PM
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Agreed, with both Voyagers outside the heliosphere we could learn about the direction and speed of these events.

But the particle flux for Voy2 still not showing any sign the spacecraft might be approaching the border.
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TheAnt
post May 20 2015, 02:01 AM
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Some quite dramatic swings in the >0,5 MeV data, together with an ever increasing trend toward the 2,3 particle per second in the >70 MeV particle data hits that something might be in the works for Voyager 2 also now.
Not saying that we're there yet, there were large swings on the graph before V1 eventually did enter interstellar space, and this does not look exactly the same either. So this is posted only a small heads up that something is happening after a quite long and unevenful timespan.

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jgoldader
post May 21 2015, 01:34 AM
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On the one hand, the V1 events were those "bottoming out" events right before breakthrough, but this is going up. On the other hand, I don't recall seeing such an abrupt jump in recent times. Gripping hand, maybe there's a high density pileup of particles caused by some shock front. I check every single day, can hardly wait... Hope she makes it through while she and I are both still functioning. laugh.gif

Jeff
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TheAnt
post May 22 2015, 11:19 AM
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Yes you're correct Jeff that it was a series of dips in the graph before V1 went into the interstellar realm. So my description was a tad too conservative. tongue.gif Tthe rise in May really made me think of a shock front, and I wondered if the magnetic field lines have taken an abrupt turn to cause such an increase of particles.
If that is the case, and if V2 actually are at the boundary, I think we got a fair chance that both you, me and V2 will be fully functional to follow this. =)

Edit for adding the graph for the past year, this looks absolutely wild!
There's a pattern to this though, after each time the particle count have peaked, it falls back to a value that is about the same as the previous top value - we can see 2 times in this graph, though there's one more further back in time also.

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TheAnt
post Nov 1 2015, 06:12 PM
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Sometime it take time for the analysis to appear. And that is the case for Voyager 1 passing the heliopause. But it might still be a whole decade before the spacecraft will be in true interstellar space. Data from IBEX have led the researchers to this conclusion.

A nice summary can be found at EurekAlert

The count for 0,5 MeV ions by Voyager 2 have made a dip after reaching values never seen before in open space, this might indicate that it is close to the same boundary. Then again, the count for higher energy particles have actually been dropping, so we might have to wait for any of the pros to give an estimate of what actually is going on here.

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Mongo
post Nov 2 2015, 04:16 PM
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Voyager Update: Probing the Boundary

QUOTE
Nathan Schwadron (University of New Hampshire) and colleagues have reanalyzed magnetic field data from Voyager 1, discovering that the direction of the magnetic field has been turning ever since the craft crossed into interstellar space. The work, published in Astrophysical Journal Letters confirms that the magnetic field direction at the center of the IBEX ‘ribbon’ is aligned with the magnetic field in the interstellar medium. Voyager is, in other words, now moving through a distorted region. By 2025, the magnetic field around it should align with the field direction found by IBEX.

At that point, we’ll be able to say that Voyager 1 has reached a more settled part of the interstellar medium, less perturbed by the ‘churn’ of the heliosphere. “This study provides very strong evidence that Voyager 1 is in a region where the magnetic field is being deflected by the solar wind,” says Schwadron in this JPL news release.

[...]

The paper is Schwadron et al., “Triangulation of the Interstellar Magnetic Field,” Astrophysical Journal Letters Vol. 813, No. 1, L20.


Abstract: Determining the direction of the local interstellar magnetic field (LISMF) is important for understanding the heliosphere's global structure, the properties of the interstellar medium, and the propagation of cosmic rays in the local galactic medium. Measurements of interstellar neutral atoms by Ulysses for He and by SOHO/SWAN for H provided some of the first observational insights into the LISMF direction. Because secondary neutral H is partially deflected by the interstellar flow in the outer heliosheath and this deflection is influenced by the LISMF, the relative deflection of H versus He provides a plane—the so-called B–V plane in which the LISMF direction should lie. Interstellar Boundary Explorer (IBEX) subsequently discovered a ribbon, the center of which is conjectured to be the LISMF direction. The most recent He velocity measurements from IBEX and those from Ulysses yield a B–V plane with uncertainty limits that contain the centers of the IBEX ribbon at 0.7–2.7 keV. The possibility that Voyager 1 has moved into the outer heliosheath now suggests that Voyager 1's direct observations provide another independent determination of the LISMF. We show that LISMF direction measured by Voyager 1 is >40° off from the IBEX ribbon center and the B–V plane. Taking into account the temporal gradient of the field direction measured by Voyager 1, we extrapolate to a field direction that passes directly through the IBEX ribbon center (0.7–2.7 keV) and the B–V plane, allowing us to triangulate the LISMF direction and estimate the gradient scale size of the magnetic field.
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Xcalibrator
post Sep 2 2017, 02:52 PM
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For what it's worth, a paper just came out ("Time-varying Heliospheric Distance to the Heliopause", Washimi, Tanaka, and Zank, Astrophysical Journal Letters 846, L9, 2017 Sep 1) that predicts Voyager 2 should reach the heliopause any day now--you know, give or take a year. They use a model that includes the effects of global merged interaction regions, injecting one of typical size once per year, as well as the varying solar wind ram pressure, which varies over the solar cycle and which they model with a couple step functions. They don't compare with previous work so I'm not sure why this hasn't been done before or what the differences are, although they say that adding the GMIRs pushes out the heliopause by about 14 AU compared to a static model. They tuned their results by 4% to match the Voyager 1 heliopause encounter, but even so there's a fair amount of uncertainty because the model predicts that the heliopause will be moving outward for the next few years just as V2 is getting really close. V2 is moving faster, so it's steadily closing the gap, but from my reading there may be even more of the out?/in?/out shenanigans than V1 saw.

Edit: Voyager particle data here.
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