It seems as though whenever I see pictures of folks in the Shuttle or at
Alpha they are always wearing long sleeves and I think long pants, too.
As it is the case that the thermal environment in those two venues is
totally under human control, I don't understand why the setpoint is so low
as to require such heavy clothing. Why not set the temperature at 80F or
so and have the humans wear just shorts and a tee shirt? Why carry bulky
clothes? Do they keep it cold so that the electronics stay cool, or is
there some other technical reason?

I seem to recall that in the High Frontier, O'Neill posits that the first
Island One would have a Hawaiian-type climate. That would seem very
reasonable to me, because otherwise clothes would have to be imported and
maintained. Why doesn't Alpha have an internal environment maintained at
Hawaii temperatures?

Ron Menich

> Why not set the temperature at 80F or so and have the humans wear
just shorts and a tee shirt?

Why stop there? Why wear clothes at all?

I'm kidding, of course, but I think the answer is the same: to feel
"covered", "protected", "safe", etc. If I were one meteroid away from
a quick decompression, I'd want to be able to just pull on a mask and
not have to worry about getting dressed. Even if the chances are
slim, I'd still /feel/ safer.

++JohnWheeler

>It seems as though whenever I see pictures of folks in the Shuttle or at
>Alpha they are always wearing long sleeves and I think long pants, too.
>As it is the case that the thermal environment in those two venues is
>totally under human control, I don't understand why the setpoint is so low
>as to require such heavy clothing. Why not set the temperature at 80F or
>so and have the humans wear just shorts and a tee shirt? Why carry bulky
>clothes? Do they keep it cold so that the electronics stay cool, or is
>there some other technical reason?

It's easier to heat a space vehicle than to cool it. Remember a space
vehicle is essentially a vacuum bottle which can only be cooled by radiation
(if you don't want to waste mass in evaporative coolers). Getting heat out
is a pain, technically. So typically space vehicles are biased to be
slightly more on the cold side than the hot side -- and they'll make up the
difference with a little bit of cheap, light, simple electrical heaters,
which they can control easily.

Populated space vehicles run the same -- they are easier to heat up than
cool, so they'll set the thermostat to a little cooler than hotter, and make
up the difference by wearing long pants instead of shorts -- cheap, simple,
reliable, safe and lighter weight than adding more cold plates, cooling
loops, etc.

As a secondary factor, most space vehicles have lower pressures and
different humidities than you may be used to on the Earth (Shuttle tends to
be pretty dry/ low humidity due to technical factors in the ECLSS system) --
which tends to have a different heat capacity and perception of temperature
in the air. So things cool off easier than in 1 standard atm. This means
while the air may be a comfortable temperature, if you exert yourself, you
will cool off faster -- and its easier to have on a bit more clothing.

Your explanation sounds reasonable for me.

Also, I was thinking that clothes probably don't wear out as quickly in
microgravity as they do on Earth. I recently discarded a pair of pants
that had developed a hole in the seat after long use. Pants in space
would very rarely develop holes in the seat , because they would never be
subjected to the repeated sit down/stand up cycling to which I subject my
Earth-bound pants.

Ron Menich

"W. Larrison"
ssi_list@...
08/21/01 09:06
PM
Please respond
to ssi_list

>It seems as though whenever I see pictures of folks in the Shuttle or at
>Alpha they are always wearing long sleeves and I think long pants, too.
>As it is the case that the thermal environment in those two venues is
>totally under human control, I don't understand why the setpoint is so low

>as to require such heavy clothing. Why not set the temperature at 80F or

>so and have the humans wear just shorts and a tee shirt? Why carry bulky

>clothes? Do they keep it cold so that the electronics stay cool, or is
>there some other technical reason?

It's easier to heat a space vehicle than to cool it. Remember a space
vehicle is essentially a vacuum bottle which can only be cooled by
radiation
(if you don't want to waste mass in evaporative coolers). Getting heat out

is a pain, technically. So typically space vehicles are biased to be
slightly more on the cold side than the hot side -- and they'll make up the

difference with a little bit of cheap, light, simple electrical heaters,
which they can control easily.

Populated space vehicles run the same -- they are easier to heat up than
cool, so they'll set the thermostat to a little cooler than hotter, and
make
up the difference by wearing long pants instead of shorts -- cheap, simple,

reliable, safe and lighter weight than adding more cold plates, cooling
loops, etc.

As a secondary factor, most space vehicles have lower pressures and
different humidities than you may be used to on the Earth (Shuttle tends to

be pretty dry/ low humidity due to technical factors in the ECLSS system)
which tends to have a different heat capacity and perception of temperature

in the air. So things cool off easier than in 1 standard atm. This means
while the air may be a comfortable temperature, if you exert yourself, you
will cool off faster -- and its easier to have on a bit more clothing.