Science a GoGo's Home Page Forums General Discussion Physics Forum Pioneer 10&11, Anomaly

Remember Pioneer 10 and 11?
Both were blasted out into Space in 1972/3 in opposite directions
Both were equipped with a Nuclear power supply, enabling them to send a radio pulse, back to Earth when accessed.
They are still both speeding out of our Galaxy to this day, 35 years later.

Ten years ago in 1997 both Pioneers transmitters were shut down, when the spacecraft were about 134 AU from each other. (One Astronomical Unit equals 93 million miles)
Later, the doppler messages decoded from both Spacecraft indicated that both craft were de-accelerating at the rate of 3000 miles per year, upon year.

That is the mysterious anomaly that has been troubling scientists as to the cause, for many years.

Both spacecrafts speed was expected to remain constant, once they had past the orbit of Pluto, and our Suns gravitational influence.
Did the marked slowing of both Pioneers, mean that local gravity changed towards the edge of our Galaxy?
Or were they encountering the invisible dark matter that supposedly prevents the edges of spinning galaxies from flying off into space?
Were they being affected by a real Michelson Morley effect? That might only be detectable in space, far away from all gravitational effects and Galactic influence?
Might the law of physics be just a little different way out in space than here, in our own neighborhood?
To envisage a Pioneer Spacecraft speeding through another part of the Galaxy, might be difficult enough, for any watching Alien to comprehend. .....It should'nt be there.
Prehaps a metal machine fabricated and built in our 'alien' universe, is not welcome? In that its atomic structure, de-crystalises, or otherwise dis-intergrates, upon entering a universe where physical properties, might be different?
Prehaps Einsteinian time dilation has affected the radio-active materials of its power supply, and the reaction on its other metals?

It seems that the answer is too important to disregard,-as the Planetary Society has just recieved funds to enable them to re-evaluate the 30 years of doppler data tapes that they have on their computers.
Their final answer to the Pioneer Anomaly, might well alter our view of physics, as it exists in other Galactic neighborhoods.
Even rewrite the physical world, as we know it.

http://planetary.org/explore/topics/past_missions/pioneer_10_and_11.html

http://www.planetary.org/programs/projects/pioneer_anomaly/update_200603.html

Mike

"They are still both speeding out of our Galaxy"

- Not yet awhile. They are speeding out of the solar system, but not the galaxy.

"Did the marked slowing of both Pioneers, mean that local gravity changed towards the edge of our Galaxy?"

- No, it doesn't mean that. The pioneers are not near the edge of the galaxy.

- Without taking account of the unexpected deceleration, they would take 80,000 years to travel the distance to the near star (4.3 lt yrs). Supposing that the 'edge' of the galaxy is only 10,000 lt yrs away, and that the Pioneers were both heading directly toward it, it would take them close to 200,000,000 yrs to get there. But as you said, they are heading in opposite directions anyway.

I would think both the speed reduction and loss of communication are likely to be the result of the Pioneers reaching the termination shock and entering the heliosheath, the region in which the solar wind is markedly slowed and compressed as it is met by incoming interstellar radiation, gas and dust particles. It seems quite possible that the Pioneers' transmitter switches failed due to a surge of electromagnetic induction.

http://en.wikipedia.org/wiki/Heliosheath#Heliosheath
http://www.darkstar1.co.uk/heliopause.html

Also, regarding Voyager I, see:
http://www.nasa.gov/vision/universe/solarsystem/voyager_agu.html

Related trivia:

Although the slowing is scientifically very significant, 3000 miles per year at 7 miles per second amounts to only about 7 minutes per year, or 0.0014%. Which means that if this continued for another 1000 years, the craft would have travelled about 221,000,000,000 miles and be 5 days behind schedule.

I often wonder if light loses energy as it travels vast distances. If so this might lead to a change in wavelength. It would give the impression the light source was moving away from us. I presume the idea has been considered and rejected.

As you suggest, Terry, the energy of a photon is inversely proportional to its wavelength. But it doesn't spontaneously lose energy, or decay (so say almost all physicists, anyway). The loss of energy is due to the stretching effect of expanding space, observed in the red shift.

http://en.wikipedia.org/wiki/Tired_light

"Tired light was first proposed in 1929 by Fritz Zwicky, who suggested that photons might slowly lose energy as they travel vast distances through a static universe by interaction with matter or other photons."

"There are a few modern proponents of nonstandard cosmologies who rely on tired light mechanisms, e.g. Crawford (1993) and Masreliez (1999), though the vast majority of physicists and astronomers accept the conclusions of various studies that such an effect either does not or cannot account for cosmological redshifts."

Objections to Tired Light:

http://www.talkorigins.org/indexcc/CE/CE425.html

Terry: "I presume the idea has been considered and rejected."

By just about everyone it would seem. I'm still trying to find references to work on it since 1999.

Good old wikipedia. Thanks for that Rede.

Rarely if ever use it. Whats the point of us all cribbing?
I prefer write to get others thinking, if possible.

Adv:
Tampax on sale.
For a limited period

Mike Kremer

Mike

"I prefer write to get others thinking, if possible."

A task that you accomplish admirably...

"Cribbing"? Dear me, Mike, we're surely not here to test each others knowledge, or else I've (all-rede!) lost the race. No, I prefer to call it research, and hope that we can share any gems we find. It's educational, don't you think? If information is right there at my fingertips, I have better things to do with my time than try to reinvent the wheel. Some people might prefer to use SAGG to give their well worked and detailed theories a dry run. Good luck to them, but they are probably a minority, and such specialist knowledge is usually way over my head. Speaking for myself, I have little scientific training so, for me, the greatest thing about SAGG is that it stimulates the learning buds, and entails joining a group of interesting people in kicking around some interesting ideas, and swatting up if necessary, until a glimmer of light dawns on them.

Keep them coming Mike. The quality of interaction is more important than being right or wrong.

"limited period" indeed!