From: vince@offshore.ai (Vincent Cate)
Newsgroups: sci.space.science
Subject: Re: Drag at Orbital Altitudes
References: <5dcb47db.0311190511.68203dac@posting.google.com>
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Message-ID: <9186edb5.0311192354.e0f9d34@posting.google.com>

cray74@hotmail.com (Mike Miller) wrote in message news:<5dcb47db.0311190511.68203dac@posting.google.com>...
> 2) How much would drag be reduced (percentage wise) if the station
> operated at 600km vs 400km? (For the sake of argument, say the station
> could get there in the first place.)

The density at 400 km averages about 3.725E-12 Kg/m^3
       and  at 600 km averages about 1.454E-13 Kg/m^3.

     drag = Cd * dragArea * 0.5 * density * v*v;

So the density alone gets you a factor of 25.  The velocity is 
slower higher up to, so you win some from that too.

My simulator (Java applet) at http://spacetethers.com/spacetethers.html
can simulate drag on sats.  Check out samples 63 to 66.

You can also get the density at some altitude in meters
with an input like:

AirTest 400000

  -- Vince