The Pioneer Anomaly Options

[remcook]

http://www.planetary.org/news/2005/pioneer_anomaly_faq.html

The planetary society may be checking it out...

The Planetary Society has committed to raise the funds to preserve the priceless Pioneer data from destruction.


After years of analysis, but without a final conclusion, NASA, astonishingly, gave up trying to solve the "Pioneer Anomaly" and provided no funds to analyze the data. The Pioneer data exists on a few hundred ancient 7- and 9-track magnetic tapes, which can only be read on "antique" outdated computers. The agency is going to scrap, literally demolish, the only computers able to access and process that data in the next few months!

[remcook]

Some background reading...

http://arxiv.org/find/astro-ph/1/ti:+pioneer/0/1/0/all/0/1

[tedstryk]

Won't New Horizons be spin stabilized when not in encounter mode?

[remcook]

Quote from alan stern:

Yes, we spin most of cruise, stopping only rarely. It costs fuel that we want to hoard for encounters and KBO DeltaV. And yes, our radio science team hopes to look for
the Pioneer anaomaly. Contact Len Tyler or Ivan Linscott at Stanford.

in the new horizons thread:
http://www.unmannedspaceflight.com/index.p...topic=675&st=20

so some more things to look forward to

[Guest_Richard Trigaux_*]

Could not the Pioneer tapes be saved on a more modern support, before scraping the computers which can read it? So far as we know there may be still valuable data to infer from them, especially with the affair of the "pioneer anomaly".

Much was already said about this anomaly:

-the gravitaion law working differently at great distance...
-effect of cosmological dark matter surrounding the sun...


or simpler:
-systematic mistakes somewhere into the measurement chain.


Perhaps the NASA and many scientists prefer the second set of explanations. But so long as the first set cannot be completely ruled out, the question remains open.

[Jeff7]

Some background reading...

http://arxiv.org/find/astro-ph/1/ti:+pioneer/0/1/0/all/0/1

I looked at some of those things, but still am not quite clear on what this anomoly is.
And what's up with saving this? I think I missed out on this stuff.

It looks like the Pioneers have long stopped transmitting, but the data hasn't been analyzed yet, and now NASA wants to destroy the computers that can read the tapes? Is that the gist of it?

[remcook]

It looks like the Pioneers have long stopped transmitting, but the data hasn't been analyzed yet, and now NASA wants to destroy the computers that can read the tapes? Is that the gist of it?

that's what I understand yes...

The anomaly is basically that the pioneer spacecraft (I think it was seen in Ulyssus and Cassini as well) accelerate slightly different than what one would expect from our understanding of gravity.

[deglr6328]

that's what I understand yes...

The anomaly is basically that the pioneer spacecraft (I think it was seen in Ulyssus and Cassini as well) accelerate slightly different than what one would expect from our understanding of gravity.

Not Cassini but Galileo. Cassini is 3-axis stabilized (thrusters). Galileo was spin stabilized. The error introduced by the use of thrusters basically washes out any hope of seeing any other miniscule anomalous effects.

[Guest_Richard Trigaux_*]

As far as I understand from readings in the press, the Pioneer probes (ant others) would slow down slighty more than expected from only the Sun gravity. This led to some interesting but far reached speculations.

Some asked if the gravity law was not exactly 1/R2.

The most consistent speculation is that, like the galaxy shows an excess (sometimes ten times) of invisible mass, called dark matter, the solar system may have some too (although much less, a fraction of a %). From close to the Sun, we feel only the Sun's attraction, but further in space we feel the Sun's more the dark matter's attraction. This could be explained if the dark matter is made of low energy subatomic particles; many would orbit the galaxy, with speeds in the 200km/s range. Some would orbit the Sun with still smaller speeds in the km/s range.


But the measurement of the anomaly is based on many far-reached and difficult estimates, such as the toss of sun's light on the space probe, or gaz leak from the reservoirs. A slight error or false assumption, and the result would be very different. This is why the Pioneer anomaly did not upset the science community. A precise measurement of this anomaly would perhaps do.

[Bob Shaw]

Not Cassini but Galileo. Cassini is 3-axis stabilized (thrusters). Galileo was spin stabilized. The error introduced by the use of thrusters basically washes out any hope of seeing any other miniscule anomalous effects.

So presumably the New Horizons vehicle won't be stable enough, for long enough, either...

[The Messenger]

As far as I understand from readings in the press, the Pioneer probes (ant others) would slow down slighty more than expected from only the Sun gravity. This led to some interesting but far reached speculations.

...
But the measurement of the anomaly is based on many far-reached and difficult estimates, such as the toss of sun's light on the space probe, or gaz leak from the reservoirs. A slight error or false assumption, and the result would be very different. This is why the Pioneer anomaly did not upset the science community.  A precise measurement of this anomaly would perhaps do.

Painstaking and careful analysis is a more exacting description.

http://arxiv.org/find/astro-ph/1/au:+Turys...S/0/1/0/all/0/1

http://arxiv.org/abs/gr-qc/0104064

http://arxiv.org/abs/gr-qc/9906112

Anderson, Nieto & Turyshev's paper- rebuttal - papers with the astrophysical community spans more than a decade now, and signatures of the anomalies have been found everywhere they have found the time and money to look for them.

The community should be giving this type of research highest priority -

Nowhere is it written in stone gravity behaves exactly as was predicted and observed a more than a century ago. If the observational data indicates otherwise, why are we so certain the status que is the status correct?

[antoniseb]

The community should be giving this type of research highest priority

The highest priority? I think finding all substantial Earth Crossing asteroids would be more important. Basic exploration of the Solar System should be more important. Looking for extra-solar planets should be more important. Galactic census missions should be more important. Studies of Sgr A* and the things orbiting it should be more important. Studies of distant Type 1a Supernova should be more important. etc.

The ESA has considered launching a probe specifically to measure this effect with greater precision, but it didn't get funded.

Perhaps you could tell us how you would probe this phenomenon, and what the various outcomes would tell us? Then we can talk about priorities.

[The Messenger]

The highest priority? I think finding all substantial Earth Crossing asteroids would be more important. Basic exploration of the Solar System should be more important. Looking for extra-solar planets should be more important. Galactic census missions should be more important. Studies of Sgr A* and the things orbiting it should be more important. Studies of distant Type 1a Supernova should be more important. etc.

The ESA has considered launching a probe specifically to measure this effect with greater precision, but it didn't get funded.

Perhaps you could tell us how you would probe this phenomenon, and what the various outcomes would tell us? Then we can talk about priorities.

Two things:

1) I would take the mother-and-hen approach suggested by Nieto. Pioneer 10 & 11 demonstrated the virtues of simple, spin stabilized, thermally balanced probes. I would add a lot of health monitoring gear, but otherwise the probes should be very simple. They should have transmitters capable of using both phase-locked loop and ultra-stable oscillator ranging frequency control, multiple bands.

There should be at least two different types of chicks - one designed with a great deal of solar drag, the second fairly streamlined. Placed into identical trajectories at the same time, this would allow differentiation of unknown forces from solar wind effects. Perhaps even better would be ‘umbrella chicks’ that could trade-off between solar sail and coast modes, thus keeping the clutch together.

The mother should hover close enough to calibrate and study emissivity and radiation, but distant enough not to disturb momentum.

2) If one assumes the Pioneer anomalies are real and not artifacts, there should be supportive evidence, and many fundamental implications.

The solar wind may not be the only force moving objects away from the center of the solar system. Anderson had to add a linear component to the solar wind to model the acceleration of Galileo and Ulysses: http://arxiv.org/PS_cache/gr-qc/pdf/0104/0104064.pdf p21:

The radio Doppler and ranging data can be fit to the noise level with a time-varying solar constant
in the fitting model [82]. We obtained values for the time-varying solar constant determined by Ulysses
FIG. 10: Galileo best fit Doppler and range residuals using CHASMP. navigational data during this south polar pass [81]. The inferred solar constant is about 40 percent larger at perihelion (1.3 AU) than at Jupiter (5.2 AU), a physical impossibility!

We sought an alternative explanation. Using physical parameters of the Ulysses spacecraft, we first converted the time-varying values of the solar constant to a positive (i.e., outward) radial spacecraft acceleration, ar, as a function of heliocentric radius.

(my bold)

Throw a spring constant into elliptical orbits, as Anderson did to model Ulysses, and all hell breaks loose. Fly-bys and orbits don’t return correct planetary masses, long distance navigation breaks down, and gravity anomalies crop up everywhere.

Such a force is consistent with known observational facts. Figuring out if it is real should be given highest priority.

[algorimancer]

It seems to me that a simple means of checking this notion would be to track long-period comets (many of them). No spacecraft required

[The Messenger]

It seems to me that a simple means of checking this notion would be to track long-period comets (many of them).  No spacecraft required

Too wide of error bars - Comets are always outgassing, changing in mass, color, orientation. We are looking at accelerations of less than 60 ppm.

Also, Radar tracking has proven to be less accurate than physical modeling suggest, as we learned from the Mars Climate orbiter and Polar Lander...perhaps Anderson's unmodeled force is the culprit.

[edstrick]

Climate orbiter was not radar tracked, it was transponder tracked. You get precise distance, but have to model angular position on the sky from indirect data. One way to get precise relative position in the sky is differential interferometry, where one vehicle, say a mars orbiter, is a reference source, and the approaching vehicle's position relative to the reference can be measured.

The problem with Climate orbiter was not with the tracking data, it was modelling the trajectory based on that data when bogus information <incorrect spacecraft peturbation values from the momentum wheel offloading with thruster firing) was included in the solution. The nav team had recognized and been bothered the entire flight by considerably (several times?) larger trajectory calculation variations than normal, but not been able to find a cause of the error with available time and resource.

Polar Lander wiped out due to either 1.) a programming error in the descent software that was almost guaranteed to eat their lunch. or 2.) any of considerable number of design defects that added risk to the landing but weren't "smoking gun" errors.

The Pioneer anomaly is just that.. it's a departure of observations from very precise, but known imperfect calculations. We don't know if there's a physical something based on "deep" important physics, or if our engineering models of non-gravitational forces on the spacecraft are subtly wrong.

It will cost at least a few hundred million dollars to fly a mission that will convincingly and unambiguously prove an "important" physics cause is either present or not, and *PRECISELY* measure that effect if it exists as a function of distance from the sun. *** NOT TRIVIAL ***.

There are a lot of other research proposals and proposed space missions with equal or greater chances of testing and getting an important answer to "deep" physics questions that would cost the same or less than a Pioneer Anomaly mission. The best strategy is to pick the strongest tests with the greatest likelyhood of surprise, for the least amount of money and do or fly those..... and to pick tests that test fundamentally different possible suprises in deep physics. Things like dark matter detection experiments, gravity wave observatories, Dark energy investigations have far more chance per doller of real surprises than a pioneer anomaly mission. We need to keep it as an open question with the possibility of a mission, but right now, it seems a high risk, probably low yield mission for the money.

[Mongo]

There are a lot of other research proposals and proposed space missions with equal or greater chances of testing and getting an important answer to "deep" physics questions that would cost the same or less than a Pioneer Anomaly mission.  The best strategy is to pick the strongest tests with the greatest likelyhood of surprise, for the least amount of money and do or fly those..... and to pick tests that test fundamentally different possible suprises in deep physics.  Things like dark matter detection experiments, gravity wave observatories, Dark energy investigations have far more chance per doller of real surprises than a pioneer anomaly mission.  We need to keep it as an open question with the possibility of a mission, but right now, it seems a high risk, probably low yield mission for the money.

The problem with a 'dark matter' mission is that the putative dark matter is entirely hypothetical, and may not (I would say probably doesn't) exist. Stanley Milgrom's MOND theory or Jakob Bekenstein's TeVeS theory seems to me to explain the observations in question much more easily than any dark matter theory does. There are also indications that the effects ascribed to 'dark energy' may also be a natural result of a full MOND or TeVeS theory.

http://xxx.lanl.gov/abs/astro-ph/0504130

On the other hand, the so-called 'Pioneer Anomaly' appears to be genuine. The alternative explanations (solar wind, asymmetrical thermal radiation, etc.) appear to be several orders of magnitude too small to adequately explain the observed acceleration. I personally would say that a proper investigation of the 'Pioneer Anomaly' would be at least as important as Gravity Probe B, and could be mounted at a reasonable cost too. The spacecraft itself would be relatively inexpensive; the biggest cost would be the launch vehicle.

Here are links to papers discussing possible approaches to a mission:

http://xxx.lanl.gov/abs/astro-ph/0504634
http://xxx.lanl.gov/abs/astro-ph/0409373
http://xxx.lanl.gov/abs/gr-qc/0409117

Bill

[Bob Shaw]

Bill:

Your links, er, don't!

Bob Shaw

[Mongo]

That's strange; I just clicked on them and they sent me to the reports that I had referenced...

If they still don't work, I suppose that you can just go to

http://xxx.lanl.gov/find/astro-ph

and do a search for 'Pioneer Anomaly'. Or else just type out the links on your address bar.

Bill

[Bob Shaw]

That's strange; I just clicked on them and they sent me to the reports that I had referenced...

If they still don't work, I suppose that you can just go to

http://xxx.lanl.gov/find/astro-ph

and do a search for 'Pioneer Anomaly'.  Or else just type out the links on your address bar.

Bill

Bill:

I promise, linky no worky.

________________________________________________________

Access Denied
Sadly, you do not currently appear to have permission to access http://xxx.lanl.gov/find/astro-ph

If you believe this determination to be in error, see http://xxx.lanl.gov/denied.html for additional information.

_________________________________________________________

Bob Shaw

[Mongo]

I promise, linky no worky.

Okay, I'll try posting the files directly to the board. Hope this works.

The first file is the 'dark energy' in TeVaS paper. The other three are the 'Pioneer Anomaly' papers.

Bill

Attached File(s)

 0504130.pdf ( 111K ) Number of downloads: 2237
 0504634.pdf ( 485.63K ) Number of downloads: 1608
 0409373.pdf ( 152.4K ) Number of downloads: 1383
 0409117.pdf ( 124.76K ) Number of downloads: 1284

 

[The Messenger]

I am at least as interested in the flight path eccentricities of Odysseus, Galileo and Pioneer 6 as the Pioneer 10 and 11. While the Pioneer probes indicate an acceleration towards the sun, an unsolicited acceleration away from the sun had to be used to model the paths of Odysseus and Galileo, and one of a greater magnitude: ~1x10^-8m/s^2.

Likewise, I mentioned the navigational problems associated with the Polar Lander and Climate orbiter, not because of the failure modes, but because of the difficulty navigators had both predicting and tracking the probes – with or without a unit conversion error.

After the Climate Orbiter failed to achieve a non-intersecting orbit, two teams of navigators worked on the flight path of the Polar Lander. Each time they tried to model and predict solar wind effects, they were frustrated – they could not correlate the small force corrections due to the solar wind with the path of the probe.

On both missions, NASA tried to use triangulation as well as the Doppler ranging data, and triangulation yielded surprisingly unsatisfactory results.

Please allow me enough latitude to use a hypothetical to demonstrate why I think we must track down the exact causes of these small force and/or navigational errors. Assume the forces are real, and assume they are caused by a gravitational equivalent to a change in the permeability-of-free-space that is a function of mass. This would mean that a probe moving towards the sun would be slowed as more energy is stored in a stronger ‘mass field’ nearer the sun.

The Newtonian equation for velocity then becomes a function of total proximal mass, not just the mass of the object in motion (Ek=Mv^2/2f(x) where f(x) @ 1 AU = 1, and becomes larger as the object approaches the sun, leaving more energy in the potential energy pool (Remember, this is ALL HYPOTHETICAL and the force changes are very small and tightly constrained.)

Look what would happen: As a probe approaches the sun, less potential energy is 'released' as kinetic. The velocity increases at a slightly slower rate than Newtonian predictions. Leaving close proximity to the Sun, the probe would require slightly less energy to achieve a greater acceleration, returning the probe to the predicted path. This is EXACTLY what the residuals look like in the Pioneer 6 pass near the limb of the sun, peaking (slowing) at closest proximity to the sun. Likewise, the 1/r ‘spring constant’ Anderson used to model the Solar wind effects upon Odysseus and Galileo follow this model.

There is more: If more potential energy is stored in a more massive environment, probes to Venus are proportionally slowed, while probes to Mars would experience a slight acceleration, achieve a slightly different orbit. This would cause us to overestimate the mass of Venue, and underestimate the mass of Mars. When we interpret the orbital gravimetric data, the smaller accelerations near the mountain peaks on Venus would then appear as negative gravity anomalies, and likewise, valley floors would appear as positive anomalies. This is what we observe.

On Mars, the situation is exactly opposite: The increase in the transfer to kinetic energy would cause us to underestimate the mass of Mars from orbiters, so the mountain peaks would be interpreted as positive gravity anomalies while valley floors would appear negative. This is also precisely what we observe.

There is more.

We now have gravity maps of Mars from distances varying from 300 to 800 km, but the 800 km data cannot be reconciled with the 300 km maps. The 300km data showing greater anomalies. The moment of inertia for Mars appears to be different if ranging data to the surface probes (Pathfinder and Viking) is used than the inertial moment necessary to explain the orbital gravity anomalies.

All of the Martian probes have landed at higher velocities than expected and, entered at higher attitudes. All descent trajectory models have required a thinner-than-expected upper atmosphere, and high surface winds.

I can go on and on, but I think that you get my point: It would not take a major change in solar dynamics to produce surprising errors. I have been arguing with Jason and Bruce that the rocks, the craters, the strata, and the Doppler descent data from Huygens could be better modeled with less shear wind and more mass.

Fortunately, missions are already in progress that can disprove this hypothesis: Messenger will pass close enough to the sun that the ‘limb effect’ observed by Pioneer 6 could be repeated. MRO will provide gravity maps at 150 km – if this hypothesis is true, MRO will map greater gravity anomalies than prior orbiters that cannot be fit with harmonic extrapolations. MCO will also provide us with a good average atmospheric gradient, one that will be steeper than expected if the planet is more massive.

Finally, careful mapping of the effects of Saturn’s moons on Cassini should reveal ‘unmodelable drag’ forces and even greater gravity anomalies than Galileo found on Ganymede.

I don’t expect any degree of agreement with this assessment, but I hope I have peaked your interest in the manifold scientific data returning from the robotic planetary missions; and there just might be more to learn than mission planners dreamed, a truly revolutionary prospective of the cosmos, one just as foreign to scientific thinking today as the Ptolemic model.

[dvandorn]

Hmmm... well, the effect must be very, very minor (at least in the local solar-system neighborhood), or else the planets wouldn't orbit in such a way as to generally validate the inverse-square law of gravitation.

It *does* occur to me that the inverse-square law relates to the "classic" three physical dimensions, and cosmologists are always saying that as many as 19 physical dimensions *must* exist. As far as we can tell (since we cannot directly measure anything outside of the three dimensions that are apparent to us), gravitation doesn't propogate along any of these other physical dimensions. Perhaps this is an indication that it *does* and the effect we are seeing is actually a relation between some other physical dimension(s) and the three we can perceive? This would mean that the inverse-square law could be maintained; we're just applying that law to a dimension that is not obviously connected to the three we can see.

I think it's time to start contemplating how these extra dimensions that cosmologists believe must exist inter-relate with the Universe as we observe it. Rather than assuming that these dimensions simply collapsed and vanished as energy levels decreased shortly after the Big Bang, maybe they still exist and interact with such things as gravitation... However, I think it's too early to say that this effect happens near massive bodies, and it's definitely too early to start making mass itself a variable factor, relative to its distance from other masses.

-the other Doug

[antoniseb]

I am at least as interested in the flight path eccentricities of Odysseus, Galileo and Pioneer 6 as the Pioneer 10 and 11. While the Pioneer probes indicate an acceleration towards the sun, an unsolicited acceleration away from the sun had to be used to model the paths of Odysseus and Galileo, and one of a greater magnitude: ~1x10^-8m/s^2.

Hi The Messenger,

We've interacted a few times on another forum. This is the clearest statement of what you've been trying to get to that I've seen. Thanks. I will now be trying to keep an eye on this.

[Guest_Richard Trigaux_*]

Thanks to recent posters this thread took an interesting turn, that we could summarize that a mission specifically dedicated to the Pionneer anomaly would be potentially very interesting, but that it is not likely to fly one day.

It could become more likely if it is send with other equipments, for instance for the study of solar wind effect, interplanetary magnetic fields, etc. The overal design of such a probe could allow to measure the "Pioneer effect" with much more accuracy, or at least to prove/disprove its existence.

How could such a probe work?
Basically a test mass, a raw piece of metal, should freely navigate into the solar system, on a trajectory fleeing the sun, while being protected of any spurious accelerations: solar wind, electric/magnetic effecs, outgassing, position control, etc.

To achieve this, it would be completelly enclosed into a metal casing, while having no physical contact/interaction with it. The casing would use thrusters to lock itself on a fixed position relative to the test mass.

So the overall thing navigates as if it was in really complete vacuum, without solar wind, outgassing, etc. and it can provide accurate informations of pure gravitationnal nature, eventually different of the 1/r2 law, or accounting for unknown bodies. The info on the trajectory corrections achieved by the casing would on its side provide very accurate data on solar wind. This makes this probe more interesting and more likely to fly than just a Pioneer anomaly test probe.

The only spurious gravitationnal effect on the test mass would be... the gravitationnal field of the probe itself. Thus the test mass should be placed right at the center of mass of the probe. An error on this would produce a permanent offset that we could not distinguish from true effects. If preleminary calculations show this is a problem, we can use a better overal design: the probe is formed of three parts, linked with cables: at the centre the protective casing, and at the extremities the radio transmitters, thrusters, and any other payload useful for science (and also useful to make this mission more likely). The whole thing rotates on an axis which is perpendicular to the sun direction, right around the test mass.
This design will allow to know preciselly the centre of mass and to adjust it. But above all, any permanent offset will be cancelled, as it will pull at times toward the Sun, at times opposite to the Sun. So we can really maintain the test mass free of spurious gravitationnal effects from the probe itself.

Such a probe would be relatively light wheight, so that it could be launched on an interstellar trajectory directly from the surface of the Earth, without using gravitationnal assistance. So it could bring results after only a few years. Otherwise we can use Jupiter' assistance.


Will this design lead one day to a real experiment?

[Guest_Richard Trigaux_*]

A rather interesting prospective explanation of the Pioneer anomaly could come from a completelly different field, from the exploration of the cosmic background radiation at 3°K by COBE and WMAP.

These two probes found results which strinkingly match the predictions of the standard cosmologic inflation theory in the very early stages of the universe, excep for some points. Here is a paper on this:
Cosmic Symphony (I did not read it, I read the french publication in the science review "Pour la Science", french edition of the Scientific American).

Among the possible explanations on these discrepancies was evoked the possibility of a cloud of matter (dust or neutral gas) near the solar system or in orbit around it. Such a cloud would be essentially of a very low density, and thus very transparent at any wavelengh. It would emit/absorb only radiations matching its black body temperature, which is, for a free body in far space, at equilibrium with the cosmic background! This would explain that such a cloud was never detected before: only a precise measurement of the cosmic background could allow for its discovery.

If such a cloud exists, its very low density multiplied by its huge dimentions would lead to a sizeable mass, more than a planet, and even in the order of a star mass.

This would perfectly explain the Pioneer anomaly, and even the variations found on this effect (at times toward the Sun, at times opposite) according if the probe goes toward the cloud or in another direction.

Eventually a Pioneer effect probe becomes more interesting.

[remcook]

some people seem to agree and applied for funding from ESA's cosmic vision 2015-2025:

http://sci.esa.int/science-e/www/object/in...fobjectid=35202

Title:  A Mission to Test the Pioneer Anomaly and to Probe the Mass Distribution in the Nearby Outer Solar System
Proposed by: Orfeu Bertolami et al.
Contact Email: orfeucosmos.ist.utl.pt

[...]

Title:  Testing the Pioneer Anomaly
Proposed by: Hansjörg Dittus et al.
Contact Email: dittuszarm.uni-bremen.de

[...]

Title:  Experimental investigation of the Pioneer anomaly
Proposed by: C. Kiefer et al.
Contact Email: kieferthp.uni-koeln.de

[...]

Title:  Significance of the Pioneer Anomaly
Proposed by: Claus Lämmerzahl et al.
Contact Email: laemmerzahlzarm.uni-bremen.de

[...]

Title:  LISA Mission and the Pioneer anomaly
Proposed by: José Luis Rosales
Contact Email: JoseLuis.Rosalesesp.xerox.com

[The Messenger]

Richard's proposed test of the Pioneer Anomaly is clever, and controls several variables. Unfortunately it also has the potential of introducing another new one: Shielding the test mass from the 'unknown force', especially if it is electromagnetic in nature: In this case if the results were nil, the Pioneer Anomaly could be constrained to a possible emf - but what emf?

The cloud solution is also interesting, but the two Pioneer probes were heading for opposite sides of the solar system and produced the same relative error. (Two identical clouds?) Also, Nieto and other researchers have been able to all but eliminate the Oort cloud and Kuiper belt objects as likely candidates for the PA, and this evaluation seems to apply to rouge clouds as well. (They also constrain the potential for local Dark Matter & Energy.

http://lanl.arxiv.org/abs/astro-ph/0506281

Antoniseb has started a thread to discuss second WMAP release, specifically in the context of the 'local' anomalies, and I will post a response there. As you know from my postings on this thread, I am of the opinion many quirky observations are interelated.

http://www.unmannedspaceflight.com/index.php?showforum=44

There is much to learn.

[Guest_Richard Trigaux_*]

Messenger,

my idea was intended to detect a gravitationnal effect (or gravitationnal-like). We could modify the shielding, for instance using a transparent shield to allow for electromagnetic effects. But in this case, we shall not know if the effect is gravitationnal or electromagnetic...
Or we can make several experiments, several test mass... but the probe has only one mass center. I do not come with more "clever" designs, unless to use several concentric shields around the test mass: one metallic, shielding the test mass from EM effects, and locked on the test mass without physical contact. And around, a second shielding, avoiding solar wind but transparent to electromagnetic effects, and locked on the first shield. This may allow for a separate measurement of both three effects, gravitationnal, EM and wind effect. But this fairly complicates the design, and does not make sure that the result would be better. Especially the intermediary shield will need some thrust, and thus it will "pollute" the results of the outer shield.

So I think it will be better to keep with my first simple design, perhaps adding it sensitive electromagnetic instruments. If gravitationnal effects are ruled out, we can still check for electromagnetic effects, but they offer much less potential for interesting discoveries. (but they cost much less to search)

Thank you also Messenger for your contribution on the Oort clouds and similar. We know litle things about the Kuyper belt and Oort cloud. We usually assume they have a syymmetrical structure (a disk for the Kuyper belt, a sphere for the Oort cloud). At least they would have gained such a symmetry after rotating around the Sun for 4 billion years. If they have such symmetrical structures, they cannot have gravitationnal effects in the inner solar sytem (a hollow spherical structure has no gravitationnal effect inside).

But many things may cause such clouds to have transcient or permanent "lumps" in it:
-part of the mass is in the form of massive bodies, such as the one recently detected which is larger than Pluto. (Many trajectory calculations should be remade accounting with it). It could even exist very dark and cold massive gaseous planets very far from the Sun.
-the solar wind shockwave with the interstellar wind concentrates mass
-a spherical cloud is in orbit around the Sun
-an interstellar cloud is currently at close vicinnity with the solar system (such clouds can have mass ranging from a giant star mass to Earth mass)
-a large wandering planet is currently at close vicinnity with the solar system


A last there is one difficulty with my probe: it will only tell us what there is in one direction. If we obtain enough precision, we could try to model the effect with an 1/R2 gravitationnal field, and find the culprit. But this will take ten years, and if the probe flight path is not in a proper direction, it will not work. So ideally we should send three probes in three perpendicular directions to definitively find (or rule out) any gravitationnal effects. In practice we could send one, wait two or three years to see the results, and take the decision to send another one in a proper direction.

[jamescanvin]

How could such a probe work?
Basically a test mass, a raw piece of metal, should freely navigate into the solar system, on a trajectory fleeing the sun, while being protected of any spurious accelerations: solar wind, electric/magnetic effecs, outgassing, position control, etc.

To achieve this, it would be completelly enclosed into a metal casing, while having no physical contact/interaction with it. The casing would use thrusters to lock itself on a fixed position relative to the test mass.

So the overall thing navigates as if it was in really complete vacuum, without solar wind, outgassing, etc. and it can provide accurate informations of pure gravitationnal nature, eventually different of the 1/r2 law, or accounting for unknown bodies. The info on the trajectory corrections achieved by the casing would on its side provide very accurate data on solar wind. This makes this probe more interesting and more likely to fly than just a Pioneer anomaly test probe.

The only spurious gravitationnal effect on the test mass would be... the gravitationnal field of the probe itself. Thus the test mass should be placed right at the center of mass of the probe. An error on this would produce a permanent offset that we could not distinguish from true effects. If preleminary calculations show this is a problem, we can use a better overal design: the probe is formed of three parts, linked with cables: at the centre the protective casing, and at the extremities the radio transmitters, thrusters, and any other payload useful for science (and also useful to make this mission more likely). The whole thing rotates on an axis which is perpendicular to the sun direction, right around the test mass.
This design will allow to know preciselly the centre of mass and to adjust it. But above all, any permanent offset will be cancelled, as it will pull at times toward the Sun, at times opposite to the Sun. So we can really maintain the test mass free of spurious gravitationnal effects from the probe itself.

Such a probe would be relatively light wheight, so that it could be launched on an interstellar trajectory directly from the surface of the Earth, without using gravitationnal assistance. So it could bring results after only a few years. Otherwise we can use Jupiter' assistance.
Will this design lead one day to a real experiment?

Interesting idea, and pretty much identical to the concept for the LISA gravitational wave mission, which would reduce the costs of such a mission considerably if the systems could be reused.

Of cource that would rely on LISA ever geiing off the ground, I wrote a undergraduate report about LISA and that was a long time ago! (~9 years) I can't remember what the planned launch date was back then but I don't think it was more than ten years, today, still ten years (2015)!

James

[Guest_Richard Trigaux_*]

The LISA observatory project will use three test masses, each with its own shield, to detect gravitationnal waves.

The purpose of the LISA and of a Pioneer effect probe is different: the LISA will have to detect much weaker effects, using laser interferometry, while a Pioneer effect probe can be accurate enough with radio location. The LISA would not be bothered with a permament offset in the results, as it is meant to detect only transcient or periodic effects. But such a permanent offset would mess up a Pionner effect probe, as it studies signals which are constant over years.

For this reason I proposed my rotative shield design to cancel any permanent offset. This cannot be used by LISA. So they are developping a very accurate tracking system: 10 nanometres! Figure that this is better than welding the shield to the test mass with steel rods. Eventually this technology may be better than my rotating design to cancel even permanent offsets. So re-using the LISA technology may save most of the development costs for a Pioneer effect probe.

[The Messenger]

All of these approaches use assumptions we should not be making. If there is a variation in the permeabiliy of space to mass necessary to explain the phenomena I outlined above, there is almost certainly a corresponding gradient in the speed of light.

This can be demonstrated with the Galileo paradox:

Put Galileo on the Dark side of Mercury, rolling his balls to measure the gravitational constant. Because of the nearby mass of the sun, the balls will roll slower, which would cause Galileo, not knowing about GR, to underestimate the G constant. EXCEPT Galileo's clock is also ticking slower, so the value would be very close to correct.

Watching the experiment from an Earth frame of reference, the balls would appear to roll slower, and a GR space curvature correction must be used to explain the phenomena.

Three things: 1) The same observations can be interpreted as a time or space dilation, depending upon the frame of reference. 2) Performing the experiment on Mercury, Galileo could be completely oblivious to the need for GR to explain the results from Earth. 3) It is relatively simple to transfer both frames of reference to a single coordinate system where the absolute pathlength through a given volume of space varies as a function of mass.

Magueijo eluded to this transformation in Faster Than the Speed of Light, where he found it difficult to prove his theory required a new physical concept; and not just a transformation of GR into a completely compatible coordinate system, where pathlengths and the speed of light vary, not time and space curvature. (I am of the opinion that this mathematic transformation provides a better conceptual bases for GR phenomenon.)

So any attempts to measure unknown or poorly characterized forces must also address an untested assumption in measurement theory: the Speed of light is an absolute constant that is not mass dependent; or more exactly: Current GR perameters correctly compensate for mass-dependant effects upon light.

Again, existing solar probes have tightly constrained any deviations from established GR constraints: Bertotti has used Cassini to constrain unexpected GR variance to a factor of 2.3x10^-5 near the Earth's orbit. Perhaps the best solar constraint on the speed of light is the Pioneer Anomally itself - 8x10^-9m/s^2, but this is only beyond the obital distance of Saturn. (Notice that since we use the two-way speed of light to determine the position of the Pioneer probes, the acceleration of the probes could be away from, rather than towards the sun, as long as it is of the same magnitude as any change in the speed of light.)

Bertotti, B., Iess, L., Tortora, P., “A test of general relativity using radio links with the Cassini spacecraft,” Nature 425, 374-376 (2003).

http://lanl.arxiv.org/PS_cache/gr-qc/pdf/0411/0411082.pdf

Again, much of the science needed to nail down these possible discrepancies can be extracted from the current generation of probes, but only if the experimentors are aware of the unbridled parameters and the need for additional onstraints.

Edited to add:

One more question about LISA - unless and until the current LIGO generation of gravity antenna detect ANY gravitational phenomena, should we be vesting in another experiment? IAOTO the waves do exist, but we may be searching with the wrong kind of antenna.

[jamescanvin]

Heading off topic but...

One more question about LISA - unless and until the current LIGO generation of gravity antenna detect ANY gravitational phenomena, should we be vesting in another experiment? IAOTO the waves do exist, but we may be searching with the wrong kind of antenna.

Well LISA will be serching in a completely different frequency band. A band which should include waves from binary neutron stars which pretty much must exists given current observations (and at a known amplitude), unlike LIGO which can only detect much more exotic and theoretical objects and mergers. So yes I do think it's worth investing in, even given the non-detections at LIGO.

[The Messenger]

Heading off topic but...
Well LISA will be serching in a completely different frequency band. ..

Damn! I'll say we need LISA, yesterday, not too many years from now. Any chance of bumping LISA ahead of PLANCK? The CMB has a local contamination issue that needs to be resolved to reathenticate, if possible, the accuracy of the WMAP results.

But A drag-free triangulated laser ranged probe orbiting the Sun will also provide constraints upon Pioneer-like acceleration anomalies if they effect lasar ranging.

[Guest_Richard Trigaux_*]

Thanks jamescanvin for the image and the info it contains.

What would be fine is if somebody have the log-log plot, amplitude versus frequency, with expected domain for each gravitationnal wave source, and the expected sensitivity of each instrument.

What I heard (to check) is that the LIGO gravitational wave observatory is curently reaching its full sensitivity, but it still detected nothing (the only thing it could detect, neutron stars spiraling, would happen only once a year in average).

[jamescanvin]

What would be fine is if somebody have the log-log plot, amplitude versus frequency, with expected domain for each gravitationnal wave source, and the expected sensitivity of each instrument.

Yes, that was what I was looking for yesterday, but couldn't while rushing round.
Couldn't have been looking very hard as a quick search this morning and, ta-dar!



I think that curve is for Advanced LIGO , Standard LIGO is about one order of magintude less sensitive.

What I heard (to check) is that the LIGO gravitational wave observatory is curently reaching its full sensitivity, but it still detected nothing (the only thing it could detect, neutron stars spiraling, would happen only once a year in average).

Yes, I don't think we need to start rethinking gravitational wave theory just yet, it's not too surprising that nothing has been detected by LIGO so far. Lets wait for Advanced LIGO first (2009)

James

[Guest_Richard Trigaux_*]

Yes, that was what I was looking for yesterday, but couldn't while rushing round.
Couldn't have been looking very hard as a quick search this morning and, ta-dar!
James

Thanks very much James it is exactly what I wished!!! This graphics tells us exactly what we can expect or not!!

I think that curve is for Advanced LIGO , Standard LIGO is about one order of magintude less sensitive.
Yes, I don't think we need to start rethinking gravitational wave theory just yet, it's not too surprising that nothing has been detected by LIGO so far. Lets wait for Advanced LIGO first (2009)

James

Yes, no need yet to rethink the gravitationnal wave theory, as LIGO today is only able to detect rare events, mainly neutron stars and black hole coalescence, and only the stronger.

Black holes coalescence is, I think, something very well understood (in the context of General realtivity. But even without relativity we can expect that star-sized masses spiraling a high speed will produce strong gravitationnal effects.). Neutron star coalescence and super nova core collapse are slightly less understood (especially SN core coalescence may be highly disordered and unsymmetrical) but the theory is still reliable. So it is expectable that we detect some events before 2009, and only some years after this date, if we detect nothing, the gravitationnal wave theory is at risk.

[dvandorn]

Once again, I'm asking a question that I probably ought to just Google up for myself, but it does go along with the thread...

One of the experiments in the Apollo 17 ALSEP was the Lunar Surface Gravimeter. As I recall, it was designed to detect gravity waves. (It failed because it was balanced in 1G and was entirely out of balance, and hence useless, in 1/6G.)

Does anyone know what types of waves the LSG was designed to detect? Would it have been more in the LISA range or the LIGO range?

I guess I'm wondering what kinds of things we might have been gathering data on for more than 30 years if the instrument had just been designed properly...

-the other Doug

[edstrick]

I'd have to check, but I think the Apollo 17 instrument's name included the term "Tidal". They were looking at freequencies below those the seismometer would detect, at least in part... looking for whole-moon "ringing" frequencies, like the ringing of the whole earth after a Richter 8+ quake.

The instrument failed because it was balanced in 1 G with the aid of a loading mass or spring which was unloaded on the moon. The problem was an arithmetic booboo in the calculation of the design for lunar gravity.. the instrument had a "bias" range that was adjustable for a range of lunar gravities, or really more accurately, for a range of instrument sensitivities... The adjustable range of the instrument was such that actual lunar gravity (very well known) was outside the adjustment range. This is similar to the focus failure on Deep Impact's hi rez camera.. The camera was "focussed" from pre-launch out of focus conditions by heating the carbon-composite truss to drive out water vapor in vaccuum, intending to slow down and stop when the instrument approached and achieved perfect focus..... it never got there due to a ground base calibration problem. The actual focus point was outside of the adjustment range.

[Bob Shaw]

The instrument failed because it was balanced in 1 G with the aid of a loading mass or spring which was unloaded on the moon.  The problem was an arithmetic booboo in the calculation of the design for lunar gravity.. the instrument had a "bias" range that was adjustable for a range of lunar gravities, or really more accurately, for a range of instrument sensitivities... The adjustable range of the instrument was such that actual lunar gravity (very well known) was outside the adjustment range.  This is similar to the focus failure on Deep Impact's hi rez camera.. The camera was "focussed" from pre-launch out of focus conditions by heating the carbon-composite truss to drive out water vapor in vaccuum, intending to slow down and stop when the instrument approached and achieved perfect focus..... it never got there due to a ground base calibration problem.  The actual focus point was outside of the adjustment range.

Oooh, dear! Don't let a certain scientist-astronaut know, this may have wasted some of that precious EVA time during which rocks could have been examined. I can just imagine a series of unexplained murders, with the victims attended to with a balance spring tied between a gnomon and a lunar rake...

[Guest_Richard Trigaux_*]

Does anyone know what types of waves the LSG was designed to detect?  Would it have been more in the LISA range or the LIGO range?

I guess I'm wondering what kinds of things we might have been gathering data on for more than 30 years if the instrument had just been designed properly...

-the other Doug

I think that, even if such an instrument was properly designed, it had far from enough sensitivity to detect expected gravitationnal waves. Gravimeters are very sensitive indeed, they can detect such "low" masses as mountains, and even less (remember the historical Cavendish experiment which measured the effect of a some kilograms mass). But this is very far from enough to detect gravitationnal waves, which are many orders of magnitude under this level of sensitivity. Otherwise it would not be necessary to build such complicated experiments as LIGO, it would be enough to send a gravimeter in the ISS.

Perhaps the most powerfull recent gravitationnal event was the supernova in 1978, but who knows what happens in the gravitationnal field.

[edstrick]

When the gravimeter was proposed, selected and designed, the PI (Weber, I think) was claiming or about to claim possible detections of grativational waves with ultrasensative suspended cylinders. The consensus then and now was that plausible sources of waves in the frequency range that the sensors could detect were many orders of magnitude too small to detect (at least at distances out where there was any chance of an event occurring). But theory in 1970 was much less precise than now, too. By observing natural tidal oscillations of the moon and very low frequency seismic signals, they hoped to have a valuable experimet regardless of whether the "blue sky" gravity wave search was a bust or not.

[Guest_Richard Trigaux_*]

When the gravimeter was proposed, selected and designed, the PI (Weber, I think) was claiming or about to claim possible detections of grativational waves with ultrasensative suspended cylinders.  The consensus then and now was that plausible sources of waves in the frequency range that the sensors could detect were many orders of magnitude too small to detect (at least at distances out where there was any chance of an event occurring).  But theory in 1970 was much less precise than now, too.  By observing natural tidal oscillations of the moon and very low frequency seismic signals, they hoped to have a valuable experimet regardless of whether the "blue sky" gravity wave search was a bust or not.

Yes I remember that there was hopes to find gravitationnal waves with large aluminium cylinders which may resonate and amplify the wave signal. The first experiments to find gravitationnal waves started with such detectors, but they never produced anything. But the search was open...

[dvandorn]

Oooh, dear! Don't let a certain scientist-astronaut know, this may have wasted some of that precious EVA time during which rocks could have been examined. I can just imagine a series of unexplained murders, with the victims attended to with a balance spring tied between a gnomon and a lunar rake...

Oh, that particular scientist-astronaut was well aware of the problem -- for one thing, when the PI found his instrument wouldn't uncage, he *insisted* that this particular scientist-astronaut must have deployed it improperly, must not have leveled it right. So Houston told him to go back and re-level the experiment -- three times. When told it would not uncage, Schmitt even kicked it, hard, and then re-leveled it again. It still did not uncage.

Schmitt was, indeed, *quite* angry that such a screw-up had cost precious lunar surface EVA time.

From what I understand, though, even with the main beam caged, the LSG actexd as a fair one-axis seismometer...

-the other Doug

[dvandorn]

I'd have to check, but I think the Apollo 17 instrument's name included the term "Tidal".

Not in the experiment title, no -- Apollo 17 carried two gravimeters, the Lunar Surface Gravimeter (LSG) and the Lunar Portable Gravimeter (LPG). The tidal reference may have been in the detailed description of the LSG, but it was not part of the instrument's name.

The LPG was the same type of instrument used by oil companies to find salt domes underneath otherwise flat land -- oil and gas are often entrained in salt domes. It detected negative anomalies on the slopes of the massifs and positive anomalies on the valley floor, indicating just how much more massive the basaltic valley fill is when compared to the massifs. IIRC, the anomalies were on the order of 10 to 30 milligals.

So, the LSG was an ultra-sensitive seismometer that hoped to use the entire mass of the Moon to detect gravity waves? Interesting... even if we now think that gravity waves would have been undetectable with such an instrument.

-the other Doug

[Bob Shaw]

Oh, that particular scientist-astronaut was well aware of the problem -- for one thing, when the PI found his instrument wouldn't uncage, he *insisted* that this particular scientist-astronaut must have deployed it improperly, must not have leveled it right.  So Houston told him to go back and re-level the experiment -- three times.  When told it would not uncage, Schmitt even kicked it, hard, and then re-leveled it again.  It still did not uncage.

Schmitt was, indeed, *quite* angry that such a screw-up had cost precious lunar surface EVA time.

From what I understand, though, even with the main beam caged, the LSG actexd as a fair one-axis seismometer...

-the other Doug

other Doug:

Was the PI's body ever found?

Bob Shaw

[edstrick]

"From what I understand, though, even with the main beam caged, the LSG actexd as a fair one-axis seismometer...
-the other Doug"

As far as I know there were no science results whatever published from the instrument in that mode. I think the sensativity was far too low for any signal other than astronauts stomping by.

[The Messenger]

...
Perhaps the most powerfull recent gravitationnal event was the supernova in 1978, but who knows what happens in the gravitationnal field.

The failure to observe any evidence of SN1987A by any gravity wave detectors is not a good omen. True, the GW spectrum of a supernova is up-in-the-air, but an explosion of that magnitude, that close, should have created enough broad spectrum transients we should have found something, especially since the timing of the event is well known.

I wouldn't pin my life's savings on Advanced LIGO - which seems to be progressing slightly ahead of schedule. Every generation of gravity wave detectors from Weber's work in the '70's on, have been built with the expectation that a GW event was just one pixal below the horizon.

Advanced LIGO:
http://www.ligo.caltech.edu/docs/G/G050364-00.pdf

Eventually, with 1-year of data at design sensitivity, the LIGO detectors will be sensitive at a level several times below the nucleosynthesis bound.

http://arxiv.org/PS_cache/astro-ph/pdf/0507/0507254.pdf

FWI worth, there is still a great deal of contraversy in the supernova community about just what the gamma rays, and expansion RINGs associated with 1987A mean. John Middleditch amoung others, is convinced both the rings and rays reveal a binary event, and he argues most supernovae involve binary systems. This grates against SN Ia theory, but his arguments, (including the 'double humped' light curves observed in many SN Ia spectra.) are strong.

http://arxiv.org/abs/astro-ph/0310671

http://arxiv.org/abs/astro-ph/0311484

[Guest_Richard Trigaux_*]

I wouldn't pin my life's savings on Advanced LIGO - which seems to be progressing slightly ahead of schedule. Every generation of gravity wave detectors from Weber's work in the '70's on, have been built with the expectation that a GW event was just one pixal below the horizon.

Advanced LIGO:
http://www.ligo.caltech.edu/docs/G/G050364-00.pdf
http://arxiv.org/PS_cache/astro-ph/pdf/0507/0507254.pdf

Very interesting article, although arduous to read. To summarize, the purpose of LIGO is to detect the cosmic background gravitationnal noise caused by very early cosmological events, far before the electromagnetic background. Today LIGO has not yet achieved this goal, but it made only short runs of data sampling which were rather aimed at improving sensitivity and eliminating instrument noise. With a long run at expected maximum sensitivity they expect to detect the level of gravitationnal waves predicted by the most recent theories of inflation. If they really achieve this design sensitivity and still not fing a gravitationnal background noise, the theories of inflation are at risk. Still only some years of work to let us know...

Every generation of gravity wave detectors from Weber's work in the '70's on, have been built with the expectation that a GW event was just one pixal below the horizon.

This is often like this in difficult scientifical achievements. Look for instance at the tokamac, the quantum computer, superconduction at ambient temperature... This is also due to the fact that the first researchers were really optimistic. Today evaluations of gravitationnal waves are, alas, much more pessimistic, and if they were know in 1970 Weber would not have started his experiment. Weber simply did what was best possible to do at his epoch, knowing what we knew.

FWI worth, there is still a great deal of contraversy in the supernova community about just what the gamma rays, and expansion RINGs associated with 1987A mean.

Please remember that the curious set of three non-coplanar rings around SN1987A were already here before the explosion. They were discovered after, with close examination of the place, but such rings are more likely of the planetary nebula family. It was said at this epoch that there will be new hubbub here when the expanding fireball would reach the first ring, 20 years later (2007). Also we are still to detect the predicted blinking of the central object indicating the presence of a pulsar.

[edstrick]

It has been hoped that cosmic sources of gravitational radiation (as opposed to supernovae and massive object collissions) are stronger than predicted, or that there's unpredicted sources that have relatively frequent events strong enough for the first generation LIGO detection systems, but basically nobody expects it. Detectors have gotten much better than Weber's original cylinders, but my impression is that expectations of predicted source strength-frequency combinations have been such that no detector so far has been expected to detect anything by the general gravitational wave community. LIGI, I believe, works at much too high a frequency for detecting big bang related radiation and the like.

As far as SN1987A goes, we're detecting the blast wave interacting with the inner edge of a lumpy ring which is progressively lighting up as the blast expands. There is still no trace of either a black hole or neutron star in the supernova remenant inside the ring, or of energy being emitted from one. Some models in the past have suggested that in some cases there may be nothing left, but those I think are in disrepute, so the non-observation of a massive object is "A Puzzlement"

[Guest_Richard Trigaux_*]

As far as SN1987A goes, we're detecting the blast wave interacting with the inner edge of a lumpy ring which is progressively lighting up as the blast expands.  There is still no trace of either a black hole or neutron star in the supernova remenant inside the ring, or of energy being emitted from one. 

Thanks for the info, edstrick. The lumpy ring you speak about is the innermost of the three rings, the one which is coplanar with the star.

  Some models in the past have suggested that in some cases there may be nothing left, but those I think are in disrepute, so the non-observation of a massive object is "A Puzzlement"

Yes there are some models predicting a nuclear explosion of the star, without gravitationnal collapse. In this case all the mass is blasted away and nothing remains in the centre. But this is for peculiar cases of binary stars, I do not think it fits for SN1987A, which is believed to be basically a gravitationnal collapse of a massive star which exhausted all its nuclear power. But the process leading from a star to a neutron star or black hole is not yet understood. The only thing sure is that there was a blast of neutrinos detected, indicating very high temperatures reached in the core. But we do not know if a black hole or a neutron star was created. By the way this star was not very massive, it could have given only a white dwarf (an idea of mine, without any waranty). I remember that the detection of a blinking light was expected 10 years after. Now 18 years passed by...

[The Messenger]

Please remember that the curious set of three non-coplanar rings around SN1987A were already here before the explosion. They were discovered after, with close examination of the place, but such rings are more likely of the planetary nebula family. It was said at this epoch that there will be new hubbub here when the expanding fireball would reach the first ring, 20 years later (2007). Also we are still to detect the predicted blinking of the central object indicating the presence of a pulsar.

News to me - can you provide a source? Middleditch based his models on fast rotating binary systems, and the resulting Gamma Rays, so I don't think prior rings cause a conundrum (prior rings being a product of the orbital dog-and-cat fight (?)).

[Guest_Richard Trigaux_*]

News to me - can you provide a source? Middleditch based his models on fast rotating binary systems, and the resulting Gamma Rays, so I don't think prior rings cause a conundrum (prior rings being a product of the orbital dog-and-cat fight (?)).

This set of three non-coplanar rings was photographied just after the blast was extinct, some months after the supernova, when astronomers began to examine the place. I remember well that it was in all the science reviews (Here in France "Science et Avenir", "Science et Vie", "Pour la science" , and also in amateur astronomy reviews. At that time the fireball from the explosion was just an unresolved point at the centre of the well resolved three rings. Previous photos of the same place showed the parent star, but were not large enough to show the rings. These rings much puzzled the astronomers, and they played a role in the planetary nebula theory (since it was found one or several planetary nebula looking like hour glasses, ressembling the rings of 1987A). They are now expected to form from binary systems. But I never heard of a companion star of SN1987A, with my opinion if it exists it must be a very weak star, white dwarf, neutron star or black hole. Anyway it puzzles me that today some people (and even scientists) seem to think that the three rings resulted from the explosion. Today the fireball of the explosion is just catching the innermost ring.


Another curious thing is that, while the fireball was still very bright, days of weeks after the explosion,I heard mentioned that just nearby there was a huge transcient infrared source, most powerfull than the entire Magellanic cloud. But I never heard of this again, perhaps it was just an observation error. Often unexplained facts are considered as mistakes and forgotten. But there may be some new thing about. Today people may think that it was the effect of a focused gamma ray beam like those predicted by some supernova theories.

Sorry, I have no other sources than my memories of the scientific press at this epoch. If you want more precise sources, I think you should look in the archives of science and astronomy reviews (like the "scientific American" in the months following the supernova, I think you cannot miss the images of the three rings.

[The Messenger]

But I never heard of a companion star of SN1987A, with my opinion if it exists it must be a very weak star, white dwarf, neutron star or black hole. Anyway it puzzles me that today some people (and even scientists) seem to think that the three rings resulted from the explosion. Today the fireball of the explosion is just catching the innermost ring.

Thanks -

Nisenson argues the 'spots' are indeed likely supernova remnants, but I am not sure if he is arguing the rings are actual remnants or "spotlighted" illuminations of existing nebula.

http://arxiv.org/abs/astro-ph/9904109

You are correct in stating a companion star for 1987A has never been discovered. The column of energy released was so enormous, Middleditch speculates a high volume of the star may have undergone 'unidirectional weak interactions'. A relativistic laser(?)

I was looking for a mechanism to explain the relativistic accelerations Nisenson is trying to interpret, when I stumbled across the possibly 'non-Newtonian' trend in the solar system I outlined above. FWIW, I haven't convinced anyone in the field this could be a real aspect of gravity, but I haven't found anyone who's eyes don't glaze over the second they realize the implications, either.

[Guest_Richard Trigaux_*]

You are correct in stating a companion star for 1987A has never been discovered.

Such a companion is deemed necessary to explain the existence of the rings (some planetary nebulae geometries are suposed to appear in binary systems). Alas we don not have precise spectra of 1987A before the explosion (it was just a blue spot among thousands of others). To explain the "disappearance" of the companion, we can suppose:
-it is very weak (white dwarf, neutron star, black hole. But I think we cannot expect the presence of a white dwarf as a companion to a large star)
-it was blasted away during the explosion
-it was absorbed some thousands years ago when 1987A was a red giant, just after involving in the rings. Eventually such three-ring geometry would be the signature of this kind of event.

Remember also that a blue star exploding as a supernova was a surprise; astronomers were thinking of SN1987A as being an ordinary blue star on its main sequence, not the likely candidate for a supernova. (It was the first time the star forming the supernova was known). The generaly retained explanation is that 1987A had undergone a red giant stage earlier, but since some thousand years it had subsided into a smaller blue star. Such variations in near-death stars are expected by theories and supported by observations.

[ljk4-1]

Such a companion is deemed necessary to explain the existence of the rings (some planetary nebulae geometries are suposed to appear in binary systems). Alas we don not have precise spectra of 1987A before the explosion (it was just a blue spot among thousands of others). To explain the "disappearance" of the companion, we can suppose:
-it is very weak (white dwarf, neutron star, black hole. But I think we cannot expect the presence of a white dwarf as a companion to a large star)
-it was blasted away during the explosion
-it was absorbed some thousands years ago when 1987A was a red giant, just after involving in the rings. Eventually such three-ring geometry would be the signature of this kind of event.

Remember also that a blue star exploding as a supernova was a surprise; astronomers were thinking of SN1987A as being an ordinary blue star on its main sequence, not the likely candidate for a supernova. (It was the first time the star forming the supernova was known). The generaly retained explanation is that 1987A had undergone a red giant stage earlier, but since some thousand years it had subsided into a smaller blue star. Such variations in near-death stars are expected by theories and supported by observations.

Perhaps it was an industrial accident.

From the article "Detectability of Extraterrestrial Technological Activities"
by Guillermo A. Lemarchand:

http://www.coseti.org/lemarch1.htm


FIGURE 2: Concept of an "artificial" blue straggler star according to Reeves (1985). In this figure, a series of hydrogen bombs or powerful laser beams are aimed at the surface of a star, creating a "hot point" and rejuvenating the unused hydrogen, thus keeping the star on the Main Sequence for a longer period of time than would be natural.

http://www.coseti.org/images/lefig_2.gif

Reeves (1985) speculated on the origin of mysterious stars called blue stragglers. This class of star was first identified by Sandage (1952). Since that time, no clear consensus upon their origins has emerged. This is not, however, due to a paucity of theoretical models being devised. Indeed, a wealth of explanations have been presented to explain the origins of this star class. The essential characteristic of the blue stragglers is that they lie on, or near, the Main Sequence, but at surface temperatures and luminosities higher than those stars which define the cluster turnoff. A review of current thinking about these stars in the light of recent visible and ultraviolet Hubble Space Telescope observations assigns an explanation to stellar mergers occurring in the dense stellar environment of globular clusters (Bailyn, 1994).

Reeves (1985) suggested the intervention of the inhabitants that depend on these stars for light and heat. According to Reeves, these inhabitants could have found a way of keeping the stellar cores well-mixed with hydrogen, thus delaying the Main Sequence turn-off and the ultimately destructive, red giant phase.

Beech (1990) made a more detailed analysis of Reeves' hypothesis and suggested an interesting list of mechanisms for mixing envelope material into the core of the star. Some of them are as follows:

* Creating a "hot spot" between the stellar core and surface through the detonation of a series of hydrogen bombs. This process may alternately be achieved by aiming "a powerful, extremely concentrated laser beam" at the stellar surface.

* Enhanced stellar rotation and/or enhanced magnetic fields. Abt (1985) suggested from his studies of blue stragglers that meridional mixing in rapidly rotating stars may enhance their Main Sequence lifetime.

If some of these processes can be achieved, the Main Sequence lifetime may be greatly extended by factors of ten or more. It is far too early to establish, however, whether all the blue stragglers are the result of astroengineering activities.

[The Messenger]

Suggestions, by anyone, of engineering on this scale, is not productive and not scientifically motivated.

[Guest_Richard Trigaux_*]

Suggestions, by anyone, of engineering on this scale, is not productive and not scientifically motivated.

I mostly agree with you, but...


Imagine a million years old civilization, with technologies such as self-reproducing machines, fusion energy, etc... and plenty of time. Soon within reach of us.

Unless such a civilisation turns more ethical/spiritual than technological, there is no limit with such a technology, and it is not impossible we discover stars and even galaxies which were engineered over millions (or billions) of years. Simply we have not yet evidences (and even not suspicion) of it. There is alway this temptation when we discover something we do not understand: and if it was artificial? Remember the first pulsars: their extreme accuracy was not yet understood, and many scientists seriously considered they could be some interstellar beacons...

Coalescence of stars are a sufficient explanation for blue stragglers. A catastrophe which could happpen in some years, projecting all their planets (inhabited?) into blaze or into the darkness of space. Living into a dense star cluster may offer aver beautiful night sky, but it is also a ver dangerous place where most plants are ejected from their orbit by star encounters. so it is not the most likely place to find evolved life.

[The Messenger]

Returning to the Pioneer Anomally:

You may or may not be aware of the curious brightening phenomenon being studied by Ann Verbiscer, per the Planetary Weblog:

"We see three different views of Saturn on different dates. The globe of Saturn hardly looks different at all at these small differences in phase angle. But look at the rings! With the minutest difference in phase angle -- from 0.13 degrees down to 0.02 degrees -- the rings suddenly flash into brilliant light. Anne told me that she saw similar effects on Saturn's icy satellites, especially Enceladus. The size of the opposition surge she saw was "drastically higher, 40% higher, than previously published values."

I'm not an astronomical observer myself so Anne had to explain to me what causes the opposition surge. One explanation is "shadow hiding" -- at any non-zero phase angle, the particles in the rings cast shadows across other particles in the rings, so that darkens the surface. But at zero phase, you see no shadows at all, and the surface looks brighter. But Anne said that "it doesn't work" to explain all of the observed opposition effect. You need something more, like coherent backscatter: that is, constructive interference of the light being reflected from the rings and Enceladus. 

There is an explanation that is consistent, actually a necessary constraint, upon the permeability hypothesis I entered above:

The rings of Saturn, the highly reflective surfaces of some of the moons, are more like mirrors than nominal planetary surfaces. The sunlight reflected by the rings, therefore, more closely resembles a mirrored reflection of the sun, and will return a loosely coherant image of the sun.

When the Earth passes exactly between the Sun and Saturn, the rings and more reflective moons brighten. Why would the reflection be brighter at the very center?

If and ony if there is curvature of space. The image of the sun is focused only at the center, at anyother position of the Earth relative to the sun and Saturn, the image is deconvoluted.

When the Earth is exactly positioned in front of the sun, a perfectly curved lens would return a much brighter reflection of the sun. That is exactly what is happening.

And why would there be curvature? If and only if the permeability of space varies, increasing the speed of light with increasing distance from the center of the solar system, and this would be true if and only if the permeability of space is a function of MASS.

OK, There may be other solutions: Fressnel lensing, for example, but the solution is a lensing solution because the amount of brightening is also a function of wavelength, as would be expected with any single density lensing element.

The curvature has to be very slight...almost undetectable, but not quite, because it produces this brilliant mirror effect exactly in the center - just as a gravitational lens should. But the Earth is too far from the sun to experience this kind of curvature, with GR, as formulated by Einstein, to be the cause. (Also the mass of the Earth is not great enough to cause a GR bending of the light.)

This also explains why there are so many 'Gravitational' lenses, and 'micro quasar' lenses in the galaxy: There is a not-so-new physical principle being manifest: The permeability of space is a function of mass, the speed of light is only a constant in an ideal vacuum that includes the absence of any matter.

Returning to the Pioneer Accelerations, they are an artifact: We use the two-way time and speed of light to determine the distance to the probes. As the speed of light increases at a rate of ~1X10^-9m/s^2, the time it takes light to reach the probes and return is less than if the speed of light were constant. We interpret this as an acceleration of the probes towards the sun, when it is actually a slight acceleration of light away from the sun. (Of course both the speed of light, and the acceleration of the probes are not independently constrained at this time, so the true acceleration of the probes is unknown.)

[Guest_Richard Trigaux_*]

Messenger, yes the Earth does have a "gravitationnal lens" effect, but it can significantly concentrates light only at a distance of several thousand light-years. This was put at work in the search of "machos" (massive objects such as blue dwarf stars, planets, brown dwarfs, black holes... explaining the dark matter around the galaxy). But the "machos" detected were very far, for instance in the Magellanic cloud, and the most common mass was around half what of the Sun, much larger than Earth. So I think the effect of gravitationnal lens is undetectable from Saturn. The opposition effect is well explained in terms of shadow hiding and back reflection from ice crystals, an effect we can also see on earth clouds (from above). The best evidence is that it was also photographied by Cassini (see somewhere on Cassini site or on this site) and from here it appears as a bright spot on the rings.

[ljk4-1]

http://www.issi.unibe.ch/teams/Pioneer/

The Pioneer Explorer Collaboration
Investigation of the Pioneer Anomaly at ISSI

First Team Meeting at ISSI in Bern, Switzerland
November 7-11, 2005

Focus: the Pioneer anomaly

To date, the Pioneer 10 and 11 spacecraft are the most precisely navigated deep-space vehicles. However, as indicated by their radio-metric data, the Pioneers’ orbit reconstructions were limited by a small, anomalous, constant, blue-shifted, Doppler frequency drift of approximately 6 x 10^-9 Hz/s. The drift can be interpreted as due to a constant sunward acceleration of a_P = (8.74 ± 1.33) 10^-10 m/s^2. This interpretation has become known as the Pioneer anomaly.

Although the most obvious explanation would be that there is a systematic origin to the effect, the limited set of the analyzed data does not support any of the suggested mechanisms. We assert that analysis of the entire existing Pioneer data is vital to understanding the anomaly and, hopefully, to finding its origin. Indeed, analysis of the entire existing Pioneer data record is critical in attacking the anomaly on two fronts: (i) an analysis of the early, not rigorously analyzed, data could yield a more accurate direction of the anomaly and hence might help to determine its origin; (ii) by using the entire data set, from 1972 to 2002, one could study the temporal evolution of the anomaly and determine if it is due to on-board nuclear fuel inventory and related heat radiation or other mechanism.

Goal: analysis of the entire Pioneer 10/11 data record

The limited data analyzed previously allowed the detection of the anomaly in the Pioneer data, but not a determination of its origin. With new knowledge of all on-board processes and a diverse team, we propose a two-step process in understanding the origin of the anomaly, namely: (i) analysis of the entire set of existing Pioneer 10 and 11 data, obtained from first launch to the last telemetry received from Pioneer 10, on 27 April 2002, when it was at a heliocentric distance of 80 AU. This data could yield critical new information about the anomaly. If the signal is confirmed and is not due to an on-board systematic, (ii) we will use our new knowledge to develop an instrumental package that will be capable to provide an independent confirmation of the anomaly. We will also study a design for a dedicated mission to explore the anomalous behavior of the Pioneer spacecraft.

Significance: finding the origin of the Pioneer anomaly

This ISSI investigation could lead to a determination of the origin of the anomaly and to a characterization of its physical properties. The proposed investigation is scientifically important, it is timely, and is well situated in Europe. The investigation would be an excellent example to demonstrate the value of interdisciplinary teams in addressing complex problems in fundamental physics and in application of new technologies in spacecraft and mission designs. The results of this study could find their way into many other areas of space-exploration applications in the near future. The most important outcome of this study will be the understanding of the Pioneer anomaly.

http://www.issi.unibe.ch/teams/Pioneer/

[edstrick]

ljk4-1: "...The Pioneer Explorer Collaboration -- Investigation of the Pioneer Anomaly at ISSI.."

I totally concur with the proposed analysis. We have an "anomaly". Not an "Anomaly" or an "ANOMALY" (if you get what I mean...).

We have an APPARENT force acting on the spacecraft. The best modelling has been unable to explain this anomaly in terms of systematic internally generated forces on the spacecraft, or known, modelable external forces acting on the spacecraft. We now need to extract the most information possible from the mission's data to see how the force varies with 1.) mission phase, 2.) radial location in solar system, and 3.) azimuth/inclination in solar system.

For example, if a reanalysis shows no anomalous acceleration before Jupiter flyby and identical accelerations afterwards... that would suggest an effect arising in an unknown effect on the spacecraft of the Jovian system environment..... particularly the extreme radiation environment.

For another example...Pioneer 11 flew "across" the solar system in a significantly inclined orbit between the Jupiter encounter and it's Saturn encounter, getting a foretaste of out-of-ecliptic science before Ulysses. If a reanalysis shows a force varying with inclination or angle around the sun in the ecliptic and then a relatively constant force after Saturn flyby puts Pioneer 11 on an escape trajectory...... Hmmmmmm.....!

[Guest_Richard Trigaux_*]

Thanks ljk4-1 for your interesting contribution. And edstrick too

To analyse the existing set of data is obviously the first thing to do before building a space probe to investigate a gaz leak on Pioneer.
-Is the effect real?
-Is it constant, or depending on distance, attitude, fuel aging, direction, planet neighbouring, distance from the ecliptic?
All this would give us clues about its nature: gravitation, electromagnetic, solar wind, local reaction...

By the way it is said that the computers able to read the Pioneer data are to be scraped by the NASA. The first thing to do is obviously to save the data on modern supports. New domain for archaeology: rumaging in old computers magnetic bands.

edstrick, I never heard that the word "anomaly" bears a capital letter, in any of its uses. The Pioneer anomaly may have a very extraordinary explanation, for instance that the probe was followed by a spaceship from another civilization, or that it was used by yogis to demonstrate their supernatural powers. Simply such kind of explanations can be envisioned only after all the other explanations failed. More likely the Pioneer anomaly bears the possibility of some fundamental discovery in physics or in astronomy, so it is worth the study. But there are many chances that we simply find a gaz leak, thruster malfunction or something trite in this style.

But of course I did not missed your point about ANOMALIES! I am no more interested than you by people who spread false informations and false theories: they only muddle things. If there is somewhere something really unexplained, they may rather spoil the discovery than encourage its study.

[deglr6328]

sooooo did the planetary soc. get the data or what...? They haven't updated on us the status of thier original $250K begathon since like March.

[edstrick]

<grin> by "anomaly" I mean an ordinary scientific/engineering unexplained datum due to inadequate modeling, systematic error in measurements, etc.... like the false indications that there was a 10'th planet making Neptune "wander", triggering the search that found Pluto.

An "Anomaly" (tone of voice emphasis implied) would be something that really starts to look like it suggests new astronomy, new physics.... something that is well defined enough and stubborn enough after sustained efforts to make it go away, that people (not just the arm-waving fringe) start to work hard on resolving it. The solar neutrion flux anomaly was one... solved by the confirmation that solar neutrinos change type en-route from the sun, so we only detect 1/3 of them with the original detectors.

And of course ANOMALY (capslock, funny font, guy with tin hat handing out mimeographed treatises to anybody he can buttonhole at a scientific meeting) is what the Hoaxland crowd assume it's most likely to be. (eyeballs rolled expression).

[Guest_Richard Trigaux_*]

<grin>  by "anomaly" I mean an ordinary scientific/engineering unexplained datum due to inadequate modeling, systematic error in measurements, etc.... like the false indications that there was a 10'th planet making Neptune "wander", triggering the search that found Pluto.

An "Anomaly"  (tone of voice emphasis implied) would be something that really starts to look like it suggests new astronomy, new physics.... something that is well defined enough and stubborn enough after sustained efforts to make it go away, that people (not just the arm-waving fringe) start to work hard on resolving it.  The solar neutrion flux anomaly was one... solved by the confirmation that solar neutrinos change type en-route from the sun, so we only detect 1/3 of them with the original detectors.

And of course ANOMALY (capslock, funny font, guy with tin hat handing out mimeographed treatises to anybody he can buttonhole at a scientific meeting) is what the Hoaxland crowd assume it's most likely to be. (eyeballs rolled expression).

Thank you for the nuances. The Pioneer anomaly if likely of the first kind (anomaly) but there is enough chance it is of the seconc kind (Anomaly) so that it is worth studying it (and re-examining the whole data set is definitively the best to start with).

By the way, the custom of wearing tin-hats comes from the idea that naughty aliens influence us by telepathy. But if telepathy exists, it is likely not an electromagnetic phenomenon, so the tin hat is of no use.

[edstrick]

Aliens?... I thought it was the CIA and FBI.... or maybe they are space aliens here to control us!

NATIONAL OUTQUIRER
(Picture of Michael Jackson, Elizabeth Taylor, and H. Ross Perot)
Headline: CELEBRITY SPACE ALIENS LIVING AMONG US.

(HRP is obviously a disguised Ferengi... the ears.. the nose.. the money...)

[Guest_Richard Trigaux_*]

Aliens?... I thought it was the CIA and FBI....

They do not need telepathy for this, they have tele...vision.

There are rumors too of electromagnetic weapons able of having effects of the brain, such as make us hear voices. Far-fetched, but not completelly impossible I think. But if ever there is one day a government pervert enough to use such weapons against its citizens, it will be that the society would have gone very very wrong far before...

[edstrick]

You know what the problem is with make-believe paranoia?

(looking around suspiciously...)

YOU'RE PROBABLY RIGHT!

[Guest_Richard Trigaux_*]

You know what the problem is with make-believe paranoia?

(looking around suspiciously...)

YOU'RE PROBABLY RIGHT!

AAAAAARRRGGHH

[ljk4-1]

Astrophysics, abstract
astro-ph/0504367
From: Gary Page [view email]
Date (v1): Sun, 17 Apr 2005 17:04:48 GMT (32kb)
Date (revised v2): Sat, 1 Oct 2005 13:46:27 GMT (43kb)

Utilizing Minor Planets to Assess the Gravitational Field in the Outer Solar System

Authors: Gary L. Page, David S. Dixon, John F. Wallin

Categories: astro-ph

Comments: Added substantial new material dealing with ability to observed effects addressed in paper

The twin Pioneer spacecraft have been tracked for over thirty years as they headed out of the solar system. After passing a heliocentric distance of 20 AU, both exhibited a systematic error in their trajectories that can be interpreted as a constant acceleration towards the sun and that has come to be known as the Pioneer Effect.

Spacecraft systematics are its most likely explanation, but there have been no convincing arguments that that is the case. The alternative, that the Pioneer Effect represents a real phenomenon, is very appealing for many reasons. What is lacking is a means of measuring the effect, its variation, its potential anisotropies, and its region of influence.

We show that minor planets provide an observational vehicle for investigating the gravitational field in the outer solar system, and thus provide a means of measuring the Pioneer Effect and potentially to either support or refute its existence as a real phenomenon. Minor planets can be used for this purpose because they have a large mass and are large and bright enough to be observed for useful intervals.

Thus, even if the Pioneer Effect does not represent a new physical phenomenon, minor planets can be used to probe the gravitational field in the outer solar system. Since there are very few intermediate range tests of gravity at the multiple AU distance scale, this is a worthwhile endeavor in its own right. It might even be possible to differentiate between the predictions of alternative explanations for the Pioneer Effect.

http://arxiv.org/abs/astro-ph/0504367

[ljk4-1]

Paper: astro-ph/0506281

replaced with revised version Mon, 24 Oct 2005 20:43:50 GMT (41kb)

Title: Analytic Gravitational-Force Calculations for Models of the Kuiper Belt,
with Application to the Pioneer Anomaly

Authors: Michael Martin Nieto

Comments: 11 pages, 8 figures, final corrections for publication

Report-no: LA-UR-05-4414

Journal-ref: Phys. Rev D 72 (2005) 083004

We use analytic techniques to study the gravitational force that would be produced by different Kuiper-Belt mass distributions. In particular, we study the 3-dimensional rings (and wedge) whose densities vary as the inverse of the distance, as a constant, as the inverse-squared of the distance, as well as that which varies according to the Boss-Peale model. These analytic calculations yield physical insight into the physics of the problem. They also verify that physically viable models of this type can produce neither the magnitude nor the constancy of the Pioneer anomaly.

\\ ( http://arXiv.org/abs/astro-ph/0506281 , 41kb)

[ljk4-1]

Paper (*cross-listing*): gr-qc/0511026

Date: Sun, 6 Nov 2005 02:40:04 GMT (162kb)

Title: Gravitational solution to the Pioneer 10/11 anomaly

Authors: J. R. Brownstein and J. W. Moffat

Comments: 11 pages, 4 figures, 1 table
\\
A fully relativistic modified gravitational theory including a fifth force
skew symmetric field is fitted to the Pioneer 10/11 anomalous acceleration. The
theory allows for a variation with distance scales of the gravitational
constant G, the fifth force skew symmetric field coupling strength omega and
the mass of the skew symmetric field mu=1/lambda. A fit to the available
anomalous acceleration data for the Pioneer 10/11 spacecraft is obtained for a
phenomenological representation of the "running" constants and values of the
associated parameters are shown to exist that are consistent with fifth force
experimental bounds. The fit to the acceleration data is consistent with all
current satellite, laser ranging and observations for the inner planets.

\\ ( http://arXiv.org/abs/gr-qc/0511026 , 162kb)

[Guest_Myran_*]

Calculations using the 'MOND' theory (Modified Newtonian dynamics) also have been applied and did fit well with the Pioneer data. No fifth force needed in that case.

Some more on MOND here:
http://www.astro.umd.edu/~ssm/mond/

[Guest_Richard Trigaux_*]

I wonder if we could do any theory of any kind, adjust parametres and obtain a fit with anything.

But if the fit goes for not only Pioneer data, but all similar data, it is more intersting. Not an evidence of any given theory, but a last of a common mechanism.

[mike]

That's what a theory is.

[elakdawalla]

sooooo did the planetary soc. get the data or what...? They haven't updated on us the status of thier original $250K begathon since like March.

We've been a little preoccupied!

There are updates on our website here, including reports from a staff member who we sent to the conference in Switzerland:
http://www.planetary.org/programs/projects...ly/updates.html
And "begathon"...I like it...captures the tone of those four-page letters nicely...

--Emily

[Guest_Myran_*]

Richard Trigaux said: I wonder if we could do any theory of any kind, adjust parametres and obtain a fit with anything.

But if the fit goes for not only Pioneer data, but all similar data, it is more intersting. Not an evidence of any given theory, but a last of a common mechanism.

Yes, why I was somewhat vary of the idea of a "fifth force" suggested here.
I like things bare bones simple, and so a strong supporter that Occam sharpen his blade.
So when MOND theory originally for explaining the rotation of galaxies also turned out to fit for the much closer Pioneer I happily accepted the notion that there might be something more that makes this idea deserves attention.
(Note: I originally read about the theory in Scientific American, and got interested in it.)

[lyford]

Call me old fashioned, but I am a bit wary of jettisoning the "old physics" when the effects are at what I understand to be the threshold of detection, and we really don't know what the environment the little guys are swimming in right now is like - we may need to look for a new theory of interstellar wind before altering the laws of motion.

Still it is fun to think about - and it IS possible I suppose -

This page from the Planetary Society puts it well:

The simple engineering explanation cannot yet be ruled out, but enough work has been done in trying all the different possibilities that even Occam's Razor allows us to cut a little way into the idea of a new physics.

[ljk4-1]

We've been a little preoccupied!

There are updates on our website here, including reports from a staff member who we sent to the conference in Switzerland:
http://www.planetary.org/programs/projects...ly/updates.html
And "begathon"...I like it...captures the tone of those four-page letters nicely...

--Emily

Dear Emily,

Speaking of TPS-funded projects, what has happened with Project BETA? Was the Harvard dish ever repaired? If not, is there an alternate plan to keep BETA running? Or is everything focused on Optical SETI now? And what has happened with that project lately?

Thank you.

[The Messenger]

Call me old fashioned, but I am a bit wary of jettisoning the "old physics" when the effects are at what I understand to be the threshold of detection, and we really don't know what the environment the little guys are swimming in right now is like - we may need to look for a new theory of interstellar wind before altering the laws of motion. 

Still it is fun to think about - and it IS possible I suppose -

Pioneer 10 & 11 are not the only odd-ball observations, and I am not talking about rocks that look like a pock-marked Elvis.

Pioneer 6 charted heavy Doppler residuals, and a linear component (similar to the term used in this paper) had to be added to the solar wind to plot both Galileo and Ulysses during interplanetary transitions. There is a possibility that when all the dots are connected, something fundamental will jump out of the wood work.

[elakdawalla]

Dear Emily, Speaking of TPS-funded projects, what has happened with Project BETA?  Was the Harvard dish ever repaired?  If not, is there an alternate plan to keep BETA running?  Or is everything focused on Optical SETI now?  And what has happened with that project lately? Thank you.

That's a good question, and I don't know the answer, and the SETI areas of our website have suffered a bit through the redesign process. We should have answers for you there and we don't. I'll try to follow up. Amir Alexander here at the Society is the one who does SETI, I'll see if he can answer your question.

--Emily

[lyford]

Pioneer 10 & 11 are not the only odd-ball observations.... (edit) ....There is a possibility that when all the dots are connected, something fundamental will jump out of the wood work.

True, but we have too few dots right now, and this is another great reason to have more outer solar system missions!

Though, infuriatingly, we will have to wait quite a long time for a return on investment, even for the New Horizons data.

I don't mean to imply that only odd balls that make odd ball observations, and I realize an anomaly to be explained can be a doorway to new understanding - Black Body Radiation anyone?

I find it fascinating nonetheless that the universe is understandable at all, and if you think about it, Science has only had a few centuries to explore the entire span of space time from our little home here. I am sure there are plenty of surprises in store.

[ljk4-1]

Astrophysics, abstract
astro-ph/0505310

From: Michael A. Ivanov [view email]

Date (v1): Sat, 14 May 2005 19:34:27 GMT (122kb)
Date (revised v2): Mon, 19 Dec 2005 16:23:51 GMT (124kb)

Low-energy quantum gravity leads to another picture of the universe

Authors: Michael A. Ivanov

Comments: 13 pages, 4 figures, LaTeX. Contribution to the 1st Crisis in
Cosmology Conference (CCC-1), Moncao, Portugal, 23-25 June 2005. A computational error amd some misprints are corrected in this version

If gravitons are super-strong interacting particles and the low-temperature graviton background exists, the basic cosmological conjecture about the Dopplerian nature of redshifts may be false: a full magnitude of cosmological redshift would be caused by interactions of photons with gravitons. Non-forehead collisions with gravitons will lead to a very specific additional relaxation of any photonic flux that gives a possibility of another interpretation of supernovae 1a data - without any kinematics. These facts may implicate a necessity to change the standard cosmological paradigm. Some features of a new paradigm are discussed. In a frame of this model, every observer has two different cosmological horizons. One of them is defined by maximum existing temperatures of remote sources - by big enough distances, all of them will be masked with the CMB radiation. Another, and much smaller, one depends on their maximum luminosity - the luminosity distance increases with a redshift much quickly than the geometrical one.

If the considered quantum mechanism of classical gravity is realized in the nature, then an existence of black holes contradicts to the equivalence principle. In this approach, the two fundamental constants - Hubble's and Newton's ones - should be connected between themselves. The theoretical value of the Hubble constant is computed. Also, every massive body would be decelerated due to collisions with gravitons that may be connected with the Pioneer 10 anomaly.

http://arXiv.org/abs/astro-ph/0505310

[ljk4-1]

General Relativity and Quantum Cosmology, abstract
gr-qc/0512121

From: Slava G. Turyshev [view email]

Date: Wed, 21 Dec 2005 21:49:36 GMT (882kb)

The Study of the Pioneer Anomaly: New Data and Objectives for New Investigation

Authors: Slava G. Turyshev, Viktor T. Toth, Larry R. Kellogg, Eunice. L. Lau, Kyong J. Lee

Comments: 42 pages, 40 figures, 3 tables

Radiometric tracking data from Pioneer 10 and 11 spacecraft has consistently indicated the presence of a small, anomalous, Doppler frequency drift, uniformly changing with a rate of ~6 x 10^{-9} Hz/s; the drift can be interpreted as a constant sunward acceleration of each particular spacecraft of a_P = (8.74 \pm 1.33) x 10^{-10} m/s^2. This signal is known as the Pioneer anomaly; the nature of this anomaly remains unexplained. We discuss the efforts to retrieve the entire data sets of the Pioneer 10/11 radiometric Doppler data. We also report on the recently recovered telemetry files that may be used to reconstruct the engineering history of both spacecraft using original project documentation and newly developed software tools. We discuss possible ways to further investigate the discovered effect using these telemetry files in conjunction with the analysis of the much extended Doppler data. We present the main objectives of new upcoming study of the Pioneer anomaly, namely i) analysis of the early data that could yield the direction of the anomaly, ii) analysis of planetary encounters, that should tell more about the onset of the anomaly, iii) analysis of the entire dataset, to better determine the anomaly's temporal behavior, iv) comparative analysis of individual anomalous accelerations for the two Pioneers, v) the detailed study of on-board systematics, and vi) development of a thermal-electric-dynamical model using on-board telemetry. The outlined strategy may allow for a higher accuracy solution for a_P and, possibly, will lead to an unambiguous determination of the origin of the Pioneer anomaly.

http://arxiv.org/abs/gr-qc/0512121

[tfisher]

I just read through the last paper linked. They've done quite well at recovering a complete data set, including telemetry data like temperature and voltage readouts useful for reconstructing thermal contributions to the Pioneers' accelerations. Another cool tidbit: there is one last opportunity to attempt to contact Pioneer 10, coming up in this February/March. (They think that, just barely maybe there is enough power still now in the old RTGs...) The round-trip light-time is 25 hours, so the contact would proceed by sending out a signal from Goldstone, waiting a day while the earth spins around once and the radio waves make their merry way, and listening for a response again at Goldstone. Somehow that image amuses me :^)

[ljk4-1]

Paper: astro-ph/0504367

Date (v1): Sun, 17 Apr 2005 17:04:48 GMT (32kb)
Date (revised v2): Sat, 1 Oct 2005 13:46:27 GMT (43kb)
Date (revised v3): Mon, 2 Jan 2006 16:12:03 GMT (36kb)

replaced with revised version Mon, 2 Jan 2006 16:12:03 GMT (36kb)

Title: Can Minor Planets be Used to Assess Gravity in the Outer Solar System?

Authors: Gary L. Page, David S. Dixon, John F. Wallin

Comments: Accepted for publication in The Astrophysical Journal

The twin Pioneer spacecraft have been tracked for over thirty years as they headed out of the solar system. After passing 20 AU from the Sun, both exhibited a systematic error in their trajectories that can be interpreted as a constant acceleration towards the Sun. This Pioneer Effect is most likely explained by spacecraft systematics, but there have been no convincing arguments that that is the case.

The alternative is that the Pioneer Effect represents a real phenomenon and perhaps new physics. What is lacking is a means of measuring the effect, its variation, its potential anisotropies, and its region of influence.

We show that minor planets provide an observational vehicle for investigating the gravitational field in the outer solar system, and that a sustained observation campaign against properly chosen minor planets could confirm or refute the existence of the Pioneer Effect.

Additionally, even if the Pioneer Effect does not represent a new physical phenomenon, minor planets can be used to probe the gravitational field in the outer Solar System and since there are very few intermediate range tests of gravity at the multiple AU distance scale, this is a worthwhile endeavor in its own right.

\\ ( http://arXiv.org/abs/astro-ph/0504367 , 36kb)

[tasp]

I bet it is not as simple as this, but I will post an idea and watch it be shredded . . .



Any possibility either Voyager craft could be spun at a few revs per hour, with the thrusters turned off, and keep the dish pointed at earth for maybe a year or two?

My thought is if we could get a confirmation of the Pioneer anomaly with a Voyager craft it might help JPL design a more capable or sophisticated 'Pioneer Anomally Probe' someday.

With the 'nodding' motion compensation used at Triton, I am cautiously optimistic that there might still be a new trick for our favorite 'old dog' to learn.

Having a spin stabilised period of flight for a Voyager might yield enough high quality tracking data at what would have to be an attractive price compared to launching another probe designed for the task.

Besides, I'm getting old and would like this mystery cleared up while I am still around . . .

[mchan]

Any possibility either Voyager craft could be spun at a few revs per hour, with the thrusters turned off, and keep the dish pointed at earth for maybe a year or two?

One problem is that something that was not designed to be spin stabilized (like Voyager) would very likely not spin very well. E.g. the spin axis would move around. In the case of Voyager, a stable spin axis (is such exists) may not align with the axis if the high gain antenna.

[ugordan]

One problem is that something that was not designed to be spin stabilized (like Voyager) would very likely not spin very well.  E.g. the spin axis would move around.  In the case of Voyager, a stable spin axis (is such exists) may not align with the axis if the high gain antenna.

Wasn't the spacecraft-solid rocket stack spin stabilized for the duration of the rocket's burn during Jupiter injection or was it also in 3-axis stabilization mode? I would have figured delivery errors would be minimized by spinning up first.

Another possible problem with spin-stabilizing is the star sensor, would it be able to cope with starfield smearing during rotation?

[Bob Shaw]

Wasn't the spacecraft-solid rocket stack spin stabilized for the duration of the rocket's burn during Jupiter injection or was it also in 3-axis stabilization mode? I would have figured delivery errors would be minimized by spinning up first.

Another possible problem with spin-stabilizing is the star sensor, would it be able to cope with starfield smearing during rotation?

If all that's required is a beacon, then setting up a slow spin where the aim point of the antenna nutates around the position of the Earth might be better than a precisely-aimed but data-free arangement. The CG and dynamic behaviour of the Voyagers must be *very* well known by now (unless something has dropped off with the cold). If data is required, that's perhaps another story. Perhaps the lesson here is that future interstellar-precursor probes should be designed with graceful aging in mind, so that as their output of data reduces it still remains - just - there.

Oh, and isn't it good to hear that there's going to be another attempt to reach Pioneer!

Bob Shaw

[ljk4-1]

Can New Horizons participate in this experiment? Or was that another item left off the menu?

[djellison]

Can New Horizons participate in this experiment?  Or was that another item left off the menu?

That's an unfair and unjustified jab at the mission.

From http://www.planetary.org/programs/projects...e_20050720.html

The Pioneers are spin-stabilized spacecraft. The Voyagers are three-axis stabilized craft that fire thrusters to maintain their orientation in space or to slew around and point their instruments. Those thruster firings would introduce uncertainties in the tracking data that would overwhelm any effect as small as that occurring with Pioneer.

This difference in the way the spacecraft are stabilized actually is one of the reasons the Pioneer data are so important and unique. Most current spacecraft are three-axis stabilized, not spin stabilized. It is unlikely another spin-stabilized craft will be sent across the solar system in the foreseeable future.

Doug

[tasp]

If an objection to putting a Voyager into a slow spin is the likelihood that it would not be possible to stop the spin, do we care?

{well, of course we care, but you catch my drift}

IIRC, some of the fields and particle experiments on Voyager work better when the craft is spinning, and the craft has spun for short periods for that very reason during planetary encounters.

Maybe this isn't so unlikely?

[ugordan]

That's an unfair and unjustified jab at the mission.

No - it cant, because it uses thrusters to manouver which would impart a small, but hard to calculate delta-V every time the spacecraft pitches, rolls and yaws.  Same reason that Voyager is of no use either.

Yes, but unlike the Voyagers, NH also has a spin mode which will be used during the long interplanetary cruise. So we might get long intervals when the s/c will be spin-stabilized and use it to get periods of precise tracking data. This will of course not be possible during the Jupiter encounter as well as the Pluto encounter phase, but at all other times (assuming thrusters will be off) it should be possible.
Seven years or so between Jupiter flyby and start of Pluto approach phase is a pretty good sample, IMHO.

[djellison]

Damn good point actually UG - hadnt thought of that.

Then again, they're planning a yearly checkout iirc though - and that may involved pitching/rolling/yawing the spacecraft to look at astronomical calibration targets, which would trash the effect wouldnt it?

activities during the approximately 8-year cruise to Pluto include annual spacecraft and instrument checkouts, trajectory corrections, instrument calibrations and Pluto encounter rehearsals.

Doug

[ugordan]

Then again, they're planning a yearly checkout iirc though - and that may involved pitching/rolling/yawing the spacecraft to look at astronomical calibration targets, which would trash the effect wouldnt it?

I don't think it would trash the effect. At least much. They'll still have periods of inertial coast in between and still see if the modelled-out Doppler plots fit with the observed segments. A residual should still be detectable, though it won't take time do reach a big, nice and well-detectable magnitude before another "trashing" period. Then again, the s/c will probably have more stable RF oscillators so the balance could still hold.
On the other side, I vaguely *seem* to remember reading somewhere that NH actually won't be a good tool to measure the acceleration, I forget why.
Might have been something with the ultrastable oscillators thing.
Might have been a pigment of my imagination...

[NMRguy]

Yes, we spin most of cruise, stopping only rarely. It costs fuel that we want to hoard for encounters and KBO DeltaV. And yes, our radio science team hopes to look for
the Pioneer anaomaly. Contact Len Tyler or Ivan Linscott at Stanford.

-Alan

Alan addressed this back in Feb 05 in the "New Horizons, Pluto and the Kuiper belt" page. It seems like he plans to take full advantage of this opportunity.

[Guest_AlexBlackwell_*]

Alan addressed this back in Feb 05 in the "New Horizons, Pluto and the Kuiper belt" page.  It seems like he plans to take full advantage of this opportunity.

Below is an excerpt from The Planetary Society's website of Merek Chertkow's report on the 2005 Pioneer Anomaly Conference:

[Slava] Turyshev introduced the possibility of working with New Horizons, NASA’s Pluto-Kuiper belt mission scheduled to launch on January 11, 2006. The Pioneer anomaly investigation team was invited to come up with a thermal model of the New Horizons spacecraft. New Horizons was developed very rapidly on a very small budget. New Horizons was developed so quickly in order to catch the small launch period that is available to get a Jupiter fly by on the way to Pluto, which cuts flight time by a few years.

New Horizons is a great mission for us to look at; they have a spin-stabilized craft, the Doppler data will be very good (not as good as Cassini, but better than Pioneer), and it will be going out to Pluto (remember we found the Pioneer anomaly at the distance of Saturn)! As Turyshev put it, this is a once in a lifetime opportunity.
Sounds great, right?! Unfortunately, the funding for New Horizons is already limited and we will have to bring our own funding, as well as figuring out the study itself.  So, time will tell if this works out.

[tty]

Might have been a pigment of my imagination... 

Just what colour is your imagination?

tty