Numerical constraints on the size of generation ships from total energy expenditure on board, annual food production and space farming techniques

TL;DR

This paper estimates the required onboard agricultural space for a generation ship to sustain a crew of 500 through farming techniques, using an advanced simulation model to ensure long-term food security during interstellar travel.

Contribution

It introduces an updated HERITAGE model that accounts for biological and demographic factors to predict onboard food production needs for interstellar generation ships.

Findings

0.45 km² of artificial land is sufficient for a crew of 500.

A combination of aeroponics and conventional farming can meet dietary needs.

The model accurately estimates caloric requirements based on crew demographics.

Abstract

In the first papers of our series on interstellar generation ships we have demonstrated that the numerical code HERITAGE is able to calculate the success rate of multi-generational space missions. Thanks to the social and breeding constraints we examined, a multi-generational crew can safely reach an exoplanet after centuries of deep space travel without risks of consanguinity or genetic disorders. We now turn to addressing an equally important question : how to feed the crew? Dried food stocks are not a viable option due to the deterioration of vitamins with time and the tremendous quantities that would be required for long-term storage. The best option relies on farming aboard the spaceship. Using an updated version of HERITAGE that now accounts for age-dependent biological characteristics such as height and weight, and features related to the varying number of colonists, such as infertility, pregnancy and miscarriage rates, we can estimate the annual caloric requirements aboard using the Harris-Benedict principle. By comparing those numbers with conventional and modern farming techniques we are able to predict the size of artificial land to be allocated in the vessel for agricultural purposes. We find that, for an heterogeneous crew of 500 people living on an omnivorous, balanced diet, 0.45 km2 of artificial land would suffice in order to grow all the necessary food using a combination of aeroponics (for fruits, vegetables, starch, sugar, and oil) and conventional farming (for meat, fish, dairy, and honey).