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Re: Voyager Reflection

Post by HVYMETL » Tue Feb 23, 2010 6:13 am

I remember reading an article in 'Science News' years ago that the slowness of the clock in Voyager differed slightly from what Einstein's T.O.R. had predicted. Does anyone recall this or have an explanation?

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Re: Voyager Reflection

Post by Orca » Thu Mar 04, 2010 5:30 am

Well, maybe Chris can answer this one: when figuring out relativistic time dilation, say between the surface of the Earth and Voyager, do you only factor relative speeds within that reference frame or must you also consider the Earth's velocity, say, around the sun as well? After all, the orbital speed of the earth is about as fast as Voyager. Or do we not count this because Voyager's initial velocity included it?

But this also begs the question, how many cascading reference frames would you include in such a calculation? I supposed we don't need to worry about anything above the solar system, as I imagine both the Earth and Voyager are still orbiting the galactic core as they were before voyager was launched.

My point is that perhaps if we ignore entire layers of the calculation, we'd see different results than we'd expect if we were looking at it from the standpoint of an Earth-Voyager system and considered Earth to be stationary.

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JPL: Engineers Diagnosing Voyager 2 Data System

Post by bystander » Fri May 07, 2010 3:52 am

Engineers Diagnosing Voyager 2 Data System
NASA JPL Voyager 2010-151 - 06 May 2010
Engineers have shifted NASA's Voyager 2 spacecraft into a mode that transmits only spacecraft health and status data while they diagnose an unexpected change in the pattern of returning data. Preliminary engineering data received on May 1 show the spacecraft is basically healthy, and that the source of the issue is the flight data system, which is responsible for formatting the data to send back to Earth. The change in the data return pattern has prevented mission managers from decoding science data.

The first changes in the return of data packets from Voyager 2, which is near the edge of our solar system, appeared on April 22. Mission team members have been working to troubleshoot and resume the regular flow of science data. Because of a planned roll maneuver and moratorium on sending commands, engineers got their first chance to send commands to the spacecraft on April 30. It takes nearly 13 hours for signals to reach the spacecraft and nearly 13 hours for signals to come down to NASA's Deep Space Network on Earth.
...
Voyager 2 is about 13.8 billion kilometers, or 8.6 billion miles, from Earth. Voyager 1 is about 16.9 billion kilometers (10.5 billion miles) away from Earth.
Is this the beginning of V'ger?

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PS: Update on Voyager 2 status

Post by bystander » Fri May 14, 2010 6:03 am

Update on Voyager 2 status
Planetary Society - 13 May 2010
Good old Voyager 2; she takes a licking and keeps on ticking. I just had a chat with project scientist Ed Stone, and he's "optimistic" that they'll fix her problem and get her back her usual work of returning data from beyond the edge of the solar system.

The mission has zeroed in on a flipped or bad bit in the flight data system being the likely culprit for the spacecraft's current problem with formatting science data properly. Remember that computers store information as strings of ones and zeroes or "on" and "off" bits. Once in a while, a passing cosmic ray can evade the radiation protection on a spacecraft and slam into a memory bit; when that happens, the bit may change value, from zero to one or vice versa. It's a lot like a transcription error in DNA; it's a sort of mutation of the code. It's possible that the flipped bit will have no or insignificant effect on the spacecraft, but once in a while, a flipped bit happens in a very important location and causes serious problems, and that's what the Voyager team thinks happened within Voyager 2's flight data systems

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Re: JPL: Engineers Diagnosing Voyager 2 Data System

Post by owlice » Fri May 14, 2010 6:46 am

bystander, thanks for the update!
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Re: JPL: Engineers Diagnosing Voyager 2 Data System

Post by wonderboy » Fri May 14, 2010 11:51 am

Maybe she has been acosted by other beings and they are sending back data to us regarding them. Was that not one of the purposes of voyager (hence the cd's on the side). We can't see her, so it might be the case :), probably not though.


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Re: JPL: Engineers Diagnosing Voyager 2 Data System

Post by neufer » Fri May 14, 2010 3:03 pm

wonderboy wrote:
Maybe she has been acosted by other beings and they are sending back data to us regarding them.
Was that not one of the purposes of voyager (hence the cd's on the side).
We can't see her, so it might be the case. - Paul
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PS: Voyager 2 status update: Yep, it was a flipped bit

Post by bystander » Tue May 18, 2010 1:57 am

Voyager 2 status update: Yep, it was a flipped bit
Planetary Society - 17 May 2010
Voyager 2's engineers have confirmed that the problem with the spacecraft was indeed the result of a single flipped bit in its software, as they predicted. A fix is planned for Wednesday, May 19. Details as reported here:
One flip of a bit in the memory of an onboard computer appears to have caused the change in the science data pattern returning from Voyager 2, engineers at NASA's Jet Propulsion Laboratory said Monday, May 17. A value in a single memory location was changed from a 0 to a 1.

On May 12, engineers received a full memory readout from the flight data system computer, which formats the data to send back to Earth. They isolated the one bit in the memory that had changed, and they recreated the effect on a computer at JPL. They found the effect agrees with data coming down from the spacecraft. They are planning to reset the bit to its normal state on Wednesday, May 19.

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PS: Voyager 2's flipped bit fixed

Post by bystander » Fri May 21, 2010 10:20 pm

Voyager 2's flipped bit fixed
Planetary Society - 21 May 2010
A happy ending to this story: JPL reported yesterday evening that the flipped bit in Voyager 2's flight data system software has been successfully toggled back to its correct value.
Engineers have successfully corrected the memory on NASA's Voyager 2 spacecraft by resetting a computer bit that had flipped. Reset commands were beamed up to the spacecraft yesterday, Wed., May 19, and engineering data received today confirm that the reset was successful. The Voyager team will continue monitoring the engineering data, and if the bit remains reset, commands to switch to the science data mode will be beamed up to Voyager 2 on Sat., May 22. Receipt of science data would then resume on Sun., May 23.
Yay for the Voyager 2 mission team!

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Re: JPL: Engineers Diagnosing Voyager 2 Data System

Post by owlice » Fri May 21, 2010 10:48 pm

YAY!!!!!!
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Re: JPL: Engineers Diagnosing Voyager 2 Data System

Post by wonderboy » Sun May 23, 2010 10:50 am

Damn and Blast, where are all the aliens!?



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UT: Voyager 2 Update from Dr. Ed Stone

Post by bystander » Wed Jun 02, 2010 3:52 pm

Voyager 2 Update from Dr. Ed Stone
Universe Today - 02 June 2010
In early May 2010, the 33-year-old Voyager 2 spacecraft experienced an anomaly where the data it returned to Earth was unreadable. Engineers diagnosed the problem as a flip of a bit in the memory in the flight data system computer that packages data to transmit back to Earth, and were able to successfully reset the computer. On May 23, Voyager 2 sent back data that was again formatted properly, but the teams wanted to check out all the systems on the spacecraft to make sure everything was working properly. We checked in with Dr. Ed Stone, former director of JPL and the project scientist for the Voyager project since 1972 to get the latest news on how Voyager 2's checkout is progressing.

"The science teams have confirmed that Voyager 2 is again transmitting science data in the expected format and the instruments are fully functional," Stone said via email. "The only remaining action is to reset the clock in the spacecraft's data system that lost time while the memory bit was in the wrong state. The reset commands will be sent to the Voyager 2 in the next two weeks."

The flipped or bad bit in the flight data system was likely caused by a cosmic ray that slipped by the radiation protection on the spacecraft. Since the computer stores information in ones and zeroes, a cosmic ray hit can change the value of a memory bit. The concern was that the flipped bit took place in an important location that could have a serious effect on the spacecraft, but fortunately, the problem was solved "easily."

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JPL: Voyager 2 at 12,000 Days: The Super-Marathon Continues

Post by bystander » Wed Jun 30, 2010 12:42 pm

Voyager 2 at 12,000 Days: The Super-Marathon Continues
NASA JPL (2010-214) 29 June 2010
NASA's plucky Voyager 2 spacecraft has hit a long-haul operations milestone today (June 28) -- operating continuously for 12,000 days. For nearly 33 years, the venerable spacecraft has been returning data about the giant outer planets, and the characteristics and interaction of solar wind between and beyond the planets. Among its many findings, Voyager 2 discovered Neptune's Great Dark Spot and its 450-meter-per-second (1,000-mph) winds.

The two Voyager spacecraft have been the longest continuously operating spacecraft in deep space. Voyager 2 launched on August 20, 1977, when Jimmy Carter was president. Voyager 1 launched about two weeks later on Sept. 5. The two spacecraft are the most distant human-made objects, out at the edge of the heliosphere -- the bubble the sun creates around the solar system. Mission managers expect Voyager 1 to leave our solar system and enter interstellar space in the next five years or so, with Voyager 2 on track to enter interstellar space shortly after that.

Having traveled more than 21 billion kilometers (13 billion miles) on its winding path through the planets toward interstellar space, the spacecraft is now nearly 14 billion kilometers (9 billion miles) from the sun. A signal from the ground, traveling at the speed of light, takes about 12.8 hours one-way to reach Voyager 2.

Voyager 1 will reach this 12,000-day milestone on July 13, 2010 after traveling more than 22 billion kilometers (14 billion miles). Voyager 1 is currently more than 17 billion kilometers (11 billion miles) from the sun.

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JPL: Voyager 1 Sees Solar Wind Decline

Post by bystander » Mon Dec 13, 2010 10:44 pm

Voyage 1 Sees Solar Wind Decline
NASA JPL Voyager | 13 Dec 2010
The 33-year odyssey of NASA's Voyager 1 spacecraft has reached a distant point at the edge of our solar system where there is no outward motion of solar wind.

Now hurtling toward interstellar space some 17.4 billion kilometers (10.8 billion miles) from the sun, Voyager 1 has crossed into an area where the velocity of the hot ionized gas, or plasma, emanating directly outward from the sun has slowed to zero. Scientists suspect the solar wind has been turned sideways by the pressure from the interstellar wind in the region between stars.

The event is a major milestone in Voyager 1's passage through the heliosheath, the turbulent outer shell of the sun's sphere of influence, and the spacecraft's upcoming departure from our solar system.

"The solar wind has turned the corner," said Ed Stone, Voyager project scientist based at the California Institute of Technology in Pasadena, Calif. "Voyager 1 is getting close to interstellar space."

Our sun gives off a stream of charged particles that form a bubble known as the heliosphere around our solar system. The solar wind travels at supersonic speed until it crosses a shockwave called the termination shock. At this point, the solar wind dramatically slows down and heats up in the heliosheath.

Launched on Sept. 5, 1977, Voyager 1 crossed the termination shock in December 2004 into the heliosheath. Scientists have used data from Voyager 1's Low-Energy Charged Particle Instrument to deduce the solar wind's velocity. When the speed of the charged particles hitting the outward face of Voyager 1 matched the spacecraft's speed, researchers knew that the net outward speed of the solar wind was zero. This occurred in June, when Voyager 1 was about 17 billion kilometers (10.6 billion miles) from the sun.

Because the velocities can fluctuate, scientists watched four more monthly readings before they were convinced the solar wind's outward speed actually had slowed to zero. Analysis of the data shows the velocity of the solar wind has steadily slowed at a rate of about 20 kilometers per second each year (45,000 mph each year) since August 2007, when the solar wind was speeding outward at about 60 kilometers per second (130,000 mph). The outward speed has remained at zero since June.

The results were presented today at the American Geophysical Union meeting in San Francisco.

"When I realized that we were getting solid zeroes, I was amazed," said Rob Decker, a Voyager Low-Energy Charged Particle Instrument co-investigator and senior staff scientist at the Johns Hopkins University Applied Physics Laboratory in Laurel, Md. "Here was Voyager, a spacecraft that has been a workhorse for 33 years, showing us something completely new again."

Scientists believe Voyager 1 has not crossed the heliosheath into interstellar space. Crossing into interstellar space would mean a sudden drop in the density of hot particles and an increase in the density of cold particles. Scientists are putting the data into their models of the heliosphere's structure and should be able to better estimate when Voyager 1 will reach interstellar space. Researchers currently estimate Voyager 1 will cross that frontier in about four years.

"In science, there is nothing like a reality check to shake things up, and Voyager 1 provided that with hard facts," said Tom Krimigis, principal investigator on the Low-Energy Charged Particle Instrument, who is based at the Applied Physics Laboratory and the Academy of Athens, Greece. "Once again, we face the predicament of redoing our models."

A sister spacecraft, Voyager 2, was launched in Aug. 20, 1977 and has reached a position 14.2 billion kilometers (8.8 billion miles) from the sun. Both spacecraft have been traveling along different trajectories and at different speeds. Voyager 1 is traveling faster, at a speed of about 17 kilometers per second (38,000 mph), compared to Voyager 2's velocity of 15 kilometers per second (35,000 mph). In the next few years, scientists expect Voyager 2 to encounter the same kind of phenomenon as Voyager 1.
http://www.nasa.gov/mission_pages/voyager/index.html
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ScottTheSculptor

Voyager Reflection

Post by ScottTheSculptor » Mon Apr 04, 2011 4:37 pm

I have a "crackpot" theory that explains the discrepencies in spacecraft time.
...
Last edited by ScottTheSculptor on Tue Aug 30, 2011 3:26 am, edited 2 times in total.
Reason: links to posts in other forums removed

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Re: Voyager Reflection

Post by bystander » Mon Apr 04, 2011 4:57 pm

ScottTheSculptor wrote:I have a "crackpot" theory that explains the discrepencies in spacecraft time.
...
This is a mainstream forum, not a place for "crackpot" speculation. It is also not the place for self promotion (spam). Read the rules.

If you have questions, feel free to ask them, but don't post wild musings and speculations and call them theories.
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Re: Voyager Reflection

Post by neufer » Tue Apr 05, 2011 1:20 pm

Chris Peterson wrote:
By my calculation, assuming that Voyager 1 was traveling at 17 km/s the entire 32 years (which it wasn't, but close enough for our purposes, I think), its clock is now behind ours by about 1.6 seconds.
Orca wrote:
Well, maybe Chris can answer this one: when figuring out relativistic time dilation, say between the surface of the Earth and Voyager, do you only factor relative speeds within that reference frame or must you also consider the Earth's velocity, say, around the sun as well? After all, the orbital speed of the earth is about as fast as Voyager. Or do we not count this because Voyager's initial velocity included it?

But this also begs the question, how many cascading reference frames would you include in such a calculation? I supposed we don't need to worry about anything above the solar system, as I imagine both the Earth and Voyager are still orbiting the galactic core as they were before voyager was launched.

My point is that perhaps if we ignore entire layers of the calculation, we'd see different results than we'd expect if we were looking at it from the standpoint of an Earth-Voyager system and considered Earth to be stationary.
General Relativistic Time Dilation of Earth clocks [proportional to (Vescape)2] exceeds all Special Relativity adjustments in this case.

Both Voyager & Earth observers would concur that Voyager clocks are ahead of those on Earth by some few seconds.
  • 1) Locally, clocks in free-fall run faster than those not in free-fall.

    2) Globally, clocks further from the sun run faster than those closer to the sun.
Voyager is both in free-fall & further from the sun.
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Re: Voyager Reflection

Post by Not a scientist » Mon Apr 18, 2011 8:10 am

Can Voyager just tell us what time it is on-board?
What time is it now on Messenger or Cassini, or even the Mars Rovers. They must all have internal clocks set to the time they departed Earth. It would be interesting to study this data and compare them to calculations here on Earth. Anybody know if this has been studied by NASA?

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Re: Voyager Reflection

Post by neufer » Mon Apr 18, 2011 3:59 pm

Not a scientist wrote:
Can Voyager just tell us what time it is on-board?
What time is it now on Messenger or Cassini, or even the Mars Rovers. They must all have internal clocks set to the time they departed Earth. It would be interesting to study this data and compare them to calculations here on Earth. Anybody know if this has been studied by NASA?
All computers contain internal clocks to regulate their data processing but these are not long term highly accurate (and hence heavy) 'atomic clocks'.

The main use of planetary exploration spacecraft to test relativity has been for the Shapiro time delay effect on 'instantaneous' communications.
http://en.wikipedia.org/wiki/Shapiro_delay wrote:
<<Radar signals passing near a massive object take slightly longer to travel to a target and longer to return than it would if the mass of the object were not present. The time delay effect was first noticed in 1964, by Irwin I. Shapiro. Shapiro proposed an observational test of his prediction: bounce radar beams off the surface of Venus and Mercury, and measure the round trip travel time. When the Earth, Sun, and Venus are most favorably aligned, Shapiro showed that the expected time delay, due to the presence of the Sun, of a radar signal traveling from the Earth to Venus and back, would be about 200 microseconds, well within the limitations of 1960s era technology. The first tests, performed in 1966 and 1967 using the MIT Haystack radar antenna, were successful, matching the predicted amount of time delay. The experiments have been repeated many times since then, with increasing accuracy. Observing radar reflections from Mercury and Venus just before and after it will be eclipsed by the Sun gives agreement with general relativity theory at the 5% level. More recently, the Cassini probe has undertaken a similar experiment which gave agreement with general relativity at the 0.002% level.
  • "In the second place our result shows that, according to the general theory of relativity, the law of the constancy of the velocity of light in vacuum, which constitutes one of the two fundamental assumptions in the special theory of relativity and to which we have already frequently referred, cannot claim any unlimited validity. A curvature of rays of light can only take place when the velocity of propagation of light varies with position. Now we might think that as a consequence of this, the special theory of relativity and with it the whole theory of relativity would be laid in the dust. But in reality this is not the case. We can only conclude that the special theory of relativity cannot claim an unlimited domain of validity ; its results hold only so long as we are able to disregard the influences of gravitational fields on the phenomena (e.g. of light)." – Albert Einstein (The General Theory of Relativity: Chapter 22)
In a near-statical gravitational field of moderate strength (say, of stars and planets, but not one of a black hole or close binary system of neutron stars) the effect may be considered as a special case of gravitational time dilation. The speed of light in meters per given interval of "local time" (calculated by the metric tensor) is a constant, however the travel time of any electromagnetic wave, or signal, moving at 299,792,458 meters per "second" is affected by the time dilation in regions of the space through which it travels. This is because the coordinate time and locally calculated time diverge as the gravitational field potential increases (by absolute value).>>
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UT: Voyager 1 Measures Magnetic Mayhem

Post by bystander » Thu Jun 02, 2011 8:45 am

Voyager 1 Measures Magnetic Mayhem
Universe Today | Tammy Plotner | 2011 May 31
When Voyager 1 passed into the heliosheath in 2004, it became the first man-made object to explore the remote edge of the Sun’s magnetic influence. Launched by NASA on September 5, 1977, the probe was designed to study the outer Solar System and eventually interstellar space. One of its missions was to look for the heliopause – the boundary at which the solar wind transitions into the interstellar medium. What it found was mayhem…

According to NASA, Voyager 1 has crossed into an area where the velocity of the hot ionized gas, or plasma, emanating directly outward from the sun has slowed to zero. Scientists suspect the solar wind has been turned sideways by the pressure from the interstellar wind in the region between stars. “The solar wind has turned the corner,” said Ed Stone, Voyager project scientist based at the California Institute of Technology in Pasadena, Calif. “Voyager 1 is getting close to interstellar space.”

Now it has entered the heliosheath, an area ranging from 1.5 to 15 billion kilometers thick (930 million to 9.3 billion miles) and starting roughly 14 billion km (8.7 billion mi) from the Sun. But there’s nothing quiet here. This is the area where outgoing flows of solar wind begin to be repelled by interstellar particles and magnetic fields pushing towards the solar system. While passing through the heliosheath, Voyager 1 experienced many sudden and drastic changes in the surrounding magnetic field driven by structures called current sheets.

The team of L. F. Burlaga: Geospace Physics Laboratory, NASA Goddard Space Flight Center and N. F. Ness of the Institute for Astrophysics and Computational Sciences have been studying the ongoing results sent back by Voyager and have come to a new conclusion – there are three distinct types of current sheets.
“The structures, appearing as proton boundary layers (PBLs), magnetic holes or humps, or sector boundaries, were identified by characteristic ffluctuations in either magnetic field strength or direction as the spacecraft crossed nearly 500 million km (310 million mi) of heliosheath in 2009. PBLs are defined by a rapid jump in magnetic field strength, with one observed event resulting in a doubling of the field strength in just half an hour.” said the team. “Passing through a sector boundary led to a sudden change in direction of the magnetic field. Magnetic holes saw the field strength drop to near zero before returning to the original background strength. Magnetic humps consisted of a sudden spike in strength and then a return to initial levels.”

But this isn’t the first time the Voyager has returned zero readings. In December 2004 the intrepid probe broke the barrier of the termination shock and data from Voyager 1′s Low-Energy Charged Particle Instrument was used to deduce the solar wind’s velocity. When the speed of the particles matched the speed of the spacecraft, scientists knew they had a null number on their records. “When I realized that we were getting solid zeroes, I was amazed,” said Rob Decker, a Voyager Low-Energy Charged Particle Instrument co-investigator and senior staff scientist at the Johns Hopkins University Applied Physics Laboratory in Laurel, Md. “Here was Voyager, a spacecraft that has been a workhorse for 33 years, showing us something completely new again.”

A new is what we need to continue our understanding of what lay at the furthest reaches of our now explorable space. Says Burlaga, “The firsthand detections made by Voyager 1 are likely to be extremely important for researchers trying to decide between current leading theories for the source and structure of current sheets.”
Current sheets in the heliosheath: Voyager 1, 2009 - L. F. Burlaga, N. F. Ness
  • Journal of Geophysical Researrch 116 A05102 (10 May 2011) DOI: [url=http:/dx.doi.org/10.1029/2010JA016309]10.1029/2010JA016309[/url]
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JPL: Probes Suggest Magnetic Bubbles at Solar System Edge

Post by bystander » Thu Jun 09, 2011 8:24 pm

Probes Suggest Magnetic Bubbles at Solar System Edge
NASA JPL-Caltech Voyager | 2011 Jun 09
Observations from NASA's Voyager spacecraft, humanity's farthest deep space sentinels, suggest the edge of our solar system may not be smooth, but filled with a turbulent sea of magnetic bubbles.

While using a new computer model to analyze Voyager data, scientists found the sun's distant magnetic field is made up of bubbles approximately 100 million miles (160 million kilometers) wide. The bubbles are created when magnetic field lines reorganize. The new model suggests the field lines are broken up into self-contained structures disconnected from the solar magnetic field. The findings are described in the June 9 edition of the Astrophysical Journal.

Like Earth, our sun has a magnetic field with a north pole and a south pole. The field lines are stretched outward by the solar wind, a stream of charged particles emanating from the star that interacts with material expelled from others in our corner of the Milky Way galaxy. The Voyager spacecraft, more than 9 billion miles (14 billion kilometers) away from Earth, are traveling in a boundary region. In that area, the solar wind and magnetic field are affected by material expelled from other stars in our corner of the Milky Way galaxy.

"The sun's magnetic field extends all the way to the edge of the solar system," said astronomer Merav Opher of Boston University. "Because the sun spins, its magnetic field becomes twisted and wrinkled, a bit like a ballerina's skirt. Far, far away from the sun, where the Voyagers are, the folds of the skirt bunch up."

Understanding the structure of the sun's magnetic field will allow scientists to explain how galactic cosmic rays enter our solar system and help define how the star interacts with the rest of the galaxy.

So far, much of the evidence for the existence of the bubbles originates from an instrument aboard the spacecraft that measures energetic particles. Investigators are studying more information and hoping to find signatures of the bubbles in the Voyager magnetic field data.

"We are still trying to wrap our minds around the implications of the findings," said University of Maryland physicist Jim Drake, one of Opher's colleagues.

Launched in 1977, the Voyager twin spacecraft have been on a 33-year journey. They are en route to reach the edge of interstellar space. NASA's Jet Propulsion Laboratory in Pasadena, Calif., built the spacecraft and continues to operate them. The Voyager missions are a part of the Heliophysics System Observatory, sponsored by the Heliophysics Division of NASA's Science Mission Directorate in Washington. JPL is a division of the California Institute of Technology in Pasadena.

To view supporting images about the research, visit: http://www.nasa.gov/sunearth .

More information about Voyager is available at: http://www.nasa.gov/voyager and http://voyager.jpl.nasa.gov .
A Big Surprise from the Edge of the Solar System
NASA Science News | Dr. Tony Phillips | 2011 Jun 09
Click to play embedded YouTube video.
Click to play embedded YouTube video.
NASA's Voyager probes are truly going where no one has gone before. Gliding silently toward the stars, 9 billion miles from Earth, they are beaming back news from the most distant, unexplored reaches of the solar system.

Mission scientists say the probes have just sent back some very big news indeed.

It's bubbly out there.

"The Voyager probes appear to have entered a strange realm of frothy magnetic bubbles," says astronomer Merav Opher of Boston University. "This is very surprising."

According to computer models, the bubbles are large, about 100 million miles wide, so it would take the speedy probes weeks to cross just one of them. Voyager 1 entered the "foam-zone" around 2007, and Voyager 2 followed about a year later. At first researchers didn't understand what the Voyagers were sensing--but now they have a good idea.

"The sun's magnetic field extends all the way to the edge of the solar system," explains Opher. "Because the sun spins, its magnetic field becomes twisted and wrinkled, a bit like a ballerina's skirt. Far, far away from the sun, where the Voyagers are now, the folds of the skirt bunch up."

When a magnetic field gets severely folded like this, interesting things can happen. Lines of magnetic force criss-cross and "reconnect". (Magnetic reconnection is the same energetic process underlying solar flares.) The crowded folds of the skirt reorganize themselves, sometimes explosively, into foamy magnetic bubbles.

"We never expected to find such a foam at the edge of the solar system, but there it is!" says Opher's colleague, University of Maryland physicist Jim Drake.

Theories dating back to the 1950s had predicted a very different scenario: The distant magnetic field of the sun was supposed to curve around in relatively graceful arcs, eventually folding back to rejoin the sun. The actual bubbles appear to be self-contained and substantially disconnected from the broader solar magnetic field.

Energetic particle sensor readings suggest that the Voyagers are occasionally dipping in and out of the foam—so there might be regions where the old ideas still hold. But there is no question that old models alone cannot explain what the Voyagers have found.

Says Drake: "We are still trying to wrap our minds around the implications of these findings."

The structure of the sun's distant magnetic field—foam vs. no-foam—is of acute scientific importance because it defines how we interact with the rest of the galaxy. Researchers call the region where the Voyagers are now "the heliosheath." It is essentially the border crossing between the Solar System and the rest of the Milky Way. Lots of things try to get across—interstellar clouds, knots of galactic magnetism, cosmic rays and so on. Will these intruders encounter a riot of bubbly magnetism (the new view) or graceful lines of magnetic force leading back to the sun (the old view)?

The case of cosmic rays is illustrative. Galactic cosmic rays are subatomic particles accelerated to near-light speed by distant black holes and supernova explosions. When these microscopic cannonballs try to enter the solar system, they have to fight through the sun's magnetic field to reach the inner planets.

"The magnetic bubbles could be our first line of defense against cosmic rays," points out Opher. "We haven't figured out yet if this is a good thing or not."

On one hand, the bubbles would seem to be a very porous shield, allowing many cosmic rays through the gaps. On the other hand, cosmic rays could get trapped inside the bubbles, which would make the froth a very good shield indeed.

"We'll probably discover which is correct as the Voyagers proceed deeper into the froth and learn more about its organization1," says Opher. "This is just the beginning, and I predict more surprises ahead."
Kinetic versus Multi-fluid Approach for Interstellar Neutrals in the Heliosphere:
Exploration of the Interstellar Magnetic Field Effects
- F Alouani-Bibi et al
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neufer
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Re: JPL: Probes Suggest Magnetic Bubbles at Solar System Edg

Post by neufer » Thu Jun 09, 2011 9:26 pm

Image
bystander wrote:Probes Suggest Magnetic Bubbles at Solar System Edge
NASA JPL-Caltech Voyager | 2011 Jun 09
Observations from NASA's Voyager spacecraft, humanity's farthest deep space sentinels, suggest the edge of our solar system may not be smooth, but filled with a turbulent sea of magnetic bubbles.

While using a new computer model to analyze Voyager data, scientists found the sun's distant magnetic field is made up of bubbles approximately 100 million miles (160 million kilometers) wide. The bubbles are created when magnetic field lines reorganize. The new model suggests the field lines are broken up into self-contained structures disconnected from the solar magnetic field. The findings are described in the June 9 edition of the Astrophysical Journal.

Like Earth, our sun has a magnetic field with a north pole and a south pole. The field lines are stretched outward by the solar wind, a stream of charged particles emanating from the star that interacts with material expelled from others in our corner of the Milky Way galaxy. The Voyager spacecraft, more than 9 billion miles (14 billion kilometers) away from Earth, are traveling in a boundary region. In that area, the solar wind and magnetic field are affected by material expelled from other stars in our corner of the Milky Way galaxy.

"The sun's magnetic field extends all the way to the edge of the solar system," said astronomer Merav Opher of Boston University. "Because the sun spins, its magnetic field becomes twisted and wrinkled, a bit like a ballerina's skirt. Far, far away from the sun, where the Voyagers are, the folds of the skirt bunch up."

Understanding the structure of the sun's magnetic field will allow scientists to explain how galactic cosmic rays enter our solar system and help define how the star interacts with the rest of the galaxy.

So far, much of the evidence for the existence of the bubbles originates from an instrument aboard the spacecraft that measures energetic particles. Investigators are studying more information and hoping to find signatures of the bubbles in the Voyager magnetic field data.

"We are still trying to wrap our minds around the implications of the findings," said University of Maryland physicist Jim Drake, one of Opher's colleagues.

Launched in 1977, the Voyager twin spacecraft have been on a 33-year journey. They are en route to reach the edge of interstellar space. NASA's Jet Propulsion Laboratory in Pasadena, Calif., built the spacecraft and continues to operate them. The Voyager missions are a part of the Heliophysics System Observatory, sponsored by the Heliophysics Division of NASA's Science Mission Directorate in Washington. JPL is a division of the California Institute of Technology in Pasadena.

To view supporting images about the research, visit: http://www.nasa.gov/sunearth .

More information about Voyager is available at: http://www.nasa.gov/voyager and http://voyager.jpl.nasa.gov .
A Big Surprise from the Edge of the Solar System
NASA Science News | Dr. Tony Phillips | 2011 Jun 09
Click to play embedded YouTube video.
Click to play embedded YouTube video.
Mission scientists say the probes have just sent back some very big news indeed.

It's bubbly out there.
Art Neuendorffer

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Voyager 1 and 2

Post by saturno2 » Sun Jun 03, 2012 2:32 pm

I have understood that Voyager 1 and 2 out of the heliosphere and entered the helios-pause.
Well, but based the plane of the ecliptic, what angle took each, and what is your reference point in the distance? ( For your way of travel)

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Re: Voyager 1 and 2

Post by Chris Peterson » Sun Jun 03, 2012 2:52 pm

saturno2 wrote:I have understood that Voyager 1 and 2 out of the heliosphere and entered the helios-pause.
Well, but based the plane of the ecliptic, what angle took each, and what is your reference point in the distance? ( For your way of travel)
When they talk about the distance these probes have traveled, it is with respect to the Sun. That's the reference point.
Chris

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Re: Voyager 1 and 2

Post by rstevenson » Sun Jun 03, 2012 5:47 pm

This page at NASA shows the current locations, updated in real time, and gives the round-trip light time from the sun.

Rob