Talk:Pioneer anomaly/Archive 2014

Pioneer anomaly solved using just high school physics?! I doubt!

What we know - (1)Pioneer 11 mass m=259kg, (2)Pioneer 11 Electric Power=155watts, (3) Efficiency for an RTG nuclear generator = 3-7%. (Source Wikipedia)

In consequence, the total Thermal Energy generated by the RTG of Pioneer 11 each second is E_tot=155Joul*100/(3-7%)=5167-2214J out of which E_radiated=E_tot-155J=5012-2059J

E_radiated=p*c (where p = the radiation momentum and c = the speed of light)

The conservation of momentum between Thermal Radiation and Pioneer 11 spacecraft tells that p=m*delta_v

Thus, delta_v_ideal/sec=acc=E_radiated/(m*c)=2.65*10^(-8)-6.45*10^(-8) m/s^2

We can now make the supposition that only 1% of p is imbalanced, this is, there is no radiation momentum in the opposite direction to compensate for it, which finally means that delta_v_real/sec=acc=1%*E_radiated/m*c=2.65*10^(-10)-6.45*10^(-10) m/s^2, a domain of values quite close to the observed 8.74±1.33×10^(−10) m/s2 unexplained acceleration toward the Sun.

In CONCLUSION, anisotropic Thermal Radiation can be at most a plausible cause of the Pioneer spacecrafts anomaly but not the definitive explanation as long as slightly modifying the imbalanced radiation momentum from 1% (hard to estimate) to a different, also small, percentage or changing the RTG efficiency can put the calculated anomalous acceleration inside the observed range 8.74±1.33×10^(−10) m/s2 or well outside it. 70.83.114.138 (talk) 21:01, 9 February 2014 (UTC)

• This is exactly how science works! In general, hypotheses can never by proven, only supported.
• The problem was that before, there was thought to be *no* plausible cause. This is why the acceleration was called 'anamalous'.
• But now we know that known forces + thermal radiation *could* explain the results. Of course, known forces + thermal effects + unknown forces could also explain the results. But invoking unknown forces is a pretty extreme step if known forces can do the job. LouScheffer (talk) 12:43, 8 February 2014 (UTC)

@70.83.114.138: Please put new talk page messages at the bottom of talk pages and sign your messages with four tildes (~~~~). Thanks.

Also note that article talk pages are for discussions about the article, not about the subject. See wp:talk page guidelines. - DVdm (talk) 13:43, 8 February 2014 (UTC)

Suggested addition to the Description of the anomaly

Place in the last paragraph of Description after "...for both spacecraft." and before "If the positions...".

Other characteristics are: (1) The anomaly has an apparent annual periodicity with an amplitude of approximately 1.6 × 10^{− 10} m s^{− 2}. (2) The anomaly has an apparent Earth sidereal daily periodicity. (3) The value of the anomaly is approximately cH_o, where c is the speed of light and H_ois the Hubble constant, but with opposite sign, which suggest a cosmological connection. (4) Although within uncertainty limits, the Pioneer 11 anomaly may be slightly larger than the Pioneer 10 anomaly. (5) The anomaly calculation by the Sigma and CHASMP program methods for Pioneer 10(I) and Pioneer 10(II) show a discrepancy while showing consistency for Pioneer 10(III). (6) The anomaly of both spacecraft may be declining with distance.. (7) The blue shift of the anomaly is significantly smaller immediately before Pioneer 11's Saturn encounter. (8) The value of anomaly averaged over a period during and after the Saturn encounter had a relatively high uncertainty. (9) A modification of gravity large enough to explain the anomaly is inconsistent with the planetary ephemeredes unless the Equivalence Principle is violated. (10) The data analysis before the encounters was insufficient to detect the Pioneer anomaly rather than there was no anomaly at less than 10 AU. (11) Turyshev, et al. (2011) found "Although the Earth directed PA is marginally preferred by the solution, the Sun, the Earth, and the spin axis directions cannot be distinguished."

Camhodge (talk) 18:33, 3 February 2014 (UTC)

I disagree with your additions [1], which is why I reverted them, twice now. Point (3) is already in the article; except you've added your own "which suggest a cosmological connection". Points (1) and (2) are incompatible with the generally accepted explanation for the anomaly, so are probably wrong. And so on; I don't think your addition adds very much William M. Connolley (talk) 10:48, 9 February 2014 (UTC)

Point 3 has also added opposite sign. Point (1), (2), and the other points are data found in the referenced papers on the Pioneer anomaly published by respected and expert scientists in peer reviewed journals. Wikipedia claims it wants content like this. Data is not wrong, the model needs to be improved. In science the data drives the model not the other way around. Do you know of a peer-reviewed journal that questions these data? If so, give a reference. You may also notice the Anderson, et al. 2002 paper is listed in the “Further reading” section. So, the data has already been referenced in the article. This content adds to the understanding of the Pioneer anomaly.Camhodge (talk) 13:35, 9 February 2014 (UTC)

I also notice the article has a "Proposed explanations" section with many other models proposed. These are also in the literature. These are also incompatable with "the generally accepted explanation for the anomaly". I request this content be reinstated.Camhodge (talk) 13:49, 9 February 2014 (UTC)

I agree that this data does not help a Wikipedia article, though they are interesting to the specialist. Specific problems are: (1) and (2) are out of date. You would need to look at the residuals of more modern solutions that include the thermal force. (3) is already there. (4) is statistically insignificant. (5) There are now at least 7 independent analyses. Just pointing out the differences of the first two is historically interesting, but not current. (6) is the subject of a separate (and later) paper, already cited in the article. (7), (8), and (10) all deal with the early data, which all agree is harder to model (more maneuvers, bigger solar forces) (9) is covered in detail already.

In short, I think most of this data is subject to lots of caveats, and so not helpful to the general Wikipedia reader, who is not an expert. If you want to add this, I personally think that a section titled something like "Potential Issues with the Thermal Solution" and then present the pros and cons of each of your points, with reference to the most recent work for each point, and with commentary explaining the significance. LouScheffer (talk) 14:05, 9 February 2014 (UTC)

Thanks Lou. I had treated the suggested addition as an introduction of the data to be explained. I will resubmit as you suggest as “Potential Issues with the Thermal Solution” section in this talk page for comment. But I notice some of the issues are statements in the text that are slightly inaccurate. For example, the statement in Explanation section “… which did not appear in the initial analysis.” It was noted by Anderson, et al., 2002. Another example, the cH should include that it was an opposite sign to the galactic redshift. (7) and (8) are both significant because the data is significant and because the Turyshev, et al. 2012 paper compared the analysis to the Pioneer 10 only. The Saturn encounter data occurred with the Pioneer 11. A later paper (Modenini and Tortora, 2013, “Pioneer 10 and 11 orbit determination analysis shows no discrepancy with Newton-Einstein's laws of gravity” http://arxiv.org/pdf/1311.4978v1.pdf ) looked at the Pioneer 11 but averaged out the Saturn and the oscillation (1) and (2) data. They recognized the (1) and (2) as data points. Should I also suggest changes to the text to correct these?

You didn’t comment on (11).

I think the thermal model is subject to lots of caveats. I think the general reader would be interested in the idea there are lots of caveats with the Pioneer anomaly. But presenting the above without a detailed technical explanation for why there are competing models presents a challenge.Camhodge (talk) 18:07, 9 February 2014 (UTC)

(11) is a consequence of geometry and not a surprise. Since Pioneer is 30 AU out, the Earth, the Sun, and the spin axis are at most 2-3 degrees apart (since the spin axis was set to point to the Earth at maneuver time). So though the theorists would love to know the force direction, and will be very hard, at best, to tell these apart from the noisy data. LouScheffer (talk) 23:02, 9 February 2014 (UTC)

Place after "Indications ..." and before "Proposed explanations".

Potential issues with the Thermal Solution

The anomaly has an apparent annual periodicity and an apparent Earth sidereal daily periodicity with an amplitude greater than the error budget. Because [Fourier analysis] is excellent at detecting resonance in data, the support for the periodicities is compelling. A later paper looked at the Pioneer 11 but averaged out the periodicity data.

The value of anomaly averaged over a period during and after the Pioneer 11 Saturn encounter had a relatively high uncertainty and a significantly lower value. The Turyshev, et al. 2012 paper compared the thermal analysis to the Pioneer 10 only. The Pioneer anomaly was unnoticed until after Pioneer 10 past its Saturn encounter. A later paper looked at the thermal recoil of the Pioneer 10 and 11 but averaged the Saturn data over a long time which had the effect of smoothing the data.

Assuming the cosmological connection is a coincidence may be overlooking a valuable clue to a better model. The a_p and cH_o have opposite signs. The study of the cosmological connection ruled out a cosmological influence on the dynamics of the Pioneer anomaly.Camhodge (talk) 14:41, 12 February 2014 (UTC)

I don't think this satisfies what LS was suggesting: because its essentially "pro" problems with the thermal solution. Not pro and con. Quoting a 2002 paper for the annual periodicity is a bit odd; if it hasn't been re-suggested since then, the idea is probably dead. the support for the periodicities is compelling is far too pro your idea. More seriously, A later paper looked at the Pioneer 11 but averaged out the periodicity data is not an honest description of http://arxiv.org/pdf/1311.4978v1.pdf; are you forgetting that people can read it? William M. Connolley (talk) 21:57, 18 February 2014 (UTC)

References

Most detailed analysis

Since article mentions that the Turyshev paper "has the most detailed analysis to date" I just wanted to point out that the analysis by Rievers and Lämmerzahl can be found in much more datail in Riever's PhD thesis. Maybe worth consideration as a further source. Xaggi (talk) 10:37, 5 June 2014 (UTC)

"A vacuum" vs "vacuum"

The third paragraph of this article says "surrounded by an ultra-high vacuum" rather than "surrounded by ultrahigh vacuum." What's the preferred nomenclature here? I did some searching and can't find a clear answer. My physics PhD coworkers seem to think that "space is a vacuum" but "spaceships are surrounded by vacuum," with the logic being that "surrounded by" or "under" are more state-like, as opposed to referencing a compartment of space, which requires an "a." Tedsanders (talk) 21:41, 1 August 2014 (UTC)

Apples and oranges. We're talking about two specific spacecraft, rather than any and all, so we talk about the specific vacuum around them. This is somewhat obfuscated by the fact that we talk about a set of two, rather than a unique indivdual. Maybe this WP:SET is helpful:

"surrounded by a vacuum" 5870k

"surrounded by vacuum" 280k

Paradoctor (talk) 23:15, 1 August 2014 (UTC)