[extropy-chat] Re: Are dwarfs better for long durationspaceflight?

[spike]

> bounces at lists.extropy.org] On Behalf Of Mike Lorrey
> Sent: Tuesday, August 30, 2005 3:17 PM
> To: ExI chat list
> Subject: Re: [extropy-chat] Re: Are dwarfs better for long
> durationspaceflight?

Danger Will Robinson!

Last time I brought this up I was smite bait for weeks.  I
was smitten by such gentle souls as Gina Miller!  Negative 
applause city (palc palc palc...)  I was the sultan of smite, 
the poster child for the excessively smitten, the charter 
member of the church of smitology, smote beyond all recognition.  

But I recovered.

There is a professional society of which I have been a member
for over 20 years, SAWE, the Society of Aerospace Weight 
Engineers.  We sit around and argue about stuff like this.  Really.

Design of a Mars mission has been a subsession in many of
our annual conferences.

Keep in mind a few basic concepts:

1.  The weight of a pressure vessel scales as the cube
of its linear dimension.

2.  A spherical pressure vessel is the most weight efficient
configuration.

3.  The linear dimension of a space vehicle should be able to
scale linearly with the linear dimension of the astronaut.  So
an astronaut half as tall should be able to use a pressure
vessel half the diameter, or one eighth as massive.  Right?

4.  Not everything scales linearly with the linear dimension
of the astronaut, but a lot of stuff will.

5.  A tiny light person will do a loooot better in weightlessness
than a big heavy person.  When weightlessness is introduced,
the body immediately dumps calcium from those big femurs, which
can cause kidney stones and a bunch of problems.  (Have you ever
had a kidney stone?  I have and I pray to evolution you never do.)

6.  We have the option of choosing people who are severely
limited in this one-G field who would do just fine in freefall,
such as spina bifida victims and paraplegics.  I know one 
personally, and she would make a fine tiny astronaut.

7.  A person's air and food needs should scale nearly in proportion
to their weight, which should scale approximately as the cube 
of their linear dimension.  Right?  

If you take issue with any of these concepts, do speak
up and state your reasoning.

Those of you who are still reading at this point, here is your 
assignment,:  Estimate the actual mathematical relationship 
between the weight of the Mars hab-module and the linear 
dimension of the astronaut.  For a very simple start, try

M = 1e4*H^3, where H is the height of the astronaut in
meters and M is the mass in Kg.  If you wish to argue that
the exponent on H should be less than 3, state your reasoning.

I can think of a reason why it could go even higher than 3 under
the circumstances we have today: given a short enough astronaut,
we could make the hab module a 4 meter diameter sphere, which
would fit in the cargo bay of the space shuttle or inside the
standard fairing of a Titan rocket (Lockheeed Martin product) or
under severe duress the Delta 4 (Booeing product).  

A spherical hab module would not waste metal, as a cylindrical
module would (see item 2 above).

Question: could we arrange for a person to live for possibly
several years in a spherical device 4 meters in diameter?  You
and I, probably not without severe distress.  But a person
one meter tip to tail?  I don't see why not.

Come on you space heads!  Think about this, think hard.  We 
might be able to put together a dynamite paper for SAWE.

spike