On Saturday, June 10, 2017 at 8:38:54 PM UTC-4, wrote:
On Tuesday, June 6, 2017 at 2:36:34 AM UTC+10, Craig Markwardt wrote:
On Thursday, June 1, 2017 at 6:44:11 AM UTC-4, wrote:
The following paragraph is exactly as written in Anderson's
paper.
... trim for brevity ...
The Cassini HGA dish properties would be much the same as those
for Pioneer. As would be the RTG surface coatings. Even if they
weren't, their properties would have been established prior to
launch. Then there's the "relatively large systematic from the
close in Cassini RTGs" to be considered.

If Turyshev's thermal solution accounts for the Pioneer anomaly,
why isn't it also required to account for a Cassini anomaly?
How do you explain the non-gravitational acceleration of
Cassini (as predicted by my theory) ???

Why don't you consult the PhD Thesis of "The non-gravitational
accelerations of the Cassini spacecraft and the nature of the
Pioneer anomaly" by Mauro di Benedetto. You've been referred to
it several times, but conveniently ignore it.

You're an analyst and your assessment of Mauro di Benedetto's
work should be fairly accurate. On 29-4-17 in your reply to a
question from old...@yahoo you wrote this paragraph;
"It's an interesting question. No effect similar to the Pioneer
anomaly has been detected with the Cassini doppler data. Cassini
is indeed a more complicated spacecraft, and there are more
trajectory disturbances for Cassini than for Pioneer. The very
detailed PhD work of Benedetto was able to rule out a
Pioneer-like anomaly using the full Cassini data set."

So, did Benedetto rule out a Pioneer-like anomaly or not?
You don't seem so sure any more.

I guess nuance is lost on you. Cassini is indeed a more complex spacecraft, there are countably more disturbing forces, but they can be understood with careful analysis. A Pioneer-like effect was ruled out. You could have read di Benedetto the work, but apparently did not.

What I object to is your apparent wish to be spoon-fed interpretations of the serious work of others so you can dismiss them, apparently without even reading them yourself. (see items 1-10 below). *YOU* made the unsubstantiated assumption about how simple it would be for someone to thermally model the Cassini spacecraft and how similar it would be to the Pioneers (item 10 below). Why don't you substantiate your claims?


Whatever your unsubstantiated assumptions, the Pioneers and
Cassini are not identical. There are several quite substantial
differences.

First of all, no-one has done a thermal model of Cassini for the
purposes of asymmetric radiation patterns, so it is not possible
to comment either way if they should be significant. These
calculations depend somewhat sensitively on where the
power-producing and -consuming components are located and the
view factors to other bodies and to space. Cassini is configured
in a much different way than the Pioneers so we cannot assume
similarity. You just decided to speculate without substantiation
that Cassini is similar to the Pioneers, but why do that without
evidence?

Second of all, there are things we *know* are very different.
Cassini is ~10x more massive than Pioneers. The Pioneers area to
mass ratio is about 10 times larger than the Cassini area to mass
ratio. This means that *accelerations* due to solar and
internally-generated thermal are about 10x smaller for the same
input signal.

If you had bothered to read the di Benedetto thesis you would
have found extensive discussions of the RTGs, which are quite
different than the Pioneer's RTGs.

I note no response. These are all valid reasons for Cassini to be not-so-simple and not-so-similar to the Pioneers. (see item 10 below)

[ re-inserting the summary of discussion that you conveniently deleted. ]
So, sorry to burst your bubble, but it turned out that Anderson et al’s
conclusions from 2001 were too simple and speculative, and also not born out
by the data or the detailed thermal modeling. Why you insist on hugging that
result when more refined results and Doppler data have followed is close to
madness.

I note that you conveniently deleted and ignored this crucial discussion. Anderson made simplifying assumptions that turned out to be incorrect or too simple. (see item #4 below)

"exact thermal coatings used by Pioneer"? Did they know something
Turyshev didn't?

Cute. Rather that learning about thermal emissivity properties,
you instead decide to invent a conspiracy theory (see #5 below).
The thermal coatings were documented, and *some* UV and radiation
tests were performed on those coatings in laboratories, but they
did not mimic the exact space environment the Pioneers
experienced. So do we really know the amount of degradation
experienced? What we do know is that most thermal coatings
degrade by changing their optical reflectivity (absorptivity) but
have very little change to the infrared emissivity. You could have
read about this but did not.

Increased absorptivity with no change in emissivity only reduces
solar radiation pressure. It has no effect whatever on the
fore/aft drive ratio from the internally generated RTG thermal
energy. Think about it. The emissivity of the surfaces hasn't
changed at all. And without the sunward drive asymmetry the
thermal solution fails.

You seem fixated upon the RTGs.

Exactly! That's where the thermal solution fails. Read the
paragraph you replied to.

[ I will quote one more sentence just before. ]
" Similar paints [13] have experienced both an increase and a decrease of up to 5% in infrared emissivity."
"Approximately 25% of the RTG coated surfaces were exposed to
solar irradiation. A calculation that takes into account the
relative contribution of RTG heat to the total anisotropy yields
a corresponding error figure of 25% in the overall error budget."

It's impossible for the RTG's to provide anything like 25% of
in the overall error budget.

The uncertainties in the surface coating does **not** help the
thermal solution at all. If absorptivity increases, emissivity
normally increases as well and the emissivity of the fore surface
will be greater than the aft surface. So the RTG's will be driven
away from the sun by the internally produced thermal energy,
which overwhelms any residual inward drive generated from solar
thermal energy absorption.

Let's get this out of the way. For the RTGs the effects of solar illumination and optical absorptivity/reflectivity are less important than for the HGA. This is because the energy input from the sun is about (using fsun=1367 W/m^ at 1AU)
fsun = 54 W/m^2 at 5AU (Jupiter)
= 14 W/m^2 at 10AU (Saturn)
= 0.5 W/m^2 at 50AU (escape)
of which 10-50% is absorbed by the white thermal coating (alpha=0.1-0.5).
Whereas the total internal RTG heat flux escaping is approximately,
frtg = 500 W/m^2 at launch
= 400 W/m^2 at 50AU (escape)
(basis: SNAP-19 Pioneer F & G final report for geometry and wattage)
In other words, the internally generated heat is dominant over the received solar flux by a factor of 20-1000x.

The total power generated by the Pioneers' RTGs is about 2500 W at beginning of life, and about 2000 W at end of life.

Now, one can solve the radiation transfer for a RTG fin which is illuminated by sun. I did this long ago based on my research on spacecraft thermal properties and established thermal principles. This included two sides of the fins with different emissivities on each side, e1 and e2.

After solving the equations, the resulting fractional flux anisotropy turns out to be,
(f1 - f2)/faverage = (e1-e2)/eaverage
The left side is the *fractional* flux difference, compared to the average of both sides, and the right side is the difference in emissivity, compared the average emissivity. This right hand number, by the way, is exactly the fractional +/- 5% increase/decrease discussed by Turyshev et al in 2012.

So the total emitted anisotropy in a pure planar geometry would be,
(P1 - P2) = 0.5*(2000W to 2500W) * (+/- 5%)
= +/- (50 W to 63 W)
By the way, this is *exactly* what Anderson et al derive in their section VIII.C. (they find a 1% emissivity difference produces 10W, I find 5% emissivity difference produces 50W: exactly the same).

This is in a simplified pure planar flat plate geometry. In reality there are non-planar "cosine" effects as noted by Anderson that limit the total anisotropy (factor 61%), and as well only a fraction of the RTG surface was exposed to sunlight (factor 25%). The total anisotropy thus estimated is about 10 W, or about 1.5e-8 cm2/s radiation pressure acceleration. Compared to the thermally modeled acceleration of about 6.5e-8, this is about +/-23%.

We can argue whether +/-23% or +/-25% is the right number. We can argue whether a more refined calculation can be done with improved view factors. But the basic physics is there.
1. There are known similar coatings which exhibit +/- 5% emissivity factors
(cf. Broadway 1971)
2. Such an emissivity difference is enough to produce about +/-25% difference
on the thermal emission model.
3. +/- 23% or +/- 25% does not qualitatively change the consistency beween
the thermal and doppler solutions.

Thus, it appears that the Turyshev et al (2012) model is on track.

By the way, if you revere the Anderson et al work so much, why do you so handily discard Anderson's work in this case, and not others? Basically Turyshev's work agrees with Anderson's work exactly on the sensitivity of the RTGs to differential emissivity of a certain percentage. But while Anderson et al assumed only 1% differential, Turyshev et al showed that similar paints, under solar irradiation test could exhibit as much as 5% differential emissivity. Turyshev produced facts and citations. What did you do?

[ re-inserting commentary from my follow-up post which you conveniently ignored ]

The "onset" in those figures is an artifact of the way the analysis was done.
The assumption made was not necessarily correct. We *know* there was
additional non-gravitational acceleration due to the electronic compartments.
This was not accounted for. Thus, we cannot rely upon the results in
Anderson's Figure 6 or 7, since they assumed what you are now claiming to
discover.

But let’s summarize the issues you seem to be willfully ignoring. You claim these UPDATED points are irrelevant, but they are exactly on point, as noted below.

1. You continue to mention that somehow Turyshev’s 2012 work is about “solar thermal” or RTGs, when that is incorrect. It is about solar thermal and RTGs yes, but mostly about internally-generated thermal. When noted, you ignore or distract.

2. You continue to ask about what is in the Turyshev 2012 paper. I continue to refer you to it, but you ignore or distract.

3. You continue to ask about what is different between the Anderson 2001 and Turyshev 2012 works. I reply with detailed points, but you ignore or distract.

4. You continue to appeal to authority of Anderson’s work for thermal aspects. However, Anderson’s work in this topic is rather crude, and limited to point-like and plate-like approximations. Even Anderson noted that a higher fidelity model could be useful and Turyshev’s 2012 work accomplished it! You continue to conveniently ignore or distract from this point. More to the point:
- Anderson made assumptions about the constancy of the "anomalous" force
that were not born out by actual data Pioneer data.
- Anderson made simplifying assumptions about the geometry and louvre
which turned out not to be valid
- Anderson made simplifying assumptions about how to estimate the
optical coefficients at D=5AU, which turned out to artificially
create the "onset" in his charts.

5. You continue to speculate how spacecraft thermal systems work based on your intuition. I’ve referred you to authoritative works, but you ignore.
- specifically you continue to speculate about how optical absorptivity
and emissivity are connected... without substantiation.
- you also speculate about how much of an effect and emissivity difference
would be without substantiation, when in fact, Turyshev's RTG differential
emissivity estimates are close to a naive estimate.

6. You’ve speculated that somehow the curve of the anomaly “onset” from Anderson’s paper is somehow rock solid, when in fact it can be explained as an artifact of how the solar radiation pressure was solved by Anderson et al. (i.e. by assuming that all other forces were zero at D=5AU, including the anomaly)

7. To bolster your case that the anomaly “onset” curve is real, you’ve decided that analysts from the 1970s were special wizards with more skill than today’s analysts. In fact, the opposite was the case: analysts of the time were still learning the craft. I provided citations to published papers about this. You conveniently ignore it.

8. You’ve tried to discount Turyshev’s 2012 work by claiming that it’s an outlier and that every other researcher could not agree with a thermal original. But these are false. Other researchers were considering a thermal origin and consistent with Turyshev’s 2012 work. You continue to ignore this.

9. You’ve speculated that it should be easy to know about or replicate the thermal quantities of the Pioneer systems. When the error of this statement was pointed out, you ignored or distracted.

10. You’ve speculated about the performance of the Cassini spacecraft and argue by analogy that Pioneer and Cassini work can be interchanged blindly. That is not true: the spacecraft were quite different and in a careful treatment must be considered separately. You’ve been referred to papers about Cassini but continue to ignore.

So I ask again: if this is so important to you, why don’t you stop ignoring important things? It's clear you have your own theory to hawk, and are willing to ignore anything that disagrees with it. So why should we listen to you?

I was hoping you could provide me with some real proof that the
anomaly doesn't exist, but sadly I've proven you wrong instead.

Actually, I've provided details, citations to research, facts, quantitative analysis. I've pointed out where Anderson's work went wrong in several areas. You have for the most part conveniently ignored those points and provided your own unsubstantiated speculation instead.

And yes, I do have a theory. But it's so far removed from current
theory that I don't think they could coexist in the same forum.

Please. There are many "new physics" theories that were stimulated by the Pioneer work and received recognition, publication and scrutiny. Those authors took the time to understand the details. You do not. Your conspiracy theories might validate your work in your own mind, but the truth is that tons of speculative work did get done. (example, Moffat's work on MOG).

What other true theories do is quantify, use evidence, refer to previous work, build a substantiated case. And yes, speculate where the evidence allows. What you are doing is just speculating while willfully ignoring the evidence. Good luck with that.

CM