Space Diet: Daily Mealworm (Tenebrio molitor) Harvest on a Multigenerational Spaceship

It has been proposed in recent years that insects are a viable food source that should be seriously considered for the future. Their high nutritional value, small size and rapid reproduction are also promising for space agriculture. In this paper, a possible future Multi-generational Spaceship with sufficient interior room to have an insect breeding room is considered. The insect of interest here is the mealworm (Tenebrio molitor), which has a very high protein content. The daily mealworm harvest aboard such a ship that satisfies the protein requirement of a stable crew population of 160 is approximated here to be ~162,000. There is also qualitative discussion of other considerations for a spaceship mealworm colony. Introduction Insects are included in the regular diet of approximately 2 Billion people, with a menu of close to 2000 edible species [1]. Yet, insect-eating, or entomophagy, has little popularity amongst Western cultures perhaps because of the perception of the practice being higher in gross factor than comfort factor. With human population growth and corresponding nutrition demands becoming an increasing concern, entomophagy has been proposed as a future sustainable food source [1]. Perhaps insect-eating is also a potential solution to nutrition for crew aboard spaceships, especially for long-duration travel [2]. Aboard spacecraft that are intended for longduration travel, sourcing food from stored stocks becomes less viable and there is an increased need for growing and harvesting food right there, with the application of bioregenerative models. However, there must be a compromise because there is limited space on the craft and energy consumption involved in agricultural practices is also limited by energy supply of the isolated ship. The insect that is considered here that can potentially form a staple part of the space crew diet is the mealworm. It is the edible larval stage of the Tenebrio molitor, a species of Darkling Beetle [3, 4]. The context for the paper’s calculation is drawn from a previously proposed multi-generational spaceship travelling for 200 years. Estimations according to anthropology and genetic studies have found that a minimum of 160 crew will maintain a stable, viable population [5]. The spaceship interior could be designed to include a mealworm breeding room. The main purpose of these mealworms will be to satisfy the protein demands of the crew. Here, the daily protein demand of the crew is estimated and the necessary daily output of the spaceship mealworm ‘farm’ is calculated. Daily Protein Requirements According to the Institute of Medicine, the recommended daily intake of protein for men and women in the age range of 17-90 are 56 and 46 grams/day respectively [6-7]. Assuming there are an equal population of men and women at any time, this means that in the 160 population, there are 80 men and 80 women. The total daily protein intake of the crew is shown in Table 1 below. Daily Mealworm Harvest Roasted mealworms have a protein content of 55.43 grams per 100 grams [8]. This is higher than meats such as chicken, pork and beef, which all have protein content in the range of 30-40g per 100g of meat [9]. Space Diet: Daily Mealworm Harvest on Spaceship, March 13 2015 Protein intake ( grams/day)