* Warning somewhat long *

Why would you have crew shifts of a year or more ? some people have
compared an SMF or island A to an oil rig situation - which if memory
serves me correctly have shifts of about 6 weeks. I would have thought
for an SMF a better comparison would be a submarine. As far as I know
with a sub you are out no longer than 3 months. ( except in exceptional
circumstances ) A submarine is a small self contained little world where
people are constantly in each other face and would not have much more
room than a SMF is likely to have. Just like an SMF you can't step
outside to get away from it all for a little while. ( granted the SMF
crew could go for a spacewalk ) In thinking about lengths of stays you
have to remember that the people who crew an SMF will be there primarily
to build things, they will not be astronauts in the original sense of
the word . They will not be doing research. They will be doing hard
work for most of the day with very little recreation ( after all we are
talking about what amounts to a tin can in space ) They are not going
to be able to go outside for a game of whatever. They will see the same
faces everyday and everything that those other people do will eventually
become annoying. In such a situation if it is kept going long enough
mistakes are going to get made, and eventually that would cost someone's
life. It won't matter how long a human body can tolerate going with out
gravity the main factor will be how long our minds can stand that
situation without going over the edge. I am assuming that unless
required by manufacture, gravity by rotation will be a waste of time,
energy, space ( inside the SMF ) and money. ( only for this size station
though )

To my way of thinking you would not want a shift to go for more than
three months. Another thing to remember is if you swap over the whole
crew every three months you are going to have a new bunch of people who
are going to be space sick , and unused to that situation ( no gravity
the main one ) and a danger to themselves and others. So rather than
swap the whole crew over you swap a third every month. This way each
crew is there for three months but there are new faces every month and
there is a mix of very experienced personnel through to the very green
personnel. You then have a question of what to do with them on the
ground and how long should they be there ? Well again to my mind you
would want them to stay down for 6 months or so - why ? well firstly
they have between 2 and 4 weeks of leave to blow off steam and see the
loved ones. Three months on / 6 months off will limit any exposure to
radiation they will have ( lets face it in an SMF there won't be much
shielding compared to an Island 1 especially at the beginning - not to
mention the public's perception to that radiation ) When they are on
the ground they can do several things , some can be used to train new
people ( I imagine there would be a high turnover in crew as some people
would find they did not like space or the conditions or they are only
there for a quick money earning trip ) Some can be used to operate the
telerobotics. Some can help develop new techniques for manufacture in
space. Some can be subcontracted out to other groundside construction
projects. And some can be used on projects which the company building
the SMF has on the ground.

You may be wondering about launch costs and so on. Well you are going to
have to launch consumable's up on a regular basis anyway, as there won't
be room to grow or manufacture anything ( other than what you are there
to make - why waste the space ) And as has been mentioned elsewhere if
you have a regular requirement for launching the costs are going to fall.

You may also wonder how the rotating shifts work in the beginning. Well
say that there is space for 30 people on the SMF when it is fully under
way. When the first components are launched ( assuming it is built here
and launched in bits ) and connected up not everything will be able to
be used straight away, some work will have to be done before the whole
thirty can move in. So you launch the first ten, when they get there
they get acclimatised and put the finishing touches to the station to
make it fully habitable.( also if there is something wrong with the
construction of the station 10 is easier to get back to earth than 30 )
After that they then start some minor manufacturing - minor because this
will be the first time something like this has been attempted and there
will be bugs to work out. And not to mention new techniques to be
applied. After the first four weeks the second crew arrive, by now the
first crew has some experience and can help show the second crew how to
adjust and what to avoid. The added numbers will add extra stresses to
the stations systems and these can be monitored to see if any changes
need to be made. Some larger manufacturing can be started as everyone
becomes familiar with things. Another 4 weeks and the third crew arrive.
They will not take as long to adjust to things as the second crew (
which would have adjusted quicker than the first crew ) By now most of
the bugs would have been ironed out of the station and with the
manufacturing techniques and things can get into full swing. Another
four weeks and the fourth crew arrives and the first crew leaves. The
second crew are now the most experienced , and the fourth the
inexperienced. This goes on and six months later the first crew arrives
again ( with some changes to personnel most likely ) and so on.

Another thing you could do is rotate the working times for each crew ie
the first crew work from 0:00 hours to 8:00 the second crew from 8:00 to
16:00 and the third from 16:00 to 24:00. The rest of the time would be
split to 4 hours before shift / 4 hours after shift and the rest
sleeping. You would then be able to have a third of the sleeping / mess
/ recreation ( gym ) areas than if they were all working the same
shift. The workers could use 2 hours before shift to exercise and 2
hours after shift. The rest would be for eating, watching tv , reading,
internet surfing , card games etc.

Every thing that can be done would be done telerobotically from Earth
which still leaves a lot of grunt work to do both inside the SMF and out.

I am assuming that the SMF would / could be used for several purpose's
these are - Manufacture of SSPS, Manufacture of Larger Stations and
other SMF's, Manufacture of craft that never enter the atmosphere and
Possibly for the maintenance of satellites.

Sorry to be so long winded but had to get that off my mind :)

I have been examining the use of various structural materials that could be used
for the construction of Pressure hulls for SMF's. An alloy usually associated
with marine work would seem to be a good choice. The alloy is a blend of 90%
Aluminium and 10% Magnesium. The alloy is heat treated at 425degC for 8 hours,
then cooled to 390degC and then quenched in oil at 160degC or in boiling water.
The Tensile strength of the alloy is 320N/mm2 when heat treated, and its
elongation at failure is 18%. Both Mg and Al can be found in abundance in lunar
highland materials.

Tony

Brett Sargeant wrote,

"Why would you have crew shifts of a year or more ? some people have
compared an SMF or island A to an oil rig situation - which if memory
serves me correctly have shifts of about 6 weeks."

It doesn't cost $100 million or more to fly a helicopter back and forth
between land and the offshore rig.

Ron Menich

Brett

04/27/01
03:46 AM
Please
respond to
ssi_list

* Warning somewhat long *

Why would you have crew shifts of a year or more ? some people have
compared an SMF or island A to an oil rig situation - which if memory
serves me correctly have shifts of about 6 weeks. I would have thought
for an SMF a better comparison would be a submarine. As far as I know
with a sub you are out no longer than 3 months. ( except in exceptional
circumstances )...

(Hi all. Sorry, I'm a new member. I usually intro myself before posting
but I don't have time right now. Just enough time for a little post.)

> Another thing you could do is rotate the working times for each
> crew ie the first crew work from 0:00 hours to 8:00 the second crew
> from 8:00 to 16:00 and the third from 16:00 to 24:00. The rest of
> the time would be split to 4 hours before shift / 4 hours after
> shift and the rest sleeping.

Why use weeks, months, years, and a 24 hour day? In space, you don't
need these time measurements. To wit:

24 hour day = rotation of the Earth
week = a religion-based measurement (see Genesis)
months = revolution of the Moon around the Earth
years = revolution of Earth around the sun

Why not create a "metric" time system? To wit:

1 metric year = OK, use the revolution of the Earth again
1 metric month = 1 deciyear = 1/10th of a year
1 metric week = 1 centiyear = 1/10th of a month
1 metric day = 1 milliyear = 1/10th of a week
etc.

Or keep a "24 hour day":

1 year = 1000 days
1 month = 100 days
1 week = 10 days (work 6, off 4, or whatever)
1 day = the same absolute length as now

Or whatever. Use the galactic year and break it down, if you like.
But why keep the current standards? Also, hasn't it been shown that
the human circadian rhythm is really more like 50-something hours
in length? I know that I personally would fare MUCH better if we had
something like 36 hour days.

Just ideas.

Darin Arrick
f r e e s p a c e f o u n d a t i o n @ y a h o o . c o m

> Why use weeks, months, years, and a 24 hour day? In space, you don't
> need these time measurements. To wit:
>
> 24 hour day = rotation of the Earth
> week = a religion-based measurement (see Genesis)
> months = revolution of the Moon around the Earth
> years = revolution of Earth around the sun
>

Actually the fundamental standard unit of time in metric is the
second. My desktop clock shows the time in seconds since January 1, 1970
(POSIX time() standard). Currently the time is 988839309. It'll roll
over the 1 Gigasecond mark later this year - time for a party? Note that
100 ksec is almost 28 hours, so a day based on seconds and simple powers
of 10 would be a bit longer than the typical Earth day. I suspect that
once we're pretty well established in space, something like the POSIX
time() standard is going to have a lot more influence (all our computers
will use it) than traditional Earth-based measures of time, but no doubt
a lot of people will keep those around for another few centuries for
old-times sake :-) Humans on Mars for example would likely take to
non-Earth time measures out of defiance (if not convenience).

Metric time schemes based on Earth days or years make much less sense
from the space perspective than one based on seconds, in any case.

Arthur