On Friday, May 5, 2017 at 8:08:05 PM UTC-4, wrote:
On Tuesday, May 2, 2017 at 6:52:52 AM UTC+10, Craig Markwardt wrote:
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On Monday, May 1, 2017 at 8:25:16 AM UTC-4, wrote:
On Wednesday, April 26, 2017 at 3:15:29 AM UTC+10, Craig Markwardt wrote:
On Monday, April 24, 2017 at 7:17:03 AM UTC-4, wrote:
On Thursday, April 20, 2017 at 7:36:10 AM UTC+10, Craig Markwardt wrote:
On Wednesday, April 19, 2017 at 5:50:36 AM UTC-4, wrote:
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Fig.2 from this link
https://arxiv.org/pdf/1204.2507v1
apparently suggests that the Pioneer anomaly may only be the
result of mismodelling of the solar thermal contribution.
Your interpretation of this paper is incorrect. This paper
(Turyshev et al 2002) demonstrates that most if not all of the
"anomalous" acceleration can be attributed to *internal* thermal
emission, generated by the RTGs and internal electronics.
I note no response.
Your comments were noted, but you were referring to the wrong
paper.
This is the exact wording from the 2012 version linked above:
Third, Fig. 2 is strongly suggestive that the previously reported
"onset" of the Pioneer anomaly may in fact be a simple result of
mismodeling of the solar thermal contribution; this question may
be resolved with further analysis of early trajectory data.
Nope, you are incorrect. The 2012 paper concludes that "thermal
recoil" is the explanation for the Pioneer anomaly. But not
*solar* thermal. Or rather, the *new* thing of that paper is
that by including the *internal* thermal effects (RTGs and
electrical compartment dissipation) the anomaly is resolved.
My paragraph above is exactly as presented in Turyshev's paper.
You will find it in the conclusion section.
OK, I acknowledge that quote now, but you are still incorrect. The conclusion of the paper is that *internally generated* thermal recoil force is a signifcant effect that has to be newly reckoned.
The quote you are referring to is a single sentence in the entire paper. It *SUGGESTS* that the "early data" points in the chart you like to refer to, *may* be because the early analysts erroneously did not account for internal heat generation. Not the entire anomaly, as you originally stated, but the early data. And it is a speculative suggestion in the final words of the paper. You don't see any quantitative or detailed substantiation of that speculation; rather, the authors forsaw perhaps further work as a way to flesh it out more.
Previous work *ALWAYS* considered solar thermal recoil forces,
and could not explain the anomaly. Again, the new thing in the
Turyshev et al 2012 paper was inclusion of internally-generated
thermal terms, and this is what "tipped the balance."
What exactly are the physical properties of these thermal terms?
Do they represent new physics that Anderson was unaware of back
in 2002?
Hey, you asked this question, I responded that you could read Turyshev et al's 2012 paper for details, and you conveniently deleted that response. Why do you ask again?
And, if you had bothered to read my other responses, you would be aware that (a) Anderson et al in 2002 did a more simplified modeling analysis (i.e. it was not "new physics," but rather model fidelity) (b) Anderson did not have access to temperature and other thermal data during the actual mission, that did become available later (Viktor Toth spent a large amount of time recovering old data disks with mission data). (c) The team "discovered" or at least had more time to consider pre-launch thermal engineering documents that Anderson did not. And (d) there was time to develop a high fidelity thermal model of the Pioneer spacecraft and validate it against actual mission temperature data.
But such an error can't reside in the mismodelling of the solar
reflection/absorption characteristics of the HGA dish because
that was accurately determined prior to launch,
Just a side note, but thermal coatings do degrade over time, due
to exposure to solar UV as well as ionizing radiation (white
coatings become darker). So one can't be so certain about these
properties. That was one of the aspects covered by the thermal
analysis reported in Turyshev et al's 2012 paper.
You apparently agree that the RTG surface coating becomes darker
over time due to both solar radiation and radiation from within
the RTG's. ... The pressure gradient will
follow the RTG line, **not the solar radiation pressure curve.** ...
I'll re-write the paragraphs you've intentionally corrupted
because they demonstrate Turyshev's error exactly. You could
perhaps explain how your "thermal terms" overcome these problems.
I'll delete those paragraphs again, because they represent a misunderstanding by your intuition. Please, if this matters to you, starting reading about spacecraft thermal properties. I referred you to one text. If it doesn't matter to you, why are you bothering speculating about what you do know know?
Almost all known thermal coatings degrade w.r.t. the optical
properties (the "alpha" coefficient), but do *not* significantly
change w.r.t the infrared emission properties (the "epsilon"
coefficient), including the coatings used on Pioneer. Therefore,
your assumptions are irrelevant.
However you wish to define "optical properties", one thing
that's certain is that if a paint surface deteriorates and
becomes more absorptive, it will also become equally more
emissive. ...
Incorrect. Optical (reflective) properties of most thermal coatings, including the coatings in question for Pioneer, do degrade. But the infrared emissivity properties do *NOT* change significantly. I referred you to a textbook on the matter, but you ignored it.
Here, let me quote for you,
"Thermal-control finishes are affected in orbit by charged particles, ultraviolet (UV) radiation, high vacuum, and the contaminant films that deposit out on almost all spacecraft surfaces. The general result of these processes is an increase in solar absorptivity with little or no effect on IR emittance." (Spacecraft Thermal Control Handbook, 2002, p. 143) But if you read onward, there are like twenty pages about degradation, why it occurs, etc.
There have been long-term studies of degradation on the International space station (Fig 4.12) which show optical but not infrared degradation.
There have been detailed studies of the reflective properties of the Cassini high gain reflector (which has temperature sensing; di Bennetto, "The non-gravitational accelerations of the Cassini spacecraft ..." 2001) which show the same.
There was work in the late 1960s and early 1970s which showed the same for the exact thermal coatings used by Pioneer (e.g. Mayer et al. 1969, "Investigation of Spacecraft Coatings," NASA CR-61267; Broadway 1971, "Radiation Effects Design Handbook, Section 2. Thermal-Control Coatings").
So whatever you do or don't want me to tell you, your intuition is incorrect, so there's no need for me to re-quote your paragraphs or engage further in your unfounded speculations about Turyshev's work. And let me say, if you claim to be serious about this, then would be well-advised to learn about all of these effects. I did.
But bringing back to your original point before you distracted...
you wondered why analysts could not know the thermal/optical
properties of the Pioneer coatings exactly today. I guess you
concede now that it's more difficult than you first wondered.
So what! ... [irrelevant discussion removed. ]
Interesting rebuttal. I'm so glad you acknowledge that your original speculation about knowing Pioneer thermal/optical properties exactly today was not substantiated.
It's obvious that either Turyshev or Anderson made a fairly
significant error. But it's strange that Anderson is deemed
wrong when a significant number of others also demonstrated the
existence of the anomaly, including yourself (2002)? Why should
this new result override all others when the average result from
all contributors well and truly favors the anomaly's existence?
That's a funny way to do physics.
What would be funny is to ALWAYS assume that the "average" of some
papers is relevant. ...
I note no response.
Still no response.
This does warrant a reply.
I was once given this response when I questioned the validity of
one of the religious beliefs; "There are literally millions of
scriptures confirming what I believe, so it must be true." But
you and I both know that no matter how full the wheelbarrow is,
it can never be a measure of reality.
Interesting rebuttal. It was *you* that claimed that the average of many papers' results should somehow rebut the Turyshev result. And now, I guess you acknowledge that was erroneous.
But actually it's not true to say no one else was considering
thermal. ...
I note no response.
Most folk can understand that the thermal solution doesn't work.
"Most folk?" That's a rather unsubstantiated throwaway claim.
It was *you* who claimed that everybody except for Turyshev et
al 2012 had ignored the thermal origin, and I had to point out
the error of your statement.
Did you??? Where did I say they ignored it?
You said, "Why should this new result override all others when the average result from *all contributors* well and truly favors the anomaly's existence?" (emph. added) When in fact, it was not true that *all others* had not considered a thermal origin for the Pioneer anomaly. So please stop pretending to be ignorant.
You act as though analysts from the 1970's were using a set of
physical laws that analysts of today are not familiar with. But
that's not the case at all. Even if modifications have been made
to some of the physical laws the analysts of today would still
know exactly how the first data points showing the onset of the
anomaly were derived.
This is unsubstantiated. I am an analyst today of the Pioneer
doppler data, and I do not have enough information from that one
"onset" chart to understand how it was derived.
But a discrepancy between observation and what was expected
according to the prevailing physics at the time was clearly
noted, and it continued to increase until the spacecraft reached
the 20 AU mark. ...
Non-sequitur. Your statement doesn't make it any easier for a
Doppler analyst to reconstruct how the data analysis was done with
early data.
I note no response.
And... if you read Anderson's paper, the discrepancy was clearly
noted... in the 1980s far after the spacecraft had passed 20AU.
There is nothing in the paper that I can find which references
earlier times, aside from the figures you point out of unknown
provenance.
Check the graph Anderson provides. It clearly shows the onset
of the anomaly. He may not have done the calculations for the
first few data points but they still warranted inclusion.
John Anderson et al: Study of the anomalous acceleration of
Pioneer 10 and 11
https://arxiv.org/pdf/gr-qc/0104064v5
There's nothing constant about that curve. The only difference
between that and my graph is the in the x/y ratio.
Actually, the other difference is that you did not bother to reproduce the error bars, which are significant.
But that is also quite beside the point. The reason that Anderson placed that graph in the paper was for historical context. To paraphrase, "Past analysts' work suggested there may be an onset." That's about it! There is no quantitative or detailed discussion about the contents those figures. And no reproduction of the results of those figures. Those two figures are neither confirmed nor refuted by Anderson's actual work.
And, if you had actually bothered to get past the historical context section, you would have found the authors spent a lot of effort to measure a change of "anomalous acceleration," and they were *NOT* able to do so with the data at hand (they broke it into batches, etc). I did a different approach, which is to consider a "jerk" to the acceleration, which is equivalent to a smoothly changing acceleration. But I did not detect such a thing.
As I pointed out many times before, by the time of 2012, Turshev had several advantages. New radiometric tracking data became available for analysis, including several more years of "deep space" cruise, as well as Saturn and Jupiter encounter data (Turyshev et al 2011). The original thermal engineering documents came to light, which were not available to Anderson et al (Turyshev et al 2012). The actual mission thermal telemetry became available, when it was not available to Anderson et al (Toth & Turyshev 2006).
I'm guessing you're going revert to some variation of the "we'll just have to take it on unconditional faith" argument. But I 'll reiterate that Turyshev's effort was validated based on the use of standard software, verified many times; using documented thermal engineering properties; and validated against the actual Pioneer temperature data. This is not faith, but substantiated and validated thermal modeling.
CM