Interstellar travelers may be helped by physicist's calculations that solve the Pioneer anomaly

October 9, 2012, University of Missouri-Columbia

Interstellar travelers may be helped by physicist's calculations that solve the Pioneer anomaly
Kopeikin may have found the solution to a puzzle that has stumped astrophysicists for decades.
(—Former President Bill Clinton recently expressed his support for interstellar travel at the 100 Year Spaceship Symposium, an international event advocating for human expansion into other star systems. Interstellar travel will depend upon extremely precise measurements of every factor involved in the mission. The knowledge of those factors may be improved by the solution a University of Missouri researcher found to a puzzle that has stumped astrophysicists for decades.

"The Pioneer spacecraft, two probes launched into space in the early 70s, seemed to violate the Newtonian law of gravity by decelerating anomalously as they traveled, but there was nothing in physics to explain why this happened," said Sergei Kopeikin, professor of physics and astronomy in MU's College of Arts and Science. "My study suggests that this so-called was not anything strange. The confusion can be explained by the effect of the expansion of the universe on the movement of photons that make up light and radio waves."

Beams of were sent to and bounced off the Pioneer spacecraft to measure the probes' movement. The time it took for the photons to complete a round trip was used to calculate the spacecrafts' distance and speed. Kopeikin's research suggests that the photons move faster than expected from the Newtonian theory thus causing the appearance of , though the craft were actually traveling at the correct speed predicted by the theory. The universe is constantly expanding and this alters the Earth-based observations of the photons bouncing off the spacecraft, causing the Pioneer probes to appear to slow down.

"Previous research has focused on mechanical explanations for the Pioneer anomaly, such as the recoil of heat from the craft's pushing the craft backwards," Kopeikin said. "However that only explains 15 to 20 percent of the observed deceleration, whereas it is the equation for photons that explains the remaining 80-85 percent."

Physicists must be careful when dealing with propagation of light in the presence of the expansion of space, noted Kopeikin, since it is affected by forces that are irrelevant in other equations. For example, the expansion of the universe affects photons, but doesn't influence the motion of planets and electrons in atoms.

"Having accurate measurements of the physical parameters of the universe help us form a basis to make plans for interstellar exploration," Kopeikin said. "Discerning the effect of the on light is important to the fundamental understanding of space and time. The present study is part of a larger on-going research project that may influence the future of physics."

The study "Celestial ephemerides in an expanding universe" was published in the journal Physical Review D.

Explore further: Precise Radio-Telescope Measurements Advance Frontier Gravitational Physics

Related Stories

Light from galaxy clusters confirms theory of relativity

September 28, 2011

All observations in astronomy are based on light emitted from stars and galaxies and, according to the general theory of relativity, the light will be affected by gravity. At the same time all interpretations in astronomy ...

Recommended for you

Helping Marvel superheroes to breathe

November 18, 2018

Marvel comics superheroes Ant-Man and the Wasp—nom de guerre stars of the eponymous 2018 film—possess the ability to temporarily shrink down to the size of insects, while retaining the mass and strength of their normal ...

Scientists explain how wombats drop cubed poop

November 18, 2018

Wombats, the chubby and beloved, short-legged marsupials native to Australia, are central to a biological mystery in the animal kingdom: How do they produce cube-shaped poop? Patricia Yang, a postdoctoral fellow in mechanical ...

Explaining a fastball's unexpected twist

November 18, 2018

An unexpected twist from a four-seam or a two-seam fastball can make the difference in a baseball team winning or losing the World Series. However, "some explanations regarding the different pitches are flat-out wrong," said ...

Scientists produce 3-D chemical maps of single bacteria

November 16, 2018

Scientists at the National Synchrotron Light Source II (NSLS-II)—a U.S. Department of Energy (DOE) Office of Science User Facility at DOE's Brookhaven National Laboratory—have used ultrabright x-rays to image single bacteria ...

Quantum science turns social

November 15, 2018

Researchers in a lab at Aarhus University have developed a versatile remote gaming interface that allowed external experts as well as hundreds of citizen scientists all over the world to optimize a quantum gas experiment ...


Adjust slider to filter visible comments by rank

Display comments: newest first

not rated yet Oct 09, 2012
I've always had the feeling that light is intertwined with the fabric of space. Perhaps light (photons) are the particle equivalent of space itself. Just thinking aloud.
4.3 / 5 (6) Oct 09, 2012
If it`s correct it should be applied for every type of EM waves we detecte. Is it confirmed by other observations?
5 / 5 (4) Oct 09, 2012
I thought in careful analysis this was fully explained by thermal radiation: See "http://en.wikiped...anomaly" and therein noted references.
5 / 5 (3) Oct 09, 2012
@Ober: not just light. Basically you're advocating for the idea that space needs "something inside" in order to exist. I believe it's called the Mach principle and nobody really knows if it's true or not.
1 / 5 (6) Oct 09, 2012
I thought in careful analysis this was fully explained by thermal radiation
However that only explains 15 to 20 percent of the observed deceleration, whereas it is the equation for photons that explains the remaining 80-85 percent. In particular, the thermal radiation exhibits quite different curve with time, as the plutonium at the Pioneer spaceprobes get depleted. The Pioneer anomaly is apparently dark matter effect.
1 / 5 (3) Oct 10, 2012
Hey man... like.. do you think that God could create a Universe that expands so fast he... like... can't run fast enough to catch up with the edge? Whoa...

;-P snark snark
2 / 5 (4) Oct 10, 2012
This does not seem to me to make sense. If the anomaly is due to the expansion of the Universe, I would expect the spacecraft to be farther away than predicted by Newtonian dynamics making the travel time of photons from the craft longer rather than shorter.

Can the expansion of the Universe really be measured over the radius of the Solar system?
4.3 / 5 (6) Oct 10, 2012
I don't know what is most odd, a physicist that proposes a prediction from new physics to what has earlier this year been successfully predicted from already known*, that he gets it published in peer review, or that science sites publish articles on such crap.

* : " We use the results of this model to evaluate the effect of the thermal recoil force on the Pioneer 10 spacecraft at various heliocentric distances. We found that the magnitude, temporal behavior, and direction of the resulting thermal acceleration are all similar to the properties of the observed anomaly.

As a novel element of our investigation, we develop a parameterized model for the thermal recoil force and estimate the coefficients of this model independently from navigational Doppler data. We find no statistically significant difference between the two estimates and conclude that once the thermal recoil force is properly accounted for, no anomalous acceleration remains."
4.6 / 5 (9) Oct 10, 2012
@ radek, Neurons_At_Work: I wouldn't bother with this unlikely physics, since such an effect added on what is now known acceleration from uneven thermal radiation would not predict the observation. I.e. you would have to reject the earlier, successful, mundane prediction in order to have your more arcane speculations make an observable effect.

@ ValeriaT: You are wrong, see the actual papers. The obvious basis for your mistake is that you don't know that thermal radiation _is_ EM photons. Added to that, your DM speculations have no basis and no quantification. In short, you are "not even wrong".
3.2 / 5 (5) Oct 10, 2012
The University of Missouri also hired Oliver Manuel, noted wingnut. Apparently this university system does not look for quality in its science professors.
1 / 5 (5) Oct 10, 2012
We can accept the sum of this and another hypothesis, based entirely on assumptions and speculation of metaphysical ideas, to account for the observed anomaly. Or, one can take a differing view that will account for the 100% of the anomaly, that is based on real testable science.

not rated yet Oct 10, 2012
As for the quote from Luke, I suspect that he is trying to encourage some of his non Physics friends to slog thorough his paper. The intro was basically a tutorial on the math that he uses in this paper.
1 / 5 (2) Oct 10, 2012
Added to that, your DM speculations have no basis and no quantification.
Of course I do have. The effect is an acceleration towards the Sun 8.74 x 10−10 m/s2. The value of this acceleration is a = H x c - it is the Hubble constant multiplied by the speed of light, plus minus roughly ten percent. In addition, recently a dark matter around solar system has been observed. In addition, the Pioneer deceleration decays exponentially with half-time about 25 years, whereas the decay half-time of 238-plutonium heat source is 88 years.
1 / 5 (3) Oct 10, 2012
In addition, we observed too many another fly-by anomalies of another space-probes, which couldn't be attributed to heat flux at all. The dark matter models could explain many of them even better, than at the case of Pioneer 10, 11 space-probes (the equatorial effects around rotating massive bodies in particular). I do agree with Kopeikin, the deceleration of Pioneer spaceprobes is probably a composite effect.
3 / 5 (2) Oct 10, 2012

Dark matter has not been observed around the solar system (or anywhere else, for that matter).
1 / 5 (1) Oct 10, 2012
When I'm talking about dark matter, I'm talking about curvature of space-time (i.e. the gravitational lensing) and about anomalies in rotational curves of stars inside of galaxies, i.e. about well confirmed phenomenological artifacts - not about WIMPS or some hypothetical particles, which may - or may not - form the dark matter. These effects are perfectly real - with compare to WIMPS - and they were observed many times (Oort, Zwicky 1934 and later). After all, all matter is formed with some curvature of space-time - from this perspective I've no problem with labeling of every gravitational lensing like the "matter".
3 / 5 (2) Oct 10, 2012

There is a trend recently to say "dark matter" and then say something like you just did, that you really mean the observed gravitational anomaly.

Why call an anomaly dark matter? Why not simply call it what it is?

Anomalies have certainly been observed, but not a single particle of dark matter has ever been observed.

1 / 5 (1) Oct 13, 2012
At the quantum level, quark pairs, when separated, demonstrate an attraction between them which increases as the distance between them increases. Perhaps, the Pioneer spacecraft are being pulled back into an orbit around the sun, and will never really leave the solar system altogether.
1 / 5 (1) Oct 14, 2012
We've been quarantined.


There was an item in New Scientist some months back (maybe last year) which suggested we are in some void region of space sort of cut-off from the rest of the universe to some degree.

Imagine if an alien species had several thousand or million years of technological development and that would mean a tremendously good understanding of energy and matter relationship, they might well be able to pull of a grand experiment which could include genetic, sociological, astrophysical aspects etc. We could be studied intimately over a very long time frame, this would explain some odd UFO sighting phenomena and other anecdotal issues !

So who knows whether our solar system is just one selected experiment of many and we are just the lab rats who happen to be so up themselves and therefore cant realise we are in the astronomical version of a Petri dish !

not rated yet Oct 14, 2012
pioneer is very close to earth when compared to the immense distance of space. so the chances of dark matter effecting the photons is very less.It's a hypothesis only but a viable one that the expansion of the space time fabric is the cause.The region there is filled with other electromagnetically charged particles, that might have an effect
not rated yet Oct 18, 2012
The region there is filled with other electromagnetically charged particles, that might have an effect
Electromagnetically charged particles are the particles of solar wind, which would be of the exactly the opposite effect.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.