I have to admit bafflement for how the data have turned out. The particle count went down until early January which suggested a slower but continued decrease, after that it have been climbing up and approaches the average level. So djellison might have been right that the environment here are quite different indeed. I abandon any pet hypothesis gladly when there's a chance for something new, interesting or unexpected. =)
Click to view attachment
Full Version: Voyager Enters Final Frontier Of Solar System
ack, I have some more innocent questions:
Are there interstellar elements still floating inside the solar system? Towards us? Has Voyager 1 and/or 2 helped determine that distinction?
Are there interstellar elements still floating inside the solar system? Towards us? Has Voyager 1 and/or 2 helped determine that distinction?
QUOTE (brellis @ Mar 14 2013, 06:20 AM) 
ack, I have some more innocent questions:
Are there interstellar elements still floating inside the solar system? Towards us? Has Voyager 1 and/or 2 helped determine that distinction?
Are there interstellar elements still floating inside the solar system? Towards us? Has Voyager 1 and/or 2 helped determine that distinction?
Oh there have been several spacecraft that have detected interstellar particles IBEX and Ulysses are two of those, the Stardust mission were to collect interstellar material, and I tend to think that also the Deep impact/EPOXI spacecraft did enter a stream of material thought to have originated outside the solar system. So there might be plenty more to find also if future spacecraft are provided with instruments to detect such.
False alarm :-(
http://voyager.jpl.nasa.gov/news/voyager_update.html
http://voyager.jpl.nasa.gov/news/voyager_update.html
You had me wonder for a bit, then I found that the NASA disclaimer seem to be referring to this item.
Though they do not say with certainty that Voyager are in interstellar space: "However, Webber notes, scientists are continuing to debate whether Voyager 1 has reached interstellar space or entered a separate, undefined region beyond the solar system."
Edit: And the headline in the piece I linked were changed to the more neutral "...entered a new region of space" a short while after my post were made.
And here's the actual paper in preprint.
Though they do not say with certainty that Voyager are in interstellar space: "However, Webber notes, scientists are continuing to debate whether Voyager 1 has reached interstellar space or entered a separate, undefined region beyond the solar system."
Edit: And the headline in the piece I linked were changed to the more neutral "...entered a new region of space" a short while after my post were made.
And here's the actual paper in preprint.
At the solar system's edge, more surprises from Voyager
Magnetic Field Observations as Voyager 1 Entered the Heliosheath Depletion Region
Search for the Exit: Voyager 1 at Heliosphere’s Border with the Galaxy
Voyager 1 Observes Low-Energy Galactic Cosmic Rays in a Region Depleted of Heliospheric Ions
QUOTE
Data from NASA's Voyager 1 spacecraft continues to provide new insight on the outskirts of our solar system, a frontier thought to be the last that Voyager will cross before becoming the first man-made object to reach interstellar space.
In papers published this week in the journal Science, scientists from the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Md., and other Voyager partner institutions provide more clarity on the region they named the "magnetic highway" in December 2012. Cruising through what scientists describe as a curious, unexpected charged-particle environment, Voyager has detected, for the first time, low-energy galactic cosmic rays, now that particles of the same energy from inside the bubble around our Sun disappeared. As a result, Voyager now sees the highest level so far of particles from outside our solar bubble that originate from the death of other nearby stars.
"Voyager 1 may be months or years from leaving the solar system—we just don't know," says APL's Stamatios Krimigis, principal investigator for Voyager's Low-Energy Charged Particle (LECP) instrument. "But the wait itself is incredibly exciting, since Voyager continues to defy predictions and change the way we think about this mysterious and wonderful gateway region to the galaxy."
Voyager 1 and 2 were launched in 1977 and between them visited Jupiter, Saturn, Uranus and Neptune. Since 1990, the twin spacecraft have been on their Interstellar Mission, on track to leave the heliosphere, which is the bubble of magnetic field and charged particles the Sun blows around itself. On Aug. 25, 2012, when Voyager 1 was about 11 billion miles (18 billion kilometers) from the Sun, the spacecraft reached the so-called magnetic highway where charged particles from inside the heliosphere zoomed out along the magnetic field as cosmic rays from far outside zoomed in. The lack of a detectable change in the direction of that magnetic field, however, convinced scientists that Voyager remained within the Sun's influence.
The new Science papers focus on observations from the summer and fall of 2012 by LECP as well as Voyager 1's Cosmic Ray and Magnetometer instruments, with additional LECP data through April 2013.
"The most dramatic part was how quickly the solar-originating particles disappeared; they decreased in intensity by more than 1,000 times, as if there was a huge vacuum pump at the entrance ramp onto the magnetic highway," says Krimigis. "We have never witnessed such a decrease before, except when Voyager 1 exited the giant magnetosphere of Jupiter, some 34 years ago."
"Surprisingly, the traveling direction of the 'inside' charged particles in this region made a difference, with those moving straightest along the magnetic field lines decreasing most quickly. Those that moved perpendicular to the magnetic field did not change as quickly," adds LECP Co-investigator Robert Decker, also of APL. The cosmic rays from outside, moving along the field lines, were somewhat more intense than those moving perpendicular to the field, and this imbalance varied significantly with time during the eight months since "It is this time-varying behavior of the cosmic rays that tells us that we're still in a region controlled by our Sun," says APL's Edmond Roelof, also an LECP co-investigator.
The multidimensional measurements speak to the unique abilities of the LECP detector, designed at APL in the 1970s. It includes a stepper motor that rotates the instrument through 45-degree steps every 192 seconds, allowing it to gather data in all directions and pick up something as dynamic as the solar wind and galactic particles. The device, designed and tested to work for 500,000 steps and last four years, has been working for nearly 36 years and well past 6 million steps.
In papers published this week in the journal Science, scientists from the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Md., and other Voyager partner institutions provide more clarity on the region they named the "magnetic highway" in December 2012. Cruising through what scientists describe as a curious, unexpected charged-particle environment, Voyager has detected, for the first time, low-energy galactic cosmic rays, now that particles of the same energy from inside the bubble around our Sun disappeared. As a result, Voyager now sees the highest level so far of particles from outside our solar bubble that originate from the death of other nearby stars.
"Voyager 1 may be months or years from leaving the solar system—we just don't know," says APL's Stamatios Krimigis, principal investigator for Voyager's Low-Energy Charged Particle (LECP) instrument. "But the wait itself is incredibly exciting, since Voyager continues to defy predictions and change the way we think about this mysterious and wonderful gateway region to the galaxy."
Voyager 1 and 2 were launched in 1977 and between them visited Jupiter, Saturn, Uranus and Neptune. Since 1990, the twin spacecraft have been on their Interstellar Mission, on track to leave the heliosphere, which is the bubble of magnetic field and charged particles the Sun blows around itself. On Aug. 25, 2012, when Voyager 1 was about 11 billion miles (18 billion kilometers) from the Sun, the spacecraft reached the so-called magnetic highway where charged particles from inside the heliosphere zoomed out along the magnetic field as cosmic rays from far outside zoomed in. The lack of a detectable change in the direction of that magnetic field, however, convinced scientists that Voyager remained within the Sun's influence.
The new Science papers focus on observations from the summer and fall of 2012 by LECP as well as Voyager 1's Cosmic Ray and Magnetometer instruments, with additional LECP data through April 2013.
"The most dramatic part was how quickly the solar-originating particles disappeared; they decreased in intensity by more than 1,000 times, as if there was a huge vacuum pump at the entrance ramp onto the magnetic highway," says Krimigis. "We have never witnessed such a decrease before, except when Voyager 1 exited the giant magnetosphere of Jupiter, some 34 years ago."
"Surprisingly, the traveling direction of the 'inside' charged particles in this region made a difference, with those moving straightest along the magnetic field lines decreasing most quickly. Those that moved perpendicular to the magnetic field did not change as quickly," adds LECP Co-investigator Robert Decker, also of APL. The cosmic rays from outside, moving along the field lines, were somewhat more intense than those moving perpendicular to the field, and this imbalance varied significantly with time during the eight months since "It is this time-varying behavior of the cosmic rays that tells us that we're still in a region controlled by our Sun," says APL's Edmond Roelof, also an LECP co-investigator.
The multidimensional measurements speak to the unique abilities of the LECP detector, designed at APL in the 1970s. It includes a stepper motor that rotates the instrument through 45-degree steps every 192 seconds, allowing it to gather data in all directions and pick up something as dynamic as the solar wind and galactic particles. The device, designed and tested to work for 500,000 steps and last four years, has been working for nearly 36 years and well past 6 million steps.
Magnetic Field Observations as Voyager 1 Entered the Heliosheath Depletion Region
QUOTE
Magnetic fields measured by Voyager 1 (V1) show that the spacecraft crossed the boundary of an unexpected region five times between days 210 and ~238 in 2012. The magnetic field strength B increased across this boundary from ≈0.2 nT to ≈0.4 nT, and B remained near 0.4 nT until at least day 270, 2012. The strong magnetic fields were associated with unusually low counting rates of >0.5 MeV/nuc particles. The direction of B did not change significantly across any of the 5 boundary crossings; it was very uniform and very close to the spiral magnetic field direction, which was observed throughout the heliosheath. The observations indicate that V1 entered a region of the heliosheath (“the heliosheath depletion region”), rather than the interstellar medium.
Search for the Exit: Voyager 1 at Heliosphere’s Border with the Galaxy
QUOTE
We report measurements of energetic (>40 keV) charged particles on Voyager 1 (V1) from the interface region between the heliosheath (HS), dominated by heated solar plasma, and the local interstellar medium (LISM) expected to contain cold nonsolar plasma and the galactic magnetic field. Particles of solar origin at V1, located at 18.5 billion km (123 AU) from the Sun, decreased by a factor >103 on 25 August 2012, while those of galactic origin (cosmic rays) increased by 9.3% at the same time. Intensity changes appeared first for particles moving in the azimuthal direction and were followed by those moving in the radial and antiradial directions with respect to the solar radius vector. This unexpected heliospheric "depletion region" may form part of the interface between solar plasma and the galaxy.
Voyager 1 Observes Low-Energy Galactic Cosmic Rays in a Region Depleted of Heliospheric Ions
QUOTE
On 25 August 2012, Voyager 1 was at 122 astronomical units when the steady intensity of low-energy ions it had observed for the last 6 years suddenly dropped for a third time and soon completely disappeared as the ions streamed away into interstellar space. Although the magnetic field observations indicate that Voyager 1 remained inside the heliosphere, the intensity of cosmic ray nuclei from outside the heliosphere abruptly increased. We report the spectra of galactic cosmic rays down to ~3 × 106 electron volts per nucleon, revealing H and He energy spectra with broad peaks from 10 × 106 to 40 × 106 electron volts per nucleon and an increasing galactic cosmic ray electron intensity down to ~10 × 106 electron volts.
Thanks for pointing out that update Mongo,
a little back-of-the-envelope math... V1 will have traveled 1% of the distance to the nearest star, on or about the year 2727 ( EDIT: not 2377 ... I sharpened my pencil)
BTW, its not pointing at the nearest star, it is heading towards the vicinity of the Solar Apex (the direction of the Sun's motion relative to nearby stars, or currently someplace southwest of the star Vega). Voyager 1 will leave the solar system aiming toward the constellation Ophiuchus.
From NASA:
In the year 40,272 AD, Voyager 1 will come within 1.7 light years of an obscure star in the constellation Ursa Minor (the Little Bear or Little Dipper) called AC+79 3888
V1 is only 17.18 light-hours from the Sun at the moment.
Voyager 2 is also escaping the solar system to the south toward the constellations of Sagitarrius and Pavo.
In about 40,000 years, Voyager 2 will come within about 1.7 light years of a star called Ross 248, a small star in the constellation of Andromeda
also see:
http://www.heavens-above.com/SolarEscape.aspx
a little back-of-the-envelope math... V1 will have traveled 1% of the distance to the nearest star, on or about the year 2727 ( EDIT: not 2377 ... I sharpened my pencil)
BTW, its not pointing at the nearest star, it is heading towards the vicinity of the Solar Apex (the direction of the Sun's motion relative to nearby stars, or currently someplace southwest of the star Vega). Voyager 1 will leave the solar system aiming toward the constellation Ophiuchus.
From NASA:
In the year 40,272 AD, Voyager 1 will come within 1.7 light years of an obscure star in the constellation Ursa Minor (the Little Bear or Little Dipper) called AC+79 3888
V1 is only 17.18 light-hours from the Sun at the moment.
Voyager 2 is also escaping the solar system to the south toward the constellations of Sagitarrius and Pavo.
In about 40,000 years, Voyager 2 will come within about 1.7 light years of a star called Ross 248, a small star in the constellation of Andromeda
also see:
http://www.heavens-above.com/SolarEscape.aspx
QUOTE (PDP8E @ Jun 27 2013, 10:44 PM)
V1 is only 17.18 light-hours from the Sun at the moment.
That's 0.00196 light years from the Sun!
Well, it's a start...
Voyager 1 might indeed be close to the Interstellar boundary now.
Yet it's only a 2 degree shift in direction of the magnetic field, and if I read this right most cosmic rays are still moving along the magnetic fieldlines. Which suggest they have been affected by it for some duration while approaching our solar system.
So even though I got very enthusiastic about the magnetic highway and that it might be a herald of interstellar space close at hand. There might be some reason to not starting to yell 'Are we there yet?'
JPL update for V1.
Yet it's only a 2 degree shift in direction of the magnetic field, and if I read this right most cosmic rays are still moving along the magnetic fieldlines. Which suggest they have been affected by it for some duration while approaching our solar system.
So even though I got very enthusiastic about the magnetic highway and that it might be a herald of interstellar space close at hand. There might be some reason to not starting to yell 'Are we there yet?'
JPL update for V1.
And another item on the question if Voyager 1 is in interstellar space or not.
Now described as 'competing models' it all is a sign of good science work on the matter.
The magnetic lines from the sun do connect to the galactic magnetic field as described
Is as far as I understand it the 'magnetic highway' that been noted.
In addition, IBEX have indeed shown that there's no bow shock, so that is consistent with the alternative hypothesis.
Science daily
Now described as 'competing models' it all is a sign of good science work on the matter.
The magnetic lines from the sun do connect to the galactic magnetic field as described
Is as far as I understand it the 'magnetic highway' that been noted.
In addition, IBEX have indeed shown that there's no bow shock, so that is consistent with the alternative hypothesis.
Science daily
Voyager press conference in 15 minutes! Regarding an article in Science embargoed until today.
Streaming here: http://www.youtube.com/watch?v=uBqYErSvi6A
EDIT: Interstellar space confirmed! http://www.jpl.nasa.gov/news/news.php?release=2013-277
Streaming here: http://www.youtube.com/watch?v=uBqYErSvi6A
EDIT: Interstellar space confirmed! http://www.jpl.nasa.gov/news/news.php?release=2013-277
as Science titles: It's Official—Voyager Has Left the Solar System
for the lucky having full access here is the paper In Situ Observations of Interstellar Plasma With Voyager 1
for the lucky having full access here is the paper In Situ Observations of Interstellar Plasma With Voyager 1
Science (as well as the BBC, CNN, infact almost everyone) makes the wrong claim ( left the solar system) rather than the claim the paper that science is publishing ACTUALLY makes ( entered interstellar space )
The two are not one and the same - very important distinction to make.
In terms of the number of objects orbiting our Sun - Voyager will be passing them by for another 300 years.
The two are not one and the same - very important distinction to make.
In terms of the number of objects orbiting our Sun - Voyager will be passing them by for another 300 years.
Wonderful, even though those two items I posted in August did convince me, it did not take that long for the rest of the space science community jumped onto the bandwagon this time. =)
And djellison is right, news media is excused but a bit embarrassing to see AAAS stating V1 have left the solar system The Oort cometary region is still far ahead.
A NASA page has gone up now: NASA Spacecraft Embarks on Historic Journey Into Interstellar Space
And djellison is right, news media is excused but a bit embarrassing to see AAAS stating V1 have left the solar system The Oort cometary region is still far ahead.
A NASA page has gone up now: NASA Spacecraft Embarks on Historic Journey Into Interstellar Space
Link already posted by me, Ant 
And yes, dates for leaving the solar system are certainly subjective. Ask a heliophysicist and they'll say this past year, a comet scientist will say several centuries from now, a planetary scientist will say 1988/9, and a mathematician will say never.
Go figure....
And yes, dates for leaving the solar system are certainly subjective. Ask a heliophysicist and they'll say this past year, a comet scientist will say several centuries from now, a planetary scientist will say 1988/9, and a mathematician will say never.
Go figure....
QUOTE (TheAnt @ Sep 13 2013, 09:18 AM)
And djellison is right, news media is excused but a bit embarrassing to see AAAS stating V1 have left the solar system The Oort cometary region is still far ahead.
on the other hand, from a dynamical point of view, Voyager is no longer bound to the Sun (since 1979 in fact), so it can be considered to have left the solar system
QUOTE (Paolo @ Sep 13 2013, 12:25 AM)
Voyager is no longer bound to the Sun (since 1979 in fact), so it can be considered to have left the solar system
So you're saying that New Horizons left the solar system as its third stage burned out, a few hundred miles above the Earth?
I don't think anyone would agree that's a fair assessment. Speed is not location. "Where are you?" "Mach 30"
QUOTE (djellison @ Sep 13 2013, 07:16 PM)
... Speed is not location. "Where are you?" "Mach 30"
Good point, Paolo/Doug! I always thought that space exploration lies in a six dimensions domain, a perfect mix of space and velocity or, better, distances and "delta-v". From this viewpoint, I think that you're both right!
Voyager finally made it! This is a historic moment, for real this time
OK but even if Voyager is currently drifting in interstellar plasma that does not change the fact that
1. Cosmic rays are still coming predominantly from one direction.
2. There has not been an significant field shift.
And Voyager 1 has about ten years of power to answer these questions. Plus who knows when Voyager 2 will enter the interstellar medium.
There is still a lot of work to be done here...
OK but even if Voyager is currently drifting in interstellar plasma that does not change the fact that
1. Cosmic rays are still coming predominantly from one direction.
2. There has not been an significant field shift.
And Voyager 1 has about ten years of power to answer these questions. Plus who knows when Voyager 2 will enter the interstellar medium.
There is still a lot of work to be done here...
Hopefully, as Voyager 2 has more instruments to bring to bear on the situation - it should help solve some of those problems.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
But the particle flux for Voy2 still not showing any sign the spacecraft might be approaching the border.
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.
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.
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. 
Jeff
Jeff
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. 
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.
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.
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.
Voyager Update: Probing the Boundary
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.
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.
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.
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.
Edit: Voyager particle data here.
Maaaaaybe something interesting is happening with Voyager 2. See plots here. 0.5 and 70 MeV particle fluxes tend to be correlated, but shortly before the V1 heliocliff they went in different directions. If this really is the precursor to breakout into the ISM, it should be clearer by next week. Plots are updated a couple times a week.
(The image above links to the regularly updated plot.)
(The image above links to the regularly updated plot.)
As of a week later, I see its spiking a lot higher, then started dropping rapidly - for those of us following along at home - if this would follow the v1 plot, would this then crash to the floor?
QUOTE (dtolman @ Sep 16 2018, 11:23 PM)
As of a week later, I see its spiking a lot higher, then started dropping rapidly - for those of us following along at home - if this would follow the v1 plot, would this then crash to the floor?
dilo included a nice plot of the V1 data in post 86 showing how the >0.5 MeV proton rate crashed to 2.1 and >70 MeV rose less dramatically to 2.26 ct/s. The latest modeling I've read about suggests that the boundary is (or was in 2017) moving outward while V2 is catching up to it. If the boundary breathes in and out, V2 may cross it more than once, making things a bit confusing. The web-page tools that let you make your own plots seem to have lost access to the latest data in the intervening years so we'll just have to wait for what they give us every few days. (Sorry, I can't figure out how to post dilo's plot directly here.)
The plots are continuing to look very promising, and they were updated not once but twice(!) today, after many months of couple-times-a-week. I'd bet the >0.5 MeV rate is below 10 ct/s by the end of next week and then we'll see it in the news.
Well, I was too optimistic about the timing, but there is some attention in the news. Not really any new info there, but yes, we are officially getting close.
Edit: Note that although the plots say "6-Hour Avg" they are actually 12-hour aves. They switched several months ago (or maybe a year or two)--don't know why.
Edit: Note that although the plots say "6-Hour Avg" they are actually 12-hour aves. They switched several months ago (or maybe a year or two)--don't know why.
The >70 Me V just need to climb from 2.05 to 2.25 and the >0.5 Me V drop from 27 to about 2. Hoping by the end of the Month...
EDIT Nov 6, 2018 LINK to plots. Both plots are about to go off scale in the correct direction!!!
EDIT Nov 6, 2018 LINK to plots. Both plots are about to go off scale in the correct direction!!!
There are some pretty big flux changes in the past two days. A watched high-energy particle detector never boils, but any day now...
It seems to be happening. Xcalibrator Plots above seem to update to latest plots automatically rather than display the plots for the day he posted (Sept 21). The November 7 Plot for >0.5 MeV has dropped to 20. I'll bet Xcalibrator's prediction of under 10 particles/second for >0.5 MeV occurs by November 11---OK it may take 3 week rather than one from Sep 21 for his prediction---but it really seems to be happening.
Edit 11/8/18 The >70MeV is now up to 2.25 (interstellar space level Voyager 1) and the >0.5 MeV down to 19 cts/sec. Moving nicely...Looks like we are in the Heliocliff. Still possible to get to 10 cts/sec by Monday
Edit 11/8/18 The >70MeV is now up to 2.25 (interstellar space level Voyager 1) and the >0.5 MeV down to 19 cts/sec. Moving nicely...Looks like we are in the Heliocliff. Still possible to get to 10 cts/sec by Monday
NASA Voyager @NASAVoyager
Rumors of Voyager 2's exit from the heliosphere have been greatly exaggerated. Check out the y-axis on this graph. It goes down to 19. We're waiting for a count of near zero heliospheric particles/sec before she's joined me in interstellar space. https://go.nasa.gov/2JThxXq
https://twitter.com/NASAVoyager/status/1060720885345079296
Rumors of Voyager 2's exit from the heliosphere have been greatly exaggerated. Check out the y-axis on this graph. It goes down to 19. We're waiting for a count of near zero heliospheric particles/sec before she's joined me in interstellar space. https://go.nasa.gov/2JThxXq
https://twitter.com/NASAVoyager/status/1060720885345079296
The Voyager Twitter is to be believed over speculation in this thread. That said 2 cts/sec in the 0.5 MeV channel is the number we want to get down to (not zero). If you look at the necessary drops to get there we need to go from about 27 at end of October to 2 outside. In five steps that would be 27, 22, 17, 12, 7, 2. We went from 27 down to 19 (almost 2 steps) and have bounced up a bit today. So when we get below 17 we will be 2/5 of the way there. Five counts/sec drops are possible in 1-2 days, but getting under 7 and close to 2 could still be some time off. We will know a lot more by Monday on how fast and how monotonic this drop is. Are we in the Heliocliff? We will know when we hit 2 and/or the Voyager team makes an announcement.
Let's see if I can show the Voyager1 plot from dilo/post86 here for more convenient comparison....
Thanks Xcalibrator, that is very helpful. I had not realized the >0.5 MeV had dropped from 25 to under 10 twice before finally bottoming out for Voyager 1. The fall is definitely not monotonic. Drop to about 17 on 10th. Back up to 19 on 11th. So we will bounce up and down for a while.....
Well we are definitely not down to 2 yet on the >0.5 MeV, but we have dropped from 26 to below 16 (as of 11/17/18) and are doing a lot of bouncing up and down. Hopefully Voyager 2 will exit the heliosphere and be down to 2 by 2019 I believe the image below will automatically update once or twice a day--check Generated Date and time at bottom. I believe time is Z and so -5 EST and -8 PST.
I believe the image below will automatically update once or twice a day--check Generated Date and time at bottom. I believe time is Z and so -5 EST and -8 PST.
Nice drop to 11 counts/sec for >0.5 MeV/nuc ions today (11/18/18), but if Voyager 2 is like Voyager 1 we may bounce back up to 24-28 counts/sec a couple of times before exiting the heliosphere for real.
Edit 11/20/18. Down to 8 counts/sec for >0.5 MeV/nuc ions. Looking promising, but could bounce all the way back up. When it gets to 6 counts/sec I think we can safely conclude we are in the Helioclif. When it gets to under 4 counts/sec I think we can conclude there will be an announcement from the mission...
Edit 11/23/18 8:44am EST. Well no data posted 11/22 (Thanksgiving in US) and the chart generated and posted 11/23 05:10:06 2018 is the same as the chart posted on 11/21---so we are not seeing recent data points.
Edit 11/20/18. Down to 8 counts/sec for >0.5 MeV/nuc ions. Looking promising, but could bounce all the way back up. When it gets to 6 counts/sec I think we can safely conclude we are in the Helioclif. When it gets to under 4 counts/sec I think we can conclude there will be an announcement from the mission...
Edit 11/23/18 8:44am EST. Well no data posted 11/22 (Thanksgiving in US) and the chart generated and posted 11/23 05:10:06 2018 is the same as the chart posted on 11/21---so we are not seeing recent data points.
New data posted. Nice drop to 6 counts/sec for >0.5 MeV/nuc ions today (Fri Nov 23 6:10:24 2018). When we got this low on the >0.5 MeV/nuc ions and above 2.2 particles/sec on the >70 MeV/nuc ions on Voyager-1 we had exited the heliosphere (see Xcalibrator chart post #144 above). We could still bounce back up, but I doubt it. I think we might hear from the Voyager team very soon.
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How far out from the sun was Voyager 1 in 2012 at the egress of the heliosphere and how this distance compares now with the Voyager 2 egress ?
"DSN Now" tells 17.9 billion kilometers for Vgr2...but this is Earth to Spacecraft distance.
I think the heliosperic "bubble" will change in size over time and make some wobbles and is also different in the direction you leave (I don't think its a round ball)
Both Voyagers are leaving the solar system in pretty different directions.
"DSN Now" tells 17.9 billion kilometers for Vgr2...but this is Earth to Spacecraft distance.
I think the heliosperic "bubble" will change in size over time and make some wobbles and is also different in the direction you leave (I don't think its a round ball)
Both Voyagers are leaving the solar system in pretty different directions.
Voyager 2 is about 144 AU from the sun currently. Voyager 1 crossed the heliopause in August 2012, then at a distance of 121 AU from the Sun. The shape of the heliosphere is definitely not spherical, and Voyager 2 is coming out at a place where the boundary is further from the sun than Voyager 1. There is more information at the Voyager web site. It took 1 year for NASA to officially report Voyager 1 entering interstellar space, because there was no precedent and no one really knew what it should look like. This is the second time, so an announcement should be a shorter than one year post exit. 
Edit: Thanks MarcF, I mixed up current Voyager distances from Sun in post above. Voyager 1 is 144 AU from the Sun currently and Voyager 2 is 119.18 AU. So Voyager 2 may be exiting about 2 AU closer to Sun than Voyager 1.
Edit: Thanks MarcF, I mixed up current Voyager distances from Sun in post above. Voyager 1 is 144 AU from the Sun currently and Voyager 2 is 119.18 AU. So Voyager 2 may be exiting about 2 AU closer to Sun than Voyager 1.
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