Mars once had atmosphere ... why not now?

On Sat, 06 Mar 2004 18:11:41 GMT, Doug...
wrote:

According to studies of the Martian upper atmosphere and its interaction
with the solar wind, Mars loses roughly one to two kilograms of
volatiles (i.e., air and water) per *second*. The observed rate of
volatiles loss means that Mars could lose *all* of its volatiles before
the Sun goes into its red giant phase, i.e., in the life of the solar
system.

Are you sure? Unless I've made a mistake in my arithmetic, I have 2
kg/second ~= 60 kilotons/year ~= 270 teratons in 4.5 billion years,
compared to the mass of the Earth's atmosphere at 5000 teratons and
the mass of the oceans at maybe a couple hundred times more.

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In article ,
says...
On Sat, 06 Mar 2004 18:11:41 GMT, Doug...
wrote:

According to studies of the Martian upper atmosphere and its interaction
with the solar wind, Mars loses roughly one to two kilograms of
volatiles (i.e., air and water) per *second*. The observed rate of
volatiles loss means that Mars could lose *all* of its volatiles before
the Sun goes into its red giant phase, i.e., in the life of the solar
system.

Are you sure? Unless I've made a mistake in my arithmetic, I have 2
kg/second ~= 60 kilotons/year ~= 270 teratons in 4.5 billion years,
compared to the mass of the Earth's atmosphere at 5000 teratons and
the mass of the oceans at maybe a couple hundred times more.

I suspect that Mars would be in danger of losing all of its volatiles
within the lifetime of the solar system, in large part, because it had
significantly less than Earth to begin with, and has been losing them at
a greater rate than Earth has.

As for my source, it is on page 12 of "Mars -- The Mystery Unfolds" by
Peter Cattermole. I quote:

"...Phobos 2 measured the flow of plasma in the solar wind and the rate
at which ions of carbon dioxide and molecular and atomic oxygen were
leaving Mars. Surprisingly, it was found that the atmosphere of the
planet is escaping at the rate of 1-2 kg every second. This may seem
insignificant, and indeed it would be for a planet such as Earth, but
for Mars, which in any case has such a tenuous mantle of air, it means
that it could lose its entire inventory of volatiles in much less than
the lifetime of the Solar System."

Doug