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re: You asked
gbaikie — (archived)

"Standard atmospheric pressure is 101,325 Pa = 101.325 kPa = 1013.25 hPa = 1013.25 mbar = 760 Torr."
http://en.wikipedia.org/wiki/Hectopascal

"Temperature decreases rapidly with height in the mesosphere(Gk. mesos = middle), the minimum of about –90 °C being reached at the mesopause located at about 80 km where atmospheric pressure is about 0.01 hPa."
http://www.auf.asn.au/meteorology/section1a.html

So, sea level Earth has 1013.25 hPa. At about 100,000' on Earth or "sea level" Mars there is about 10 hPa [mbars].

At around 80 km [262,480'] on Earth there is about .01 hPa or about 1/1000th of Mars' sea level or Earth at 100,000'

The weight of air at sea level 1.222 kilograms per cubic meter. Or 1222 grams. At 100,000 it's about 12 grams per cubic meter and at 80 km it's about .012 grams per cubic meter.
A cubic km has 1 billion cubic meters, so a cubic km at 80 km weighs about 12 million grams, 12 thousand kg, or 12 tonnes.

At sea level Earth has surface are of 510,100,000 sq km.
At 80 km the surface area would be:
Equatorial radius (km) 6,378.14 + 80 km, so 6458 km
So, it's about 524,089,645 sq km. So the volume of sky between 80 km and 81 km the air weighs 6.29 billion tonnes.

Hmm, much more than I thought it would weigh.

Ok, so if 20 billion tonnes were leaving Earth every year, at a rate of .05 billion tonnes per day uniformly and smoothly across all of Earth, not only wouldn't it bring down the satellites, but could have little impact upon their orbits, I would guess one might able to have as much as 100 billion tonnes per year without having much affect upon satellites.

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