Re: Do the space ships and satellites which leave earth, affect the earth....?

Dove - you are right that spaceships and satellites
take a small amount of matter away from the surface of the Earth.
But this amount is very, very small. For example, consider a 
2 metric-ton satellite, which has a mass of 2000 kg. The Earth's
mass is 6x10^24 kg, so the satellite has only
3x10^(-25), or 0.0000000000000000000000003 times the mass of the Earth.
Pretty small, so even a million satellites will not have much effect.

The Earth also gains mass when meteorites fall to the ground from space.
I don't know how big the total mass gain is, but it might even be enough
to balance mass loss due to satellites.

The Earth's orbit will change in time, but this will be due more to
gravitational perturbations from the other planets, and slight changes
in the mass of the Sun as it ages. I don't know if rocket exhaust, for
example, causes chemical changes in the atmosphere; it might be 
interesting to try and find out about this on the Web.

Pauline