Voyager 1 Has Left the Building

[H3LL]

Originally Posted by rjh01

The particles from the sun generating the solar wind are mostly protons and electrons. These do not have much penetrating power.

Ref: http://en.wikipedia.org/wiki/Solar_wind

Thanks. Learnt about Interstellar Medium as well.




.

[Mudcat]

Originally Posted by Cylinder

The distinct drop in solar particles is holding:

http://voyager.gsfc.nasa.gov/GIF/v1la.12m.gif
Image courtesy NASA/Goddard Space Flight Center

This actually actually confirms a theory I've had since I was about ten that scanning the stars for communications (ie SETI), while well intentioned, is ultimately futile.

I mean, we're already losing Voyager I to interstellar noise, what makes people think we could pick up an alien comminuque in all that from even the closest of solar systems to ours?

[rjh01]

Originally Posted by H3LL

Thanks. Learnt about Interstellar Medium as well.




.

That is ok. I think the best person to answer a question is someone who is not asking the question. This is one example of what I mean.

[fuelair]

Just hope it doesn't come back with a really big buddy!!!! Somebody has to be concerned for the Red shirts!!!!!

[Skeptic Ginger]

Originally Posted by Mudcat

.... we're already losing Voyager I to interstellar noise, ...

Got any links about this? It seems to me we're reading signals from these distant craft quite well.

[Mudcat]

Originally Posted by Skeptic Ginger

Got any links about this? It seems to me we're reading signals from these distant craft quite well.

I'm not sure where I would get a link for that... Except maybe the same place that the poster I quoted got his chart from. You might notice the drop in communication, unless I'm misreading it and it means something else entirely.

[Cylinder]

Originally Posted by Mudcat

I'm not sure where I would get a link for that... Except maybe the same place that the poster I quoted got his chart from. You might notice the drop in communication, unless I'm misreading it and it means something else entirely.

I think you're misinterpreting the data unless you have some information from GFSC that hasn't been released. Using a smaller-scale (4-month) graph, what you're seeing is a very dramatic drop in solar particles hitting the instrument:



This drop corresponds with an increase of higher-energy galactic particles (mainly protons thought to be accelerated by supernovea)



The insrtuments have detected relatively short-lived changes in solar flux (the rate at which the particles strike the sensor) but the latest is more dramatic, more persistent and corresponds to the increase in the galactic background. The correlation seems to argue against instrumentation and they are still seemingly getting the same rate of data (the blue dots) which doesn't really support a communication difficulty.

It does point strongly, IMO, to something very different happening than the earlier drops (see the large scale graph) - which have been interpreted as bubbles of interstellar medium where you see a slight drop in solar wind and then a return to baseline. Notice each graph around the last week of August.

As pointed out in the excellent Houston Chronicle article posted earlier by spin0, two of the three measuements expected upon Voyager 1's arrival into interstellar space have been observed - the other being a shift in the direction of the magnetic field. This last observation is much more subtle than the sudden shift of a compass needle and apparently takes weeks of observations and analysis.

[Skeptic Ginger]

Originally Posted by Mudcat

...unless I'm misreading it and it means something else entirely.

Cyl has it covered.

[rwguinn]

Ha! The Grey Lensman has grabbed it with a tractor rod and it's just outrunning the solar particles now!

[Cylinder]

I was trying to find some information on the magnometer instrument and found this bit of helpful information from our freinds over at VHO:

Quote:

The average magnetic field strength produced by the spacecraft at thelocation of the outboard magnetometer of the dual magnetometers system on V1 and V2 is about 0.1 - 0.2 nT, comparable to the most probable magnetic field strength in the inner heliosheath and significantly larger than the most probable magnetic field strength in the distant supersonic solar wind. The spacecraft magnetic field is a complex, time-dependent signal that mustbe removed from the measured magnetic field signal in order to derive the ambient magnetic fields of the solar wind and heliosheath. Corrections must also be made for spurious magnetic signals and noise associated with the telemetry system, ground tracking systems, and other factors. Extracting the signal describing the solar wind and heliosheath from the many sources of uncertainty is a complex and partly subjective process that requires understanding of the instrument and judgment based on experience in dealing with the ever-changing extraneous signals.

We estimate that for the V1 MAGdata the 1-sigma the uncertainty the 48 sec averages for each of the components of the magnetic field BR, BT, and BN is typically +/- 0.02 nT; the uncertainty in magnitude F1 is typically +/- 0.03 nT. F1, BR, BT, and BN can differ from one another and they may vary with time, but there is no practical way to determine these uncertainties more precisely at present.

NASA's Voyager MAG Experiments Home

[CynicalSkeptic]

Originally Posted by Squeegee Beckenheim

/even more pedantic nerd

The internet says Voyager 6 was a 20th century space probe.

[Damien Evans]

Originally Posted by CynicalSkeptic

The internet says Voyager 6 was a 20th century space probe.

Wikipedia redirects Voyager 6 to Star Trek TMP and doesn't mention it in the Voyager Program page. I don't think it exists.

Incidentally, Deep Space 1 and 2 have already been launched.

http://en.wikipedia.org/wiki/Deep_Space_1
http://en.wikipedia.org/wiki/Deep_Space_2

[spin0]

Originally Posted by Damien Evans

Wikipedia redirects Voyager 6 to Star Trek TMP and doesn't mention it in the Voyager Program page. I don't think it exists.

As you say, it doesn't exist. There's only Voyager 1&2.

Originally in 60's and 70's Voyager-program planned for four probes to take advantage of the rare "free-ride" alignment of outer planets. The probes were planned to go out in pairs. But for budgetary reasons (as NASA needed money to fly some guys around the globe) the program was cut and was left with just the two Voyagers still going strong. By sticking to the original plan there would have been close-up photos of Pluto over ten years ago, and not just two but four probes providing groundbreaking new data of heliosphere. But can't complain - the two Voyagers are just amazing!

[Mikeys]

Originally Posted by tfk

The scale of things.

It takes 16+ HOURS for the radio signals to get to the earth. Compare that with 8 minutes from the sun, and it is 16 x 60/8 = 120x further than the 93 million miles to the sun. Over 11,000 million miles away..!

Yeah, I know there are simpler ways to do that calc, but I've been doing it that way for about 20 years.

And, yeah I know that 11,000 million is VERY similar to 11 billion, but billions are tough to grasp.

But the point of this post is the bit of trivia that the transmitters on board the Voyagers (& Pioneers) are 8 Watt transmitters.

They use about as much energy as a small Christmas tree lightbulb.

Those sumbitches were clever boys, 35 years ago.

8 min is for Light, not Sound, to get to the earth

[Hellbound]

Originally Posted by Mikeys

8 min is for Light, not Sound, to get to the earth

Just out of curiosity, what do think a radio signal is?

[BenBurch]

Originally Posted by rwguinn

Ha! The Grey Lensman has grabbed it with a tractor rod and it's just outrunning the solar particles now!

I want a Bergholm drive!

[Craig B]

Originally Posted by Hellbound

Just out of curiosity, what do think a radio signal is?

You mean the BBC presenters aren't shouting down a speaking tube with my loudspeaker at the other end, like the captain on the bridge of a dreadnought battleship, sending orders to the gun turrets?

[Hellbound]

Originally Posted by Craig B

You mean the BBC presenters aren't shouting down a speaking tube with my loudspeaker at the other end, like the captain on the bridge of a dreadnought battleship, sending orders to the gun turrets?

Heh. Yeah, I was trying to determine if the post I responded to was serious or not.

I think I've been Poe'ed.

[spin0]

The plateaus in Voyager 1 measurements have stayed the same since August: http://voyager.gsfc.nasa.gov/heliopa...ecenthist.html
The drop looks pretty dramatic in the graphs. It's interesting how there seems to be no modulation of solar activity in the solar wind measument any more, none, just a flat line.

There will be presentations about Voyagers in AGU's 2012 fall meeting Dec 3. Some of the abstracts seem to argue that the results are an indication of interstellar medium, some that it's a region within the heliosheath. It's not yet clear if Voyager 1 has actually crossed the heliopause into the interstellar medium, and if so then confirming it will take time.

I couldn't figure out how to link to the abstratcs but they are easy to find by searching "Voyager" in 2012 Fall Meeting scientific program. Man, I wish they'd webcast some of those presentations and QA sessions, could be some lively discussion there.

[Soapy Sam]

I can't help wondering if a sudden drop in something from behind and increase in something from ahead, given both are pretty faint, might be due to some minor change in orientation, or other antenna degradation, rather than due to a change in the signal intensity?

[spin0]

Voyager 1 has been changing it's orientation periodically (roll maneuvers) in order to get different angles for measuring components of the magnetic field. They are not the reason for the results of the energetic particle measurements, there has been a real (and rather radical) change in the radiation enviroment.

[spin0]

I guess somebody's gonna ask it in this press conference - AGU's media advisory: http://fallmeeting.agu.org/2012/impo...ia-advisory-4/

Quote:

Voyager press availability
Monday, 3 December, 12:30 p.m.

Scientists with NASA’s Voyager mission will present the latest findings from the mission to the edge of the solar system, and will be available to answer questions from journalists.

Participants:
Ed Stone, Voyager project scientist, California Institute of Technology, Pasadena, Calif., USA;
Leonard Burlaga, Voyager magnetometer team scientist, NASA Goddard Space Flight Center,
Greenbelt, Maryland, USA;
Stamatios (“Tom”) Krimigis, Voyager low-energy charged particle instrument principal investigator, Johns Hopkins University Applied Physics Laboratory, Laurel, Maryland, USA.

Will be broadcasted live here: http://live.projectionnet.com/agupress/fm2012.aspx
Related documents will be posted here: http://fallmeeting.agu.org/2012/medi...al-press-room/

Don't know if registration needed. I hope not.

[spin0]

SO close but no consensus yet: Report: Humanity Leaves the Solar System — Or Maybe Not

Quote:

According to new scientific findings set for publication in the journal Geophysical Research Letters, Voyager I has pushed into the great unknown.

NASA, however, remains skeptical about these new conclusions. “Consensus of the mission team is that NASA’s Voyager spacecraft has not left the solar system,” a NASA social media specialist told TIME via e-mail. “Statement soon from NASA Jet Propulsion Laboratory.”

Very well said in the article:

Quote:

What’s not in dispute among any of the scientists is that the spacecraft is now, undeniably, in a new and unexplored region—pushing the reach of humanity farther than it’s ever gone before. What we call that place is, in many respects, less important than the fact that we’re there at all.

[Cylinder]

Geophysical Research Letters has published a paper that's causing a minor dust-up.

Quote:

At the Voyager 1 spacecraft in the outer heliosphere the intensities of both anomalous cosmic rays (ACR) and galactic cosmic rays (GCR) changed suddenly and decisively on August 25th (121.7 AU from the Sun). Within a matter of a few days, the intensity of 1.9-2.7 MeV protons and helium nuclei had decreased to less than 0.1 of their previous value and eventually the intensities decreased by factors of at least 300-500. Also on August 25th the GCR protons, helium and electrons increased suddenly in just 2 or 3 days by factors of up to two. The intensities of the GCR nuclei of all energies from 2 to 400 MeV then remained essentially constant with intensity levels and spectra that may represent the local GCR. The suddenness of these intensity changes indicate that V1 has crossed a well-defined boundary for energetic particles at this time possibly related to the heliopause.

The release of the paper combined with some media outlets omitting the qualifiers, prompted NASA to respond:

Quote:

"The Voyager team is aware of reports today that NASA's Voyager 1 has left the solar system," said Edward Stone, Voyager project scientist based at the California Institute of Technology, Pasadena, Calif. "It is the consensus of the Voyager science team that Voyager 1 has not yet left the solar system or reached interstellar space. In December 2012, the Voyager science team reported that Voyager 1 is within a new region called 'the magnetic highway' where energetic particles changed dramatically. A change in the direction of the magnetic field is the last critical indicator of reaching interstellar space and that change of direction has not yet been observed."

The original paper is worth reading and relatively accessibile to the lay reader - like me.

[elgarak]

Quote:

So far Voyager 1 has 'left the Solar System' by passing through the termination shock three times, the heliopause twice, and once each through the heliosheath, heliosphere, heliodrome, auroral discontinuity, Heaviside layer, trans-Neptunian panic zone, magnetogap, US Census Bureau Solar System statistical boundary, Kuiper gauntlet, Oort void, and crystal sphere holding the fixed stars.

[pakeha]

Originally Posted by Cylinder

Geophysical Research Letters has published a paper that's causing a minor dust-up.



The release of the paper combined with some media outlets omitting the qualifiers, prompted NASA to respond:



The original paper is worth reading and relatively accessibile to the lay reader - like me.

Thanks for the links!