One of the problems with the popular far out topics like "UFOs" or the "Face on Mars" is that they get in the way of the real mysteries and weird things that scientists are puzzling over.

Here's one: Apparently Pioneer 10 and 11 Doppler data does not match the expected solar system model. There is a Doppler residual signal that represents an anomalous acceleration toward the Sun. (This data currently comes from Pioneer 10, and some earlier data from Pioneer 11 before a switch failure disabled it in 1990.)

The page linked here leads to an interesting summary. Further down there is a link to a PDF file of the very technical 95 page paper. It's worth a look if this topic is of interest to you.

The Planetary Society also has a great article about this in their November/December issue. You can read a little description of it if you go here and scroll down. But the complete article is not available on line.

Thanks for the link Chip.
I have heard of the anamolous acceleration before but never seen the full report.

I wish they'd use some format that I can read ; never can understand the symbology of these posts. What is $a_P ?

Anyway, what's your thought as to the cause?

[quote]
On 2002-01-21 19:34, Gsquare wrote:
Thanks for the link Chip.




Anyway, what's your thought as to the cause?
My guess? LIE's are much MUCH more Profitable
currently than truth. & probably so for some time into the near future!

As per the "$a_P etc..." they're talking about magnitudes and also equations later, but this seems to be a case of computers not having the characters necessary to completely resolve the original figure, and so "$" is being substituted. Or "$" has been assigned a different meaning - but my computer is not privy that "secret handshake." (-;
One can still read through the description to get the gist of what they're saying. In the big paper, the equations are clear.

As for what is causing the acceleration toward the Sun, in the paper they've ruled out Planet X (research of which was part of their original use of Pioneer Doppler telemetry,) so the mystery is really a conundrum. In the Planetary Society article, they imply that this little esoteric puzzle (which will not capture the public's imagination) is one of those things that could actually have very far reaching effects on physics, as well as other fields such as space navigation. Something out there is acting upon these spacecraft over time. All the choices as to what it is, based on known factors, don't fit.


<font size=-1>[ This Message was edited by: Chip on 2002-01-22 12:34 ]</font>

[quote]
On 2002-01-22 10:06, HUb' wrote:
True, but this is too esoteric to be popular or profitable. Doppler research detecting anomalies in space probe velocity (and what that may imply) doesn't capture the general public's imagination. This research seems very levelheaded and avoids sensationalism, at least to me. (-;

This anomalous Pioneer 10/11 acceleration is

(8.74 +/- 1.25) * 10^-8 cm/s^2

The original's dollar signs and other odd symbols are inputs for TeX, a common system for setting up mathematics-heavy documents. If you've ever composed HTML pages by hand, working with TeX will be a similar experience. For more, see http://www.tug.org

The acceleration of the Earth in its orbit is 0.593 cm/s^2 on average (1 AU)*(2*pi/yr)^2

making this anomalous acceleration 1.5*10^-7 of that.

However, Pioneer 10 was 67 AU from the Sun in 1997, when its mission was downgraded to a sort of background status, and Pioneer 11 was 40 AU from the Sun when contact with it was lost in 1995. This means that the anomalous acceleration is ~10^-4 of the Sun'as acceleration of them at that distance.

Finally, I note that calculated nongravitational effects, such as radiation reaction from the spacecraft's radio transmissions and the glow of the RTG's, are not much smaller than the anomalous acceleration itself, suggesting that one may have to model such effects more carefully.

Also, there are no similar effects reported for the Voyager spacecraft, so these may be due to some quirk of the Pioneers.

That's because they don't use MathML

I'm one amongst those freaks who preach in the desert about the virtues of the Math mark-up languague (I have suggested it to BA for the new software, but I know the majority of software vendors don't implement it in their packages). It could ban those weird characters, at least from the Internet.



<font size=-1>[ This Message was edited by: Argos on 2002-01-24 15:51 ]</font>

Thank you for some very insightful points concerning this! I think radiation reaction was accounted for -- but I find no accounting for the other things you've mentioned.

Chip

The authors of that paper had attempted to account for radiation reaction, but they seemed to have used some rather simplistic models, suggesting that more careful modeling might cause the discrepancy to disappear.

Thank you Lpetrich; especially for the data on the magnitude of the effect.

I was of the opinion that in interplanetary ranging determinations, an estimate of solar radiation effects was always done, even on Voyagers, but I am unaware of the order of magnitude of such. Your data is helpful.
I'll come back to this when I have time.

G^2

<font size=-1>[ This Message was edited by: Gsquare on 2002-01-26 14:12 ]</font>

Thank you, lpetrich. I read the Planetary Report account late today and had wondered about the details concerning the Pioneers' acceleration toward the Sun. You have mostly cleared up my misunderstandings about the article.

I read your posts whenever I find them, because you are always clear about your information.

ljbrs [img]/phpBB/images/smiles/icon_smile.gif[/img] [img]/phpBB/images/smiles/icon_biggrin.gif[/img]

__________________
"There is in the universe neither center nor circumference." Giordano Bruno Born 1548. Torched 1600.

[quote]Also, there are no similar effects reported for the Voyager spacecraft, so these may be due to some quirk of the Pioneers. [quote]

If you look at the following link, you will see the quote.

"Now six space scientists, armed with many years of Pioneer data, supplemented with trajectory information from Galileo and Ulysses, have carried out the first thorough analysis of the problem and find the anomaly to be as persistent as ever. (The Voyager spacecraft are less useful for determining acceleration anomalies.)"

I would suspect that means that they don't have the right kind of data for the Voyager missions or trust the data enough to use it in determining the acceleration anomalies. Also, Galileo and Ulysses do show those acceleration anomalies, so I suspect the acceleration is pretty well confirmed.

http://www.aip.org/enews/physnews/19...t/pnu391-1.htm

As I mentioned in another thread...

The reason the Voyager data can't be used is that they are thruster-stabilized, and it's impossible to crunch out the effects of those thruster burns to high enough accuracy to see this (small) anomaly.

The Pioneers are relatively simple spin-stabilized vehicles, so there's no thruster effects to muddy the waters. (Well, far less, anyhow; they must have used thrusters for maneuvering, but probably not since their last planetary encounters.)

Thanks. I figured there would be a simple reason why its data couldn't be used.

Could Kuiper Belt objects, or some other group of small bodies like them be the expanation for the Pioneers's acceleration?

Is this confirmed, now?

I suspect that they have ignored all the dust in the solar system. The cumulative effect of this as you travel away from the sun may add to the gravitational attraction. This dust is seen as the Zodiacal light and shows up very dramatically in the IRAS and COBE all sky maps.
http://antwrp.gsfc.nasa.gov/apod/ap980128.html
Very small particles of this may be a transparent medium. The dust is concentrated in the ecliptic plane.

Interesting idea. Also may explain why Voyager data may be unaffected. Pioneer 10 is 3 degrees out of the ecliptic. Pioneer 11 is 17 degrees out of the ecliptic. Voyager 1 is 35 degrees out of the ecliptic. And, Voyager 2 is 48 degrees out of the ecliptic.

Drag from striking dust particles on a spin stabilized craft may explain why the anomilies only affect the Pioneer project measurably. The Voyager project would be less affected due to their steeper angle out of the ecliptic. (less dust to create drag on a thruster stabilized craft.)

__________________
Valiant Dancer

Other spacecrafts data can't be used in determing, if there is an anomaly in their flights. Therefore, it is not known that the anomilies only affect the Pioneer project measurably. Here is quote from CNN from NASA's, John Anderson. "The scientists were unable to calculate the effects of distant gravity on other deep space probes, like Voyager I or Voyager 2, because they employ a different kind of orientation and propulsion system, Anderson said."
http://www.cnn.com/2001/TECH/space/0...ery/index.html

<a name="20020302.8:30"> page 20020302.8:30 aka ? Math




http://www.cnn.com/2001/TECH/space/0...ery/index.html

Has transmitter frequency drift been ruled out?
[1] vote for frequency drift
{um the Xtals cooling} etc

This link says, "Astronomers studied the Doppler shift of the radio signals to help calculate the distances of the probes, "

What about transit time ? Isn't that the method for distance determination ? How can Doppler do it with any accuracy? Wouldn't that give only radial velocity ?

G^2

Latest issue of Nature has a small tidbit about this...
Apparently Anderson and Turyshev want to submit a proposal to NASA for funding a detailed re-sifting of the Pioneer data....They even proposed a spacecraft to test the anomaly....a neat idea...a spacecraft followed by a reflective ball...bouncing lasers of the ball would measure the distance and account for any unexpected accelerations due to the systems on the spacecraft itself. However, chances are small of such a mission being funded, with costs estimated at $.5 bil if I read my zeros correctly.

__________________
"Its full of stars!"

http://spaceprojects.arc.nasa.gov/Sp...neer/path.html
--
Ok so P10 is Going BackWords of the Sun's direction?
===
What does it mean?
::::;
Which direction is Forward
?????
I currently use the Square Vega,A,A,A as the $ward direction
//tilt\\ and place Px in that Space heading this way {Back Wards}
So Px &amp; P10 have the same general direction of motion
Maybe Px has P10 in a TractiVe Beam

Toward Vega, apparently.

__________________
Everything I need to know I learned through Googling.

20041006 8:32AM Pt from NH465 {really rare post {its the Math Lab Computer$
http://www.w3.org/Math/
http://www.w3.org/Math/XSL/
http://www.w3.org/2003/03/Translatio...wTech.html#XSL

Regarding the 'accelerating' Pioneer crafts exiting the solar system, they're actually accelerating towards the sun, so are slowing down. The linked paper below does also mention that spin is being affected, (see pg. 23) so that periodic adjustments are executed. One (way out) possibility is that the crafts are entering denser gravity G regions, so their centripetals are affected, giving greater spin (in one direction only, so one will spin faster while the opposite direction will spin slower), and it may also account for increasing inertial mass, which given constant momentum would slow them down. No evidence this is so, so only a supposition at present.

Study of the anomalous acceleration of Pioneer 10 and 11

Gsquare, I realize this thread is more than two years old, but thought just for fun:

G^2 = g c^2 pi^2

This equation seems to work, if little g is the proton to proton gravitational constant (ie. g = 5.9e-39 dimensionless). Take the sqare root and you're pretty close to Newton's G constant! :roll:

__________________
Caveat Lector. Experimentum summus judex...

Toward Vega[/url], apparently
http://www.w3.org/Math/
http://www.w3.org/Math/XSL/
http://www.w3.org/2003/03/Translatio...wTech.html#XSL[/quote]

5:31 AM 10/7/04 sqU/O^ie(A'misH {Math Hour}BBC)
----
well ?: the thread has found a path to a Math moments
that appear to do some Math in an HTML format
====
although i've click the site, i've not spent many min.
in any aspect spacificly writing any script
::::
Todays Sceens:?:? I'll leave the apartment earily
and insure the NW Entry to SB2 is locked { }Y ( )N
????
once in SB2 i'll just check to insure both sites are
occupied &amp; move along.. So the posting place is A?
//tilt\\
OK? starting at 8: NH465 {Math} 9? {?} 10: ubrn204
and Noon LH {Studio}

7:05 not omly was SB2 NW open this room 169 was empty
-----
now back to the chase {in a little while}

?xml vers deleted BY me see pi MAN ref &lt; 2005

thats from the XMS page and i've no Idea {delete if required2} I did SO DO

now back to 169 7:10 no longer empty
some one came in to turn on all the Machines
only this one {has Sound} was already on

enter Girl .. { With sound } exit me to next station 7:12

http://www.w3.org/1999/xhtml
http://www.w3.org/1998/Math/MathML


thats from the XMS page and i've no Idea {delete if required2}

1 to begin with my Math Methode is itterative
2. {not as clever OR AS FAST as REcursive
3: &amp; sometimes {maybe often} does not work

---
here I was trying to see what I would see using W3
so far its a total unknow to me
and My translating abilities are very slow {iterative}

Interesting. But the units on the left don't match the units on the right, so the coincidence depends upon the units.

And I looked into it a little closer. I found the same claim elsewhere (are you Coppernicus2?). When I tried to find how that "proton to proton gravitational constant" was computed, I was led to this page. Weirdly, it appears to be a ratio of gravitational force to the electromagnetic force for two protons, but it is multiplied by the fine structure constant--which cancels the charges! So, it ends up equal to the ratio of Gp^2 to (c times h-bar), where p is the mass of a proton.

http://www.space-talk.com/ForumE/sho...er=4]elsewhere

http://hyperphysics.phy-astr.gsu.edu...couple.html#c5


when viewing hbase forces
it reminds me that i wish i knew if there were a way for me to
fill in the right side {see SmartCal} ( top link below) of my index page
without using FORMS?
------
INDEX.HTML page formatting doeth elude me.. and I think I prefer
NOT TO USE FORMS?/?




8:47 and this REMinds me a trick i lernt yesterday
click link H_ba above
once you see Ag
then at the top {Menu Bar}? click V_iew (then click Sourc_e)
GOOD LUCK