The Pioneer 10 spacecraft shown in the final stages of manufacturing
Image: NASA
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Editor's Note: JR Minkel is in St. Louis this week for the annual "April meeting" of the American Physical Society. See his other blog posts on dark matter, the Higgs boson and the timeline for the Large Hadron Collider, and check back for frequent updates.
ST. LOUIS—Ten years ago, NASA researchers discovered that the Pioneer 10 and 11 spacecraft had fallen slightly behind course during their 35-year journeys to the outer reaches of the solar system. In what has become known as the Pioneer anomaly, which was the subject of one of the talks this weekend at the American Physical Society here in St. Louis, nobody knows for sure why it happened. It probably stemmed from leaking gas or heat.
But there's also the possibility, however remote, that gravity doesn't behave the way we expect. Until recently, researchers haven't had the data to distinguish the different possibilities. That changed in 2006, when NASA physicist Slava Turyshev, a co-discoverer of the anomaly, was visiting a colleague at the NASA Ames Research Center. The Moffett Field, Calif.–facility was about to throw out hundreds of magnetic disks containing the Pioneer telemetric data—temperature and power readings that the twin craft had sent back to NASA once every few minutes until they traveled out of range. (NASA finally lost contact with Pioneer 10 in 2003, after 31 years. It had lost contact with Pioneer 11 in 1995.)
Turyshev and his colleagues rescued the data, and Viktor Toth, a computer programmer in Ottawa, Ontario, volunteered to write brand new code that extracted the telemetry readings from the raw 1s and 0s encoded in the magnetic disks.
A group of some 50 researchers, including Turyshev, is now trying to match the data to a detailed computer model of the craft's inner workings. The model is designed to mimic the flow of heat and electricity produced by the craft's generators, which harnessed the heat from radioactive plutonium and turned a fraction of it into electricity to power the craft. The remaining heat [see note below] was lost to space or spread to other parts of the craft such as the antenna, which influenced each probe's overall momentum.
So far the model accounts for about 30 percent of the observed anomaly for Pioneer 10 at a single distance of 25 astronomical units (2.3 billion miles, or 3.7 billion kilometers) from the sun, Turyshev reported. The group still has to extend the model to other distances and to Pioneer 11. The full verdict may not be in for some time. "I'm trying to ensure we apply every relevant piece of information," Turyshev says. "It is likely that the thermal explanation will explain part of the anomaly," he says, but exactly how much is up for grabs.
He notes that the team is also expanding the original analysis that identified the anomaly from 11 years' worth of transmissions from Pioneer 10 and four years from Pioneer 11. Turyshev says the group now has access to 30 and 20 years of data, respectively, and will begin examining it in the coming weeks.
If the anomaly does turn out to have a straightforward explanation, researchers could use it to improve navigation for sensitive space experiments to test gravitational effects, notes programmer Toth. And if not? "If we actually had a means in the solar system here to measure deviations from Einstein's gravity, that would be phenomenal," he says.
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21 Comments
Add CommentNASA Ames Research Center is in California not (Ames,) Iowa.
Reply | Report Abuse | Link to thisHas anyone considered the possibility of micro objects and interplanetary materials interacting with the probes? This could account for a possible portion of the deviation as transferrence of momentum to micro objects could be very significant over a period of 30 years. If those objects had opposite trajectories they would slow the probes minutely. I know that there isn't much of this in interplanetary space, but there has to be some. Has anyone measured the amount of material that exists in this space?
Reply | Report Abuse | Link to thisWhy is NASA always throwing important stuff away. Anybody see those hi-def moon landing video tapes yet?...
Reply | Report Abuse | Link to thisIn deep space the sattelite absorbs enough electrons to become partially negatively charged. The force of the sun's weak electric field on the charged spacecraft is the source of the deviation. It's much, much less complicated than all these folks are tyring to make it out to be.
Reply | Report Abuse | Link to thisIt is worth noting that an Astronomical Unit is 93 million miles (or 150 million km), and not the reported 930 million.
Reply | Report Abuse | Link to thisSpreading articles over multiple pges is very annoying, as it is clearly done to stick more adverts in your visitors' faces.
Reply | Report Abuse | Link to thisAnnoying your visitors will only push people towards blocking adverts totally.
nasa throws money away that could better serve terrestrial needs. junk 'em.
Reply | Report Abuse | Link to thisCould the anomaly be caused by the very small amounts of matter in "empty" space? Gravity from this matter would add to the gravitational pull from the sun and its planets and their moons. This matter would also tend to be denser nearer the sun, one would expect, so there would be more of this matter's gravity from behind the space craft than from in front.
Reply | Report Abuse | Link to thisI think that we need to go back to the drawing board concerning gravity. Specifically, does gravity have another "node" that we now attribute to "dark matter", or is dark matter actually another "node" in what we call the mass of the galaxy?
Reply | Report Abuse | Link to thisGood research program!
Joe Webb
A slight tweeking of the relativistic effects on the spacecraft's motion may eliminate the anomaly altogether and give better paradigm for future long distant space journeys. The data of the two journeys that has been learned is a good opportunity to find the actual value for "c squared" which may be different then the theoretical value presently used. For long journeys into deep space, such as to Pioneer 10 and 11 rocket journeys, scientists will have to take into consideration, the new corrected gain in mass, caused by the force of the rocket engines and Jupiter's gravity, during its acceleration, into their calculations. ( I explain this - mass gain - in my book - "The Mind of Mankind" as the "space energy level"of a body.) This will give them a more accurate picture of the Pioneers' space journeys. The Pioneer Anomaly effect is an excellent opportunity to empirically check the true relativistic mass gain of long journeys into deep space.
Reply | Report Abuse | Link to thisAs a s/w engineer, the whole idea of rescuing old data and making simulations out of them is very interesting to me. Maybe now, with all that processing power available and the something@Home projects becoming so popular, it's time to re-visit all those completed missions' data and see if there's anything interesting there.
Reply | Report Abuse | Link to thisI bet so-called "dark matter" in our solar system would account for the missing mass to cause a slight de celeration.
Reply | Report Abuse | Link to thisWhy not ask Vasily Yanchilin for explanation?
Reply | Report Abuse | Link to thisThe general theory of relativity is based on the assumption that the propagation speed of electromagnetic waves is constant. "Einstein himself did not believe that the speed of light is unrelated to everything else in the universe, but took that constancy as a working hypothesis" about a hundred years ago when quantum mechanics still had to be invented. This is what Yanchilin writes in his book "The Quantum Theory of Gravitation". The Russian scientist offers a new theory, based on the hypothesis that c depends on the potential of the total mass of the kosmos. Then nearer to mass time goes faster, which is contradictory with Einstein's opinion but harmonic to the enormous tempo of the Big Bang. The book is available in the Library of Congress, unless it is banned. Information to the subject on Wikipedia is removed by unknown persons who operate like in the Middle Ages disliked books were burnt.
Reply | Report Abuse | Link to thisThe new theory sees gravity as "a purely quantummechanic effect". Consider an electron -a particle which can pass through two holes at the same moment?!- as innumerous times appearing and disappearing within a sphere with Heisenberg dimensions. To explain further I call those appearances iets and have the name electron reserved for the total. In the half of the electron sphere nearer to an external mass time runs faster and more iets will show up than in the most distant half. But inside the distribution must stay equal. As a result the electron mass, the sphere, moves towards that foreign object.
Reply | Report Abuse | Link to thisI hope Vasily Yanchilin will be invited to explain more clearly and give solution to the Pioneer problem.
When gravity, gas leaks etc have been exhausted will we look at electricity? What if the sun's emitted stream of charged particles is actually part of a low density plasma discharge?
Reply | Report Abuse | Link to thishttp://www.thunderbolts.info/
tpod/2008/arch08/080320pioneer.htm
The cause of pioneer anomaly has been identified as due to the recently discovered charge-mass interaction from years of studies on general relativity. Thus this anomaly is an evidence for the necessity of unification between electromagnetism and gravitation.
Reply | Report Abuse | Link to thisThe cause of pioneer anomaly has been identified as due to the recently discovered charge-mass interaction from years of studies on general relativity. Thus, this anomaly is an evidence for the necessity of unification between gravitation and electromagnetis,
Reply | Report Abuse | Link to thisThe cause of pioneer anomaly has been identified as due to recently discovered charge-mass interaction.
Reply | Report Abuse | Link to thisI Think that the error is the fact that the algorithm use for the Doppler shift use a relativist time dilation factor whick should not be used when a coherent transponder is employed. The frequency in the Pioneer vessel is impose by the receiving frequency transmitted by the Earth's station.
Reply | Report Abuse | Link to thisThe inboard transponder is locked on this frequency ( including the Doppler shift) and a PLL electronic circuit is used to produce a downlink frequency synchronized with the input frequency. The time dilation factor cannot modify the frequency.
If you do not include this factor, you obtain a difference of 8.48 x 10-10 m/s at a distance of 30 AU and 8.22 x 10-10 at 50 AU. This is very close to the published value of 8.74 e-10 m/s +- 1.33. I have written a more detailed version of this explanation at: http://cafe.rapidus.net/remsimar/pioneeranomaly.doc
Remy Simard, Eng, MScA
I Think that the error is the fact that the algorithm use for the Doppler shift use a relativist time dilation factor whick should not be used when a coherent transponder is employed. The frequency in the Pioneer vessel is impose by the receiving frequency transmitted by the Earth's station.
Reply | Report Abuse | Link to thisThe inboard transponder is locked on this frequency ( including the Doppler shift) and a PLL electronic circuit is used to produce a downlink frequency synchronized with the input frequency. The time dilation factor cannot modify the frequency.
If you do not include this factor, you obtain a difference of 8.48 x 10-10 m/s at a distance of 30 AU and 8.22 x 10-10 at 50 AU. This is very close to the published value of 8.74 e-10 m/s +- 1.33. I have written a more detailed version of this explanation at: http://cafe.rapidus.net/remsimar/pioneeranomaly.doc
Remy Simard, Eng, MScA