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Re: I found the food numbers!

>I found the analysis I did on food mass numbers!!!
> Date	6/29/95 Subject	Food Mass
>The farms discussed in the "Space Settlements: A design study" (the book I
>reference frequently, and STRONGLY recommend) lists the farm mass per
>person at about 36 tons of which 22 tons is soil.  The farm includes
>everything from farm animals to fish, and all normal grains and vegetables.
>The idea was to make it capable of providing all normal food needed for a
>standard North American diet for a population of 10,000.  Said diet
>according to their numbers weighed about 1.67 tons per-person per year.
>They also assumed that with intensive care this farm could produce twice
>the yield of the best farms on earth.
> Now we found that rations for field troops or explorers weighed about 2.2
>kilos per day (.8 tons per year) and dehydrated could be a lot less.  But
>over all; 36 tons per person is about 21 years of food mass at their 1.67
>tons per year, or 45  food years at our .8 tons per year.  I'm not even
>going to bother with freeze dried numbers.  We won't want to be out that
>long!  Even if you assume no soil.  The mass is still 14 tons per person.
>Which comes to 8.38 year of 1.67 tons per year food years, or 17.5 years at
>our .8 tons per year.  Then I realized that the farm design required
>doubling the internal volume of the hab centrifuge. Which would add another
>20 to 230 tons per person!  (the latter if you shielded the farm
>Any way I ran it, the mass for a transportable, self sustaining farm, wound
>up greater than the stored food mass for the duration of our projected
>missions. Given that the stored mass would decline as the mission went on
>(on good thing for the return flight), stored food would be simpler and
>more reliable than trying to maintain a running farm during a mission, and
>the farm would almost double the size of the full g gravitation sections
>needed in the ship.  I decided to dump the idea and assume ultra frozen and
>dried foods stored in the zero g section of the ship.  We could have a
>couple gardens for fun and fresh Veggies, but I'd assume they were just a
>couple plants in the corner of peoples apartments.  You might do an
>analysis to see if hydroponics for the vegies would weigh less than storing
>frozen veggies.  I.E. we store the meat, flour, rice, milk, ect.., but grow
>the fruits and vegetables.  But for my porpoises I assumed the mass numbers
>wouldn't show an advantage.
>Oh, while on the topic of Mass.  The drive system people seem to be going
>through hoops to build a huge, high efficiency (relativistic exhaust)
>engine to keep the necessary reaction mass amounts down to grams per day.
>I would suggest that if we aren't going to recycle our -- ah-- food by
>products.  The crew will be providing a few tons of usable mass per day.
>Dehydrate, incinerate to plasma or ionize, and pump it into the
>accelerator.  With an electro-magnetic accelerator (as apposed to a thermal
>rocket) the type of mass used is unimportant, and for ship design purposes
>using the same stored mass to feed the crew and drive system is very
>elegant and efficient.

Reply to Kelly

If we dump our "waste" into the fuel hopper we lose all that water that we
are going to need unless you plan to squeeze all the water out first. I'm
not adverse to putting unusable waste into the "fuel chain" for the ship but
lets be sure we don't need it for other reasons first, please.