An invisible hand?

I hesitate to start yet another Pioneer 10 thread :-) but there's an
article in the current issue of "The Economist" on a possible link
between the Pioneer anomaly and the Allais effect (the effect on a
pendulum during a solar eclipse)
Read it at
http://www.economist.com/printedition/PrinterFriendly.cfm?Story_ID=3104321.
There's a link to Chris Duif's paper at
http://arxiv.org/ftp/gr-qc/papers/0408/0408023.pdf
--
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Remove spam and invalid from address to reply.

"Jonathan Silverlight"
wrote...
in message news

I hesitate to start yet another Pioneer 10 thread :-) but there's an
article in the current issue of "The Economist" on a possible link
between the Pioneer anomaly and the Allais effect (the effect on a
pendulum during a solar eclipse)
Read it at

http://www.economist.com/printedition/PrinterFriendly.cfm?Story_ID=3104321
..
There's a link to Chris Duif's paper at
http://arxiv.org/ftp/gr-qc/papers/0408/0408023.pdf
--
What have they got to hide? Release the ESA Beagle 2 report.
Remove spam and invalid from address to reply.

Never hesitate to be interesting, Jonathan... This is great stuff!

Where our spacecraft are concerned, let's see... we have found
gravitational anomalies associated with both the Pioneers, 10 and
11, also with the Ulysses and Galileo crafts, but i've found nothing
about any such anomalies associated with either Voyager, 1 or 2.

The Pioneers are probably not that mysterious. If we see our
young Sun beginning to spew out its solar wind at a million mph,
outcasting the smaller debris in its accretion disk to areas (still in
and near the ecliptic) beyond Neptune, then there is probably just
a lot of small masses out there pulling on them, helping the Sun
slow them down. And there may be some effect on them caused
by the abrubt and shocking slow down of the solar wind as well.
Maybe this "termination shock" has a small braking action on the
Pioneers? Then there's always the unknown effects of the Sun's
heliopause if it's been reached by the Pioneers.

Ulysses' orbit brings it near the ecliptic and near Jupiter, and i
wonder if the anomaly isn't more, or perhaps less, pronounced at
these times? I haven't been able to find anything on this. It's the
Galileo one which seems the most mysterious to me. Didn't it
always orbit closely to Jupiter? so wouldn't this close proximity
to a gas giant drown out any possible gravitational anomalies?

And the Voyagers? Well, Voyager 1 was shot out of the plane
of the ecliptic by Saturn, and Voyager 2 was shot out in about
the opposite direction, also away from the ecliptic, by its close
encounter with Neptune. Could this mean that, since no such
anomalies have been noted for these two, then there is a valid
association between these anomalies and the ecliptic?

And the Allais effect! At first i'm thinking in classical terms and
envisioning an unusually strong distortion of planet Earth during
a solar eclipse. This tidal effect stretches the Earth out into more
of a football shape. Now imagine a line going through the centers
of the Earth, Moon and Sun. The mass of the Earth would tend
to temporarily concentrate in toward the center along this line.
This would in turn cause the surface of Earth nearest the eclipse
to have a slightly higher g. And the surface opposite the eclipse,
too, would have a higher g.

But then i think, wouldn't this effect be manifested slowly? It
should begin *before* the eclipse begins, grow slowly, then
lessen and lessen, but not get back to normal until some time
*after* the eclipse is over. According to the graphs, the Allais
effect starts promptly just as the eclipse begins, and then ends
promptly as the eclipse is ended.

Also, from a classical standpoint, there would have to be some
lag due to the fact that the Sun is actually 8 minutes (or about
one degree of arc, and isn't this 2 Sun-diameters?) ahead of the
position we see during an eclipse. Yet this Allais effect still starts
just as the Moon begins to take a bite out of the Sun, and stops
just as the Moon totally vacates the Sun's visual image. Couldn't
this be a good piece of evidence in favor of the Sun's gravitational
effect taking as long as light to reach the Earth?

It's probably just a coincidence that the Allais effect and the
gravitational anomalies are of the same order of magnitude. And
yet a curious one to be sure.

And on a tangent, insofar as what impact this has on a flowing-
space model of gravity, we'll just have to give it more thought.

happy days and...
starry starry nights!

--
Invisible the hand which builds a spinning galaxy,
Unseen the busy fingers bursting stars so tenderly,
We may not see the fireballs who sizzle thru our skies,
Oh! what the use for us to have such dark, unlucky eyes?
I note the need as night approach with sparkling stars asea.

Paine Ellsworth

On Fri, 27 Aug 2004 08:39:01 GMT, Painius wrote:
Never hesitate to be interesting, Jonathan... This is great stuff!

Where our spacecraft are concerned, let's see... we have found
gravitational anomalies associated with both the Pioneers, 10 and
11, also with the Ulysses and Galileo crafts, but i've found nothing
about any such anomalies associated with either Voyager, 1 or 2.

The Pioneers are probably not that mysterious. If we see our
young Sun beginning to spew out its solar wind at a million mph,
outcasting the smaller debris in its accretion disk to areas (still in
and near the ecliptic) beyond Neptune, then there is probably just
a lot of small masses out there pulling on them, helping the Sun
slow them down.

This has already been proposed and dismissed. If there were any large
concentration of mass outside Neptune, surely we would be able to detect
anomalies in Neptune's orbit? Also, this would imply incerasing
acceleration while the craft were inside of the bulk of these bodies and a
decrease once it traversed most of them on the way out.

And there may be some effect on them caused
by the abrubt and shocking slow down of the solar wind as well.
Maybe this "termination shock" has a small braking action on the
Pioneers? Then there's always the unknown effects of the Sun's
heliopause if it's been reached by the Pioneers.

I'm finding it hard to believe that solar wind has enough density at those
distances from the Sun to exert some drag on the spacecraft. If so, this
effect would have to be very noticeable here at Earth. We are talking about
a few particles per cubic centimeter here on Earth, hardly enough to do any
mechanical effect. Also, I don't believe the Pioneers arrived at the
termination shock since Voyager 1 overtook them and AFAIK, it hasn't
reached it either, yet.

Ulysses' orbit brings it near the ecliptic and near Jupiter, and i
wonder if the anomaly isn't more, or perhaps less, pronounced at
these times? I haven't been able to find anything on this. It's the
Galileo one which seems the most mysterious to me. Didn't it
always orbit closely to Jupiter? so wouldn't this close proximity
to a gas giant drown out any possible gravitational anomalies?

Perhaps Galileo measurements were made on route to Jupiter? In any case,
measuring this anomaly so close to the Sun is very difficult due to the
effects of solar radiation pressure which can be hard to model and take
into consideration. The anomaly with the Pioneers was observed once the
craft got far enough from the Sun for the light pressure to become
insignificant.

And the Voyagers? Well, Voyager 1 was shot out of the plane
of the ecliptic by Saturn, and Voyager 2 was shot out in about
the opposite direction, also away from the ecliptic, by its close
encounter with Neptune. Could this mean that, since no such
anomalies have been noted for these two, then there is a valid
association between these anomalies and the ecliptic?

The reason no anomalies were observed with the Voyagers is because none
*could* be measured. The two spacecraft are 3 axis stabilized, using
maneuvering thrusters to keep the antenna pointed at Earth. Constant firing
of these thrusters changes the spacecraft's momentum all the time (and in a
random fashion, too), thus drowning any anomaly out...

--
The butler did it.

"Ugo" wrote...
in message ...

On Fri, 27 Aug 2004 08:39:01 GMT, Painius wrote:

Never hesitate to be interesting, Jonathan... This is great stuff!

Where our spacecraft are concerned, let's see... we have found
gravitational anomalies associated with both the Pioneers, 10 and
11, also with the Ulysses and Galileo crafts, but i've found nothing
about any such anomalies associated with either Voyager, 1 or 2.

The Pioneers are probably not that mysterious. If we see our
young Sun beginning to spew out its solar wind at a million mph,
outcasting the smaller debris in its accretion disk to areas (still in
and near the ecliptic) beyond Neptune, then there is probably just
a lot of small masses out there pulling on them, helping the Sun
slow them down.

This has already been proposed and dismissed. If there were any large
concentration of mass outside Neptune, surely we would be able to detect
anomalies in Neptune's orbit? Also, this would imply incerasing
acceleration while the craft were inside of the bulk of these bodies and a
decrease once it traversed most of them on the way out.

Thanks, Ugo... i was aware that it had been proposed, but i did
not know that it had been dismissed. And how could it be so
readily dismissed? We still have no idea how many TNOs are
out there, KBOs and such. And astronomers are proposing that
there are quite a few.

We need to establish an upper limit to the TNO number (mass,
quantity, density, whatever) which would not give Neptune an
orbital anomaly. And then we can check if this number (or a
lesser density number) falls within a window that would have an
effect on the Pioneers during and after they pass through them.
Are you saying that this or something similar has been done?

And there may be some effect on them caused
by the abrubt and shocking slow down of the solar wind as well.
Maybe this "termination shock" has a small braking action on the
Pioneers? Then there's always the unknown effects of the Sun's
heliopause if it's been reached by the Pioneers.

I'm finding it hard to believe that solar wind has enough density at those
distances from the Sun to exert some drag on the spacecraft. If so, this
effect would have to be very noticeable here at Earth. We are talking
about
a few particles per cubic centimeter here on Earth, hardly enough to do
any
mechanical effect. Also, I don't believe the Pioneers arrived at the
termination shock since Voyager 1 overtook them and AFAIK, it hasn't
reached it either, yet.

How will we know? The terminal shock effect, even with just
a relatively small density, might be likened to driving on the
highway at 70mph and coming up on a traffic jam where the
cars are moving at a much slower speed. Of course, here we
are talking about a solar wind traveling at a million mph and
rather abruptly slowing to about 200,000 mph. Wouldn't a
slowdown of the Pioneers and Voyagers be one possible
indication?

You mention below that the Voyagers would be insensitive to
such anomalies. So this could mean that both the Pioneers
and the Voyagers have reached the the solar wind's terminal
shock, couldn't it? The Pioneers could be reacting to it while
the Voyagers can't.

Ulysses' orbit brings it near the ecliptic and near Jupiter, and i
wonder if the anomaly isn't more, or perhaps less, pronounced at
these times? I haven't been able to find anything on this. It's the
Galileo one which seems the most mysterious to me. Didn't it
always orbit closely to Jupiter? so wouldn't this close proximity
to a gas giant drown out any possible gravitational anomalies?

Perhaps Galileo measurements were made on route to Jupiter? In any case,
measuring this anomaly so close to the Sun is very difficult due to the
effects of solar radiation pressure which can be hard to model and take
into consideration. The anomaly with the Pioneers was observed once the
craft got far enough from the Sun for the light pressure to become
insignificant.

And yet, it *has* been measured... _curious_.

And the Voyagers? Well, Voyager 1 was shot out of the plane
of the ecliptic by Saturn, and Voyager 2 was shot out in about
the opposite direction, also away from the ecliptic, by its close
encounter with Neptune. Could this mean that, since no such
anomalies have been noted for these two, then there is a valid
association between these anomalies and the ecliptic?

The reason no anomalies were observed with the Voyagers is because none
*could* be measured. The two spacecraft are 3 axis stabilized, using
maneuvering thrusters to keep the antenna pointed at Earth. Constant
firing
of these thrusters changes the spacecraft's momentum all the time (and in
a
random fashion, too), thus drowning any anomaly out...

--
The butler did it.

Might be interesting if they could devise an experiment to
check for the anomaly by temporarily disabling these
thrusters, hmm?

happy days and
starry starry nights!

--
Cut like a knife,
Chop like an axe,
Break out the sax,
Drop out the strife!

Paine Ellsworth

On Sat, 28 Aug 2004 07:01:38 GMT, Painius wrote:
Thanks, Ugo... i was aware that it had been proposed, but i did
not know that it had been dismissed. And how could it be so
readily dismissed? We still have no idea how many TNOs are
out there, KBOs and such. And astronomers are proposing that
there are quite a few.

Argh... This is the 3rd time I'm writing this reply. The first 2 times my
machine reset by an unlucky set of circumstances...

*groans*

Anyway, space beyond Neptune is one *very* big expanse and if you combined
the masses of all the TNOs, it still probably wouldn't be that large of a
mass. So their effects are negligible, especially if you consider all those
TNOs to be spread out evenly. Think of them as the asteroid belt beyond
Neptune...

We need to establish an upper limit to the TNO number (mass,
quantity, density, whatever) which would not give Neptune an
orbital anomaly. And then we can check if this number (or a
lesser density number) falls within a window that would have an
effect on the Pioneers during and after they pass through them.
Are you saying that this or something similar has been done?

I'm not saying that. I remember reading a paper about Pioneer 10 anomaly
where they dismissed that. Try googling for "pioneer anomalous
acceleration" for more info.

How will we know? The terminal shock effect, even with just
a relatively small density, might be likened to driving on the
highway at 70mph and coming up on a traffic jam where the
cars are moving at a much slower speed. Of course, here we
are talking about a solar wind traveling at a million mph and
rather abruptly slowing to about 200,000 mph. Wouldn't a
slowdown of the Pioneers and Voyagers be one possible
indication?

I can't stress hard enough how *rare* solar wind is, especially at those
distances. The only effects of reaching the termination shock would be
electrical/magnetical/radiowave effects. These would only be measured by
the instruments still operating aboard the Voyagers.

You mention below that the Voyagers would be insensitive to
such anomalies.

I didn't say that. I said the anomaly would be impossible to pick out from
the Doppler data due to noise induced by constant thruster firings. The
anomaly could very well be there also, but is simply drowned out by the
attitude control system. Similar difficulties arose from light pressure
effects much nearer the Sun with Galileo, Ulysses and Cassini.

So this could mean that both the Pioneers
and the Voyagers have reached the the solar wind's terminal
shock, couldn't it? The Pioneers could be reacting to it while
the Voyagers can't.

No. The instruments onboard would be picking the transition up. In any
case, the anomaly has been observed on Pioneer 10 since around 1990 (if
memory serves), and that's a looong way to traverse the termination shock
unnoticed, isn't it?

Perhaps Galileo measurements were made on route to Jupiter? In any case,
measuring this anomaly so close to the Sun is very difficult due to the
effects of solar radiation pressure which can be hard to model and take
into consideration. The anomaly with the Pioneers was observed once the
craft got far enough from the Sun for the light pressure to become
insignificant.

And yet, it *has* been measured... _curious_.

I didn't say the "anomaly" wasn't measured with Galileo. I'm saying that,
as far as I know, the data aren't very clear because of ligh pushing on the
spacecraft. One also has to take into consideration the energy radiated
away from the RTGs which also complicate things. In the end, the data on
the 3 probes inside Jupiter's orbit are inconclusive, AFAIK.
Again, I say that the only (?) reason the anomaly on Pioneers was detected
so far away from the Sun is due to light pressure becoming negligible
there.

The reason no anomalies were observed with the Voyagers is because none
*could* be measured. The two spacecraft are 3 axis stabilized, using
maneuvering thrusters to keep the antenna pointed at Earth. Constant
firing
of these thrusters changes the spacecraft's momentum all the time (and in
a
random fashion, too), thus drowning any anomaly out...

Might be interesting if they could devise an experiment to
check for the anomaly by temporarily disabling these
thrusters, hmm?

It certainly would be interesting, but I think it is impossible. To get
tracking and Doppler data on a Voyager, the spacecraft antenna must be
pointed more or less precisely at Earth. If you were to shut down attitude
control for a long enough time for the anomaly to kick in with a detectable
speed change, the spacecraft would already have drifted off Earth point and
would require that the antenna be positioned properly again for
measurement. And guess what? That's the job of attitude control thrusters.
They would need to be fired again to point to Earth again and would thus
mess up all the anomalous speed change (small as it was). That's how things
are now and that's why spin stabilized or reaction wheel stabilized
spacecraft are only candidates for these kinds of measurements.

For new data on this matter, we'll probably have to wait for the New
Horizons mission to Pluto and Kuiper belt...

--
The butler did it.