http://www.foxnews.com/story/0,2933,334090,00.html


Mysteriously, four spacecraft that flew past the Earth have each displayed unexpected anomalies in their motions.

These newfound enigmas join the so-called "Pioneer anomaly" as hints that unexplained forces may appear to act on spacecraft.

A decade ago, after rigorous analyses, anomalies were seen with the identical Pioneer 10 and 11 spacecraft as they hurtled out of the solar system.

Both seemed to experience a tiny but unexplained constant acceleration toward the sun. In other words, they were moving just a little bit slower than they should be, and by the same amount.

You might check this thread on the Astronomy section from a couple of months ago:

NASA Baffled by Unexplained Force Acting on Space Probes

Jim

(my bold)
As I asked in the title to this post is the possibility of the anomaly limited only to unexplained forces?

The reason for this is that general relativity is well established to answer the nature of forces in what for most purposes could be calculated in static frames.

That leaves two further (possibly more) options and the first being that due to the velocity of the craft is there additional calculations required for dynamic changing reference frames ... which leads to the second option.

Yes I know I am a pain always coming back to this but ... is it space? Everything is explained in terms of geodesics or the stretch of space. Could there be a very slight underlying geodesic giving a layered effect to space which is only noticeable when the curvature is traversed at speed or calculated over time interval?

__________________
"Nature is obliged to let reality determine its laws, whereas mathematics is under no such constraint."

I have been giving this a bit of thought and as usual have managed not to make myself at all clear. In fact I was about to post this reply in the wrong thread until I did a quick reread.

It is rocket science actually. If there is a second underlying geodesic then all the data from the telemetry and from others that did not alter should be able to determine if there is an underlying shape of space beneath what we know.

From the time of mission, start position, end position and velocity of each of the flybys then a basic size, curvature and shape could be determined. It is just a matter of plugging in the numbers.

__________________
"Nature is obliged to let reality determine its laws, whereas mathematics is under no such constraint."

What is the possibility that these spacecraft are acting as condensation nuclei gathering matter that is de ionizing out of the solar wind, there for increasing in mass, at the same time the additional new mass had a lower velocity, thus lowering the composite velocity. Self gravitation, surface tension of liquids, or static attraction might be stronger than radiational pressure or solar gravity at these distances.

What are the chances that some day we will have a "comet pioneer"?

*grins* Anyone for V-ger? (think Star Trek, the Movie)

Wouldn't mass accretion show up as a more constant effect, & a steadily increasing one at that?

__________________
* Never doubt there is Truth; just doubt that you have it!

Mass unless variable due to changed velocity indicates extreme speed.

Forces being variable indicates a secondary interaction between close mass association introducing the possibility of additional forces or unexplained effects from known forces.

(The apparent double metric of space geometry is still my favoured position. Simply because it allows a compression of space (Newtonian gravity) and a curvature of space/time (rubber sheet analogy) to coexist. That way the known forces, energies and masses must adapt around a dual geometry that gives each a unique characteristic interaction and not a separate secondary force, energy or mass).

__________________
"Nature is obliged to let reality determine its laws, whereas mathematics is under no such constraint."

what is the comparison between our probes leaving the Solar System and a comet?

There's too much I don't know about the objects to Google Newton's equation and fill in the blanks.

(lazy student bailout tactic)

There was a paper in a recent issue of Physical Review Letters that went into this topic. I referenced it in this post in a thread dedicated to one of Jerry's interminable tirades on this topic. Basically, the paper concludes that the effect is real, but makes no conclusions as to cause. It does make predictions to what deviation we should have seen in the path of the Rosetta probe in November of 2007. I don't know if anything has been published on this probe's path.

In any case, I'd point out that the size of these anomalies is tiny, on the order of mm/sec for an object moving at several thousand km/sec. It's amazing that we can measure them at all.

PS, I don't even rate Fox as a reliable source for political news, much less scientific. Advice to future posters, use a press release from AIP, APS, NASA, or some other scientific agency rather than one from any news source. I include Scientific American, Science News, and New Scientist in this latter category. They may be better than Fox, but they still have a regrettable taste for expressing tentative results in a dramatic fashion that overstates their significance.

__________________
"I often say that when you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind." - William Thompson, 1st Baron Lord Kelvin

"If it was so, it might be, and if it were so, it would be, but as it isn't, it ain't. That's logic!" - Tweedledee

This isn't right. This isn't even wrong. - Wolfgang Pauli

Dark matter within our own solar system? More Jupiterian moons than previously thought? More Ort cloud bodies than previously thought?

Some combination thereof?

Lot's of possibilities.

__________________
I am Mugs, of the Alien clan of Usa, Nordamerica, a Terran, of Sol.

Perception isn't reality. It's merely an abstraction thereof, and quite often not a very good one at that.

"Staying young requires the unceasing cultivation of the ability to unlearn old falsehoods." - Heinlein

"Freedom begins when you tell Ms. Grundy to go fly a kite." - Heinlein

or, for the probes passing the earth, 3rd or 4th order deviations from spherical in the earth. Or mascons in the earth.

Those would be the ones I would check first.

I believe that the 'speed of light' is not an exact 'constant', as Einstein decided, but rather operates within (slight) 'variances' that 'fluctuate' (slightly) from 299 792 458 m/s to 314,000,000 m/s.

If our 'math' (method) is correct then it seems that our 'light speed constant' is not really an exact 'constant'. So, perhaps, the velocity of the craft was not fluctuating but the 'apparent' fluctuations are an indication of slight fluctuations in the speed of light (and all electromagnetic energies).

.

That's about a five-percent difference. Do you really think that such a large variation would have gone undetected all this time?

__________________
Microsoft is over if you want it.

The bar has been lowered for the promotion of ATM ideas; the bar for the acceptance of ATM ideas must remain high.

The electric universe folks say the constant small acceleration toward the sun is due to the spacecraft picking up a static electric charge on its outside that is attracted toward the sun's slighly positive charge, the spacecraft becomes a partially negative body moving in a circular orbit through a spherically symetric weak electric field. The nice thing about that theory is it explains why the devation from keppler's predictions take the form of a small constant acceleration in the direction of the sun. I read recently that the latest solar wind observations show a net electron backdraft toward the sun. That would support the notion of a mild positive charge to the sun, and begin to tie together the whole theory.

Yes (possibly). Because the 5% difference would not be a constant. The 'mean variance' would be 2.5%, and (opinion) any 'discrepancies' would be interpreted as fluctuations in distance or the velocity of the object (craft, in this instance) being monitored.

In the 'craft' matter that is the topic (in this thread), we have seeming anomalies in the craft's velocity. According to Einstein any fluctuations in light speed would be 'transmuted' to either an increase or decrease in an object's mass OR a fluctuation in time.

In this instance we have (seeming) temporal fluctuations so, it seems, that the possibility of variations in light speed (radio communications between the craft and Earth to determine the craft's velocity) are a (theoretical) possibility.

I wouldn't bet the farm that that is the case (light speed fluctuations) but the possibility seems practical.

.

So you are suggesting that a spacecraft sent to the Moon or Mars could be 2.5-5% further away/closer than we might determine? That this variance would go unnoticed?

I guess we got real lucky Cassini entered orbit around Saturn safely, considering we could have missed by 75 million kilometers.

The probes are accelerating away from the Sun.

__________________
papageno


"Why waste time learning, when ignorance is instantaneous?" - Hobbes (Calvin and Hobbes)

"It's all about context!" - Vince Noir (The Mighty Boosh)

"I've never heard of such a brutal and shocking injustice that I cared so little about!" - Zapp Brannigan (Futurama)

The original article said this:

These newfound enigmas join the so-called "Pioneer anomaly" as hints that unexplained forces may appear to act on spacecraft.

A decade ago, after rigorous analyses, anomalies were seen with the identical Pioneer 10 and 11 spacecraft as they hurtled out of the solar system.

Both seemed to experience a tiny but unexplained constant acceleration toward the sun. In other words, they were moving just a little bit slower than they should be, and by the same amount.


I should never have trusted fox news

Actually they got that part right. The anomalous acceleration is indeed toward the Sun.

The Pioneer probes are moving away from the sun. They are moving too fast to be held by the sun, but they are slowing down, almost all of that due to the sun's gravity. As I recall, the evidence suggested anomalous acceleration more or less towards the sun, but I don't think they have been able to pin that down exactly. If, for instance, evidence suggests acceleration towards Earth, that has somewhat different implications (possibly suggesting certain problems with measurement) than acceleration towards the sun.

__________________
I say there is an invisible elf in my backyard. How do you prove that I am wrong?

Disclaimer: Avatar is not an official NASA image and does not imply any specific interplanetary or interstellar capability.

The Leif Ericson Cruiser

Van Rijn asked "I say there is an invisible elf in my backyard. How do you prove that I am wrong?"

I