Pioneer anomaly

[backspace]

From the main page:<br />http://www.space.com/scienceastronomy/mystery_monday_041018.html<br /><br />Out of curiousity, why can't they use the Voyagers to aid in these measurements? Too much activity on the voyager team to fit in these observations?<br /><br />Seems to me they could easily use these probes rather than paying to have another craft hurled out into the void with very little science return.

 

[backspace]

It's the wording of the proposed craft - "free of any sources of radiation" - that makes me think that any payload above and beyond the navigation and gravity sensing equipment is going to be a bit of a joke at the least.

 

[shishka]

2 possibilities come to my mind after reading about the possible explanations for the slowing down of the Pioneer spacecraft:<br /><br />1) dust. It might not add up to much at any one point, but it is out there. After travelling over a billion of miles, it seems conceivable to me all that colliding--however small--adds up. And, not knowing exactly where or in how much mass these areas of dust might be as Poineer travels, I can't see how it can be measured in advance.<br /><br />2) escape velocity. We all know that if you don't have the proper speed leaving Earth, you'll eventually fall back. Now, take this idea to the solar system scale. Could it be that the Pioneer spacecraft never had enough speed to escape the gravity of the solar system?<br /><br />Please, if I'm goofy on these ideas, let me know so I can sleep at night. Thanks!

 

[halman]

shishka,<br /><br />The velocity of the Pioneer spacecraft was known to be in excess of solar escape velocity. Therefore, some outside influence must have come into play to slow it down.<br /><br />Dust is a plausable theory, as the Ort cloud does contain a lot of matter.<br /><br />Could this be an effect of gravity waves? The Solar System is too crowded to examine gravity properly. Interplanetary space is much more likely to be an environment where gravity effects can be studied properly. <div class="Discussion_UserSignature"> The secret to peace of mind is a short attention span. </div>

 

[summoner]

They have a similar thread over on the BadAstronomy board. Someone there mentioned that Voyager isn't as affected as Pioneers because Voyagers are thurst stabilized vs. spin stabilized for Pioneers. <div class="Discussion_UserSignature"> <p> </p><p> </p><p> </p><p> <br /><table cellpadding="0" cellspacing="0" style="width:271px;background-color:#FFF;border:1pxsolid#999"><tr><td colspan="2"><div style="height:35px"><img src="http://banners.wunderground.com/weathersticker/htmlSticker1/language/www/US/MT/Three_Forks.gif" alt="" height="35" width="271" style="border:0px" /></div>

 

[backspace]

perhaps rebounding plasma shocks from the heliopause? If indeed the Voyagers saw them, there has to be some force in that rebound, however slight... enough big flares over time....<br /><br />This is all verging on the limits of our understanding of physics. I'm going to say the heliopause has something to do with it...

 

[CalliArcale]

<blockquote><font class="small">In reply to:</font><hr /><p>The velocity of the Pioneer spacecraft was known to be in excess of solar escape velocity. Therefore, some outside influence must have come into play to slow it down.<p><hr /></p></p></blockquote><br /><br />And as far as anyone knows, it still is in excess of solar escape velocity. It is extremely unlikely that anything has slowed them further.<br /><br />By the way, there will be no more measurements with Pioneer 10 or Pioneer 11; both are now unable to communicate with Earth, and the Pioneer team has reluctantly conceded the fact. The last attempted communciation session, using the Arecibo observatory (the biggest radio transceiver on Earth), failed to get any response from Pioneer 10. Pioneer 11 failed a number of years previously. So all work on this effect has to be done using existing data.<br /><br />But there is hope; a new probe, called New Horizons, is being designed and built to become the first spacecraft to encounter Pluto. They also hope to encounter one or more Kuiper Belt Objects. In order to acheive this before Pluto's atmosphere freezes out, it will be on a solar escape trajectory. It's the only way to get there in time. If this effect is real, it should affect New Horizons as well -- and this time, they can be watching for it in advance. <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>

 

[earth_bound_misfit]

Hmmm, thats strange, I was speaking with one of the guys from the deep space network (at Canberra) a few months back, he told me that Pioneer was still in contact. When did Pioneer 10 comms fail? <div class="Discussion_UserSignature"> <p> </p><p> </p><p>----------------------------------------------------------------- </p><p>Wanna see this site looking like the old SDC uplink?</p><p>Go here to see how: <strong>SDC Eye saver </strong>  </p> </div>

 

[drwayne]

http://amesnews.arc.nasa.gov/releases/2003/03_25HQ.html<br /><br />Wayne <div class="Discussion_UserSignature"> <p>"1) Give no quarter; 2) Take no prisoners; 3) Sink everything."  Admiral Jackie Fisher</p> </div>

 

[drwayne]

And:<br /><br />http://nssdc.gsfc.nasa.gov/database/MasterCatalog?sc=1972-012A<br /><br />Wayne <div class="Discussion_UserSignature"> <p>"1) Give no quarter; 2) Take no prisoners; 3) Sink everything."  Admiral Jackie Fisher</p> </div>

 

[CalliArcale]

To be fair, your buddies at Canberra probably didn't know; for several years now, communicating with Pioneer 10 has required extraordinary efforts beyond the capabilities of the equipment at Canberra. <img src="/images/icons/wink.gif" /> And the sessions were rare, because of the amount of effort and careful synchronization required. (Basically, they had to beam a powerful signal out to Pioneer 10, and then wait for it to respond. And even then, they still could only get the carrier signal. They haven't gotten scientific data or telemetry from it in years.) <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>

 

[aaron38]

Unfortunately for the New Horizons mission it doesn't sound like it will be supplied with enough plutonium to keep the probe alive out to the Kuiper Belt. With the minimum plutonium load, will it stay alive longer than Pioneer?<br /><br />http://www.space.com/spacenews/businessmonday_041004.html

 

[CalliArcale]

I could be mistaken, but I didn't think the quantity of plutonium makes much difference to its longevity; the plutonium itself will still be putting out plenty of heat today, tomorrow, ten years from now, a century from now. The real trouble is that the thermocouples wear out.<br /><br />Then again, maybe it's a signal strength problem. The quantity of plutonium does affect maximum wattage of the RTG, and that limits the strength of the transmitter. A probe might as well be dead if you can't talk to it. <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>

 

[drwayne]

Junction degradation is a big part of power roll off to be sure.<br /><br />Wayne <div class="Discussion_UserSignature"> <p>"1) Give no quarter; 2) Take no prisoners; 3) Sink everything."  Admiral Jackie Fisher</p> </div>

 

[earth_bound_misfit]

Thank you Cali, I with slapp him around a bit next time I see him <img src="/images/icons/smile.gif" /> . Probably I just heard him wrong, still thats an extraordinary misson, designed for 21 months, yet lasting 30 years! <div class="Discussion_UserSignature"> <p> </p><p> </p><p>----------------------------------------------------------------- </p><p>Wanna see this site looking like the old SDC uplink?</p><p>Go here to see how: <strong>SDC Eye saver </strong>  </p> </div>

 

[trockner]

What if the damn contraption CAN'T be shut down? What if it's too far gone now to be stopped even by MIB/CENT/COM? <br /><br />What if the robot delivers its plaque to Their Imperial Majesties, The Extraterrestrials???<br /><br />THEN what're we gonna do???<img src="/images/icons/shocked.gif" />

 

[bobvanx]

Come over to my house an' I'll SHOW ya'll what we k'n do.

 

[alokmohan]

Is that correct?

 

[CalliArcale]

Yes, it is correct. The Pioneers rotate constantly, which greatly stabilizes them and probably contributed largely to the ability to keep communicating with them for so long -- they didn't need to use as much fuel to align themselves. The Voyagers, on the other hand, do not rotate. <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>

 

[mrmorris]

<font color="yellow">"...Voyager isn't as affected as Pioneers ..."</font><br /><br />I would imagine it's more of an issue that the Voyager thrusters make the calculations much more difficult to calculate. It's a lot easier to calculate small deviations for a purely ballistic course as opposed to one that periodically applies thrust.

 

[CalliArcale]

Yes, you are correct, mrmorris. The spin-stabilization makes the Pioneers a more accurate data point. Since the effect is extremely slight, it would be overwhelmed by the Voyager's own propulsion and attitude control systems. In fact, the slightness of the affect is near the margin for error in the Pioneer data as well, so some have disputed the reality of it. <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>

 

[halman]

CalliArcale,<br /><br />When computing the velocity of an object leaving the Solar System, gravity effects from the major bodies, primarily the Sun, are used to determine what losses are to be expected. Yet, the Pioneer craft are far enough away that the total mass of the Solar System must be influencing the velocity. There is no accurate method that I am aware of for calculating that mass. Perhaps these anomalies could help in that process. <div class="Discussion_UserSignature"> The secret to peace of mind is a short attention span. </div>

 

[remcook]

...but if the acceleration is constant with time, despite the constellation of the planets...it must be something else then

 

[halman]

remcock,<br /><br />I am speculating wildly, but it seems to me that the position of the planets would become less of a factor the further out from the Sun an object is. At some point, that must lose its effect, because the variation would be lost in the overall field. <div class="Discussion_UserSignature"> The secret to peace of mind is a short attention span. </div>

 

[alokmohan]

Something else ,that is remcock on each board in the universe.