Recycling the Circulating Air
It is most important to control an atmosphere. Without air men die quickly. Perhaps the simplest way of proportioning O2 and CO2 is through plants. About 60 ft of leaves are needed to convert one human’s CO2 exhalations into O2 and Carbon in a plant’s tissues.
Illumination at the correct wavelength and of sufficient intensity is needed to cause plants to “inhale” CO2 through their stoma, and exhale O2. One of the most important mini-factories on the ship would manufacture and/or refurbish light bulbs, fluorescent tubes and such.
Recycling and purifying the circulating water
Filtering, clathrating (as with zeolites), evaporation of distillation, then finally filter cleaning and zeolite reactivation should suffice to keep drinking, cooking, washing, toilet, and other circulating waters sweet and clean.
Plants can enter the cycle by digesting mineral residue left after water, or watery substances, are respectively distilled or heated to dry ash.
Thermal and or electrical energy is needed to recycle water. It would be abundant – indeed – overly abundantly available.
Recycling of human, animal, and plant wastes or remains
Recycling of wastes and remains may be accomplished by a combination of bacterial digestion or thermal incineration. In both cases the remains would be fed to plants.
In the case in which all plants died catastrophically waste could be in incinerated and the ash stored, and/or dumped.
Food could be plentifully available as garden products including carrots, radishes, potatoes, beans, peas, lettuce, bonzi, lemons, oranges, lines, pears, apples, potatoes, rye, wheat, sorgum, barley, rabbits, chickens, catfish, snails, shrimp, and octopus.
Raising the food, maintaining seed stocks, caring for special plants such as bonzi citrus groves, would be hard, painstaking work, But perhaps rewarding for a lonely voyager.
Space to live in
Space would not only be ample for the retired explorer-engineer on a one-way retirement mission to the stars, it should, and certainly would be, interestingly comfortable. Somehow a frank Lloyd Wright of architectural layout and interior decorating will appear among humankind’s legions of skilled educated people who will design such quarters as a labor of love.
A sphere of 30 feet in diameter would accommodate four decks. This would be a vast region for a lone person.
Footnotes: CO2 (carbon dioxide) will be scrubbed out of the habitats atmosphere chemically as is done on Trident submarines. Hopefully the green plants will make the use of scrubbing unnecessary, and ideally the scrubbers will forever be on standby.