From The Planetary Society update:
Our strategy for the upcoming analysis of the newly available data can be summed up as follows: First, studying the early mission data may help us unambiguously determine whether the acceleration points towards the Earth, the Sun, or some other direction. Second, we hope to find out how the anomaly begins or if it was present throughout the mission. Third, we hope to be able to determine how this anomalous acceleration changed over time. Fourth, we will compare data from the two Pioneers to see if we can discern any notable differences in their behavior. Lastly, we will use the MDRs to develop a better engineering model of the spacecraft, making use, for instance, of finite element analysis methods to understand its thermal behavior.
In March 2006, for the very last time the Earth will be in a favorable position to receive Pioneer 10's radio signal. It is possible that Pioneer 10 is still able to transmit, despite the age of its electronics, the extreme coldness of deep space, and the diminishing amount of electrical power on board. The possibility that the Deep Space Network will attempt to reacquire Pioneer 10's weak signal is currently being investigated, raising the hope, however faint, that we may yet have another data point to aid in our investigation of the Pioneers' enigmatic behavior.
The rest is here:
http://planetary.org/programs/projects/pio...ate_200601.html
Full Version: The Pioneer Anomaly
QUOTE (ljk4-1 @ Feb 1 2006, 04:02 AM)
From The Planetary Society update:
Our strategy for the upcoming analysis of the newly available data ...
The rest is here:
http://planetary.org/programs/projects/pio...ate_200601.html
Our strategy for the upcoming analysis of the newly available data ...
The rest is here:
http://planetary.org/programs/projects/pio...ate_200601.html
So this data was recovered and is now safe. Good move. Now serious work can begin.
QUOTE (Richard Trigaux @ Feb 1 2006, 01:27 AM)
So this data was recovered and is now safe. Good move. Now serious work can begin.
It is an extremely difficult and tedious proposition. Each operation of a thruster must be accounted for, and every encounter with a third body - a moon, a planet, and a planetary system requires accurate mass and distance estimates.
It will be interesting to see if the Pioneer probe data pans out in the lower orbits like Cassini, Galileo, and Ulysses. Each of these probes experienced, (or rather, accelerations were measured), that exceed the 'Pioneer' effect by at least one magnitude, however, it is not possible to untangle the measured acceleration from the solar wind: It is in the same direction. (I think this measured anomally in Galileo and Ulysses is also in the opposite direction from the Pioneer probe acceleration - I don't have any numbers, other than a magnitude for Cassini.)
We will be lucky if we can hear from Pioneer in March, but if I remember correctly, the probe is no longer executing commands, so it may not be possible to enter the Doppler-repeater mode necessary for accurate distant measurements. (In this mode, the Pioneer probes echoed back an ultrastable signal sent from the Earth a harmonic frequency. If we are only listening to the Pioneer transmitter, there is not sufficent accuracy in the on-board timing to obtain accurate distance estimates.)
QUOTE (The Messenger @ Feb 1 2006, 03:54 PM)
We will be lucky if we can hear from Pioneer in March, but if I remember correctly, the probe is no longer executing commands,
Why the probe is no longer executing commands? if it is because the power it receives is too weak, it would be worth using a large radio transmitter, such as Arecibo. Obtaining a last point of Pioneer effect is worth some seconds of Arecibo I think
QUOTE (The Messenger @ Feb 1 2006, 03:54 PM)
It will be interesting to see if the Pioneer probe data pans out in the lower orbits like Cassini, Galileo, and Ulysses. Each of these probes experienced, (or rather, accelerations were measured), that exceed the 'Pioneer' effect by at least one magnitude, however, it is not possible to untangle the measured acceleration from the solar wind: It is in the same direction. (I think this measured anomally in Galileo and Ulysses is also in the opposite direction from the Pioneer probe acceleration - I don't have any numbers, other than a magnitude for Cassini.)
It is not sure at all that the solar wind has a constant amplitude (speed, density, directio) everywhere. Especially it could be weaker out of the ecliptic,and eventually very variable. Ulysse data should tell us.
QUOTE (Richard Trigaux @ Feb 2 2006, 10:54 AM)
Why the probe is no longer executing commands? if it is because the power it receives is too weak, it would be worth using a large radio transmitter, such as Arecibo. Obtaining a last point of Pioneer effect is worth some seconds of Arecibo I think
It doesn't have to execute commands at all. All we need is detection of its carrier signal to measure the Doppler effect.
QUOTE (Richard Trigaux)
It is not sure at all that the solar wind has a constant amplitude (speed, density, directio) everywhere. Especially it could be weaker out of the ecliptic,and eventually very variable. Ulysse data should tell us.
It's a constant misconception/mixup that the solar wind is pushing on these probes. While to some extent you might say a force is being felt, a few particles per cubic cm hardly amount to much.
In reality, solar light pressure is the culprit in exerting quite measurable forces and torques on the spacecraft.
The same goes for a solar sail, it doesn't really ride on solar wind, but on light from the sun.
QUOTE (ugordan @ Feb 2 2006, 05:05 AM)
It doesn't have to execute commands at all. All we need is detection of its carrier signal to measure the Doppler effect.
Measuring the carrier would give us the velocity, but not the distance, and the probes native carrier is much too unstable to gain an accurate reading of the velocity.
In the 'repeater' mode, the Pioneer probes would listen to a frequency from earth, then rebroadcast the same pattern at a frequency multiple. Since the ultrastable signal from Earth controls the oscillator, both timing elements are known with great precision.
QUOTE
It's a constant misconception/mixup that the solar wind is pushing on these probes. While to some extent you might say a force is being felt, a few particles per cubic cm hardly amount to much.
In reality, solar light pressure is the culprit in exerting quite measurable forces and torques on the spacecraft.
The same goes for a solar sail, it doesn't really ride on solar wind, but on light from the sun.
In reality, solar light pressure is the culprit in exerting quite measurable forces and torques on the spacecraft.
The same goes for a solar sail, it doesn't really ride on solar wind, but on light from the sun.
True, but the thermal effect is a little easier to model that the solar wind - for one thing, the particles in the solar wind may contain any charge, and this charge may either attract or repel the craft upon impact.
On both Ulysses and Galilio, Anderson & Co. had to use an unexpected solar vector to model the Solar wind effects, and a similar deviation was noticed in Cassini. The polarity of these vectors near Jupiter is opposite of what I stated earlier; that is, the apparent acceleration is towards the sun, just like Pioneer.
In any case, the PI's do not consider solar wind or heating effects to be primary candidates. A very comprehensive treatment of the problem can be found in:
http://arxiv.org/PS_cache/gr-qc/pdf/0104/0104064.pdf
QUOTE (Anderson-etal)
Currently, we find no mechanism or theory that explains the anomalous acceleration. What we can say with some confidence is that the anomalous acceleration is a line of sight constant acceleration of the spacecraft toward the Sun.
Even though fits to the Pioneers appear to match the noise level of the data, in reality the fit levels are as much as 50 times above the fundamental
noise limit of the data.
Until more is known, we must admit that the most likely cause of this effect is an unknown systematic. (We ourselves are divided as to whether “gas leaks” or “heat” is this “most likely cause.”)
The arguments for “gas leaks” are: i) All spacecraft experience a gas leakage at some level. ii) There is enough gas available to cause the effect. iii) Gas leaks require not new physics. However, iv) it is unlikely that the two Pioneer spacecraft would have gas leaks at similar rates, over the entire data interval, especially then the valves have been used for so many maneuvers... v) Most importantly, it would require that these gas leaks be precisely pointed towards the front of the spacecraft so as not to cause a large spin-rate changes. But vi) it could still be true anyway.
The main arguments for “heat” are: i) There is so much heat available that a small amount of the total could cause the effect. ii) In deep space the spacecraft will be in approximate thermal equilibrium. The heat should then be emitted at an approximately constant rate, deviating from a constant only because of the slow exponential decay of the Plutonium heat source. It is hard to resist the notion that this heat somehow must be the origin of the effect. However, iii) there is no solid explanation in hand as to how a specific heat mechanism could work. Further, iv) the decrease in the heat supply over time should have been seen by now.
...
Finally, we observe that if no convincing explanation is to be obtained, the possibility remains that the effect is real. It could even be related to cosmological quantities, as has been intimated...This possibility necessitates a cautionary note on phenomenology: At this point in time, with the limited results available, there is a phenomenological equivalence between the [standard] and [alternative] points of view. But somehow, the choice one makes affects one’s outlook and direction of attack. If one has to consider new physics one should be open to both points of view. In the unlikely event that there is new physics, one does not want to miss it because one had the wrong mind set.
Even though fits to the Pioneers appear to match the noise level of the data, in reality the fit levels are as much as 50 times above the fundamental
noise limit of the data.
Until more is known, we must admit that the most likely cause of this effect is an unknown systematic. (We ourselves are divided as to whether “gas leaks” or “heat” is this “most likely cause.”)
The arguments for “gas leaks” are: i) All spacecraft experience a gas leakage at some level. ii) There is enough gas available to cause the effect. iii) Gas leaks require not new physics. However, iv) it is unlikely that the two Pioneer spacecraft would have gas leaks at similar rates, over the entire data interval, especially then the valves have been used for so many maneuvers... v) Most importantly, it would require that these gas leaks be precisely pointed towards the front of the spacecraft so as not to cause a large spin-rate changes. But vi) it could still be true anyway.
The main arguments for “heat” are: i) There is so much heat available that a small amount of the total could cause the effect. ii) In deep space the spacecraft will be in approximate thermal equilibrium. The heat should then be emitted at an approximately constant rate, deviating from a constant only because of the slow exponential decay of the Plutonium heat source. It is hard to resist the notion that this heat somehow must be the origin of the effect. However, iii) there is no solid explanation in hand as to how a specific heat mechanism could work. Further, iv) the decrease in the heat supply over time should have been seen by now.
...
Finally, we observe that if no convincing explanation is to be obtained, the possibility remains that the effect is real. It could even be related to cosmological quantities, as has been intimated...This possibility necessitates a cautionary note on phenomenology: At this point in time, with the limited results available, there is a phenomenological equivalence between the [standard] and [alternative] points of view. But somehow, the choice one makes affects one’s outlook and direction of attack. If one has to consider new physics one should be open to both points of view. In the unlikely event that there is new physics, one does not want to miss it because one had the wrong mind set.
Any chance there is a foreign object like a small meteoroid that impacted and stuck onto the Pioneer probes that may be affecting things?
QUOTE (ljk4-1 @ Feb 2 2006, 05:07 PM)
Any chance there is a foreign object like a small meteoroid that impacted and stuck onto the Pioneer probes that may be affecting things?
if it had an effect such as removing a part of the structure, it may change the thermal model in the way it receives thrust from solar light. But more likely many dust did not produced large break-up, but many pin-holes which change the thermal property, in a way similar for all the probes. (Or in a different way, as there may be seasons for interplanetary dust).
QUOTE (ljk4-1 @ Feb 2 2006, 10:07 AM)
Any chance there is a foreign object like a small meteoroid that impacted and stuck onto the Pioneer probes that may be affecting things?
Very unlikely. The two Pioneer probes are moving in nearly opposite directions, and we are talking about a constant acceleration towards the sun, not a one-time change in a velocity vector. So unless microparticle bombardment is both uniform and omni-directional, this can all-but be ruled out.
Another interesting observation: The Viking probes are losing power at a slower rate than nuclear theory predicts. Currently, the only explanation for this is an increase in the efficiency of the thermalcouples converting nuclear energy into electrical energy as the temperature decreases. (This is an expected improvement, but apparently the magnitude of improvement is greater-than-expected.)
Contact with Pioneer 10 should give us another data point concerning this thermal efficiency phenomenon. While unexpected quantum efficiency in an ultra-cold environment may be a factor, we cannot rule out the possibility that the nuclear decay efficiency and/or rate is an extremely weak function of the radiative and/or the gravimetric environment.
Astrophysics, abstract
astro-ph/0602161
From: R. H. Sanders [view email]
Date: Tue, 7 Feb 2006 16:51:22 GMT (43kb)
Solar system constraints on multi-field theories of modified dynamics
Authors: R.H. Sanders
Comments: 10 pages, 5 figures, submitted MNRAS
Any viable theory of modified Newtonian dynamcs (MOND) as modified gravity is likely to require fields in addition to the usual tensor field of General Relativity. For such theories the MOND phenomenology emerges from an effective fifth force probably associated with a scalar field. Here I consider the constraints imposed upon such theories by solar system phenomenology, primarily by the absence of significant deviations from inverse square attraction in the inner solar system as well as detectable local preferred frame effects. The current examples of multi-field theories can be constructed to satisfy these constraints and such theories lead inevitably to an anomalous non inverse-square force in the outer solar system.
http://arxiv.org/abs/astro-ph/0602161
astro-ph/0602161
From: R. H. Sanders [view email]
Date: Tue, 7 Feb 2006 16:51:22 GMT (43kb)
Solar system constraints on multi-field theories of modified dynamics
Authors: R.H. Sanders
Comments: 10 pages, 5 figures, submitted MNRAS
Any viable theory of modified Newtonian dynamcs (MOND) as modified gravity is likely to require fields in addition to the usual tensor field of General Relativity. For such theories the MOND phenomenology emerges from an effective fifth force probably associated with a scalar field. Here I consider the constraints imposed upon such theories by solar system phenomenology, primarily by the absence of significant deviations from inverse square attraction in the inner solar system as well as detectable local preferred frame effects. The current examples of multi-field theories can be constructed to satisfy these constraints and such theories lead inevitably to an anomalous non inverse-square force in the outer solar system.
http://arxiv.org/abs/astro-ph/0602161
I'm surprised that you haven't mentioned this one yet, ljk4-1 
Planetary Radio had an interview with JPL's John Anderson on February 6, 2006:
Closing In On An Interplanetary Mystery: The Pioneer Anomaly.
Under a category similar to "DVD Extras": Emily Lakdawalla and Bruce Betts.
Planetary Radio had an interview with JPL's John Anderson on February 6, 2006:
Closing In On An Interplanetary Mystery: The Pioneer Anomaly.
Under a category similar to "DVD Extras": Emily Lakdawalla and Bruce Betts.
QUOTE (AlexBlackwell @ Feb 8 2006, 07:11 PM)
I'm surprised that you haven't mentioned this one yet, ljk4-1
Planetary Radio had an interview with JPL's John Anderson on February 6, 2006:
Closing In On An Interplanetary Mystery: The Pioneer Anomaly.
Under a category similar to "DVD Extras": Emily Lakdawalla and Bruce Betts.
Planetary Radio had an interview with JPL's John Anderson on February 6, 2006:
Closing In On An Interplanetary Mystery: The Pioneer Anomaly.
Under a category similar to "DVD Extras": Emily Lakdawalla and Bruce Betts.
The signal was too weak for me to detect.
Thanks for catching that one.
General Relativity and Quantum Cosmology, abstract
gr-qc/0509021
From: Andreas Rathke [view email]
Date: Wed, 7 Sep 2005 12:45:40 GMT (259kb)
Pioneer anomaly: What can we learn from LISA?
Authors: Denis Defrere, Andreas Rathke
Comments: 19 pages, 4 figures. Talk given by D. Defrere at the conference "Lasers, Clocks, and Drag-Free", ZARM, Bremen, Germany, 30 May - 1 June 2005
The Doppler tracking data from two deep-space spacecraft, Pioneer 10 and 11, show an anomalous blueshift, which has been dubbed the "Pioneer anomaly". The effect is most commonly interpreted as a real deceleration of the spacecraft - an interpretation that faces serious challenges from planetary ephemerides. The Pioneer anomaly could as well indicate an unknown effect on the radio signal itself. Several authors have made suggestions how such a blueshift could be related to cosmology. We consider this interpretation of the Pioneer anomaly and study the impact of an anomalous blueshift on the Laser Interferometer Space Antenna (LISA), a planned joint ESA-NASA mission aiming at the detection of gravitational waves. The relative frequency shift (proportional to the light travel time) for the LISA arm length is estimated to 10E-16, which is much bigger than the expected amplitude of gravitational waves. The anomalous blueshift enters the LISA signal in two ways, as a small term folded with the gravitational wave signal, and as larger term at low frequencies. A detail analysis shows that both contributions remain undetectable and do not impair the gravitational-wave detection.
This suggests that the Pioneer anomaly will have to be tested in the outer Solar system regardless if the effect is caused by an anomalous blueshift or by a real force.
http://arxiv.org/abs/gr-qc/0509021
gr-qc/0509021
From: Andreas Rathke [view email]
Date: Wed, 7 Sep 2005 12:45:40 GMT (259kb)
Pioneer anomaly: What can we learn from LISA?
Authors: Denis Defrere, Andreas Rathke
Comments: 19 pages, 4 figures. Talk given by D. Defrere at the conference "Lasers, Clocks, and Drag-Free", ZARM, Bremen, Germany, 30 May - 1 June 2005
The Doppler tracking data from two deep-space spacecraft, Pioneer 10 and 11, show an anomalous blueshift, which has been dubbed the "Pioneer anomaly". The effect is most commonly interpreted as a real deceleration of the spacecraft - an interpretation that faces serious challenges from planetary ephemerides. The Pioneer anomaly could as well indicate an unknown effect on the radio signal itself. Several authors have made suggestions how such a blueshift could be related to cosmology. We consider this interpretation of the Pioneer anomaly and study the impact of an anomalous blueshift on the Laser Interferometer Space Antenna (LISA), a planned joint ESA-NASA mission aiming at the detection of gravitational waves. The relative frequency shift (proportional to the light travel time) for the LISA arm length is estimated to 10E-16, which is much bigger than the expected amplitude of gravitational waves. The anomalous blueshift enters the LISA signal in two ways, as a small term folded with the gravitational wave signal, and as larger term at low frequencies. A detail analysis shows that both contributions remain undetectable and do not impair the gravitational-wave detection.
This suggests that the Pioneer anomaly will have to be tested in the outer Solar system regardless if the effect is caused by an anomalous blueshift or by a real force.
http://arxiv.org/abs/gr-qc/0509021
General Relativity and Quantum Cosmology, abstract
gr-qc/0602003
From: Antonio F. Ranada [view email]
Date: Wed, 1 Feb 2006 15:30:16 GMT (10kb)
A model for the Pioneer Anomaly
Authors: Antonio F. Ranada, Alfredo Tiemblo
Comments: 11 pages, no figures
We propose an explanation to the Pioneer Anomaly, the anomalous blueshift in the radio signals from the Pioneer 10/11 spacecrafts that remains unexplained 30 years after being discovered by a NASA team around 1975. It was detected as a Doppler shift that does not correspond to any known motion of the ships. In 1998, after many unsuccessful efforts to account for it, the discoverers suggested "the possibility that the origin of the anomalous signal is new physics".
We show here that the phenomenon has the same observational footprint as an acceleration of the atomic clocks time with respect to the astronomical time.
Surprisingly, this curious new idea turns out to be compatible with current physics; lacking a unified theory of quantum physics and gravitation, we cannot discard it a priori.
We expound a mechanism that produces such an acceleration as a result of the coupling of the background gravitation and the quantum vacuum. This suggests a solution to the riddle, in which the velocity of a receding ship, as deduced from the Doppler effect, is smaller than the value predicted by the standard theory of gravitation.
We conclude that the Pioneer Anomaly is probably the signature of the difference between the marches of the astronomical clock of the orbit and the atomic clock inside the ship.
http://arxiv.org/abs/gr-qc/0602003
gr-qc/0602003
From: Antonio F. Ranada [view email]
Date: Wed, 1 Feb 2006 15:30:16 GMT (10kb)
A model for the Pioneer Anomaly
Authors: Antonio F. Ranada, Alfredo Tiemblo
Comments: 11 pages, no figures
We propose an explanation to the Pioneer Anomaly, the anomalous blueshift in the radio signals from the Pioneer 10/11 spacecrafts that remains unexplained 30 years after being discovered by a NASA team around 1975. It was detected as a Doppler shift that does not correspond to any known motion of the ships. In 1998, after many unsuccessful efforts to account for it, the discoverers suggested "the possibility that the origin of the anomalous signal is new physics".
We show here that the phenomenon has the same observational footprint as an acceleration of the atomic clocks time with respect to the astronomical time.
Surprisingly, this curious new idea turns out to be compatible with current physics; lacking a unified theory of quantum physics and gravitation, we cannot discard it a priori.
We expound a mechanism that produces such an acceleration as a result of the coupling of the background gravitation and the quantum vacuum. This suggests a solution to the riddle, in which the velocity of a receding ship, as deduced from the Doppler effect, is smaller than the value predicted by the standard theory of gravitation.
We conclude that the Pioneer Anomaly is probably the signature of the difference between the marches of the astronomical clock of the orbit and the atomic clock inside the ship.
http://arxiv.org/abs/gr-qc/0602003
Quotes from the article "Listening for Pioneer 10":
Centauri Dreams is following the Pioneer 10 story with great interest, and not just in terms of the anomalous effects that continue to keep this mission in the news. Ponder that Pioneer 10 was launched in 1972 and consider that even with the technologies of its day, the probe may still be able to communicate with Earth.
We have learned so much in the interim about hardened electronics and autonomous self-repair that there is reason to believe probes to even remoter locations in the Kuiper Belt and beyond are feasible providing we can solve the propulsion conundrum.
...
It’s too late for New Horizons, of course, but any followup Pluto/Kuiper Belt mission would have such an opportunity. On that score, see T. Bondo, R. Walker, A. Rathke et al., “Preliminary Design of an Advanced Mission to Pluto,” scheduled to appear in the proceedings of the 24th International Symposium on Space Technology and Science, Miyazaki, Japan, June 2006, and already available online (PDF warning).
http://www.centauri-dreams.org/?p=534
Centauri Dreams is following the Pioneer 10 story with great interest, and not just in terms of the anomalous effects that continue to keep this mission in the news. Ponder that Pioneer 10 was launched in 1972 and consider that even with the technologies of its day, the probe may still be able to communicate with Earth.
We have learned so much in the interim about hardened electronics and autonomous self-repair that there is reason to believe probes to even remoter locations in the Kuiper Belt and beyond are feasible providing we can solve the propulsion conundrum.
...
It’s too late for New Horizons, of course, but any followup Pluto/Kuiper Belt mission would have such an opportunity. On that score, see T. Bondo, R. Walker, A. Rathke et al., “Preliminary Design of an Advanced Mission to Pluto,” scheduled to appear in the proceedings of the 24th International Symposium on Space Technology and Science, Miyazaki, Japan, June 2006, and already available online (PDF warning).
http://www.centauri-dreams.org/?p=534
QUOTE (ljk4-1 @ Feb 9 2006, 09:29 AM)
General Relativity and Quantum Cosmology, abstract
gr-qc/0602003
From: Antonio F. Ranada [view email]
Date: Wed, 1 Feb 2006 15:30:16 GMT (10kb)
A model for the Pioneer Anomaly
Authors: Antonio F. Ranada, Alfredo Tiemblo
Comments: 11 pages, no figures
We propose an explanation to the Pioneer Anomaly, the anomalous blueshift in the radio signals from the Pioneer 10/11 spacecrafts that remains unexplained 30 years after being discovered by a NASA team around 1975. It was detected as a Doppler shift that does not correspond to any known motion of the ships. In 1998, after many unsuccessful efforts to account for it, the discoverers suggested "the possibility that the origin of the anomalous signal is new physics".
We show here that the phenomenon has the same observational footprint as an acceleration of the atomic clocks time with respect to the astronomical time...
http://arxiv.org/abs/gr-qc/0602003
gr-qc/0602003
From: Antonio F. Ranada [view email]
Date: Wed, 1 Feb 2006 15:30:16 GMT (10kb)
A model for the Pioneer Anomaly
Authors: Antonio F. Ranada, Alfredo Tiemblo
Comments: 11 pages, no figures
We propose an explanation to the Pioneer Anomaly, the anomalous blueshift in the radio signals from the Pioneer 10/11 spacecrafts that remains unexplained 30 years after being discovered by a NASA team around 1975. It was detected as a Doppler shift that does not correspond to any known motion of the ships. In 1998, after many unsuccessful efforts to account for it, the discoverers suggested "the possibility that the origin of the anomalous signal is new physics".
We show here that the phenomenon has the same observational footprint as an acceleration of the atomic clocks time with respect to the astronomical time...
http://arxiv.org/abs/gr-qc/0602003
...It also has the same observational footprint as an increase in the speed of light with increasing distance from the center of mass. A family of observations that don't fit the mold could be a clue that all is not well in the beeg peekture.
Astrophysics, abstract
astro-ph/0602266
From: Joao Magueijo [view email]
Date: Sun, 12 Feb 2006 20:46:43 GMT (240kb)
MOND habitats within the solar system
Authors: Jacob Bekenstein, Joao Magueijo
MOdified Newtonian Dynamics (MOND) is an interesting alternative to dark matter in extragalactic systems. We here examine the possibility that mild or even strong MOND behavior may become evident well inside the solar system, in particular near saddle points of the total gravitational potential. Whereas in Newtonian theory tidal stresses are finite at saddle points, they are expected to diverge in MOND, and to remain distinctly large inside a sizeable oblate ellipsoid around the saddle point. We work out the MOND effects using the nonrelativistic limit of the T$e$V$e$S theory, both in the perturbative nearly Newtonian regime and in the deep MOND regime. While strong MOND behavior would be a spectacular ``backyard'' vindication of the theory, pinpointing the MOND-bubbles in the setting of the realistic solar system may be difficult.
Space missions, such as the LISA Pathfinder, equipped with sensitive accelerometers, may be able to explore the larger perturbative region.
http://arxiv.org/abs/astro-ph/0602266
astro-ph/0602266
From: Joao Magueijo [view email]
Date: Sun, 12 Feb 2006 20:46:43 GMT (240kb)
MOND habitats within the solar system
Authors: Jacob Bekenstein, Joao Magueijo
MOdified Newtonian Dynamics (MOND) is an interesting alternative to dark matter in extragalactic systems. We here examine the possibility that mild or even strong MOND behavior may become evident well inside the solar system, in particular near saddle points of the total gravitational potential. Whereas in Newtonian theory tidal stresses are finite at saddle points, they are expected to diverge in MOND, and to remain distinctly large inside a sizeable oblate ellipsoid around the saddle point. We work out the MOND effects using the nonrelativistic limit of the T$e$V$e$S theory, both in the perturbative nearly Newtonian regime and in the deep MOND regime. While strong MOND behavior would be a spectacular ``backyard'' vindication of the theory, pinpointing the MOND-bubbles in the setting of the realistic solar system may be difficult.
Space missions, such as the LISA Pathfinder, equipped with sensitive accelerometers, may be able to explore the larger perturbative region.
http://arxiv.org/abs/astro-ph/0602266
QUOTE (ljk4-1 @ Jan 13 2006, 09:44 AM)
I don't want this turning into the Dark Matter/Energy Topic (unless of course that is what is affecting the Pioneer probes), but I wanted to share this news item while we are still on the subject:
Dark Matter Galaxy?
Summary - (Thu, 12 Jan 2006) Astronomers think they might have found a "dark galaxy", that has no stars and emits no light. Although the galaxy itself, located 50 million light years from Earth, is practically invisible, it contains a small amount of neutral hydrogen which emits radio waves. If astronomers are correct, this galaxy contains ten billion times the mass of Sun, but only 1% of this is hydrogen - the rest is dark matter.
http://www.universetoday.com/am/publish/pp...hi.html?1212006
If there is life in that galaxy, just try to imagine how utterly different it probably is from ours.
Dark Matter Galaxy?
Summary - (Thu, 12 Jan 2006) Astronomers think they might have found a "dark galaxy", that has no stars and emits no light. Although the galaxy itself, located 50 million light years from Earth, is practically invisible, it contains a small amount of neutral hydrogen which emits radio waves. If astronomers are correct, this galaxy contains ten billion times the mass of Sun, but only 1% of this is hydrogen - the rest is dark matter.
http://www.universetoday.com/am/publish/pp...hi.html?1212006
If there is life in that galaxy, just try to imagine how utterly different it probably is from ours.
Astrophysics, abstract
astro-ph/0602271
From: Galina Korotkova Gennadievna [view email]
Date: Mon, 13 Feb 2006 08:03:04 GMT (90kb)
Disturbed isolated galaxies: indicators of a dark galaxy population?
Authors: I.D.Karachentsev, V.E.Karachentseva, W.K.Huchtmeier
Comments: 5 pages, 1 figure. Astronomy and Astrophysics, accepted
We report the results of our search for disturbed (interacting) objects among very isolated galaxies. The inspections of 1050 northern isolated galaxies from KIG and 500 nearby, very isolated galaxies situated in the Local Supercluster yielded five and four strongly disturbed galaxies, respectively. We suggest that the existence of "dark" galaxies explains the observed signs of interaction. This assumption leads to a cosmic abundance of dark galaxies (with the typical masses for luminous galaxies) that is less than ~1/20 the population of visible galaxies.
http://arxiv.org/abs/astro-ph/0602271
General Relativity and Quantum Cosmology, abstract
gr-qc/0601055
From: Lorenzo Iorio [view email]
Date (v1): Sat, 14 Jan 2006 16:11:23 GMT (36kb)
Date (revised v2): Fri, 20 Jan 2006 16:04:50 GMT (37kb)
Date (revised v3): Mon, 13 Feb 2006 16:40:21 GMT (38kb)
What do the orbital motions of the outer planets of the Solar System tell us about the Pioneer anomaly?
Authors: Lorenzo Iorio
Comments: Latex2e, 13 pages, 3 tables, 4 figures, 15 references. Reference added. Stressed the fact that, even by assuming errors in the planetary orbital elements 30 times larger that those published by Pitjeva, the anomalous Pioneer effects on Uranus, Neptune, Pluto still remain well larger and, thus, detectable if present. Small corrections to the numerical values of Table 1 and Table 3: conclusions unchanged
Subj-class: General Relativity and Quantum Cosmology; Space Physics
In this paper we investigate the effects that an anomalous acceleration as that experienced by the Pioneer spacecraft after they passed the 20 AU threshold would induce on the orbital motions of the Solar System planets placed at heliocentric distances of 20 AU or larger as Uranus, Neptune and Pluto. It turns out that such an acceleration, with a magnitude of about 8 X 10^-10 m s^-2, would affect their orbits with secular and short-period signals large enough to be detected with the present-day level of accuracy in orbit determination. The absence of such anomalous signatures in the latest data analyses rules out the possibility that in the region 20-40 AU of the Solar System an anomalous force field inducing a constant and radial acceleration of that size is present.
http://arxiv.org/abs/gr-qc/0601055
gr-qc/0601055
From: Lorenzo Iorio [view email]
Date (v1): Sat, 14 Jan 2006 16:11:23 GMT (36kb)
Date (revised v2): Fri, 20 Jan 2006 16:04:50 GMT (37kb)
Date (revised v3): Mon, 13 Feb 2006 16:40:21 GMT (38kb)
What do the orbital motions of the outer planets of the Solar System tell us about the Pioneer anomaly?
Authors: Lorenzo Iorio
Comments: Latex2e, 13 pages, 3 tables, 4 figures, 15 references. Reference added. Stressed the fact that, even by assuming errors in the planetary orbital elements 30 times larger that those published by Pitjeva, the anomalous Pioneer effects on Uranus, Neptune, Pluto still remain well larger and, thus, detectable if present. Small corrections to the numerical values of Table 1 and Table 3: conclusions unchanged
Subj-class: General Relativity and Quantum Cosmology; Space Physics
In this paper we investigate the effects that an anomalous acceleration as that experienced by the Pioneer spacecraft after they passed the 20 AU threshold would induce on the orbital motions of the Solar System planets placed at heliocentric distances of 20 AU or larger as Uranus, Neptune and Pluto. It turns out that such an acceleration, with a magnitude of about 8 X 10^-10 m s^-2, would affect their orbits with secular and short-period signals large enough to be detected with the present-day level of accuracy in orbit determination. The absence of such anomalous signatures in the latest data analyses rules out the possibility that in the region 20-40 AU of the Solar System an anomalous force field inducing a constant and radial acceleration of that size is present.
http://arxiv.org/abs/gr-qc/0601055
General Relativity and Quantum Cosmology, abstract
gr-qc/0602089
From: Kjell Tangen [view email]
Date: Wed, 22 Feb 2006 15:35:17 GMT (92kb)
Could the Pioneer anomaly have a gravitational origin?
Authors: Kjell Tangen
Comments: 9 pages, 1 figure
If the Pioneer anomaly has a gravitational origin, it would, according to the equivalence principle, distort the motions of the planets in the Solar System. Since no anomalous motion of the planets have been detected, it is generally believed that the Pioneer anomaly can not originate from a gravitational source in the Solar System. However, this conclusion becomes less obvious when considering models that either imply modifications to gravity at long range or gravitational sources localized to the outer Solar System, given the uncertainty in the orbital parameters of the outer planets. Following the general assumption that the Pioneer spacecrafts move geodesically in a spherically symmetric spacetime metric, we derive the metric disturbance that is needed in order to account for the Pioneer anomaly. We then analyze the residual effects on the astronomical observables of the outer planets that would arise from this metric disturbance, given an arbitrary metric theory of gravity. The computed residuals are much larger than the observed residuals, and we are lead to the conclusion that the Pioneer anomaly can not originate from a metric disturbance and therefore that the motion of the Pioneer spacecrafts must be non-geodesic. Since our results are model independent, they can be applied to rule out any model of the Pioneer anomaly that implies that the Pioneer spacecrafts move geodesically in a perturbed spacetime metric, regardless of the origin of this metric disturbance.
http://arxiv.org/abs/gr-qc/0602089
gr-qc/0602089
From: Kjell Tangen [view email]
Date: Wed, 22 Feb 2006 15:35:17 GMT (92kb)
Could the Pioneer anomaly have a gravitational origin?
Authors: Kjell Tangen
Comments: 9 pages, 1 figure
If the Pioneer anomaly has a gravitational origin, it would, according to the equivalence principle, distort the motions of the planets in the Solar System. Since no anomalous motion of the planets have been detected, it is generally believed that the Pioneer anomaly can not originate from a gravitational source in the Solar System. However, this conclusion becomes less obvious when considering models that either imply modifications to gravity at long range or gravitational sources localized to the outer Solar System, given the uncertainty in the orbital parameters of the outer planets. Following the general assumption that the Pioneer spacecrafts move geodesically in a spherically symmetric spacetime metric, we derive the metric disturbance that is needed in order to account for the Pioneer anomaly. We then analyze the residual effects on the astronomical observables of the outer planets that would arise from this metric disturbance, given an arbitrary metric theory of gravity. The computed residuals are much larger than the observed residuals, and we are lead to the conclusion that the Pioneer anomaly can not originate from a metric disturbance and therefore that the motion of the Pioneer spacecrafts must be non-geodesic. Since our results are model independent, they can be applied to rule out any model of the Pioneer anomaly that implies that the Pioneer spacecrafts move geodesically in a perturbed spacetime metric, regardless of the origin of this metric disturbance.
http://arxiv.org/abs/gr-qc/0602089
General Relativity and Quantum Cosmology, abstract
gr-qc/0511026
From: J. R. Brownstein [view email]
Date (v1): Sun, 6 Nov 2005 02:40:04 GMT (162kb)
Date (revised v2): Fri, 17 Mar 2006 19:20:20 GMT (29kb)
Date (revised v3): Fri, 17 Mar 2006 21:22:19 GMT (29kb)
Gravitational solution to the Pioneer 10/11 anomaly
Authors: J. R. Brownstein, J. W. Moffat
Comments: 12 pages, 3 figures, 2 tables. Accepted for publication in Classical and Quantum Gravity, March 17, 2006
A fully relativistic modified gravitational theory including a fifth force skew symmetric field is fitted to the Pioneer 10/11 anomalous acceleration. The theory allows for a variation with distance scales of the gravitational constant G, the fifth force skew symmetric field coupling strength omega and the mass of the skew symmetric field mu=1/lambda. A fit to the available anomalous acceleration data for the Pioneer 10/11 spacecraft is obtained for a phenomenological representation of the "running" constants and values of the associated parameters are shown to exist that are consistent with fifth force experimental bounds. The fit to the acceleration data is consistent with all current satellite, laser ranging and observations for the inner planets.
http://arxiv.org/abs/gr-qc/0511026
gr-qc/0511026
From: J. R. Brownstein [view email]
Date (v1): Sun, 6 Nov 2005 02:40:04 GMT (162kb)
Date (revised v2): Fri, 17 Mar 2006 19:20:20 GMT (29kb)
Date (revised v3): Fri, 17 Mar 2006 21:22:19 GMT (29kb)
Gravitational solution to the Pioneer 10/11 anomaly
Authors: J. R. Brownstein, J. W. Moffat
Comments: 12 pages, 3 figures, 2 tables. Accepted for publication in Classical and Quantum Gravity, March 17, 2006
A fully relativistic modified gravitational theory including a fifth force skew symmetric field is fitted to the Pioneer 10/11 anomalous acceleration. The theory allows for a variation with distance scales of the gravitational constant G, the fifth force skew symmetric field coupling strength omega and the mass of the skew symmetric field mu=1/lambda. A fit to the available anomalous acceleration data for the Pioneer 10/11 spacecraft is obtained for a phenomenological representation of the "running" constants and values of the associated parameters are shown to exist that are consistent with fifth force experimental bounds. The fit to the acceleration data is consistent with all current satellite, laser ranging and observations for the inner planets.
http://arxiv.org/abs/gr-qc/0511026
QUOTE (ljk4-1 @ Mar 22 2006, 09:26 AM)
General Relativity and Quantum Cosmology, abstract
gr-qc/0511026
From: J. R. Brownstein [view email]
Date (v1): Sun, 6 Nov 2005 02:40:04 GMT (162kb)
Date (revised v2): Fri, 17 Mar 2006 19:20:20 GMT (29kb)
Date (revised v3): Fri, 17 Mar 2006 21:22:19 GMT (29kb)
Gravitational solution to the Pioneer 10/11 anomaly
Authors: J. R. Brownstein, J. W. Moffat
Comments: 12 pages, 3 figures, 2 tables. Accepted for publication in Classical and Quantum Gravity, March 17, 2006
A fully relativistic modified gravitational theory including a fifth force skew symmetric field is fitted to the Pioneer 10/11 anomalous acceleration. The theory allows for a variation with distance scales of the gravitational constant G, the fifth force skew symmetric field coupling strength omega and the mass of the skew symmetric field mu=1/lambda. A fit to the available anomalous acceleration data for the Pioneer 10/11 spacecraft is obtained for a phenomenological representation of the "running" constants and values of the associated parameters are shown to exist that are consistent with fifth force experimental bounds. The fit to the acceleration data is consistent with all current satellite, laser ranging and observations for the inner planets.
http://arxiv.org/abs/gr-qc/0511026
gr-qc/0511026
From: J. R. Brownstein [view email]
Date (v1): Sun, 6 Nov 2005 02:40:04 GMT (162kb)
Date (revised v2): Fri, 17 Mar 2006 19:20:20 GMT (29kb)
Date (revised v3): Fri, 17 Mar 2006 21:22:19 GMT (29kb)
Gravitational solution to the Pioneer 10/11 anomaly
Authors: J. R. Brownstein, J. W. Moffat
Comments: 12 pages, 3 figures, 2 tables. Accepted for publication in Classical and Quantum Gravity, March 17, 2006
A fully relativistic modified gravitational theory including a fifth force skew symmetric field is fitted to the Pioneer 10/11 anomalous acceleration. The theory allows for a variation with distance scales of the gravitational constant G, the fifth force skew symmetric field coupling strength omega and the mass of the skew symmetric field mu=1/lambda. A fit to the available anomalous acceleration data for the Pioneer 10/11 spacecraft is obtained for a phenomenological representation of the "running" constants and values of the associated parameters are shown to exist that are consistent with fifth force experimental bounds. The fit to the acceleration data is consistent with all current satellite, laser ranging and observations for the inner planets.
http://arxiv.org/abs/gr-qc/0511026
The Tangen and Iorio papers place real constraints upon odd-ball gravitmetric theories which could have accounted for the Pioneer anomaly. This paper is just an exercise in curve fitting. Introducing distant forces that suddenly appear, as needed, to explain observations, is better left to Hobbitary universes. No more dark stuff, please.
Astrophysics, abstract
astro-ph/0502582
From: Michael Makoid . D. [view email]
Date (v1): Mon, 28 Feb 2005 16:46:47 GMT (362kb)
Date (revised v2): Sat, 25 Mar 2006 16:33:55 GMT (368kb)
Ab Initio Calculation of the Anomalous Acceleration of Pioneer 10 In Vacuo
Authors: Russell Anania, Michael Makoid (Creighton University, Omaha, NE.)
Comments: 16 pages with two jpeg figures
The anomalous acceleration of Pioneer 10 is presented as a calculation using a simple optical model. The model is based on the bending of background gravity behind the Sun in the same way that light is bent by the Sun. Structures of ponderable matter about the Solar system, neutron stars, and galaxies are described. Viewable red and blue shiftings of light are predicted.
http://arxiv.org/abs/astro-ph/0502582
astro-ph/0502582
From: Michael Makoid . D. [view email]
Date (v1): Mon, 28 Feb 2005 16:46:47 GMT (362kb)
Date (revised v2): Sat, 25 Mar 2006 16:33:55 GMT (368kb)
Ab Initio Calculation of the Anomalous Acceleration of Pioneer 10 In Vacuo
Authors: Russell Anania, Michael Makoid (Creighton University, Omaha, NE.)
Comments: 16 pages with two jpeg figures
The anomalous acceleration of Pioneer 10 is presented as a calculation using a simple optical model. The model is based on the bending of background gravity behind the Sun in the same way that light is bent by the Sun. Structures of ponderable matter about the Solar system, neutron stars, and galaxies are described. Viewable red and blue shiftings of light are predicted.
http://arxiv.org/abs/astro-ph/0502582
QUOTE (ljk4-1 @ Mar 28 2006, 11:05 AM)
Astrophysics, abstract
astro-ph/0502582
Authors: Russell Anania, Michael Makoid (Creighton University, Omaha, NE.)
The anomalous acceleration of Pioneer 10 is presented as a calculation using a simple optical model. The model is based on the bending of background gravity behind the Sun in the same way that light is bent by the Sun. Structures of ponderable matter about the Solar system, neutron stars, and galaxies are described. Viewable red and blue shiftings of light are predicted.
http://arxiv.org/abs/astro-ph/0502582
astro-ph/0502582
Authors: Russell Anania, Michael Makoid (Creighton University, Omaha, NE.)
The anomalous acceleration of Pioneer 10 is presented as a calculation using a simple optical model. The model is based on the bending of background gravity behind the Sun in the same way that light is bent by the Sun. Structures of ponderable matter about the Solar system, neutron stars, and galaxies are described. Viewable red and blue shiftings of light are predicted.
http://arxiv.org/abs/astro-ph/0502582
What we are talking about here is matter behaving as if there is a optical density assignable to free space space that is a function of mass - many times greater than predicted by GR
What these two have failed to evaluate, is the effect such a gravitational gradient would have upon the orbits (or the predicted masses) of the planets
Astrophysics, abstract
astro-ph/0603790
From: Ettore Minguzzi [view email]
Date: Wed, 29 Mar 2006 14:44:25 GMT (8kb)
Possible relation between galactic flat rotational curves and the Pioneers' anomalous acceleration
Authors: E. Minguzzi
Comments: Latex2e, 6 pages, no figures
We consider a generic minimal modification of the Newtonian potential, that is a modification that introduces only one additional dimensional parameter. The modified potential depends on a function whose behavior for large and small distances can be fixed in order to obtain respectively (i) galactic flat rotational curves and (ii) a universal constant acceleration independent of the masses of the interacting bodies (Pioneer anomaly). Then using a dimensional argument we show that the Tully-Fisher relation for the maximal rotational velocity of spiral galaxies follows without any further assumptions. This result suggests that the Pioneer anomalous acceleration and the flat rotational curves of galaxies could have a common origin in a modified gravitational theory. The relation of these results with the Modified Newtonian Dynamics (MOND) is discussed.
http://arxiv.org/abs/astro-ph/0603790
astro-ph/0603790
From: Ettore Minguzzi [view email]
Date: Wed, 29 Mar 2006 14:44:25 GMT (8kb)
Possible relation between galactic flat rotational curves and the Pioneers' anomalous acceleration
Authors: E. Minguzzi
Comments: Latex2e, 6 pages, no figures
We consider a generic minimal modification of the Newtonian potential, that is a modification that introduces only one additional dimensional parameter. The modified potential depends on a function whose behavior for large and small distances can be fixed in order to obtain respectively (i) galactic flat rotational curves and (ii) a universal constant acceleration independent of the masses of the interacting bodies (Pioneer anomaly). Then using a dimensional argument we show that the Tully-Fisher relation for the maximal rotational velocity of spiral galaxies follows without any further assumptions. This result suggests that the Pioneer anomalous acceleration and the flat rotational curves of galaxies could have a common origin in a modified gravitational theory. The relation of these results with the Modified Newtonian Dynamics (MOND) is discussed.
http://arxiv.org/abs/astro-ph/0603790
General Relativity and Quantum Cosmology, abstract
gr-qc/0601055
From: Lorenzo Iorio [view email]
Date (v1): Sat, 14 Jan 2006 16:11:23 GMT (36kb)
Date (revised v2): Fri, 20 Jan 2006 16:04:50 GMT (37kb)
Date (revised v3): Mon, 13 Feb 2006 16:40:21 GMT (38kb)
Date (revised v4): Sat, 1 Apr 2006 15:06:33 GMT (79kb)
What do the orbital motions of the outer planets of the Solar System tell us about the Pioneer anomaly?
Authors: Lorenzo Iorio, Giuseppe Giudice
Comments: Latex2e, 19 pages, 3 tables, 10 figures, 18 references. Authorship changed; new figures added for a direct comparison with the observable quantities. Accepted for publication in New Astronomy
Subj-class: General Relativity and Quantum Cosmology; Space Physics
In this paper we investigate the effects that an anomalous acceleration as that experienced by the Pioneer spacecraft after they passed the 20 AU threshold would induce on the orbital motions of the Solar System planets placed at heliocentric distances of 20 AU or larger as Uranus, Neptune and Pluto. It turns out that such an acceleration, with a magnitude of 8.74\times 10^-10 m s^-2, would affect their orbits with secular and short-period signals large enough to be detected according to the latest published results by E.V. Pitjeva, even by considering errors up to 30 times larger than those released. The absence of such anomalous signatures in the latest data rules out the possibility that in the region 20-40 AU of the Solar System an anomalous force field inducing a constant and radial acceleration with those characteristics affects the motion of the major planets.
http://arxiv.org/abs/gr-qc/0601055
gr-qc/0601055
From: Lorenzo Iorio [view email]
Date (v1): Sat, 14 Jan 2006 16:11:23 GMT (36kb)
Date (revised v2): Fri, 20 Jan 2006 16:04:50 GMT (37kb)
Date (revised v3): Mon, 13 Feb 2006 16:40:21 GMT (38kb)
Date (revised v4): Sat, 1 Apr 2006 15:06:33 GMT (79kb)
What do the orbital motions of the outer planets of the Solar System tell us about the Pioneer anomaly?
Authors: Lorenzo Iorio, Giuseppe Giudice
Comments: Latex2e, 19 pages, 3 tables, 10 figures, 18 references. Authorship changed; new figures added for a direct comparison with the observable quantities. Accepted for publication in New Astronomy
Subj-class: General Relativity and Quantum Cosmology; Space Physics
In this paper we investigate the effects that an anomalous acceleration as that experienced by the Pioneer spacecraft after they passed the 20 AU threshold would induce on the orbital motions of the Solar System planets placed at heliocentric distances of 20 AU or larger as Uranus, Neptune and Pluto. It turns out that such an acceleration, with a magnitude of 8.74\times 10^-10 m s^-2, would affect their orbits with secular and short-period signals large enough to be detected according to the latest published results by E.V. Pitjeva, even by considering errors up to 30 times larger than those released. The absence of such anomalous signatures in the latest data rules out the possibility that in the region 20-40 AU of the Solar System an anomalous force field inducing a constant and radial acceleration with those characteristics affects the motion of the major planets.
http://arxiv.org/abs/gr-qc/0601055
Paper (*cross-listing*): gr-qc/0604047
Date: Mon, 10 Apr 2006 13:33:42 GMT (601kb)
Title: Does a Teleconnection between Quantum States account for Missing Mass,
Galaxy Ageing, Lensing Anomalies, Supernova Redshift, MOND, and Pioneer
Blueshift?
Authors: Charles Francis
Comments: 20 pages, 12 figs. Submitted to Proc Roy Soc A
\\
Empirical implications of a teleparallel displacement of momentum between
initial and final quantum states, using conformally flat quantum coordinates
are investigated. An exact formulation is possible in an FRW cosmology in which
cosmological redshift is given by 1+z=a_0^2/a^2(t). This is consistent with
current observation for a universe expanding at half the rate and twice as old
as indicated by a linear law, and, in consequence, requiring a quarter of the
critical density for closure. After rescaling Omega so that Omega=1 is critical
density in the teleconnection model, it is found that for given cosmological
parameters, Omega, Omega_k and Omega_Lambda, luminosity distance is a factor
sqrt(1+z) greater than in the corresponding standard model. Best fits to data
from the SuperNova Legacy Survey for a flat space Lambda cosmology is
Omega=1.07 and for a Lambda=0 cosmology, Omega=1.15. It will require many
observations of supernovae at z>1 to eliminate either the standard or
teleconnection magnitude-redshift relation. Quantum coordinates exhibit an
acceleration in time, resulting in the anomalous Pioneer blue-shift and in the
flattening of galaxies' rotation curves. These appear as optical effects and do
not affect classical motions. Milgrom's phenomenological law (MOND) is
precisely obeyed. A no CDM teleconnection model resolves inconsistencies
between galactic profiles found from lensing data, rotation curves and analytic
models of galaxy evolution.
\\ ( http://arXiv.org/abs/gr-qc/0604047 , 601kb)
Date: Mon, 10 Apr 2006 13:33:42 GMT (601kb)
Title: Does a Teleconnection between Quantum States account for Missing Mass,
Galaxy Ageing, Lensing Anomalies, Supernova Redshift, MOND, and Pioneer
Blueshift?
Authors: Charles Francis
Comments: 20 pages, 12 figs. Submitted to Proc Roy Soc A
\\
Empirical implications of a teleparallel displacement of momentum between
initial and final quantum states, using conformally flat quantum coordinates
are investigated. An exact formulation is possible in an FRW cosmology in which
cosmological redshift is given by 1+z=a_0^2/a^2(t). This is consistent with
current observation for a universe expanding at half the rate and twice as old
as indicated by a linear law, and, in consequence, requiring a quarter of the
critical density for closure. After rescaling Omega so that Omega=1 is critical
density in the teleconnection model, it is found that for given cosmological
parameters, Omega, Omega_k and Omega_Lambda, luminosity distance is a factor
sqrt(1+z) greater than in the corresponding standard model. Best fits to data
from the SuperNova Legacy Survey for a flat space Lambda cosmology is
Omega=1.07 and for a Lambda=0 cosmology, Omega=1.15. It will require many
observations of supernovae at z>1 to eliminate either the standard or
teleconnection magnitude-redshift relation. Quantum coordinates exhibit an
acceleration in time, resulting in the anomalous Pioneer blue-shift and in the
flattening of galaxies' rotation curves. These appear as optical effects and do
not affect classical motions. Milgrom's phenomenological law (MOND) is
precisely obeyed. A no CDM teleconnection model resolves inconsistencies
between galactic profiles found from lensing data, rotation curves and analytic
models of galaxy evolution.
\\ ( http://arXiv.org/abs/gr-qc/0604047 , 601kb)
In a talk on the Pioneer Anomaly last week at the ISDC (see a few other comments in my post on a Pioneer imaging thread), two things emerged regarding the value of the recovered but not analyzed tracking data.
1.) The anomaly on both Pioneers in the current data does not vary with distance from the sun or time starting at about Uranus' orbit (current data availability) Extending the data much further inward will help search for non-constant forces, particularly ones due to heating of the spacecraft or reflectd sunlight, etc.
2.) Current data says the apparent force is radially inward toward the "inner solar system". The recovered data will enable testing of whether the force is toward the sun, toward the earth, along the spacecraft's axis of rotation (usually but not always exactly toward the earth), or aligned with the spacecrafts velocity vector relative to the sun. In the current data, all these directions are approximately the same and cannot be sorted out.
This will enable testing for and exclusion of a very large number of possible forces acting on the spacecraft. For example, the force of the transmitted radio beam is small but not trivial. That force is always along the spin axis and normally approximately ponited at Earth. For another example, Pioneer 11 was in a low eccentricity orbit around the sun between Jupiter and Saturn examples, and a "drag-like" force would be in it's direction of travel, not radially inward.
1.) The anomaly on both Pioneers in the current data does not vary with distance from the sun or time starting at about Uranus' orbit (current data availability) Extending the data much further inward will help search for non-constant forces, particularly ones due to heating of the spacecraft or reflectd sunlight, etc.
2.) Current data says the apparent force is radially inward toward the "inner solar system". The recovered data will enable testing of whether the force is toward the sun, toward the earth, along the spacecraft's axis of rotation (usually but not always exactly toward the earth), or aligned with the spacecrafts velocity vector relative to the sun. In the current data, all these directions are approximately the same and cannot be sorted out.
This will enable testing for and exclusion of a very large number of possible forces acting on the spacecraft. For example, the force of the transmitted radio beam is small but not trivial. That force is always along the spin axis and normally approximately ponited at Earth. For another example, Pioneer 11 was in a low eccentricity orbit around the sun between Jupiter and Saturn examples, and a "drag-like" force would be in it's direction of travel, not radially inward.
Astrophysics, abstract
astro-ph/0504634
From: Andreas Rathke [view email]
Date (v1): Thu, 28 Apr 2005 15:19:02 GMT (163kb)
Date (revised v2): Thu, 1 Jun 2006 08:46:23 GMT (125kb)
Options for a nondedicated mission to test the Pioneer anomaly
Authors: Dario Izzo, Andreas Rathke
Comments: 29 pages, uses AIAA style files. Improved presentation, shortened, some technicalities from v1 omitted, updated references, to appear in Journal of Spacecraft and Rockets
The Doppler-tracking data of the Pioneer 10 and 11 spacecraft show an unmodelled constant acceleration in the direction of the inner Solar System. Serious efforts have been undertaken to find a conventional explanation for this effect, all without success at the time of writing. Hence the effect, commonly dubbed the Pioneer anomaly, is attracting considerable attention. Unfortunately, no other space mission has reached the long-term navigation accuracy to yield an independent test of the effect. To fill this gap we discuss strategies for an experimental verification of the anomaly via an upcoming space mission. Emphasis is put on two plausible scenarios: nondedicated concepts employing either a planetary exploration mission to the outer Solar System or a piggybacked micro-spacecraft to be launched from a mother spacecraft travelling to Saturn or Jupiter. The study analyses the impact of a Pioneer anomaly test on the system and trajectory design for these two paradigms. It is found that both paradigms are capable of verifying the Pioneer anomaly and determine its magnitude at 10% level. Moreover the concepts can discriminate between the most plausible classes of models of the anomaly, a central force, a blueshift of the radio signal and a drag-like force. The necessary adaptions of the system and mission design do not impair the planetary exploration goals of the missions.
http://arxiv.org/abs/astro-ph/0504634
astro-ph/0504634
From: Andreas Rathke [view email]
Date (v1): Thu, 28 Apr 2005 15:19:02 GMT (163kb)
Date (revised v2): Thu, 1 Jun 2006 08:46:23 GMT (125kb)
Options for a nondedicated mission to test the Pioneer anomaly
Authors: Dario Izzo, Andreas Rathke
Comments: 29 pages, uses AIAA style files. Improved presentation, shortened, some technicalities from v1 omitted, updated references, to appear in Journal of Spacecraft and Rockets
The Doppler-tracking data of the Pioneer 10 and 11 spacecraft show an unmodelled constant acceleration in the direction of the inner Solar System. Serious efforts have been undertaken to find a conventional explanation for this effect, all without success at the time of writing. Hence the effect, commonly dubbed the Pioneer anomaly, is attracting considerable attention. Unfortunately, no other space mission has reached the long-term navigation accuracy to yield an independent test of the effect. To fill this gap we discuss strategies for an experimental verification of the anomaly via an upcoming space mission. Emphasis is put on two plausible scenarios: nondedicated concepts employing either a planetary exploration mission to the outer Solar System or a piggybacked micro-spacecraft to be launched from a mother spacecraft travelling to Saturn or Jupiter. The study analyses the impact of a Pioneer anomaly test on the system and trajectory design for these two paradigms. It is found that both paradigms are capable of verifying the Pioneer anomaly and determine its magnitude at 10% level. Moreover the concepts can discriminate between the most plausible classes of models of the anomaly, a central force, a blueshift of the radio signal and a drag-like force. The necessary adaptions of the system and mission design do not impair the planetary exploration goals of the missions.
http://arxiv.org/abs/astro-ph/0504634
If you've got new scientist...there's an article about the pioneer anomaly:
http://www.newscientist.com/article/mg19025541.800.html
I haven't actually read it, but maybe someone can tell us what it's about
http://www.newscientist.com/article/mg19025541.800.html
I haven't actually read it, but maybe someone can tell us what it's about
QUOTE (remcook @ Jun 2 2006, 07:22 PM)
If you've got new scientist...there's an article about the pioneer anomaly:
http://www.newscientist.com/article/mg19025541.800.html
I haven't actually read it, but maybe someone can tell us what it's about
http://www.newscientist.com/article/mg19025541.800.html
I haven't actually read it, but maybe someone can tell us what it's about
There's a plan to re-examine all the tracking data which still exists, and to tie down the specific trajectory deviations which should nail the problem - it turns out that the competing explanations all result in unique vectors being imposed upon the trajectory so there may yet be a clear answer. Oh, and the tracking data being used this time is for a much longer time period than previous analyses used.
Bob Shaw
QUOTE (Bob Shaw @ Jun 2 2006, 08:34 PM)
...it turns out that the competing explanations all result in unique vectors being imposed upon the trajectory so there may yet be a clear answer...
Bob Shaw
Bob Shaw
That depend on. My prefered non-standard explanation would be that a small amount of dark matter would be linked to the solar system, creating a gravitationnal field which would peak at the distance of Jupiter or Saturn, decrease in 1/r2 beyond, and be null around Earth, because we would be inside this mass. If dark matter is formed of material weakly interacting particules, they still obey to gravitation, and thus they must be in orbit around the galaxy, at speeds in the 200/300km/s range. So it is expectable that some were caugh by the solar system and may orbit around it.
This said, I think we can seriously consider such kind of extraordinary hypothesis only after correct examination of all the existing data, and eliminating all the causes linked to the probe, solar wind, etc. Especially each hypothesis will have its own recognizable profile.
Dark matter. It's so deliciously undefined that it can be used as a chimera, explaining away any mass or gravity anomalies without requiring us to put forth any kind of realistic or organized description of its behavior or organization.
What we observe of the visible universe shows that mass tends to clump. Yes, some percentage of the mass of the Universe is present in a non-clumped cloud of gas and dust that extends between the galaxies and is wrapped into and around galaxies. But the vast majority of the mass we can see and measure is all bound up in gravitationally significant clumps -- from small rocky bodies all the way up to supermassive black holes.
The only thing the theoreticians can tell us about dark matter is that it cannot be seen and does not interact with normal matter and energy -- except gravitationally. Regular matter and dark matter must interact gravitationally, or else the reason for proposing its existence in the first place simply goes away in a puff of logic.
Now, the Pioneer anomaly is, as I understand it, a very slight anomalous acceleration twoards the inner solar system. Which would indicate that there is some unmodeled mass in the inner system that isn't accounted for in our current understanding of the mass of the Sun and inner planets.
If dark matter is responsible for this unmodeled acceleration, should we be thinking in terms of a "clump" of dark matter somewhere in the inner system? Since it begs incredulity to believe that dark matter simply exists as a smooth soup of undetectable matter, do we assume that there is some "extra" mass somewhere in the inner system that can account for this?
If so, where does this extra mass show up in the motions of the planets?
It doesn't.
This leads me to believe that either the Pioneer anomaly is the result of a defect in measurement of the probe's trajectory, or a defect in our model of gravitation. I don't think it makes sense to postulate mass that only affects *some* other masses in the solar system, but not others.
-the other Doug
What we observe of the visible universe shows that mass tends to clump. Yes, some percentage of the mass of the Universe is present in a non-clumped cloud of gas and dust that extends between the galaxies and is wrapped into and around galaxies. But the vast majority of the mass we can see and measure is all bound up in gravitationally significant clumps -- from small rocky bodies all the way up to supermassive black holes.
The only thing the theoreticians can tell us about dark matter is that it cannot be seen and does not interact with normal matter and energy -- except gravitationally. Regular matter and dark matter must interact gravitationally, or else the reason for proposing its existence in the first place simply goes away in a puff of logic.
Now, the Pioneer anomaly is, as I understand it, a very slight anomalous acceleration twoards the inner solar system. Which would indicate that there is some unmodeled mass in the inner system that isn't accounted for in our current understanding of the mass of the Sun and inner planets.
If dark matter is responsible for this unmodeled acceleration, should we be thinking in terms of a "clump" of dark matter somewhere in the inner system? Since it begs incredulity to believe that dark matter simply exists as a smooth soup of undetectable matter, do we assume that there is some "extra" mass somewhere in the inner system that can account for this?
If so, where does this extra mass show up in the motions of the planets?
It doesn't.
This leads me to believe that either the Pioneer anomaly is the result of a defect in measurement of the probe's trajectory, or a defect in our model of gravitation. I don't think it makes sense to postulate mass that only affects *some* other masses in the solar system, but not others.
-the other Doug
QUOTE (Bob Shaw @ Jun 2 2006, 02:34 PM)
There's a plan to re-examine all the tracking data which still exists, and to tie down the specific trajectory deviations which should nail the problem - it turns out that the competing explanations all result in unique vectors being imposed upon the trajectory so there may yet be a clear answer. Oh, and the tracking data being used this time is for a much longer time period than previous analyses used.
Bob Shaw
Bob Shaw
Anderson & company had trouble mapping solar wind acceleration coefficients for both Gemini and Galileo-They ended up adding an additional term that varied by ~1/r at a magnitude much greater than the Pioneer anomaly. Since this factor held an exactly solar vector, it is impossible to differentiate the 'unexpected force' from an unexpected attenuation in the solar wind. (Which could be as simple as deionization over time and distance.)
If the bulk of the Pioneer data leads to a similar conclusion, the next step may be something to give us a better feel for the solar wind...Something like the Planetary Society's solar sail
dvandorn, I quoted this explanation based on dark matter only to say that all the competing hypothesis would not give a constant acceleration. In the instance, dark matter would form a symmetrical fuzzy cloud all around the Sun (like it does around galaxies). If so, we could detect it as an acceleration toward the sun, peaking somewhere around Jupiter and Saturn, and decreasing inside or beyond. So if we found such a behaviour, we could point at such an explanation.
But I agree with you that such explanations are not very likely, and that only the complete examination of the full data set and eliminating all the standard hypothesis (like de-ionisation of the solar wind, as says The Messenger) will allow is to take non-standard hypothesis as working hypothesis.
What I am afraid is that, even if the problem is fixed in a standard way, there will be still tens of years of speculation and nutter litterature about it...
But I agree with you that such explanations are not very likely, and that only the complete examination of the full data set and eliminating all the standard hypothesis (like de-ionisation of the solar wind, as says The Messenger) will allow is to take non-standard hypothesis as working hypothesis.
What I am afraid is that, even if the problem is fixed in a standard way, there will be still tens of years of speculation and nutter litterature about it...
Centauri Dreams' latest take on the Pioneer Anomaly, including
descriptions of what was almost lost in terms of data on and from
Pioneer 10 and 11.
To quote:
New Scientist is running an interesting piece [subscription required for full access] on Slava Turyshev (JPL), who plans to investigate the so-called Pioneer Anomaly by re-flying the mission virtually. It’s a fascinating tale for various reasons, not the least of which is how close we came to losing much if not all of the precious Pioneer data.
For one thing, 400 reels of magnetic tapes housing information about the trajectories of the two spacecraft had to be saved from years of neglect and transferred to DVD.
Full article here:
http://www.centauri-dreams.org/?p=688
descriptions of what was almost lost in terms of data on and from
Pioneer 10 and 11.
To quote:
New Scientist is running an interesting piece [subscription required for full access] on Slava Turyshev (JPL), who plans to investigate the so-called Pioneer Anomaly by re-flying the mission virtually. It’s a fascinating tale for various reasons, not the least of which is how close we came to losing much if not all of the precious Pioneer data.
For one thing, 400 reels of magnetic tapes housing information about the trajectories of the two spacecraft had to be saved from years of neglect and transferred to DVD.
Full article here:
http://www.centauri-dreams.org/?p=688
That is great new at last that the data was saved, and that it is now available for correct study.
To summarize, some of the main hypothesis, from the likeliest from the unlikeliest.
-interaction between the ship and the solar wind and radiation was not modeled corectly, or was made wrong by some unexpected thing (for instance paint changing of color with UV)
-solar wind don't behave as expected (for instance de-ionization)
-there is an unknown planet of a significant mass (things like brown star, white dwarf, black holes... seem too large, unless they are very far)
-there is an invisible cloud of matter in close vicinity of our solar system (this was also debated about the low frequency noise in the cosmic background)
-there is an unconventionnal mass around there, such as a bit of dark matter
-there are unknown novel physical effects
-1/R2 gravitation law would be no longer valid at larger distance (MOND hypothesis) which would also explain the behaviour of galaxies and galaxy clusters without dark matter.
With my opinion those hypothesis should be examined into this order, and we should pass from a likelier hypothesis to an unlikelier one only if th first is proven false.
To summarize, some of the main hypothesis, from the likeliest from the unlikeliest.
-interaction between the ship and the solar wind and radiation was not modeled corectly, or was made wrong by some unexpected thing (for instance paint changing of color with UV)
-solar wind don't behave as expected (for instance de-ionization)
-there is an unknown planet of a significant mass (things like brown star, white dwarf, black holes... seem too large, unless they are very far)
-there is an invisible cloud of matter in close vicinity of our solar system (this was also debated about the low frequency noise in the cosmic background)
-there is an unconventionnal mass around there, such as a bit of dark matter
-there are unknown novel physical effects
-1/R2 gravitation law would be no longer valid at larger distance (MOND hypothesis) which would also explain the behaviour of galaxies and galaxy clusters without dark matter.
With my opinion those hypothesis should be examined into this order, and we should pass from a likelier hypothesis to an unlikelier one only if th first is proven false.
According to the NS article, the data tapes were just about to go in a skip when Our Hero arrived to save them! Great skin of the teeth stuff!
Bob Shaw
Bob Shaw
Maybe something attached themselves to the Pioneers....
QUOTE (ljk4-1 @ Jun 6 2006, 02:26 PM)
Maybe something attached themselves to the Pioneers....
space leeches?
30 Years of Pioneer Spacecraft Data Rescued:
The Planetary Society Enables Study of the Mysterious Pioneer Anomaly
Pasadena, CA, - There's a mystery at the edge of our solar system. Two
spacecraft, Pioneers 10 and 11, which were launched to Jupiter and
Saturn more than 30 years ago, are hurtling towards the edge of our
solar system -- but at a slower than expected rate. Called the "Pioneer
Anomaly," http://planetary.org/programs/projects/pioneer_anomaly/ the
effect of this slowing is small, but measurable, and so far unexplained.
Full article here:
http://planetary.org/about/press/releases/...craft_Data.html
The Planetary Society Enables Study of the Mysterious Pioneer Anomaly
Pasadena, CA, - There's a mystery at the edge of our solar system. Two
spacecraft, Pioneers 10 and 11, which were launched to Jupiter and
Saturn more than 30 years ago, are hurtling towards the edge of our
solar system -- but at a slower than expected rate. Called the "Pioneer
Anomaly," http://planetary.org/programs/projects/pioneer_anomaly/ the
effect of this slowing is small, but measurable, and so far unexplained.
Full article here:
http://planetary.org/about/press/releases/...craft_Data.html
QUOTE (Richard Trigaux @ Jun 5 2006, 11:39 PM)
That is great new at last that the data was saved, and that it is now available for correct study.
To summarize, some of the main hypothesis, from the likeliest from the unlikeliest.
1-interaction between the ship and the solar wind and radiation was not modeled correctly, ...)
2-solar wind don't behave as expected (for instance de-ionization)
3-there is an unknown planet of a significant mass ..
4-there is an invisible cloud of matter in close vicinity of our solar system...
5-there is an unconventionnal mass around there, such as a bit of dark matter
6-there are unknown novel physical effects
7-1/R2 gravitation law would be no longer valid at larger distance (MOND hypothesis) ...
we should pass from a likelier hypothesis to an unlikelier one only if th first is proven false.
To summarize, some of the main hypothesis, from the likeliest from the unlikeliest.
1-interaction between the ship and the solar wind and radiation was not modeled correctly, ...)
2-solar wind don't behave as expected (for instance de-ionization)
3-there is an unknown planet of a significant mass ..
4-there is an invisible cloud of matter in close vicinity of our solar system...
5-there is an unconventionnal mass around there, such as a bit of dark matter
6-there are unknown novel physical effects
7-1/R2 gravitation law would be no longer valid at larger distance (MOND hypothesis) ...
we should pass from a likelier hypothesis to an unlikelier one only if th first is proven false.
The linearity of what we have observed rules-out items one through five, unless both probes experienced virtually identical, linear responses to what should be non-linear functions (possible, but peculiar). It is disappointing to me, that after all the careful analysis Anderson, Nieto and Turyshev have given to us, a mission dedicated to nailing this down is not a major priority. There are a lot of dots that need to be connected.
QUOTE (The Messenger @ Jun 7 2006, 01:18 AM)
The linearity of what we have observed rules-out items one through five, unless both probes experienced virtually identical, linear responses to what should be non-linear functions (possible, but peculiar). It is disappointing to me, that after all the careful analysis Anderson, Nieto and Turyshev have given to us, a mission dedicated to nailing this down is not a major priority. There are a lot of dots that need to be connected.
Linearity? I have heard several versions, a force toward the Sun for Pioneers, backward for others... We really need to study the data, and obtain real curves, not just some dots.
QUOTE (Richard Trigaux @ Jun 6 2006, 11:34 PM)
Linearity? I have heard several versions, a force toward the Sun for Pioneers, backward for others... We really need to study the data, and obtain real curves, not just some dots.
The residual acceleration in the plots in the Anderson & co definitive paper are quite linear at distances competing effects from solar pressure can be seperated from the anomaly >12AU (~-8x10^-10m/s^2). It is clear from their work that they think this effect extends into the inner solar system (where it may or may not appear to be linear), but they are only able to state that the anomally is not a function of raw solar pressure after the residual acceleration becomes negative.
http://arxiv.org/PS_cache/gr-qc/pdf/0104/0104064.pdf p19-20
There is at least one more unprobability you should add to the list: A very slight increase in the speed of the light used to measure the acceleration. In one of the papers ljk4-1 posted above, they demonstrated that the pioneer anomalies can be modeled as a lensing effect; which effectively means the speed of light increases with increasing distance from the sun. GR already allows this (expressed as space 'de' contraction), but the magnitude would have to be many times greater than predicted by GR - this may or may not fall into the 'unknown-novel' category.
Speed of the light??
What is the speed of the light in an ionized medium like the solar wind? Certainly a bit slower than c. Was this effect accounted for? And if so, was the model accounting with eventual de-ionization of the solar wind? or other anisotropy, like magnetic field keeping part of the wind into the ecliptic plane?
What is the speed of the light in an ionized medium like the solar wind? Certainly a bit slower than c. Was this effect accounted for? And if so, was the model accounting with eventual de-ionization of the solar wind? or other anisotropy, like magnetic field keeping part of the wind into the ecliptic plane?
Astrophysics, abstract
astro-ph/0606197
From: Mauro Sereno [view email]
Date: Thu, 8 Jun 2006 15:28:39 GMT (49kb)
Dark matter vs. modifications of the gravitational inverse-square law. Results from planetary motion in the solar system
Authors: M. Sereno (Univ. Zuerich), Ph. Jetzer (Univ. Zuerich)
Comments: 7 pages, 4 figures, accepted for publication in MNRAS
Dark matter or modifications of the Newtonian inverse-square law in the solar-system are studied with accurate planetary astrometric data. From extra-perihelion precession and possible changes in the third Kepler's law, we get an upper limit on the local dark matter density, rho_{DM} < 3*10^{-16} kg/m^3 at the 2-sigma confidence level. Variations in the 1/r^2 behavior are considered in the form of either a possible Yukawa-like interaction or a modification of gravity of MOND type. Up to scales of 10^{11} m, scale-dependent deviations in the gravitational acceleration are really small. We examined the MOND interpolating function mu in the regime of strong gravity. Gradually varying mu suggested by fits of rotation curves are excluded, whereas the standard form mu(x)= x/(1+x^2)^{1/2} is still compatible with data. In combination with constraints from galactic rotation curves and theoretical considerations on the external field effect, the absence of any significant deviation from inverse square attraction in the solar system makes the range of acceptable interpolating functions significantly narrow. Future radio ranging observations of outer planets with an accuracy of few tenths of a meter could either give positive evidence of dark matter or disprove modifications of gravity.
http://arxiv.org/abs/astro-ph/0606197
astro-ph/0606197
From: Mauro Sereno [view email]
Date: Thu, 8 Jun 2006 15:28:39 GMT (49kb)
Dark matter vs. modifications of the gravitational inverse-square law. Results from planetary motion in the solar system
Authors: M. Sereno (Univ. Zuerich), Ph. Jetzer (Univ. Zuerich)
Comments: 7 pages, 4 figures, accepted for publication in MNRAS
Dark matter or modifications of the Newtonian inverse-square law in the solar-system are studied with accurate planetary astrometric data. From extra-perihelion precession and possible changes in the third Kepler's law, we get an upper limit on the local dark matter density, rho_{DM} < 3*10^{-16} kg/m^3 at the 2-sigma confidence level. Variations in the 1/r^2 behavior are considered in the form of either a possible Yukawa-like interaction or a modification of gravity of MOND type. Up to scales of 10^{11} m, scale-dependent deviations in the gravitational acceleration are really small. We examined the MOND interpolating function mu in the regime of strong gravity. Gradually varying mu suggested by fits of rotation curves are excluded, whereas the standard form mu(x)= x/(1+x^2)^{1/2} is still compatible with data. In combination with constraints from galactic rotation curves and theoretical considerations on the external field effect, the absence of any significant deviation from inverse square attraction in the solar system makes the range of acceptable interpolating functions significantly narrow. Future radio ranging observations of outer planets with an accuracy of few tenths of a meter could either give positive evidence of dark matter or disprove modifications of gravity.
http://arxiv.org/abs/astro-ph/0606197
Very interesting work.
Now just remains to compare the pioneer effect to the above results. If the Pioneer effect is larger, its origin must be searched into trite explanations (solar wind interaction and the like). The only interesting explanation would be about an unexpected behaviour of the solar wind.
Now just remains to compare the pioneer effect to the above results. If the Pioneer effect is larger, its origin must be searched into trite explanations (solar wind interaction and the like). The only interesting explanation would be about an unexpected behaviour of the solar wind.
I wonder if the recently announced one quadrillion members of the outer
Sol system play any role in the Pioneer Anomaly?
Sol system play any role in the Pioneer Anomaly?
Test of the Pioneer anomaly with the Voyager 2 radio-ranging distance measurements to Uranus and Neptune
http://arxiv.org/abs/gr-qc/0608127
http://arxiv.org/abs/gr-qc/0608127
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