To: "Ellen Mackenzie" 
Cc: atm{at}shore.net, owner-atm{at}shore.net
From: Hugues.Laroche{at}ses-astra.com
Reply-To: Hugues.Laroche{at}ses-astra.com



Hi Ellen,

>10,000 and 30,000 tons  of space dust falls on the earth annually.
> What  effect has this had with the earth's orbit

This is going a bit OT...

Here it is not how much falls on the Earth which matters, since Earth's mass
and debris mass are neglible w.r.t. Sun's mass. Which matters more is the
average distribution of momentum that the space dust applies to the Earth.
 And, I guess that is a vast and complicated subject.
Extrapolating from the geostationary satellites' dynamics, one can split
the effects from 3 components of this momentum:
- out-of [ecliptic] plane -> modifies the ecliptic plane w/o changing the
  semi-major axis of the Earth's orbit.
- along the Sun-Earth's instantaneous line: modifies the eccentricity of
  the orbit w/o  changing the SMA of the Earth's orbit.
- along the Earth's flight path: modifies the SMA and eccentricity of
  the orbit.
One thing is probably true about the average momentum: the average space
dust orbits the sun more or less in the plane of the ecliptic and in the
same
sense of rotation as the planets themselves. But is it uniform in all directions?
The planets and in particular Jupiter impose a forcing on the
"allowed" dust particles orbits, and solar pressure modifies them
as well. How all this
does come into play?

I stop here or the list owner will start to be angry about me. Next time I grind :-)
I will think further. Does anybody know more about this (post off-list)?

Clear skies,

Hugues




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