Voyager Enters Final Frontier Of Solar System |
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Voyager Enters Final Frontier Of Solar System |
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#31
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![]() Senior Member ![]() ![]() ![]() ![]() Group: Members Posts: 2454 Joined: 8-July 05 From: NGC 5907 Member No.: 430 ![]() |
PHYSICS NEWS UPDATE
The American Institute of Physics Bulletin of Physics News Number 778 May 26, 2006 by Phillip F. Schewe, Ben Stein, and Davide Castelvecchi www.aip.org/pnu THE MISSHAPEN SOLAR SYSTEM. Having traveled far beyond the planets in their 28.5-year journey, the two Voyager spacecraft are providing new information on the heliosphere, the teardrop-shaped bubble that separates the solar system from interstellar space. At this week's Joint Assembly Meeting in Baltimore of the American Geophysical Union (AGU) and several other geophysics-related societies, Ed Stone of Caltech reported that the heliosphere is deformed, according to Voyager observations, with the teardrop's rounded edge bulging at the top (the northern hemisphere of the solar system) and squashed at the bottom (the southern hemisphere). (See pictures and movies at http://www.nasa.gov/vision/universe/solars...er_2006agu.html ) As Rob Decker of Johns Hopkins University Applied Physics Laboratory explained, the asymmetry is due to a magnetic field from interstellar space pushing on the southern hemisphere. The field is about 1/100,000 the strength of Earth's field but its effects can be felt for billions of miles, since it is acting over a large area on the very dilute gas at the solar system's edge. The interstellar field even squashes an important spherical zone inside the heliosphere, called the termination shock. Analogous to the circle that forms when water splatters on a sink, the termination shock represents the boundary at which the rapidly traveling solar wind (the stream of charged gas from the sun) slows down abruptly and piles up. Voyager 2's measurements indicate that the southern part of the termination sphere might be a billion miles closer to the sun than the northern part. Moreover, forces from the solar wind cause the termination shock to breathe in and out roughly every dozen years. Voyager 1 has already ventured beyond the termination shock, to the heliosheath, the region where solar wind and interstellar gas mix. So in a way, the end of the solar system is not clearly defined. Stone guesses it could be another 10 years (3-4 billion miles) before the two spacecraft pass through the heliopause (the very outermost boundary of the heliosphere) and enter purely interstellar space. The spacecraft have about another 15 years of power left in them. (Session SH02 at meeting; see http://www.agu.org/meetings/ja06/?content=search) Do you have a link to the press kit? Or a press kit etc. of any of the other encounters? Analyst There is the Voyager Neptune Travel Guide online: http://ntrs.nasa.gov/archive/nasa/casi.ntr..._1990004096.pdf Other online Voyager documents from NASA can be found here by scrolling all the way down (the spacecraft are listed in alphabetical order): http://www.geocities.com/bobandrepont/unmannedpdf.htm -------------------- "After having some business dealings with men, I am occasionally chagrined,
and feel as if I had done some wrong, and it is hard to forget the ugly circumstance. I see that such intercourse long continued would make one thoroughly prosaic, hard, and coarse. But the longest intercourse with Nature, though in her rudest moods, does not thus harden and make coarse. A hard, sensible man whom we liken to a rock is indeed much harder than a rock. From hard, coarse, insensible men with whom I have no sympathy, I go to commune with the rocks, whose hearts are comparatively soft." - Henry David Thoreau, November 15, 1853 |
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#32
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![]() Senior Member ![]() ![]() ![]() ![]() Group: Members Posts: 2454 Joined: 8-July 05 From: NGC 5907 Member No.: 430 ![]() |
Voyager Reports March 3, 2006 to March 24, 2006 Available
http://voyager.jpl.nasa.gov/mission/weekly-reports/index.htm -------------------- "After having some business dealings with men, I am occasionally chagrined,
and feel as if I had done some wrong, and it is hard to forget the ugly circumstance. I see that such intercourse long continued would make one thoroughly prosaic, hard, and coarse. But the longest intercourse with Nature, though in her rudest moods, does not thus harden and make coarse. A hard, sensible man whom we liken to a rock is indeed much harder than a rock. From hard, coarse, insensible men with whom I have no sympathy, I go to commune with the rocks, whose hearts are comparatively soft." - Henry David Thoreau, November 15, 1853 |
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#33
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![]() Junior Member ![]() ![]() Group: Members Posts: 21 Joined: 17-August 06 Member No.: 1048 ![]() |
There's a new story at science.nasa.gov about some of the things Voyager 1 has found within the heliosheath. Magnetic turbulence, a slower than expected solar wind, and unexpected anomalous cosmic ray intensities are the main things mentioned. I hope this helps make the case for continued funding.
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#34
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![]() Senior Member ![]() ![]() ![]() ![]() Group: Members Posts: 2492 Joined: 15-January 05 From: center Italy Member No.: 150 ![]() |
This is not exactly a new: Voyager 2 entered the heliosheath on August 30, 2007.
http://voyager.jpl.nasa.gov/news/voyager_squashed.html However, incredibly, I completely ignored the event on this page and only now I "discovered" it by looking to these eloquent plots: http://web.mit.edu/space/www/voyager/voyag...plot_recent.gif (in the past, I was looking more often to these data but in recent months I'm more and more busy ![]() Looking to this Forum section, it seems nobody noticed it... cannot believe anyone missed it like me! ![]() Addendum: based on Solar System Simulator, cross occurred at 83.7 AU from sun, about 10 AU closer than Voyager-1! -------------------- I always think before posting! - Marco -
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#35
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![]() Senior Member ![]() ![]() ![]() ![]() Group: Members Posts: 2492 Joined: 15-January 05 From: center Italy Member No.: 150 ![]() |
Further infos: As you know, contrary to his brother, Voyager 2 has a working Plasma Science instrument that can directly measure the velocity, density and temperature of the solar wind.
I downloaded hourly data from this plasma science page. Following plots shows trend of measured proton speed, thermal speed (temperature) and density (second plot is a temporal enlargement covering the transition (window is 0.1 years or 36.5 days large): As mentioned in the article, Voyager-2 had at least five shock crossings over a couple of days; perhaps they are the density peaks visible in second plot. QUESTION: why there is a so large hiatus (11 days) in the data immediately after this event??? Too strange for a coincidence! They also found a much lower temperature beyond the shock than was predicted; anyway, based on following scatter plots (referred to data in the narrow temporal window of second plot above) there is a good correlation (almost inverse-square) between these twoparameters: Any comment is welcomed! -------------------- I always think before posting! - Marco -
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#36
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![]() Senior Member ![]() ![]() ![]() ![]() Group: Members Posts: 1628 Joined: 5-March 05 From: Boulder, CO Member No.: 184 ![]() |
I saw a nice talk that Ed Stone gave on this topic three days ago. It will be interesting to follow along for a decade or so to see what the magnetic field looks like when Voyager gets completely into the interstellar medium.
-------------------- Steve [ my home page and planetary maps page ]
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#37
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![]() Member ![]() ![]() ![]() Group: Members Posts: 754 Joined: 9-February 07 Member No.: 1700 ![]() |
(edit: of course this is old news to UMSF thread readers!)
The solar system is 'dented' as reported in this CNN Article. I'm curious about how they refer to 'north' and 'south', and whether the motion of the Sun through the Milky Way impacts the escape velocities of the Voyagers. (2nd edit: I thought I had asked the velocity question somewhere before, and found that dmuller provided insight in this post over in the New Horizons thread. thank you dmuller!) |
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#38
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![]() Senior Member ![]() ![]() ![]() ![]() Group: Members Posts: 1729 Joined: 3-August 06 From: 43° 35' 53" N 1° 26' 35" E Member No.: 1004 ![]() |
In the latest issue of Astronomy & Astrophysics
Imaging the heliosheath using HSTOF energetic neutral atoms and Voyager 1 ion data |
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#39
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Member ![]() ![]() ![]() Group: Members Posts: 293 Joined: 22-September 08 From: Spain Member No.: 4350 ![]() |
You may want to look at Voyager 2 wind speed data:
http://web.mit.edu/afs/athena/org/s/space/...yager_data.html There was a nice spike last month, from ~225 km/s to ~325 km/s, the fastest speed since it crossed the termination shock. |
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Guest_PhilCo126_* |
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#40
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Guests ![]() |
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#41
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![]() Senior Member ![]() ![]() ![]() ![]() Group: Members Posts: 1729 Joined: 3-August 06 From: 43° 35' 53" N 1° 26' 35" E Member No.: 1004 ![]() |
The latest issue of Astronomy & Astrophystics (v491 n1) has some articles about heliospheric science, including results from Voyager, Ulysses, Cassini, Nozomi etc.
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#42
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![]() Senior Member ![]() ![]() ![]() ![]() Group: Members Posts: 2492 Joined: 15-January 05 From: center Italy Member No.: 150 ![]() |
Grazie, Paolo. Very interesting!
-------------------- I always think before posting! - Marco -
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Guest_Enceladus75_* |
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#43
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I'm curious to know what science instruments are still functional on each Voyager. I'm aware that the cameras are now permanently turned off Voyager 2 has some more capability at measuring fields and particles over Voyager 1, but what instruments are actually still operational?
And for how long are they expected to remain operational? |
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#44
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Member ![]() ![]() ![]() Group: Members Posts: 293 Joined: 22-September 08 From: Spain Member No.: 4350 ![]() |
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#45
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![]() Senior Member ![]() ![]() ![]() ![]() Group: Members Posts: 2492 Joined: 15-January 05 From: center Italy Member No.: 150 ![]() |
and about instruments (from wikipedia):
As of the present date, the Voyager 2 and Voyager 1 scan platforms, including all of the platform instruments, have been powered down. The ultraviolet spectrometer (UVS) on Voyager 1 was active until 2003, when it too was deactivated. Gyro operations will end in 2010 for Voyager 2 and 2011 for Voyager 1. Gyro operations are used to rotate the probe 360 degrees six times a year to measure the magnetic field of the spacecraft, which is then subtracted from the magnetometer science data. -------------------- I always think before posting! - Marco -
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