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Computer Forensics to Help Solve Pioneer Mystery
Matthew Sparkes writes "Launched 35 years ago on Friday, Pioneer 10 was the first spacecraft to reach the outer Solar System and return pictures of Jupiter, closely followed by Pioneer 11. However, the twin Pioneer spacecraft drifted off course (see number 8) by hundreds of thousands of kilometres during their three-decade mission, and NASA eventually lost contact with them. An international team of scientists, including many amatuer hobbyists, are re-analysing the tracking and telemetry data in the hope of discovering the reason."
As the article states: So if the direction of deceleration is towards Earth, then you might be able to consider the mystery solved and blame it on the process of collecting the data. But if the deceleration is towards the sun or another direction, we have an observation of an unknown effect in physics. If the latter is the case, I think the mystery is just starting to be understood--with a long ways to go and many more observations before we can consider it solved.
My work here is dung.
while it is possible that the explanation will be mundane--such as thrust from gas leakage--the possibility of entirely new physics is also being considered. http://en.wikipedia.org/wiki/Pioneer_anomaly
Strangest of all:
Data from the Galileo and Ulysses spacecraft indicate a similar effect
Libertarian Leaning Political Discussion Forum.
Heh. I think most of us here on Slashdot would want this anomaly to be due to new and k3wl physics rather than some mundane error. The Pioneer anomaly is one of, if not the most interesting unexplained observation I know of.
V'ger.
I suppose it would actually be P'neer, but that just doesn't sound right somehow.
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> And another guess, but surely the gentlest squirrel's fart as
> the craft left Earth could translate to huge discrepancies by
> the time they get to the other side of the solar system?
Yes, a one-off measurement error at launch would turn into hundreds of thousands of miles difference years later. However, the positions of the craft all along the way show it is still slowing down too fast.
In your terms, the squirrel must be hiding on board and farting from time to time on a reqular basis and in the direction of travel, slowing it.
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We are still in contact with the Voyager probes, and they have, at this point, traveled further out of the solar system than the Pioneer probes. Has the same anomaly been spotted in their trajectories too? That would be of great importance in weeding out possible phenomena.
It seems to be a no-brainer that the most likely cause is gravitaional force from something we didnt know was there. Some kupier belt trash, comet that passed it years ago, who knows. I'm frankly surprised that these types of navigational issues were/are not expected .....
Here's a link to the cannonical paper on the issue: http://arxiv.org/abs/gr-qc/0104064
Also, if you're interested, and in the New York area, some of the scientists who've been working on this are speaking at the Hayden planetarium in a few weeks: http://haydenplanetarium.org/programs/asimov/
Just to give a feel for what obsessive level of detail we're dealing with, here's a list of the possible causes considered in the paper above. The numbers after each listing are the bias and uncertainty in units of 10^-8 cm/sec^2. Listings with only one number only have an uncertainity, not a bias.
1 Systematics generated external to the spacecraft:
a) Solar radiation pressure and mass +0.03 ±0.01
b) Solar wind ± 10^-5
c) Solar corona ±0.02
d) Electro-magnetic Lorentz forces ± 10^-4
e) Influence of the Kuiper belt's gravity ±0.03
f) Influence of the Earth orientation ±0.001
g) Mechanical and phase stability of DSN antennae ± 0.001
h) Phase stability and clocks ± 0.001
i) DSN station location ± 10^-5
j) Troposphere and ionosphere ± 0.001
2 On-board generated systematics:
a) Radio beam reaction force +1.10 ±0.11
b) RTG heat reflected off the craft -0.55 ±0.55
c) Differential emissivity of the RTGs ±0.85
d) Non-isotropic radiative cooling of the spacecraft ±0.48
e) Expelled Helium produced within the RTGs +0.15 ±0.16
f) Gas leakage ±0.56
g) Variation between spacecraft determinations +0.17 ±0.17
3 Computational systematics:
a) Numerical stability of least-squares estimation ±0.02
b) Accuracy of consistency/model tests ±0.13
c) Mismodeling of maneuvers ±0.01
d) Mismodeling of the solar corona ±0.02
e) Annual/diurnal terms ±0.32