Pioneer [gravitational] anomaly put to the test

Physics World ^ | September 2004 | Slava Turyshev and John Anderson

[r9etb]

The tragectories have been effected by cloaked Romulin vessels observing us from the edge of the solar system.

For years I've wanted to write a Science Fiction short story where aliens intercept the Pioneer vehicles, decode the famous plaques thereon, and discover that we're a form of "cosmic cockroaches" that need to be exterminated.

[Red Badger]

Maybe it's just that the Pioneer's are now going DOWNHILL!...

[NicknamedBob]

I have a mental picture of an "ice-rimed" and ancient Mariner coasting slowly along. The gradual accumulation of interstellar frost would be something they have no way to measure.

The overall mass would obey the same gravitational rules, but the accumulating frost would be at a slower velocity, gradually slowing the craft in an inexplicable manner.

[spodefly]

For years I've wanted to write a Science Fiction short story where aliens intercept the Pioneer vehicles, decode the famous plaques thereon, and discover that we're a form of "cosmic cockroaches" that need to be exterminated.

The aliens may have a point:

[js1138]

[Physicist]

As I say on all of these threads, I think there is a conventional physics explanation for the anomaly.

For one thing, there almost can't be anything wrong with gravity. Any gravitational effect large enough to explain the anomaly would noticeably affect the ephemerises of the outer planets. Yes, it is mathematically possible to dream up some function whereby the probes are affected but Pluto and Neptune are not, but that's awfully contrived and poorly motivated.

My expectation is that the probes have acquired a significant electrical charge during their journey. This causes their trajectories to bend slightly as the probes pass through the sun's magnetic field (to say nothing of the local galactic magnetic field). This bending causes the probe to acquire a momentum component that is transverse to its direction of travel, but because its total momentum is roughly constant, its momentum along our line of sight (which is what the Doppler shift measures) is necessarily reduced. We have no way to measure the transverse momentum component.

If this idea has been rejected, I'd like to see a quantitative reason.

[tnlibertarian]

Our Solar System is a gigantic Dyson sphere and all the galaxies Hubble is exposing is actually just some of the fancier porch lights of people who live on it's surface.

Now that's just silly.
People on the surface of Dyson spheres wouldn't need porch lights. It's day all the time. It's the reflection from the bodies of water.

[RadioAstronomer]

If this idea has been rejected

Not that I know of. :-)

[PatrickHenry]

My expectation is that the probes have acquired a significant electrical charge during their journey.

Now that I read your post, I recall that we've had a thread (or maybe two) on this topic before. But it's been at least a year. Anyway, kinks like this need to get worked out. Anomalies are where the action is.

[tortoise]

As I say on all of these threads, I think there is a conventional physics explanation for the anomaly.

Since we are on the subject of gravitational anomalies, do you know of a good explanation of the Allais effect? Might the probe anomalies be a manifestation of whatever causes this other gravitational anomaly?

I hesitate to stray from conventional physics regarding gravitation for vaguely related theoretical reasons, but there are some strange chinks in the mathematical armor of conventional physics models at the quantum level that may be showing themselves. Maybe Gravity Probe B will shed some light on this, given the precision of its instruments.

[Physicist]

Since we are on the subject of gravitational anomalies, do you know of a good explanation of the Allais effect?

Yeah, somebody pointed out this paper on a previous thread. Ironically, the author is the notorious face-on-Mars/infinite-speed-of-gravity guy, Tom Van Flandern. If nothing else, the publication of this paper in Phys. Rev. D. proves that the scientific establishment is not out to silence him.

[zeugma]

They didn't mention it in the article, but I think the voyager spacecraft have exhibted similar characteristics. I recall reading another article about this, and they mentioned that one reason one can rule out outgassing from the craft is because it is not just one craft that appears to be slowing down in a manner not predicted by current theories, but is all of them. This would be rather a important fact IMnsHO if it is true.

Does anyone know if the Mariner craft have exhibted any unpredicted orbital deviations? I think the Mariner craft are still in orbit around the Sun between Earth and Venus if I remember it correctly. Looks like I get to dig around NASA's sites a bit this evening. :-)

[longshadow]

Anomalies are where the action is.

You know we just love it when you talk dirty like that.....

;-)

[PatrickHenry]

A gravitational anomaly walks into a bar. The bartender asks: "The usual?"

"No," says the anomaly.

[ccmay]

Klingon tractor beams.

-ccm

[Nick Danger]

a prolonged encounter with an asteroid

The "unseen large mass" would seem to be ruled out by the fact that the two probes were launched a year apart, yet both exhibited the same effect. The "asteroid" would have to be damned lucky to be in exactly the same position, relative to the second probe, that it was to the first.

[grey_whiskers]

For years I've wanted to write a Science Fiction short story where aliens intercept the Pioneer vehicles, decode the famous plaques thereon, and discover that we're a form of "cosmic cockroaches" that need to be exterminated.

Humor Columnist Dave Barry of the Miami Herald beat you to it. See his piece "Bring Back Carl's Plaque." ;-)

[grey_whiskers]

This bending causes the probe to acquire a momentum component that is transverse to its direction of travel, but because its total momentum is roughly constant, its momentum along our line of sight (which is what the Doppler shift measures) is necessarily reduced.

It'd take an accelerator jock to think of this. Kind of reminds me of GC/Mass Spec. Can we check the estimate of the charge by looking at curvature of the flight path, the mass, and the applied B field? (Wink, nudge)

[grey_whiskers]

You know we just love it when you talk dirty like that.....

;-)

Apparently these degeneracies are clasically forbidden!