Rocket debris thrown into Space

[happyhacker]

When a rocket engine exhausts into Space what happens to the particles or molecules that are thrown out?

My interest is firstly where do they go e.g.: orbit the Earth or other planetary body if from a shuttle, orbit the Sun if ejected outside the capturing influence of a planetary body, or just head off on their initial trajectory into the interplanetary void. Secondly, being presumably considered pollution (unless the particles are joining naturally occurring particles in that medium they end up in e.g. hydrogen), are we creating a long term problem like Space junk orbiting Earth but 'clouds' of stuff out there. My definition of 'Space' here I assume to be cislunar and beyond (e.g. when we head off to Mars). I suppose if this question was looked at another way: are we leaving permanent traces of our activity in Space due to current and proposed rocket technology (although I guess Voyager 1 will only be giving off particles of its structure as it travels).

Many thanks.

 

[trurle]

Gaseous products are rapidly expelled from vicinity of Earth by solar radiation pressure and solar wind on timescale of days and is not considered a pollution; the aluminum oxide powder from solid-fuel rocket exhaust have residence time measured in months to years and can be potentially a problem, causing solar panels coverglass erosion or such. These orbiting dust streams are rare though - only few interplanetary probes had flight profiles allowing large weights of powdered solids to enter orbit of Earth.