In article ,
Richard Saam wrote:
An interesting calculation.

Here is another for Pioneer Spacecraft deceleration 'a'

a ~ 2*Area*rho*c2 / M
~ 2*(58,965 cm2)*(6.38E-30 g/cm3)*(3E10 cm/sec)^2 /(241,000 g)
~ 2.8E10-9 cm/sec2 for Pioneer spacecraft

I haven't paid attention to the Pioneer anomaly stuff lately, so
I apologize if I'm just being stupid, but I don't see the physics
behind this relation. In particular, I don't see how c gets involved.
If you assume that the spacecraft is moving at velocity v through a cloud
of stationary particles that bounce elastically off of it whenever they hit
it, then you get a relation something like the above, but with v instead
of c. That makes a big difference, of course.

In addition, the dark matter particles are thought to be weakly interacting,
so most of them pass right through Pioneer without exerting any force
on it at all.


Your average calculated local density of 7 x 10^{-25} g/cm^3
is quite a bit higher than 30 x 6.38E-30 g/cm^3 or 2E-28 g/cm^3
but there still remains a conceptual mechanism
on how dark matter influences solar objects
according to their area/mass
(Pioneer some and planets negligible).
Perhaps the local dark matter density is on the order of
30 x 6.38E-30 g/cm3 or 2E-28 g/cm^3.

The calculation I did was based on well-measured Galactic dynamics. If
you want to get a different answer, you'll have to come up with a different
explanation for the motion of stars in the Galaxy.

-Ted

--
[E-mail me at , as opposed to .]