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宇宙海洋と宇宙養殖の概念
Concept of Space Ocean and Aquaculture
遠藤 雅人 1
Masato ENDO1
1

東京海洋大学 学術研究院 海洋生物資源学部門，Department of Aquatic Biosciences, Research Organization,
Tokyo University of Marine Science and Technology

1. Introduction
In this paper, the concept of the space ocean and aquaculture1) is introduced and also the technologicaldevelopment and future prospects of space aquaculture that will contribute to the establishment of the spaceocean, based on research conducted to date are explained.
2.

Space Ocean
There is a core biome as a concept of an artificial environment that cuts out the global environment as a place

where humans live outside of the earth. The hydrosphere in the core biome is called “the space ocean”.
Seawater is filled in a large pool, and selected aquatic organisms such as fish, crustaceans, and seaweed arereleased into it to build an ecosystem, and it is planned to simulate the global environment by exchanging
substances with the biome such as the land zone. As we look forward to long-term residence in space, theexistence of oceans or water bodies is considered important as a food source, a means of avoiding cosmic
radiations, and a place of relaxation.
However, in order to construct a space ocean based on the traditional idea of a core biome, which involves
carving out the Earthʹs ocean and selecting and incorporating various aquatic organisms into one hydrosphereto maintain an existing ecosystem, it is necessary to use groups of organisms that are less likely to migrate or
be predated, or envision expanding the vast ocean into space. In other words, if the space ocean is considered
as a copy of the Earthʹs ocean, the maintenance and management of the ecosystem becomes a major issue.
3.

Aquaculture in SpaceFor living on Mars or other planets, where it is difficult to smoothly supply resources due to the distancefrom the earth, a controlled ecosystem life support system CELSS that provides the place of human habitatand produces food with material recycling is necessary. Therefore, experimental studies with the aim ofdeveloping a higher-order food production technology of supplying animal protein by applying fish farming(Aquaculture) in space have been conducted. Aquaculture in space, it is conceived to produce individualorganisms at a high density, divide each organism and accommodate into modules, and control the movement
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First, our studies were aimed at producing of the edible fish, tilapia Oreochromis niloticus from their waste
by establishment artificial food chain. The assumed material flow from tilapia waste to their juveniles wasanalyzed using these experimental data. These results showed that 5.17% of nitrogen and 5.54% of phosphorus
excreted from reared tilapia are accumulated in tilapia fry in one food chain cycle. In addition, aquaponics,
which uses tilapia rearing water as liquid fertilizer for hydroponic cultivation of vegetables, has been studied
for a long time, and the use of these complex food production technologies also will be able to enrich the foodsituation in space.
Next, experiments using aircraft on tilapiaʹs swimming and feeding behavior under different gravity wasconducted. From the results, it was also clarified that swimming and feeding are possible by irradiating visible
light from one direction even under
microgravity and it is possible tomaintain their posture from about
0.1G,

and

under0.2Gunderwithout lighting. These results
suggest that tilapia show thenormal swimming and is possible
by fully adapting to the gravity ofthe moon and Mars (Figure 1).
In the future, it is necessary to
study aquaculture technology witha view to alternation of generations,assuming long-term fish breeding.

Figure 1. Application of tilapia aquaculture in space
4.

Conclusions
For establish a space ocean that simulates the Earthʹs ocean, it must be large enough to maintain a minimum

number of organisms at low densities for food chains and generational changes under low nutrient conditions.
The challenge is to maintain this ongoing ecosystem without causing it to collapse. The elemental technologyof space aquaculture that can reduce this scale and control material circulation in the food chain of theecosystem will contribute to the realization of not only material recycling-type seafood production in space inthe future, but also the space ocean. It is believed that this will greatly contribute to solving the various issues
required for its establishment.
References1)

M. Endo, R. Masuda and Y. Yamashiki: Space ocean and aquaculture. In Human Spaceology - Three Core
Concepts for Space Migration , Kyoto University Press (2023).
© 2023 by the authors. Submitted for possible open access publication under theterms and conditions of the Creative Commons Attribution (CC BY) license(http://creativecommons.org/li censes/by/4.0/).

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