Newsgroups: alt.sci.planetary
From: henry@spsystems.net (Henry Spencer)
Subject: Re: any nasa pipedreams of venutian exploration
Date: Wed, 8 Sep 1999 14:29:34 GMT

In article <zJoB3.1015$2H4.56136@typhoon01.swbell.net>,
Lithium <lith@swbell.net> wrote:
>Has nasa ever publically released any halfway realistic ideas on venutian
>exploration?

Not that I recall.  Manned exploration of Venus is really hard.  The
pressure is manageable, although the thick air complicates the problem of
getting back up to orbit afterward (which is already hard because of the
strong gravity).  The temperature is the really bad problem.  Unmanned
Venus probes sometimes are deliberately chilled to sub-freezing
temperatures before descent, to give them a bit longer before they
overheat, and still typically have a working lifetime of an hour.  Nobody
has yet come up with a good way to cool things well enough for extended
surface stays.

>believe there are enviro suits that can handle nearly that level of heat
>(ever seen those guys running around in volcano calderas?).

The air around those guys, while hot by shirtsleeves standards, is
hundreds of degrees cooler than Venus's atmosphere (and also much thinner,
so it moves heat rather less effectively).

A Venus suit probably would be covered with a thick layer of insulation to
keep external heat out, and the heat generated by the occupant and his
equipment would go into melting a block of ice in his backpack, the water
from which would then be used to cool joints etc. and then vented as steam
(perhaps in front of the faceplate, to help keep it cool; if you get the
steam relatively hot before venting it, it will be transparent rather than
misty).

The suit would be good for only short stays outside, limited by the size
of the ice block.  (Cooling the ice to cryogenic temperatures first might
help, although it would complicate heat-exchanger design.)  The ship would
have to be cooled by some magic technology.

The suit would probably have to be powered.  Existing spacesuits (with
backpacks) are far too heavy for a near-1G environment; in fact they're
too heavy for Mars, never mind Venus.  And the Venus suit will be heavier.
--
The good old days                   |  Henry Spencer   henry@spsystems.net
weren't.                            |      (aka henry@zoo.toronto.edu)

Newsgroups: alt.sci.planetary
From: henry@spsystems.net (Henry Spencer)
Subject: Re: any nasa pipedreams of venutian exploration
Date: Thu, 9 Sep 1999 16:20:08 GMT

In article <090919990051484058%cpruett6809@home.com>,
Chris Pruett  <cpruett6809@home.com> wrote:
>> The suit would be good for only short stays outside, limited by the size
>> of the ice block.  (Cooling the ice to cryogenic temperatures first might
>> help, although it would complicate heat-exchanger design.)  The ship would
>> have to be cooled by some magic technology.
>
>Provided one has sufficent electricity and good insulation, couldn't
>one use fairly standard refrigeration on the ship?

Well, "fairly standard" refrigeration generally isn't designed to push heat
out into a 500degC environment!  The standard operating principles could be
used, yes, but the engineering details would be a major challenge, going
well beyond the current state of the art.

>A nuclear reactor could provide the power.  Even a _really_ hot RTG.

The problem with using any form of thermal power is that then *it* has to
reject its waste heat into a 500degC environment too, which hurts
efficiency and adds nasty engineering problems.  However, nuclear power of
some flavor would be about the only way to go, I think.

>How about dry ice instead of water for the suits?  CO2 is readily
>available while water would need to be imported.

There's more water vapor in Venus air than in Mars air.  But extracting it
would be harder than extracting CO2, for sure.  I don't know how the
tradeoffs would turn out; water is a rather better coolant.
--
The good old days                   |  Henry Spencer   henry@spsystems.net
weren't.                            |      (aka henry@zoo.toronto.edu)