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."

Comments

Pioneer anomaly

[mastershake_phd]

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

What of Other Craft?

[necro81]

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.

Ive never seen the big mystery with this ...

[gentimjs]

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 .....

Re:Do they have all the original calculations?

[mcelrath]

The codes used took into account all the major sources of gravity, including all the planets and major asteroids. These are some of the same codes that have been used to place many, many other probes in proper orbits around planetary bodies as far away as Saturn, and land on tiny things like asteroids and comets.

The damned thing about the Pioneer anomaly is that the acceleration is constant and the measurement is exceedingly simple. It's just position vs. time. There isn't much that can mess with that, and since individual communications with the craft are uncorrelated with each other, there shouldn't be any kind of drift (relativistic clock drifts are taken into account). Since the acceleration is constant over a distance from roughly Jupiter to well past Pluto, and gravity follows a force law that goes like 1/r^2, you can't add a single source of gravity (e.g. a new planet) -- the force wouldn't be constant. You can't make the sun slightly heavier. You can't add dark matter to do it: the dark matter would have to conspire to have a density as a function of distance from the sun that mimicked the constant acceleration. Such a density profile has more dark matter at the edges of the solar system, which would not be stable. It should collapse and concentrate near the sun. The acceleration is approximately the same magnitude as the expansion of the universe, but it's in the wrong direction, and our current understanding of dark energy wouldn't cause such an effect anyway.

Personally, I think we've got gravity totally wrong.

-- Bob