Could collisions with Dark Matter explain the spacecraft fly-by anomalies?

wrote:

In sci.astro Yousuf Khan wrote:
Sounds like he's talking about the Aether Theory without actually
mentioning the Aether here.

Technology Review: Blogs: arXiv blog: The Clue That Could Explain The
Fly-By Anomalies
"Last year, we looked at an idea from Stephen Adler at Princeton
University, that suggested the change in velocity could caused by
collisions between the spacecraft and particles of dark matter. Adler
even calculated the kind of distribution of dark matter particles that
would explain the observed changes in velocity--a kind of halo of them
around Earth. "

No. Adler's papers investigate the possibility that the flyby anomalies
might be caused by drag as spacecraft pass through a cloud of dark
matter gravitationally bound to the Earth. In his most recent preprint
he suggests a specific experimental signature (collisions with dark
matter should slightly heat the spacecraft).

Heat the spacecraft but not ultracryogenic single phonon detectors?
Adler is curve fitting crapola against real observations.

The relevant preprints are arXiv:0903.4879, arXiv:0908.2414, and
arXiv:0910.1564.

let's not get all jiggy - the last arxiv below,

http://arxiv.org/abs/gr-qc/0205059
Pioneer anomaly
http://arXiv.org/abs/gr-qc/0307042
Rationalized Pioneer anomaly
http://arXiv.org/abs/gr-qc/9810085
Believable rationalized Pioneer anomaly
http://arXiv.org/abs/gr-qc/gr-qc/0310088
Believable Pioneer anomaly updated
http://www.arxiv.org/abs/gr-qc/0411020
Pioneer anomaly
http://arXiv.org/abs/physics/0502123
Commentary on Pioneer anomaly minutia
http://arXiv.org/abs/gr-qc/0506139
http://math.ucr.edu/home/baez/open.questions.html
http://arxiv.org/abs/0710.2656
1/3 modeled away


--
Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
http://www.mazepath.com/uncleal/lajos.htm#a2

Dear eric gisse:

On Oct 14, 9:01*pm, eric gisse wrote:
Uncle Al wrote:

[...]

Uncle Al calls "bull****" on undetected matter
in space in sufficient quantities to detectably
alter local orbits, by collision cross-section or
by naked gravitation. *If somebody comes up
with a reproducible lab signal (not the Italian
stuff), Uncle Al will apologize.

Correct.

Any dark matter sufficiently dense to alter
spacecraft orbits (and that bar is pretty high to
begin with) will do...what to planetary and lunar
orbits? The answer is an exercise for the reader.

The effect is a function of distance from the boost body, and if it
resolved to similar "viscosity" models, would be on the order of v^2.
Since inside the Roche limit is out for rocky bodies, we are left with
~1 km/sec for our Moon, vs. ~7.5 km/sec for a satellite. The problem
is, an orbit encounters the "two kinds" of Dark Matter, the stuff "in
front" and the stuff "behind", so it should average to (perhaps) zero
net effect.

But this too should be detectable. Were it not horse manure.

David A. Smith

On Oct 14, 1:57*am, Yousuf Khan wrote:
Sounds like he's talking about the Aether Theory without actually
mentioning the Aether here.

Technology Review: Blogs: arXiv blog: The Clue That Could Explain The
Fly-By Anomalies
"Last year, we looked at an idea from Stephen Adler at Princeton
University, that suggested the change in velocity could caused by
collisions between the spacecraft and particles of dark matter. Adler
even calculated the kind of distribution of dark matter particles that
would explain the observed changes in velocity--a kind of halo of them
around Earth. "http://www.technologyreview.com/blog/arxiv/24232/?a=f

* * * * Yousuf Khan

I wonder how he determined the aerodynamic drag coefficient for dark
matter.

Tom Davidson
Richmond, VA

Peter Webb wrote:

"Yousuf Khan" wrote in message
...
Sounds like he's talking about the Aether Theory without actually
mentioning the Aether here.


No, its got nothing whatsoever to do with that.

Doesn't the Aether Theory say that things moving in space in a certain
direction shall feel a "wind" as they move? That sounds like what he's
talking about.

Technology Review: Blogs: arXiv blog: The Clue That Could Explain The
Fly-By Anomalies
"Last year, we looked at an idea from Stephen Adler at Princeton
University, that suggested the change in velocity could caused by
collisions between the spacecraft and particles of dark matter. Adler
even calculated the kind of distribution of dark matter particles that
would explain the observed changes in velocity--a kind of halo of them
around Earth. "
http://www.technologyreview.com/blog/arxiv/24232/?a=f

Yousuf Khan

Funny that the earth is surrounded by enough of these to noticeably slow
a spaceship, but none has even been observed on earth. I wonder if the
paper has an explanation of this curious fact ...


There's a lot that's funny about Dark Matter.

Yousuf Khan

Dear Yousuf Khan:

"Yousuf Khan" wrote in message
...
Peter Webb wrote:

"Yousuf Khan" wrote in message
...
Sounds like he's talking about the Aether Theory
without actually mentioning the Aether here.

No, its got nothing whatsoever to do with that.

Doesn't the Aether Theory say that things moving in
space in a certain direction shall feel a "wind" as
they move?

No. That aether has been discounted. So that leaves no aether,
or an aether in which matter propagates as freely as light does.

That sounds like what he's talking about.

It sounds like it is described that way, but it not an aether.
It is a "ponderable" magic fairy dust.

Technology Review: Blogs: arXiv blog: The Clue
That Could Explain The Fly-By Anomalies
"Last year, we looked at an idea from Stephen
Adler at Princeton University, that suggested the
change in velocity could caused by collisions
between the spacecraft and particles of dark
matter. Adler even calculated the kind of distribution
of dark matter particles that would explain the
observed changes in velocity--a kind of halo of them around
Earth. "
http://www.technologyreview.com/blog/arxiv/24232/?a=f

Funny that the earth is surrounded by enough of
these to noticeably slow a spaceship,

Actually, anomalously boost... both more or less of what we
intended.

but none has even been observed on earth. I
wonder if the paper has an explanation of this
curious fact ...

There's a lot that's funny about Dark Matter.

Yes.

David A. Smith

On Oct 14, 6:56*pm, Yousuf Khan wrote:
Peter Webb wrote:

"Yousuf Khan" wrote in message
...
Sounds like he's talking about the Aether Theory without actually
mentioning the Aether here.

No, its got nothing whatsoever to do with that.

Doesn't the Aether Theory say that things moving in space in a certain
direction shall feel a "wind" as they move? That sounds like what he's
talking about.

The "wind" here is Galactic gravity which is responsible for flyby
anomalies, especially pronounced at perihelion and aphelion, where the
planet
is aligned with the Sun and Galactic Center. At aphelion galactic
gravity
is additive and subtractive at perihelion. John Curtis

Technology Review: Blogs: arXiv blog: The Clue That Could Explain The
Fly-By Anomalies
"Last year, we looked at an idea from Stephen Adler at Princeton
University, that suggested the change in velocity could caused by
collisions between the spacecraft and particles of dark matter. Adler
even calculated the kind of distribution of dark matter particles that
would explain the observed changes in velocity--a kind of halo of them
around Earth. "
http://www.technologyreview.com/blog/arxiv/24232/?a=f

Yousuf Khan

Funny that the earth is surrounded by enough of these to noticeably slow
a spaceship, but none has even been observed on earth. I wonder if the
paper has an explanation of this curious fact ...

There's a lot that's funny about Dark Matter.

Ultimate disposition of dark matter may require abandonment of
heliocentric system in favor of a galactic frame. Copernicus and
Kepler
will join Ptolemy, Newton will require modification. John Curtis

* * * * Yousuf Khan

Uncle Al wrote:
[...]

Uncle Al calls "bull****" on undetected matter in space in sufficient
quantities to detectably alter local orbits, by collision
cross-section or by naked gravitation. If somebody comes up with a
reproducible lab signal (not the Italian stuff), Uncle Al will
apologize.


Correct.

Any dark matter sufficiently dense to alter spacecraft orbits (and that bar
is pretty high to begin with) will do...what to planetary and lunar orbits?
The answer is an exercise for the reader.

"John Curtis" wrote in message
...
On Oct 14, 6:56 pm, Yousuf Khan wrote:
Peter Webb wrote:

"Yousuf Khan" wrote in message
...
Sounds like he's talking about the Aether Theory without actually
mentioning the Aether here.

No, its got nothing whatsoever to do with that.

Doesn't the Aether Theory say that things moving in space in a certain
direction shall feel a "wind" as they move? That sounds like what he's
talking about.

The "wind" here is Galactic gravity which is responsible for flyby
anomalies, especially pronounced at perihelion and aphelion, where the
planet
is aligned with the Sun and Galactic Center. At aphelion galactic
gravity
is additive and subtractive at perihelion. John Curtis

Technology Review: Blogs: arXiv blog: The Clue That Could Explain The
Fly-By Anomalies
"Last year, we looked at an idea from Stephen Adler at Princeton
University, that suggested the change in velocity could caused by
collisions between the spacecraft and particles of dark matter. Adler
even calculated the kind of distribution of dark matter particles that
would explain the observed changes in velocity--a kind of halo of them
around Earth. "
http://www.technologyreview.com/blog/arxiv/24232/?a=f

Yousuf Khan

Funny that the earth is surrounded by enough of these to noticeably slow
a spaceship, but none has even been observed on earth. I wonder if the
paper has an explanation of this curious fact ...

There's a lot that's funny about Dark Matter.

Ultimate disposition of dark matter may require abandonment of
heliocentric system in favor of a galactic frame. Copernicus and
Kepler
will join Ptolemy, Newton will require modification. John Curtis


Ultimate disposition of dork matter theory may require
abandonment of a galactic frame. Curtis and Khan will
join the black hole brigade, Newton will require no
modification. Androcles.

In sci.astro eric gisse wrote:

Any dark matter sufficiently dense to alter spacecraft orbits (and
that bar is pretty high to begin with) will do...what to planetary
and lunar orbits?

Not necessarily very much. The interactions aren't gravitational
-- there's no principle of equivalence at work here -- and the
acceleration due to drag can be much greater for a small object
than a large one.

Adler's proposal is probably not what's really happening -- he himself
says only that "the dark matter scenario is not currently ruled out,
but requires dark matter to be non-self-annihilating, with the dark
matter scattering cross section on nucleons much larger, and the dark
matter mass much lighter, than usually assumed." But he's not an
idiot, and he has looked at whether the model would have any other
observable effects on Solar System measurements.

(He is, in particular, looking at a model in which dark matter is
gravitationally bound to the Earth and other planets. This would
make the density near the Earth much higher than the average
Solar System density.)

I'm not arguing that Adler is right. But this is nontrivial stuff, and
can't be dismissed by hand-waving; you have to really do the math.

Steve Carlip

On Oct 13, 10:57*pm, Yousuf Khan wrote:
Sounds like he's talking about theAetherTheory without actually
mentioning theAetherhere.

Technology Review: Blogs: arXiv blog: The Clue That Could Explain The
Fly-By Anomalies
"Last year, we looked at an idea from Stephen Adler at Princeton
University, that suggested the change in velocity could caused by
collisions between the spacecraft and particles of dark matter. Adler
even calculated the kind of distribution of dark matter particles that
would explain the observed changes in velocity--a kind of halo of them
around Earth. "http://www.technologyreview.com/blog/arxiv/24232/?a=f

* * * * Yousuf Khan

LeSage theory predicts exactly what is observed for the Pioneer
slowing. It predicts that all objects not in closed orbits will slow
down. This is known as Feynman's drag.