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#11
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Ranging and Pioneer
Oh No wrote: The position of Pioneer was calculated from Doppler information. This statement is misleading. The position(s) of Pioneer(s) at any given time was calculated using classical trajectory dynamics (with GR corrections taken into account). So was the anticipated velocity hence Doppler shift of antenna signal at any given time. What was observed by NASA/JPL was an accumulating deviation from predicted Doppler shift, which led Anderson et al. to infer an apparent classically anomalous acceleration of the probes. These apparent classically anomalous accelerations were tabulated against predicted positions, not against altered positions inferred from such apparent classically anomalous accelerations of the probes. John (Liberty) Bell http://global.accelerators.co.uk (Change John to Liberty to respond by email) |
#12
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Ranging and Pioneer
Oh No wrote:
The position of Pioneer was calculated from Doppler information. Ranging was not available. Can anyone explain why ranging could not be used? Is this just a limit on available technology, or is there a more fundamental reason? Regards The following reference provides a mission to quantify the anomalous effect with ranging capability: ref1:A MISSION TO EXPLORE THE PIONEER ANOMALY H. Dittus, S.G. Turyshev, J.D. Anderson et al http://arxiv.org/pdf/gr-qc/0506139 3.3. A Dedicated Mission Concept Quote "In particular, we emphasize a precision formation flying as a feasible flight system concept for the proposed mission. For this architecture, a passive sphere covered with cornercube retroreflectors is laser-ranged from the primary craft." Unquote This is an excellent idea. My fear is that 'area to mass' ratio will not be designed into the "passive sphere" If the "passive sphere" is designed as a bowling ball rather than a soccer ball the anomalous deceleration effect will not be measured above the noise. Why not have several passive objects with an array of geometric shapes (Platonic solids for a start) with a range of 'area to mass' ratios all fitted with cornercube retroreflectors and ranged from the primary craft. Ref2: Seconds of Data, Years of Trying Photonics Spectra, May 2006 Vol 40, Issue 5, p 56 This reference provides a good perspective on capability of detecting laser space ranging data within the context of receiving ranging information from the Messenger Mission to Mercury. After much effort, the distance to the Laser Altimeter Instrument on the Messenger Mission to Mercury was measured at 23,964,675,433.9 +/- .2 m. (14,890,958.9 statute miles) (~.16 AU) Ref1 would appear to be the only reasonable approach for ranging small distant (from earth) space object trajectories Richard Saam |
#13
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Ranging and Pioneer
Richard Saam wrote: Oh No wrote: The position of Pioneer was calculated from Doppler information. Ranging was not available. Can anyone explain why ranging could not be used? Is this just a limit on available technology, or is there a more fundamental reason? Regards Here is an extreme case in terms of Beta Pictoris at many light years distance arXiv:astro-ph/0601244 v1 11 Jan 2006 Dynamic motions are inferred from atomic molecular quantum transitions. The time (frequency) of such transitions are assumed the same there and here from which observed differences in frequencies are related to dynamic motions. The problem is the same as you identify. How does one "range" the motions of Asteroid size objects (which do not have quantum transitions) in Beta Pictoris other than observing the gross newtonian gravity motions of the system as a whole. The problem could be solved if only a radar signal could be sent, reflected for obtaining active ranging information. In fact, with the (still functional) Pioneer, the possibility of obtaining ranging data is enhanced by the fact that it contains a narrow beam broadcast antenna directed towards the Earth, which can be turned on and off via ground control. Whether or not NASA thought to accuirately design and measure such turn on/off delays prior to launch, in order to facilitate such a ranging test, is, of course, another matter. John (Liberty) Bell http://global.accelerators.co.uk (Change John to Liberty to respond by email) |
#14
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Ranging and Pioneer
In message .com,
"John (Liberty) Bell" writes Richard Saam wrote: Oh No wrote: The position of Pioneer was calculated from Doppler information. Ranging was not available. Can anyone explain why ranging could not be used? Is this just a limit on available technology, or is there a more fundamental reason? Regards Here is an extreme case in terms of Beta Pictoris at many light years distance arXiv:astro-ph/0601244 v1 11 Jan 2006 Dynamic motions are inferred from atomic molecular quantum transitions. The time (frequency) of such transitions are assumed the same there and here from which observed differences in frequencies are related to dynamic motions. The problem is the same as you identify. How does one "range" the motions of Asteroid size objects (which do not have quantum transitions) in Beta Pictoris other than observing the gross newtonian gravity motions of the system as a whole. The problem could be solved if only a radar signal could be sent, reflected for obtaining active ranging information. In fact, with the (still functional) Pioneer, the possibility of obtaining ranging data is enhanced by the fact that it contains a narrow beam broadcast antenna directed towards the Earth, which can be turned on and off via ground control. Whether or not NASA thought to accuirately design and measure such turn on/off delays prior to launch, in order to facilitate such a ranging test, is, of course, another matter. Even when Pioneer 10 and 11 were fully functional (and contact was lost with 11 in 1995 and 10 in 2003) the fact remains that they couldn't do the type of ranging involving transmitting and receiving a modulated signal that was done with Galileo and Ulysses. They certainly wouldn't have used anything as drastic as turning the transmitter on and off. |
#15
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Ranging and Pioneer
In message .com,
"John (Liberty) Bell" writes Richard Saam wrote: Oh No wrote: The position of Pioneer was calculated from Doppler information. Ranging was not available. Can anyone explain why ranging could not be used? Is this just a limit on available technology, or is there a more fundamental reason? Regards Here is an extreme case in terms of Beta Pictoris at many light years distance arXiv:astro-ph/0601244 v1 11 Jan 2006 Dynamic motions are inferred from atomic molecular quantum transitions. The time (frequency) of such transitions are assumed the same there and here from which observed differences in frequencies are related to dynamic motions. The problem is the same as you identify. How does one "range" the motions of Asteroid size objects (which do not have quantum transitions) in Beta Pictoris other than observing the gross newtonian gravity motions of the system as a whole. The problem could be solved if only a radar signal could be sent, reflected for obtaining active ranging information. In fact, with the (still functional) Pioneer, the possibility of obtaining ranging data is enhanced by the fact that it contains a narrow beam broadcast antenna directed towards the Earth, which can be turned on and off via ground control. Whether or not NASA thought to accuirately design and measure such turn on/off delays prior to launch, in order to facilitate such a ranging test, is, of course, another matter. Even when Pioneer 10 and 11 were fully functional (and contact was lost with 11 in 1995 and 10 in 2003) the fact remains that they couldn't do the type of ranging involving transmitting and receiving a modulated signal that was done with Galileo and Ulysses. They certainly wouldn't have used anything as drastic as turning the transmitter on and off. |
#16
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Ranging and Pioneer
Jonathan Silverlight wrote: In message .com, "John (Liberty) Bell" writes Richard Saam wrote: Oh No wrote: The position of Pioneer was calculated from Doppler information. Ranging was not available. Can anyone explain why ranging could not be used? Is this just a limit on available technology, or is there a more fundamental reason? Regards Here is an extreme case in terms of Beta Pictoris at many light years distance arXiv:astro-ph/0601244 v1 11 Jan 2006 Dynamic motions are inferred from atomic molecular quantum transitions. The time (frequency) of such transitions are assumed the same there and here from which observed differences in frequencies are related to dynamic motions. The problem is the same as you identify. How does one "range" the motions of Asteroid size objects (which do not have quantum transitions) in Beta Pictoris other than observing the gross newtonian gravity motions of the system as a whole. The problem could be solved if only a radar signal could be sent, reflected for obtaining active ranging information. In fact, with the (still functional) Pioneer, the possibility of obtaining ranging data is enhanced by the fact that it contains a narrow beam broadcast antenna directed towards the Earth, which can be turned on and off via ground control. Whether or not NASA thought to accuirately design and measure such turn on/off delays prior to launch, in order to facilitate such a ranging test, is, of course, another matter. Even when Pioneer 10 and 11 were fully functional (and contact was lost with 11 in 1995 and 10 in 2003) According to Anderson et al. contact was not lost with Pioneer 10. The transmitter was switched off via ground control to conserve energy, thereby allowing it to be switched on again at a later date, for further tests. the fact remains that they couldn't do the type of ranging involving transmitting and receiving a modulated signal that was done with Galileo and Ulysses. They certainly wouldn't have used anything as drastic as turning the transmitter on and off. No, but they could now, if they knew switch on/off times accurately, in order to test whether the unexpected apparent anomalous acceleration had real consequences in terms of resultant reduced elapsed distance. John (Liberty) Bell http://global.accelerators.co.uk (Change John to Liberty to respond by email) |
#17
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Ranging and Pioneer
"John (Liberty) Bell" writes: Oh No wrote: The position of Pioneer was calculated from Doppler information. This statement is misleading. The position(s) of Pioneer(s) at any given time was calculated using classical trajectory dynamics (with GR corrections taken into account). So was the anticipated velocity hence Doppler shift of antenna signal at any given time. What was observed by NASA/JPL was an accumulating deviation from predicted Doppler shift, which led Anderson et al. to infer an apparent classically anomalous acceleration of the probes. These apparent classically anomalous accelerations were tabulated against predicted positions, not against altered positions inferred from such apparent classically anomalous accelerations of the probes. Your statement is also misleading. While it is true that the trajectory was "predicted" by classical mechanics, what you don't say is that the parameters of the trajectory (initial conditions) were adjusted in order to provide the best possible fit of the model to the Doppler observations. Thus in a very real sense, the Doppler observations can be used to "calculate" the position of the Pioneer spacecraft. Despite the adjustment of all possible classical "knobs" in the model, the anomaly remains. CM |
#18
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Ranging and Pioneer
Jonathan Silverlight wrote: In message .com, "John (Liberty) Bell" writes Richard Saam wrote: Oh No wrote: The position of Pioneer was calculated from Doppler information. Ranging was not available. Can anyone explain why ranging could not be used? Is this just a limit on available technology, or is there a more fundamental reason? Regards Here is an extreme case in terms of Beta Pictoris at many light years distance arXiv:astro-ph/0601244 v1 11 Jan 2006 Dynamic motions are inferred from atomic molecular quantum transitions. The time (frequency) of such transitions are assumed the same there and here from which observed differences in frequencies are related to dynamic motions. The problem is the same as you identify. How does one "range" the motions of Asteroid size objects (which do not have quantum transitions) in Beta Pictoris other than observing the gross newtonian gravity motions of the system as a whole. The problem could be solved if only a radar signal could be sent, reflected for obtaining active ranging information. In fact, with the (still functional) Pioneer, the possibility of obtaining ranging data is enhanced by the fact that it contains a narrow beam broadcast antenna directed towards the Earth, which can be turned on and off via ground control. Whether or not NASA thought to accuirately design and measure such turn on/off delays prior to launch, in order to facilitate such a ranging test, is, of course, another matter. Even when Pioneer 10 and 11 were fully functional (and contact was lost with 11 in 1995 and 10 in 2003) the fact remains that they couldn't do the type of ranging involving transmitting and receiving a modulated signal that was done with Galileo and Ulysses. They certainly wouldn't have used anything as drastic as turning the transmitter on and off. Notwithstanding the fact that Anderson et al. claimed (I think in 2004) that Pioneer 10 was still functional, with its antenna turned off to conserve energy, the fact remains that, if their reported apparent anamolous acceleration is real, this should mean that the effect of turning the antenna on or off should, by now, be observable on Earth more than 1 second before originally expected. Knowledge of the antenna turn on/off times to an accuracy better than this, is, I suggest, not too much to ask for the adequate pre-launch documentation of a piece of kit (and space program) of this cost. Performing such a proposed test is hardly drastic, and far from expensive (if adequate pre-launch documentation exists), given that NASA/JPL have already turned off the antenna, and plan on switching it on again at some unspecified time in the future. John (Liberty) Bell http://global.accelerators.co.uk (Change John to Liberty to respond by email) |
#19
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Ranging and Pioneer
Jonathan Silverlight writes
Even when Pioneer 10 and 11 were fully functional (and contact was lost with 11 in 1995 and 10 in 2003) the fact remains that they couldn't do the type of ranging involving transmitting and receiving a modulated signal that was done with Galileo and Ulysses. They certainly wouldn't have used anything as drastic as turning the transmitter on and off. Is it the case that these two ought to be able to show the anomalous pioneer acceleration, or are there too many other confounding influences for it to be readily isolated? -- Oz This post is worth absolutely nothing and is probably fallacious. |
#20
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Ranging and Pioneer
In message .com,
"John (Liberty) Bell" writes Jonathan Silverlight wrote: Even when Pioneer 10 and 11 were fully functional (and contact was lost with 11 in 1995 and 10 in 2003) the fact remains that they couldn't do the type of ranging involving transmitting and receiving a modulated signal that was done with Galileo and Ulysses. They certainly wouldn't have used anything as drastic as turning the transmitter on and off. Notwithstanding the fact that Anderson et al. claimed (I think in 2004) that Pioneer 10 was still functional, with its antenna turned off to conserve energy, Would you like to cite a source for that? Anyway, what do you mean "with its antenna turned off"? The Pioneers used travelling wave tubes in their transmitters, and although they were occasionally turned off everyone was surprised when they were turned on again and still worked :-) the fact remains that, if their reported apparent anamolous acceleration is real, this should mean that the effect of turning the antenna on or off should, by now, be observable on Earth more than 1 second before originally expected. Quite apart from more formal publications, the Pioneer anomaly has been discussed on Usenet for at least five years http://groups.google.com/group/sci.p...hread/a88ae76f f5a0f575/c3f9417441fff44e?lnk=st&q=%22pioneer+anomaly%22+tu ryshev&rnum=1# c3f9417441fff44e http://tinyurl.com/pdk47 and it's been established by correspondence with Slava Turyshev that a simple round-trip time measurement isn't sufficiently accurate to solve the problem, even if it could be done. You _have_ done some research on this topic, haven't you? -- Mail to jsilverlight at the address shown is more likely to be seen! |
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