When to stop refuelling

In the HITCH HIKERS GUIDE to the galaxy series they mention a planet
where they weigh you on arrival and on leaving and if they must match
or you must be lighter to leave otherwise they chop off enough to make
up the difference.

This got me thinking about what a large volume of refuelling vessels
would do to a planetary environment.  Has anyone done any investigation
of the amount of Hydrogen fuel taken from a high tech high population
starport class A world in one year?  Is this a significant effect on
the planetary ecology?  How about over a 10 or 50 or 100 year period?

When would this become a problem and force all refuelling to happen
offworld at gas giants etc?

Just a thought ...


Bruce...          [email removed]