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Pioneer Anomaly 2017



 
 
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  #31  
Old April 25th 17, 06:15 PM posted to sci.astro
Craig Markwardt[_2_]
external usenet poster
 
Posts: 137
Default Pioneer Anomaly 2017

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:
On Saturday, April 1, 2017 at 7:47:20 AM UTC+11, Craig Markwardt wrote:
---
---
The question is what tolerance was required for the analysis. Anderson
et al's analysis was quite back of the envelope. A few Watts makes a
difference, so it was important to treat the analysis in more detail.

...
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.

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.

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.

But actually it's not true to say no one else was considering
thermal. ...


I note no response.

....
For John Anderson's analysis, each data point was obviously
generated using a common logic. ...


Absolutely not. The data points you are referring to in your own
plot are taken from Anderson's paper, Figure 7. If you had read
the Anderson et al 2002 paper more carefully you would have
understood that this figure represented the early analysis, of
analysts working in an operational environment and trying to
navigate the spacecraft. The analysis was not performed in a
totally rigorous way by the same analysts or with the same criteria.

As they pointed out in the paper, when the spacecraft reached about
20 AU, the search for unmodeled accelerations could begin in more
earnest, and more attention to detail was made... but 20 AU is way
past the so-called "onset" around 5AU! At the time of the Anderson
et al 2002 paper, the early data was lost (unavailable) and only
those graphical figures remained, not the original data. Thus, when
it came time to do new, more careful work, their group had to begin
with data starting about 1980, and there was no way to look for a
putative onset around 5 AU which occurred in the early 1970s.
[ Later, after Anderson's work, a small amount of earlier data was
recovered. ]

Just to be clear, during the early to mid 1970s, the data formats,
the software, and the analysis teams were in much more flux. NASA
was in the business of navigating spacecraft (and not high
sensitivity spacecraft physics), and was just learning how powerful
the radiometric techniques could be. You can go back and read all
of the DSN status documents if you want: they are public and online.
But the point is that what we know and do today to navigate
spacecraft, does not and did not apply to what was done in the early
1970s when this was a new field. You cannot say that anything was
done with a "common logic" or "invariant" comparing today to then.


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.

Furthermore, let's be clear what was happening in the early 1970s. The Pioneer spacecraft were the first spacecraft to be sent to the outer solar system, with long cruise phases. Earlier spacecraft were kept inside the Earth-Moon system, or directed to the inner solar system. This new direction required new attention to detail and modeling of the physical effects of the space environment. No, the physical laws did not change, but the modeling capability within the software that was used did not capture all of the physics with the same fidelity.

Effects such as spacecraft spin and new relativistic physics were being incorporated at that time. You can read the paper of Wong & Lubeley from 1974 (AIAA Paper No. 74-845) which demonstrates how the orbit determination groups were incorporating new software with better capabilities.

Effects such as spacecraft propellant valve leaks were harder to understand, and navigation analysts had to make do. What physical laws does one apply to a valve that is leaky???

Before encountering Jupiter, both Pioneer spacecraft performed frequent maneuvers (every few weeks), which disturbed the orbit determination process, and also introduced more possibilities for leaks.

Within the first 20 AU, the solar system radiation pressure is significant. In fact, before Jupiter approach, the radiation pressure is dominant over most of the force terms and is many times the "anomalous" acceleration. You pointed out thermal coatings, but let us not forget that the exact geometry of the spacecraft has an effect. Is the antenna treated as parabolic or flat-plate? What about the cut-outs and antenna feeds, how are those treated? These are not simple "physical law" issues. They have to do with how accurately the spacecraft systems can be modeled. Early in the mission, with computing power limited, some short cuts were inevitably taken.

I would also like to point out that the planetary positions, which we know so accurately today, were not known as accurately at the time. In fact, the Pioneer and Voyager encounters were used to refine the positions of the planets based on the fly-by data. But, before the fly-by, the knowledge of the planet positions ... and the corresponding acceleartions ... were less well known. Thus, there is some uncertainty there too.

So, please do not pretend that the state of affairs in the early 1970s can really be compared to the state today.

The figure which you have referred to which shows the "onset" of the acceleration, you have replotted. What you failed to show was the uncertainty range (error bars) of the points. If you had displayed those as well, you would have seen that the bars are very large and that early data is not necessarily as stringent as you say.



... The analysts weren't stupid back then, they noticed
this error and reported it. They couldn't explain it and neither
could anyone else. Your suggestion that the analyst were too busy
trying to navigate the spacecraft to properly analyze the
evidence is absurd. They weren't exactly alone in the world were
they!


Please let me clear. The Pioneer navigators were brilliant for their time. I referred you to one paper. There are several, and it is evident that they were highly skilled at their craft. BUT... they were also not able to fully exploit the capability of the radiometric data they were using. This was evident in their own records which show they were upgrading the software steadily with new capabilities. That early data MAY NOT have been as accurate as desired.

I also want to say that I am in no way criticizing John Anderson or his team of co-authors. His science track record is quite excellent, and it is clear that they are very capable as well. BUT AGAIN... the question is how good does someone have to be. And the Turyshev paper demonstrated that a higher quality thermal analysis can resolve the Pioneer "anomaly."

....
According to you, "when the spacecraft reached about 20 AU, the
search for unmodelled accelerations could begin in more earnest,
and more attention to detail was made". Why do you think a more
precise analysis of the more distant data points will be of any
use? It becomes quickly apparent where the curve is heading. But
so what? The horse has already bolted.


First of all, the quote is actually what Anderson et al. said in their paper, not me. And second of all, what is your point? If the goal is to accurately measure the "onset" of the anomaly, then the early data which would or could have shown that is largely lost forever. If the goal is to get an accurate measure of the anomaly in late days (20 AU) then the Anderson et al 2002 paper is just fine... but it doesn't prove or disprove any of your claims then. Anderson's paper claims the acceleration is consistent with being constant, quite the opposite of your claim!


The unnecessarily huge error margin I'm referring to is of course
the 25% generated by the unknown performance of the RTG coating.
Precise details of the coating are well known, so why hasn't this
question been addressed years ago. In Turyshev's paper it was
stated that "the properties of the RTG paint are, in principle,
measurable by a thermal vacuum chamber test of a hot RTG
analogue". So how can this huge error still exist? After more
than 40 years!


Problem 1. The exact Pioneer thermal coating materials no longer exist, so what do you suggest we do? (even if the formula still exists, there is significant variance from batch to batch, which provides its own uncertainty)
Problem 2. The space environment destroys thermal coatings. Do you have access all of the relevant space environments? (UV light, ionizing radation, extreme temperatures)
Problem 3. Funding. Doing the job properly requires access to facilities that are expensive, and technicians that are expensive. No money is available for this.

You doing a vacuum test with Plutonium is rather laughable, but please do not: Plutonium is toxic.

Why do I get the impression that huge error margins are a good
thing in the case of the Pioneer anomaly?


Thankfully you have the wrong impression.

The Turyshev team have perhaps managed to squeeze out a positive
result within the error bars, but they certainly haven't managed
to remove the problem. They could only shift it down a little at
best.


You can believe what you wish, but the Turyshev result shows that
the thermal and doppler solutions are consistent - within the
tolerances (see their Figure 4).


"believe" is the key word here isn't it.


I don't see you providing an alternate analysis of the thermal or doppler data. And, other researchers working independently have found similar results (see Bertolami's work that I pointed out earlier). Turyshev et al's work demonstrates within the evidence and known tolerances that the Pioneer "anomaly" has largely been resolved.

CM

  #32  
Old April 28th 17, 05:06 PM posted to sci.astro
[email protected]
external usenet poster
 
Posts: 73
Default Pioneer Anomaly 2017

Il giorno martedì 25 aprile 2017 19:15:29 UTC+2, Craig Markwardt ha scritto:
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:
On Saturday, April 1, 2017 at 7:47:20 AM UTC+11, Craig Markwardt wrote:
---
---
The question is what tolerance was required for the analysis. Anderson
et al's analysis was quite back of the envelope. A few Watts makes a
difference, so it was important to treat the analysis in more detail.
...
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.

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.

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.

But actually it's not true to say no one else was considering
thermal. ...


I note no response.

...
For John Anderson's analysis, each data point was obviously
generated using a common logic. ...

Absolutely not. The data points you are referring to in your own
plot are taken from Anderson's paper, Figure 7. If you had read
the Anderson et al 2002 paper more carefully you would have
understood that this figure represented the early analysis, of
analysts working in an operational environment and trying to
navigate the spacecraft. The analysis was not performed in a
totally rigorous way by the same analysts or with the same criteria.

As they pointed out in the paper, when the spacecraft reached about
20 AU, the search for unmodeled accelerations could begin in more
earnest, and more attention to detail was made... but 20 AU is way
past the so-called "onset" around 5AU! At the time of the Anderson
et al 2002 paper, the early data was lost (unavailable) and only
those graphical figures remained, not the original data. Thus, when
it came time to do new, more careful work, their group had to begin
with data starting about 1980, and there was no way to look for a
putative onset around 5 AU which occurred in the early 1970s.
[ Later, after Anderson's work, a small amount of earlier data was
recovered. ]

Just to be clear, during the early to mid 1970s, the data formats,
the software, and the analysis teams were in much more flux. NASA
was in the business of navigating spacecraft (and not high
sensitivity spacecraft physics), and was just learning how powerful
the radiometric techniques could be. You can go back and read all
of the DSN status documents if you want: they are public and online.
But the point is that what we know and do today to navigate
spacecraft, does not and did not apply to what was done in the early
1970s when this was a new field. You cannot say that anything was
done with a "common logic" or "invariant" comparing today to then.


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.

Furthermore, let's be clear what was happening in the early 1970s. The Pioneer spacecraft were the first spacecraft to be sent to the outer solar system, with long cruise phases. Earlier spacecraft were kept inside the Earth-Moon system, or directed to the inner solar system. This new direction required new attention to detail and modeling of the physical effects of the space environment. No, the physical laws did not change, but the modeling capability within the software that was used did not capture all of the physics with the same fidelity.

Effects such as spacecraft spin and new relativistic physics were being incorporated at that time. You can read the paper of Wong & Lubeley from 1974 (AIAA Paper No. 74-845) which demonstrates how the orbit determination groups were incorporating new software with better capabilities.

Effects such as spacecraft propellant valve leaks were harder to understand, and navigation analysts had to make do. What physical laws does one apply to a valve that is leaky???

Before encountering Jupiter, both Pioneer spacecraft performed frequent maneuvers (every few weeks), which disturbed the orbit determination process, and also introduced more possibilities for leaks.

Within the first 20 AU, the solar system radiation pressure is significant. In fact, before Jupiter approach, the radiation pressure is dominant over most of the force terms and is many times the "anomalous" acceleration. You pointed out thermal coatings, but let us not forget that the exact geometry of the spacecraft has an effect. Is the antenna treated as parabolic or flat-plate? What about the cut-outs and antenna feeds, how are those treated? These are not simple "physical law" issues. They have to do with how accurately the spacecraft systems can be modeled. Early in the mission, with computing power limited, some short cuts were inevitably taken.

I would also like to point out that the planetary positions, which we know so accurately today, were not known as accurately at the time. In fact, the Pioneer and Voyager encounters were used to refine the positions of the planets based on the fly-by data. But, before the fly-by, the knowledge of the planet positions ... and the corresponding acceleartions ... were less well known. Thus, there is some uncertainty there too.

So, please do not pretend that the state of affairs in the early 1970s can really be compared to the state today.

The figure which you have referred to which shows the "onset" of the acceleration, you have replotted. What you failed to show was the uncertainty range (error bars) of the points. If you had displayed those as well, you would have seen that the bars are very large and that early data is not necessarily as stringent as you say.



... The analysts weren't stupid back then, they noticed
this error and reported it. They couldn't explain it and neither
could anyone else. Your suggestion that the analyst were too busy
trying to navigate the spacecraft to properly analyze the
evidence is absurd. They weren't exactly alone in the world were
they!


Please let me clear. The Pioneer navigators were brilliant for their time. I referred you to one paper. There are several, and it is evident that they were highly skilled at their craft. BUT... they were also not able to fully exploit the capability of the radiometric data they were using. This was evident in their own records which show they were upgrading the software steadily with new capabilities. That early data MAY NOT have been as accurate as desired.

I also want to say that I am in no way criticizing John Anderson or his team of co-authors. His science track record is quite excellent, and it is clear that they are very capable as well. BUT AGAIN... the question is how good does someone have to be. And the Turyshev paper demonstrated that a higher quality thermal analysis can resolve the Pioneer "anomaly."

...
According to you, "when the spacecraft reached about 20 AU, the
search for unmodelled accelerations could begin in more earnest,
and more attention to detail was made". Why do you think a more
precise analysis of the more distant data points will be of any
use? It becomes quickly apparent where the curve is heading. But
so what? The horse has already bolted.


First of all, the quote is actually what Anderson et al. said in their paper, not me. And second of all, what is your point? If the goal is to accurately measure the "onset" of the anomaly, then the early data which would or could have shown that is largely lost forever. If the goal is to get an accurate measure of the anomaly in late days (20 AU) then the Anderson et al 2002 paper is just fine... but it doesn't prove or disprove any of your claims then. Anderson's paper claims the acceleration is consistent with being constant, quite the opposite of your claim!


The unnecessarily huge error margin I'm referring to is of course
the 25% generated by the unknown performance of the RTG coating.
Precise details of the coating are well known, so why hasn't this
question been addressed years ago. In Turyshev's paper it was
stated that "the properties of the RTG paint are, in principle,
measurable by a thermal vacuum chamber test of a hot RTG
analogue". So how can this huge error still exist? After more
than 40 years!


Problem 1. The exact Pioneer thermal coating materials no longer exist, so what do you suggest we do? (even if the formula still exists, there is significant variance from batch to batch, which provides its own uncertainty)
Problem 2. The space environment destroys thermal coatings. Do you have access all of the relevant space environments? (UV light, ionizing radation, extreme temperatures)
Problem 3. Funding. Doing the job properly requires access to facilities that are expensive, and technicians that are expensive. No money is available for this.

You doing a vacuum test with Plutonium is rather laughable, but please do not: Plutonium is toxic.

Why do I get the impression that huge error margins are a good
thing in the case of the Pioneer anomaly?


Thankfully you have the wrong impression.

The Turyshev team have perhaps managed to squeeze out a positive
result within the error bars, but they certainly haven't managed
to remove the problem. They could only shift it down a little at
best.

You can believe what you wish, but the Turyshev result shows that
the thermal and doppler solutions are consistent - within the
tolerances (see their Figure 4).


"believe" is the key word here isn't it.


I don't see you providing an alternate analysis of the thermal or doppler data. And, other researchers working independently have found similar results (see Bertolami's work that I pointed out earlier). Turyshev et al's work demonstrates within the evidence and known tolerances that the Pioneer "anomaly" has largely been resolved.

CM


.... rerephrasing the last question : is Cassini having a Dppler shift like Pioneer , and yearly and dayly ?
  #33  
Old April 28th 17, 05:49 PM posted to sci.astro
Craig Markwardt[_2_]
external usenet poster
 
Posts: 137
Default Pioneer Anomaly 2017

On Friday, April 28, 2017 at 12:06:57 PM UTC-4, wrote:
... rerephrasing the last question : is Cassini having a Dppler shift like Pioneer , and yearly and dayly ?


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.

CM
  #34  
Old April 30th 17, 08:22 AM posted to sci.astro
[email protected]
external usenet poster
 
Posts: 73
Default Pioneer Anomaly 2017

Il giorno venerdì 28 aprile 2017 18:49:32 UTC+2, Craig Markwardt ha scritto:
On Friday, April 28, 2017 at 12:06:57 PM UTC-4, wrote:
... rerephrasing the last question : is Cassini having a Dppler shift like Pioneer , and yearly and dayly ?


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.

CM


... like you note rightly , the Cassini'trajectory was not a good example for my rerephrasation ...but the work of Benedetto is interesting ..
... maybe the Voyager I was a better example : have you controlled in that Doppler shift an analogy with the Pioneer anomaly ?
  #35  
Old May 1st 17, 01:25 PM posted to sci.astro
[email protected]
external usenet poster
 
Posts: 22
Default Pioneer Anomaly 2017

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:

---
---
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.

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. But if in the unlikely event where RTG radiation
increases reflectivity, solar radiation would do likewise.

From RTG based darkening alone, all RTG surfaces will fade at the
same almost linear rate. The consequent solar radiation pressure
shortfall will deviate from the normally expected pressure and
reduce at that same rate as well. The pressure gradient will
follow the RTG line, **not the solar radiation pressure curve.**

http://members.optusnet.com.au/mskeon/solrtg.jpg

But surface darkening attributable to solar radiation will alter
exponentially. Theory may predict that this darkening will
significantly add to the inward acceleration closer to the sun
and taper off in a manner which compares with the Pioneer
anomaly over increasing distance, but that's not the case at all.
The darker sun facing surface will now radiate more of the RTG
internal thermal energy than the back face, overwhelming the
absorption capability of the solar radiation, thus driving the
spacecraft outward.

Don't tell me it won't.

Another problem is that absorbed solar thermal energy will also
radiate more readily from the darkened face. That applies to the
HGA dish as well.

The fix is to claim increased reflectability over time.
Probability: 1/1000000

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.

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.

...

---
---

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. It didn't start out big. The anomaly was reported
by responsible physicist you know. They weren't just hand waving
to attract attention.

Furthermore, let's be clear what was happening in the early
1970s. The Pioneer spacecraft were the first spacecraft to be
sent to the outer solar system, with long cruise phases. Earlier
spacecraft were kept inside the Earth-Moon system, or directed to
the inner solar system. This new direction required new
attention to detail and modeling of the physical effects of the
space environment. No, the physical laws did not change, but the
modeling capability within the software that was used did not
capture all of the physics with the same fidelity.

Effects such as spacecraft spin and new relativistic physics were
being incorporated at that time. You can read the paper of Wong
& Lubeley from 1974 (AIAA Paper No. 74-845) which demonstrates
how the orbit determination groups were incorporating new
software with better capabilities.

Effects such as spacecraft propellant valve leaks were harder to
understand, and navigation analysts had to make do. What
physical laws does one apply to a valve that is leaky???

Before encountering Jupiter, both Pioneer spacecraft performed
frequent maneuvers (every few weeks), which disturbed the orbit
determination process, and also introduced more possibilities for
leaks.

Within the first 20 AU, the solar system radiation pressure is
significant. In fact, before Jupiter approach, the radiation
pressure is dominant over most of the force terms and is many
times the "anomalous" acceleration. You pointed out thermal
coatings, but let us not forget that the exact geometry of the
spacecraft has an effect. Is the antenna treated as parabolic
or flat-plate?

What about the cut-outs and antenna feeds, how are those
treated? These are not simple "physical law" issues. They have
to do with how accurately the spacecraft systems can be modeled.
Early in the mission, with computing power limited, some short
cuts were inevitably taken.


Each component would need to be analyzed properly, with a fairly
in depth description of the processes involved if the analysis
was expected to be taken seriously.

Which raises some questions here.
What data was plugged into the 2012 Turyshev computer simulation?
Were the RTG emissions and solar radiation pressures correctly
represented? Or were they in fact mismodeled as was the
assumption regarding Anderson's work?

Does the simulation software contribute toward the outcome? If
so, what was the programmer's information source? Was the
programmer or the source biased in any way? How could anyone
know any of this?

In the end it comes down to unconditional belief.

I would also like to point out that the planetary positions,
which we know so accurately today, were not known as accurately
at the time. In fact, the Pioneer and Voyager encounters were
used to refine the positions of the planets based on the fly-by
data. But, before the fly-by, the knowledge of the planet
positions ... and the corresponding acceleartions ... were less
well known. Thus, there is some uncertainty there too.

So, please do not pretend that the state of affairs in the early
1970s can really be compared to the state today.

The figure which you have referred to which shows the "onset" of
the acceleration, you have replotted. What you failed to show
was the uncertainty range (error bars) of the points. If you had
displayed those as well, you would have seen that the bars are
very large and that early data is not necessarily as stringent as
you say.

... The analysts weren't stupid back then, they noticed
this error and reported it. They couldn't explain it and neither
could anyone else. Your suggestion that the analyst were too busy
trying to navigate the spacecraft to properly analyze the
evidence is absurd. They weren't exactly alone in the world were
they!


Please let me clear. The Pioneer navigators were brilliant for
their time. I referred you to one paper. There are several, and
it is evident that they were highly skilled at their craft.
BUT... they were also not able to fully exploit the capability of
the radiometric data they were using. This was evident in their
own records which show they were upgrading the software steadily
with new capabilities. That early data MAY NOT have been as
accurate as desired.

I also want to say that I am in no way criticizing John Anderson
or his team of co-authors. His science track record is quite
excellent, and it is clear that they are very capable as well.
BUT AGAIN... the question is how good does someone have to be.
And the Turyshev paper demonstrated that a higher quality thermal
analysis can resolve the Pioneer "anomaly."

...
According to you, "when the spacecraft reached about 20 AU, the
search for unmodelled accelerations could begin in more earnest,
and more attention to detail was made". Why do you think a more
precise analysis of the more distant data points will be of any
use? It becomes quickly apparent where the curve is heading. But
so what? The horse has already bolted.


First of all, the quote is actually what Anderson et al. said in
their paper, not me. And second of all, what is your point?
If the goal is to accurately measure the "onset" of the anomaly,
then the early data which would or could have shown that is
largely lost forever. If the goal is to get an accurate measure
of the anomaly in late days (20 AU) then the Anderson et al 2002
paper is just fine... but it doesn't prove or disprove any of
your claims then. Anderson's paper claims the acceleration is
consistent with being constant, quite the opposite of your claim!


But he does acknowledge that there was an observed onset of the
anomaly which indicated a deviation from well known standard
physics at the time.

---
---

The Turyshev team have perhaps managed to squeeze out a positive
result within the error bars, but they certainly haven't managed
to remove the problem. They could only shift it down a little at
best.

You can believe what you wish, but the Turyshev result shows that
the thermal and doppler solutions are consistent - within the
tolerances (see their Figure 4).


"believe" is the key word here isn't it.


I don't see you providing an alternate analysis of the thermal or
doppler data. And, other researchers working independently have
found similar results (see Bertolami's work that I pointed out
earlier). Turyshev et al's work demonstrates within the evidence
and known tolerances that the Pioneer "anomaly" has largely been
resolved.


That's better, but "has been largely resolved" is still a
gigantic overstatement. There's only a slight chance that the
anomaly no longer exists because it can only barely squeeze
between the questionable error margins. But at least nobody is
claiming absolute proof any more.

-----

Max Keon

  #36  
Old May 1st 17, 09:52 PM posted to sci.astro
Craig Markwardt[_2_]
external usenet poster
 
Posts: 137
Default Pioneer Anomaly 2017

Opening note...
Don't tell me it won't.


Hey bud, this is an open discussion forum. Whatever you think I should or should not say is completely irrelevant.


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:

---
---
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. 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."


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.** ...


Your writing appears to be motivated by intuition, but that is not the case.. You can find a more correct and physics- and engineering-motivated discussion in books like "Spacecraft Thermal Control Handbook." Also, there are quite a few reference books on the degradation of thermal coatings from the time in the public domain.

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.

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.


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.

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.


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.

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.


Furthermore, let's be clear what was happening in the early
1970s. The Pioneer spacecraft were the first spacecraft to be
sent to the outer solar system, with long cruise phases. Earlier
spacecraft were kept inside the Earth-Moon system, or directed to
the inner solar system. This new direction required new
attention to detail and modeling of the physical effects of the
space environment. No, the physical laws did not change, but the
modeling capability within the software that was used did not
capture all of the physics with the same fidelity.

Effects such as spacecraft spin and new relativistic physics were
being incorporated at that time. You can read the paper of Wong
& Lubeley from 1974 (AIAA Paper No. 74-845) which demonstrates
how the orbit determination groups were incorporating new
software with better capabilities.

Effects such as spacecraft propellant valve leaks were harder to
understand, and navigation analysts had to make do. What
physical laws does one apply to a valve that is leaky???

Before encountering Jupiter, both Pioneer spacecraft performed
frequent maneuvers (every few weeks), which disturbed the orbit
determination process, and also introduced more possibilities for
leaks.

Within the first 20 AU, the solar system radiation pressure is
significant. In fact, before Jupiter approach, the radiation
pressure is dominant over most of the force terms and is many
times the "anomalous" acceleration. You pointed out thermal
coatings, but let us not forget that the exact geometry of the
spacecraft has an effect. Is the antenna treated as parabolic
or flat-plate?

What about the cut-outs and antenna feeds, how are those
treated? These are not simple "physical law" issues. They have
to do with how accurately the spacecraft systems can be modeled.
Early in the mission, with computing power limited, some short
cuts were inevitably taken.


Each component would need to be analyzed properly, with a fairly
in depth description of the processes involved if the analysis
was expected to be taken seriously.


Exactly. In the early 1970s, the computing power did not exist to do the in-depth analysis required. The operational need did not exist either. But I see now that you understand that the process is not just about physical laws, but something more.

Which raises some questions here.
What data was plugged into the 2012 Turyshev computer simulation?

The answers are in the Turyshev 2012 paper and its predecessors.

Were the RTG emissions and solar radiation pressures correctly
represented?

Discussed in the Turyshev 2012 paper. "Correct" is a matter of tolerance.

Or were they in fact mismodeled as was the
assumption regarding Anderson's work?

Thanks for the loaded question. Anderson et al did not "mismodel" anything intentionally. The level of fidelity was lower and they did not have the thermal data available at the time required to check, which Turyshev et al did have by 2012.


Does the simulation software contribute toward the outcome? If
so, what was the programmer's information source?


The software is validated against all the missions supported by JPL for radiometric navigation, and the thermal modeling software is standard in the industry. That's why I say it has been validated: it has successfully been used thousands of times to correctly predict temperatures and emission profiles of equipment under test. And, let's not forget that Anderson et al 2002 compared multiple independent software suites, to guard against software errors.

Thermal modeling software also has many inputs. All the inputs for thermal/optical properties were taken from Pioneer engineering documentation, but error tolerances were also considered. *AND*, then the simulations were validated against actual spacecraft measured temperatures. This temperature record was not readily available for Anderson et al to use in 2001, but was for later work.

In the end it comes down to unconditional belief.


Please. It comes down to a consideration of an analysis using established techniques, which has been validated against known data (both other spacecraft and Pioneer itself). There are mountains of documentation on this, which you ignored or barely skimmed over. It's easy for you to just cast out that claim without substantiation, and I reject it.


So, please do not pretend that the state of affairs in the early
1970s can really be compared to the state today.


Again, no response.


The figure which you have referred to which shows the "onset" of
the acceleration, you have replotted. What you failed to show
was the uncertainty range (error bars) of the points. If you had
displayed those as well, you would have seen that the bars are
very large and that early data is not necessarily as stringent as
you say.


Again, no response.

....
First of all, the quote is actually what Anderson et al. said in
their paper, not me. And second of all, what is your point?
If the goal is to accurately measure the "onset" of the anomaly,
then the early data which would or could have shown that is
largely lost forever. If the goal is to get an accurate measure
of the anomaly in late days (20 AU) then the Anderson et al 2002
paper is just fine... but it doesn't prove or disprove any of
your claims then. Anderson's paper claims the acceleration is
consistent with being constant, quite the opposite of your claim!


But he does acknowledge that there was an observed onset of the
anomaly which indicated a deviation from well known standard
physics at the time.


Who acknowledges it? As I noted above, aside from the figures from unknown sources which you care to reproduce deceptively (see above), Anderson et al 2002 do not mention an "onset" in the paper.

Again, I note that Anderson's claim is that the Pioneer anomaly is consistent with being constant. There was no evidence in the data available for something varying with time. This completely undercuts your own conclusion.

CM
  #37  
Old May 5th 17, 09:07 AM posted to sci.astro
[email protected]
external usenet poster
 
Posts: 73
Default Pioneer Anomaly 2017

Il giorno lunedì 1 maggio 2017 22:52:52 UTC+2, Craig Markwardt ha scritto:
Opening note...
Don't tell me it won't.


Hey bud, this is an open discussion forum. Whatever you think I should or should not say is completely irrelevant.


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:

---
---
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. 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."


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.** ...


Your writing appears to be motivated by intuition, but that is not the case. You can find a more correct and physics- and engineering-motivated discussion in books like "Spacecraft Thermal Control Handbook." Also, there are quite a few reference books on the degradation of thermal coatings from the time in the public domain.

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.

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.


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.

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.


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.

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.


Furthermore, let's be clear what was happening in the early
1970s. The Pioneer spacecraft were the first spacecraft to be
sent to the outer solar system, with long cruise phases. Earlier
spacecraft were kept inside the Earth-Moon system, or directed to
the inner solar system. This new direction required new
attention to detail and modeling of the physical effects of the
space environment. No, the physical laws did not change, but the
modeling capability within the software that was used did not
capture all of the physics with the same fidelity.

Effects such as spacecraft spin and new relativistic physics were
being incorporated at that time. You can read the paper of Wong
& Lubeley from 1974 (AIAA Paper No. 74-845) which demonstrates
how the orbit determination groups were incorporating new
software with better capabilities.

Effects such as spacecraft propellant valve leaks were harder to
understand, and navigation analysts had to make do. What
physical laws does one apply to a valve that is leaky???

Before encountering Jupiter, both Pioneer spacecraft performed
frequent maneuvers (every few weeks), which disturbed the orbit
determination process, and also introduced more possibilities for
leaks.

Within the first 20 AU, the solar system radiation pressure is
significant. In fact, before Jupiter approach, the radiation
pressure is dominant over most of the force terms and is many
times the "anomalous" acceleration. You pointed out thermal
coatings, but let us not forget that the exact geometry of the
spacecraft has an effect. Is the antenna treated as parabolic
or flat-plate?

What about the cut-outs and antenna feeds, how are those
treated? These are not simple "physical law" issues. They have
to do with how accurately the spacecraft systems can be modeled.
Early in the mission, with computing power limited, some short
cuts were inevitably taken.


Each component would need to be analyzed properly, with a fairly
in depth description of the processes involved if the analysis
was expected to be taken seriously.


Exactly. In the early 1970s, the computing power did not exist to do the in-depth analysis required. The operational need did not exist either. But I see now that you understand that the process is not just about physical laws, but something more.

Which raises some questions here.
What data was plugged into the 2012 Turyshev computer simulation?

The answers are in the Turyshev 2012 paper and its predecessors.

Were the RTG emissions and solar radiation pressures correctly
represented?

Discussed in the Turyshev 2012 paper. "Correct" is a matter of tolerance..

Or were they in fact mismodeled as was the
assumption regarding Anderson's work?

Thanks for the loaded question. Anderson et al did not "mismodel" anything intentionally. The level of fidelity was lower and they did not have the thermal data available at the time required to check, which Turyshev et al did have by 2012.


Does the simulation software contribute toward the outcome? If
so, what was the programmer's information source?


The software is validated against all the missions supported by JPL for radiometric navigation, and the thermal modeling software is standard in the industry. That's why I say it has been validated: it has successfully been used thousands of times to correctly predict temperatures and emission profiles of equipment under test. And, let's not forget that Anderson et al 2002 compared multiple independent software suites, to guard against software errors.

Thermal modeling software also has many inputs. All the inputs for thermal/optical properties were taken from Pioneer engineering documentation, but error tolerances were also considered. *AND*, then the simulations were validated against actual spacecraft measured temperatures. This temperature record was not readily available for Anderson et al to use in 2001, but was for later work.

In the end it comes down to unconditional belief.


Please. It comes down to a consideration of an analysis using established techniques, which has been validated against known data (both other spacecraft and Pioneer itself). There are mountains of documentation on this, which you ignored or barely skimmed over. It's easy for you to just cast out that claim without substantiation, and I reject it.


So, please do not pretend that the state of affairs in the early
1970s can really be compared to the state today.


Again, no response.


The figure which you have referred to which shows the "onset" of
the acceleration, you have replotted. What you failed to show
was the uncertainty range (error bars) of the points. If you had
displayed those as well, you would have seen that the bars are
very large and that early data is not necessarily as stringent as
you say.


Again, no response.

...
First of all, the quote is actually what Anderson et al. said in
their paper, not me. And second of all, what is your point?
If the goal is to accurately measure the "onset" of the anomaly,
then the early data which would or could have shown that is
largely lost forever. If the goal is to get an accurate measure
of the anomaly in late days (20 AU) then the Anderson et al 2002
paper is just fine... but it doesn't prove or disprove any of
your claims then. Anderson's paper claims the acceleration is
consistent with being constant, quite the opposite of your claim!


But he does acknowledge that there was an observed onset of the
anomaly which indicated a deviation from well known standard
physics at the time.


Who acknowledges it? As I noted above, aside from the figures from unknown sources which you care to reproduce deceptively (see above), Anderson et al 2002 do not mention an "onset" in the paper.

Again, I note that Anderson's claim is that the Pioneer anomaly is consistent with being constant. There was no evidence in the data available for something varying with time. This completely undercuts your own conclusion..

CM

PS.:
... could somebody give to me the email address of Mauro De Benedetto , rocket trajectory 'analist ?
  #38  
Old May 6th 17, 01:08 AM posted to sci.astro
[email protected]
external usenet poster
 
Posts: 22
Default Pioneer Anomaly 2017

On Tuesday, May 2, 2017 at 6:52:52 AM UTC+10, Craig Markwardt wrote:
---
---
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:

---
---
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.

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?

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.

+ You apparently agree that the RTG surface coating becomes darker
+ over time due to both solar radiation and radiation from within
+ the RTG's. But if in the unlikely event where RTG radiation
+ increases reflectivity, solar radiation would do likewise.
+
+ From RTG based darkening alone, all RTG surfaces will fade at the
+ same almost linear rate. The consequent solar radiation pressure
+ shortfall will deviate from the normally expected pressure and
+ reduce at that same rate as well. The pressure gradient will
+ follow the RTG line, **not the solar radiation pressure curve.**
+
+ http://members.optusnet.com.au/mskeon/solrtg.jpg
+
+ But surface darkening attributable to solar radiation will alter
+ exponentially. Theory may predict that this darkening will
+ significantly add to the inward acceleration closer to the sun
+ and taper off in a manner which compares with the Pioneer
+ anomaly over increasing distance, but that's not the case at all.
+ The darker sun facing surface will now radiate more of the RTG
+ internal thermal energy than the back face, overwhelming the
+ absorption capability of the solar radiation, thus driving the
+ spacecraft outward.

If you tell me it won't, I won't believe you.

Your writing appears to be motivated by intuition, but that is not
the case. You can find a more correct and physics- and
engineering-motivated discussion in books like "Spacecraft Thermal
Control Handbook." Also, there are quite a few reference books
on the degradation of thermal coatings from the time in the public
domain.

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. And that's where the Turyshev solution fails. He has
obviously made wrong assumptions in this area.

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! If the paint surfaces facing the sun increased solar
thermal absorption into the RTG's by any amount, solar radiation
pressure will be reduced, but the emissive power emanating from
those surfaces will still be greater than the absorption and the
spacecraft will be driven away from the sun.

The only way the spacecraft can be driven toward the sun is if
the sun facing surfaces become more reflective. And that's not
a viable option.

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.

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 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.

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.

---
Snip more of the same.
---

-----

Max Keon


  #39  
Old May 8th 17, 10:27 PM posted to sci.astro
Craig Markwardt[_2_]
external usenet poster
 
Posts: 137
Default Pioneer Anomaly 2017

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:
---
---
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:
---
---
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
  #40  
Old May 14th 17, 08:50 AM posted to sci.astro
[email protected]
external usenet poster
 
Posts: 73
Default Pioneer Anomaly 2017

Il giorno venerdì 5 maggio 2017 10:07:49 UTC+2, ha scritto:
Il giorno lunedì 1 maggio 2017 22:52:52 UTC+2, Craig Markwardt ha scritto:
Opening note...
Don't tell me it won't.


Hey bud, this is an open discussion forum. Whatever you think I should or should not say is completely irrelevant.


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:
---
---
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. 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."


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.** ...


Your writing appears to be motivated by intuition, but that is not the case. You can find a more correct and physics- and engineering-motivated discussion in books like "Spacecraft Thermal Control Handbook." Also, there are quite a few reference books on the degradation of thermal coatings from the time in the public domain.

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.

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.


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.

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.


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.

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.


Furthermore, let's be clear what was happening in the early
1970s. The Pioneer spacecraft were the first spacecraft to be
sent to the outer solar system, with long cruise phases. Earlier
spacecraft were kept inside the Earth-Moon system, or directed to
the inner solar system. This new direction required new
attention to detail and modeling of the physical effects of the
space environment. No, the physical laws did not change, but the
modeling capability within the software that was used did not
capture all of the physics with the same fidelity.

Effects such as spacecraft spin and new relativistic physics were
being incorporated at that time. You can read the paper of Wong
& Lubeley from 1974 (AIAA Paper No. 74-845) which demonstrates
how the orbit determination groups were incorporating new
software with better capabilities.

Effects such as spacecraft propellant valve leaks were harder to
understand, and navigation analysts had to make do. What
physical laws does one apply to a valve that is leaky???

Before encountering Jupiter, both Pioneer spacecraft performed
frequent maneuvers (every few weeks), which disturbed the orbit
determination process, and also introduced more possibilities for
leaks.

Within the first 20 AU, the solar system radiation pressure is
significant. In fact, before Jupiter approach, the radiation
pressure is dominant over most of the force terms and is many
times the "anomalous" acceleration. You pointed out thermal
coatings, but let us not forget that the exact geometry of the
spacecraft has an effect. Is the antenna treated as parabolic
or flat-plate?

What about the cut-outs and antenna feeds, how are those
treated? These are not simple "physical law" issues. They have
to do with how accurately the spacecraft systems can be modeled.
Early in the mission, with computing power limited, some short
cuts were inevitably taken.

Each component would need to be analyzed properly, with a fairly
in depth description of the processes involved if the analysis
was expected to be taken seriously.


Exactly. In the early 1970s, the computing power did not exist to do the in-depth analysis required. The operational need did not exist either. But I see now that you understand that the process is not just about physical laws, but something more.

Which raises some questions here.
What data was plugged into the 2012 Turyshev computer simulation?

The answers are in the Turyshev 2012 paper and its predecessors.

Were the RTG emissions and solar radiation pressures correctly
represented?

Discussed in the Turyshev 2012 paper. "Correct" is a matter of tolerance.

Or were they in fact mismodeled as was the
assumption regarding Anderson's work?

Thanks for the loaded question. Anderson et al did not "mismodel" anything intentionally. The level of fidelity was lower and they did not have the thermal data available at the time required to check, which Turyshev et al did have by 2012.


Does the simulation software contribute toward the outcome? If
so, what was the programmer's information source?


The software is validated against all the missions supported by JPL for radiometric navigation, and the thermal modeling software is standard in the industry. That's why I say it has been validated: it has successfully been used thousands of times to correctly predict temperatures and emission profiles of equipment under test. And, let's not forget that Anderson et al 2002 compared multiple independent software suites, to guard against software errors.

Thermal modeling software also has many inputs. All the inputs for thermal/optical properties were taken from Pioneer engineering documentation, but error tolerances were also considered. *AND*, then the simulations were validated against actual spacecraft measured temperatures. This temperature record was not readily available for Anderson et al to use in 2001, but was for later work.

In the end it comes down to unconditional belief.


Please. It comes down to a consideration of an analysis using established techniques, which has been validated against known data (both other spacecraft and Pioneer itself). There are mountains of documentation on this, which you ignored or barely skimmed over. It's easy for you to just cast out that claim without substantiation, and I reject it.


So, please do not pretend that the state of affairs in the early
1970s can really be compared to the state today.


Again, no response.


The figure which you have referred to which shows the "onset" of
the acceleration, you have replotted. What you failed to show
was the uncertainty range (error bars) of the points. If you had
displayed those as well, you would have seen that the bars are
very large and that early data is not necessarily as stringent as
you say.


Again, no response.

...
First of all, the quote is actually what Anderson et al. said in
their paper, not me. And second of all, what is your point?
If the goal is to accurately measure the "onset" of the anomaly,
then the early data which would or could have shown that is
largely lost forever. If the goal is to get an accurate measure
of the anomaly in late days (20 AU) then the Anderson et al 2002
paper is just fine... but it doesn't prove or disprove any of
your claims then. Anderson's paper claims the acceleration is
consistent with being constant, quite the opposite of your claim!

But he does acknowledge that there was an observed onset of the
anomaly which indicated a deviation from well known standard
physics at the time.


Who acknowledges it? As I noted above, aside from the figures from unknown sources which you care to reproduce deceptively (see above), Anderson et al 2002 do not mention an "onset" in the paper.

Again, I note that Anderson's claim is that the Pioneer anomaly is consistent with being constant. There was no evidence in the data available for something varying with time. This completely undercuts your own conclusion.

CM

PS.:
.. could somebody give to me the email address of Mauro De Benedetto , rocket trajectory 'analist ?


.... are you again there ? .... consider the point of max anomaly or the point of max changement of anomaly ! .. and so you understand the uselessness to discuss around the RTG or similar things for resolving the Pioneer anomaly .. i think ..
 




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