Question:
Is it possible to remove some poisonous clouds from Venus so we can live
there?  How can this be done?

Answer from Sanjay Limaye on April 16, 1996:
There are two ways this query can be addressed, depending on which part of
the query we focus on.  Here is one answer.  In a reply to follow, I will
answer the actual question asked.

The key aspect of your query is to change Venus so that we can live there.
The poisonous clouds are a blend of haze of sub-micron sized particles and
one micron (radius) sized cloud droplets of sulfuric acid.  However, this
cloud/haze layer bottoms out at about 30 km above the surface, and as far
as we know, the atmosphere below this level is relatively clear. The
poisonous clouds therefore are not the most important issue on first look,
in terms of habitability since we would not come in contact with it.

     There are several aspects of habitability on Venus besides the
poisonous clouds that we need to worry about.  Assuming that you would want
to live on the surface of Venus (as opposed to floating around in the
atmosphere), one would need to worry about the surface "Venusair" pressure
(air is what we breathe on earth, with a known composition of nitrogen,
oxygen and carbon dioxide with trace amounts of water vapor and other gases.
 On Venus, we don't have a word yet to describe what we would breathe, so I
am calling it Venusair!)

     Venusair, or more technically, the atmosphere of Venus, is mostly
carbon dioxide and nitrogen, with a surface pressure of about 90 times the
mean sea level atmospheric pressure on the earth.  This is equivalent to
diving one kilometer in the ocean.  Further, the surface temperature is
close to 750 degrees Kelvin, or approximately 475 degrees C everywhere, from
the equator to the poles).  Human beings cannot withstand such high pressure
or the temperatures.  The amount of sunlight reaching down to the surface is
significantly reduced due to the clouds/haze/fog that is similar to the
"smog" found in the summer time in cities such as Los Angeles in terms of
the optical properties.  Which means that for agriculture, there may be
insufficient sunlight.

     So, to be able to live on the surface of Venus,  the poisonous clouds
are not the problem, because this cloud does not reach down to the surface,
but remains approximately 30 km above the surface at least up to about 60
degrees latitude in the north, and by symmetry, in the south.  At higher
latitudes, we do not have any measurements of the cloud structure yet, but
would be nice to have (new space  missions!).    The key to surviving on the
surface of Venus without the use of pressurized habitats, suits, etc., is to
reduce the surface pressure and to reduce the temperature.  Even then, we
would run into other issues such as the circadian rhythm and the day/night
durations.  Remember, the daylight on Venus near the equator would last for
about 58.5 days, as would the night!  This is akin to living in polar
latitudes on the earth.

     How can we reduce the surface pressure on Venus and the temperature?
 If we were to bake the rocks on the earth, the carbon dioxide trapped in
rocks would be released into the atmosphere, increasing the air pressure and
the air temperature due to increased greenhouse effect.  Will the reverse
occur on Venus if we were to lower the temperature?


Here is another answer to this question that pertains to the way it is asked:

The clouds on Venus are a blend of haze of small particles of sulfuric acid
of about 0.2-0.3 micron radius and a "cloud" of slightly larger droplets of
sulfuric acid, of about 1 micron radius.  The cloud part thins out near the
top, at around 60-70 km above the surface, leaving only the haze, while the
haze/cloud mixture bottoms out at around 30 km above the surface with some
layering in between.  Since sulfuric acid is known to react with many
substances, namely alkaline compounds, it would be straightforward to
neutralize the acid with what would amount to a planetary dose of antacid
chemicals that are advertised on television!  What about the residue though?
 Will it stay in the atmosphere or fall out like dust?