Voyager Enters Final Frontier Of Solar System Options

[Xcalibrator]

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.)

[Xcalibrator]

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.

[Xcalibrator]

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.

[Floyd]

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!!!

[Xcalibrator]

There are some pretty big flux changes in the past two days. A watched high-energy particle detector never boils, but any day now...

[Floyd]

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

[alan]

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

[Floyd]

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.

[Xcalibrator]

Let's see if I can show the Voyager1 plot from dilo/post86 here for more convenient comparison....

[Floyd]

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.....

[Floyd]

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.

[Floyd]

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.

[Floyd]

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.



x

[Roby72]

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.

[Floyd]

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.