posted on May, 4 2003 @ 06:38 PM
It is true that tons of dust does enter the atmosphere on a continuous basis, and you do raise a valid point about the effects of the continuous
addition of mass to the planet.
However, keep in mind that even millions of tons is a drop in the bucket compared to the total mass of the planet already.
As far as the addition of space dust resulting in less atmosphere, there is no apparent correlation to this effect. To my knowledge, the earths
atmosphere has always been approximately equal to its current pressure. It is true that during the carboniferrous period (from 360 to 290 million
years ago) the atmospheric concentration of Oxygen was significantly higher (some estimates as high as 30-35%) which did result in very large
creatures (my favorite example is the dragonfly with a 12 foot wingspan... such creatures could not live today as the O2 concentration would not
It is also true that the atmosphere outgasses at the upper edge of outer space, but such outgassing is minor compared to the overall volume of the
atmosphere. What volume of gas is lost into space is often made up from other sources, such as during volcanic eruptions.
As far as the loss atmosphere from Mars, that is a very interesting subject: It is estimated that approximately 1 billion years in the past, Mars had
an atmosphere approximately 1/2 to 1/3 the surface pressure of the earth (currently Mars holds 1/100 surface pressure of earth). A very interesting
theory is that a comet or asteroid may have impacted Mars at a very oblique angle, larger than 45 degrees. The impact shock wave, because it was at
such a large angle, may have blasted a large amount of atmosphere beyond escape velocity, essentially blowing it off the planet.
Incidentally, this may also explain the presence of Phobos and Diemos, as remnants of either the bedrock blown up into orbit from the impact, or
possibly, remnants of the original impactor which skipped off the surface and back up into orbit.