Ask A Scientist© General Science Archive

 
name         Joan
status       other
age          50s

Question -   Not being a scientist just an observer by nature. I have
a question. My question is with all the space exploration and satelites
etc, etc. being launched into space. Some of which are designated to
return to earth. Would this penetration through our atmoshpere, weaken
the atmospheric density. If anything I would think that it would.
Consider the ballon that is blown up and the air let out a number of
times. Or even better, try piercing the womb a number of times to check
on a unborn child's condition. I see a tendency to weaken the outer layer
on each. Is indeed the world's atmoshpere effected and if so how by
continuing to enter and exit it?
Also if it does affect our atmosphere, would this have any bearing on the
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I'm not sure I fully understand your question, but I think you're concerned
that the atmosphere might be harmed by space vehicle launches and/or orbit
operations.

The upper limit of the atmosphere is not a sharply defined boundary, such as
the surface of a lake or ocean. It is more like the boundary between
daylight and dark, and is marked with a gradual decrease in density with an
increase in altitude. So repeated transitions of this boundary by spacecraft
should not affect any physical properties it may have.

The upper atmosphere is bombarded daily with millions of micrometeorites,
which "burn up" in the atmosphere, and fall to the earth's surface as dust
particles. Rockets and high altitude aircraft operations may have some
minimal effect on the upper atmosphere with the introduction of the
by-products of combustion, and their chemical reaction with the gases in the
upper atmosphere. Studies are ongoing to try to ascertain whether these
effects are harmful or not.

So any effects of space operations on the atmosphere would be chemical
rather than physical.

Wendell Bechtold, Meteorologist
Forecaster, National Weather Service
Weather Forecast Office, St. Louis, MO
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The atmosphere is not like a balloon or a womb.  There is no boundary layer
between space and the air that might be weakened by being penetrated.  The
air merely becomes less dense as you go further from earth until air
molecules become so rare that they are difficult to notice.  The only thing
keeping air molecules near earth is earth's gravity.

------
The ozone layer is affected by a particular kind of air pollution that
acts as a catalyst to break down ozone.  A craft entering or leaving earth
could pollute the atmosphere as it moves through it, but this would make a
very, very tiny contribution compared to the major causes of ozone depletion.

Tim Mooney 
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The earth's atmosphere is a fluid.  When something enters it or passes
through it, no hole is left behind.  Your analogies of a balloon or a womb
are of containers that enclose  a fluid;  there is no such container
holding the earth's atmosphere in.  Instead, it is held in place by the
earth's gravity.  In a way, entering and leaving the earth's atmosphere is
similar to diving in and out of the ocean.  You won't poke any holes in the
ocean, or stretch its surface.

That said, the atmosphere IS composed of distinct layers, such as the
troposphere (the layer closest to the ground, where we live) and the
stratosphere (the layer above the troposphere, whose ozone content is
diminishing).  There is a distinct boundary between these layers, and very
little mixing of gases between them.  A lot of objects penetrating this
"tropopause" might have some effect on it, but I've never heard an
atmospheric scientist express any concern.


Richard Barrans Jr., Ph.D.
Chemical Separations Group
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