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宇宙に地球の生態系は必要か？
Do We Need a Terrestrial Ecosystem ?
山敷庸亮 1
Yosuke YAMASHIKI 1
京都大学大学院総合生存学館 SIC 有人宇宙学研究センター，
SIC Human Spaceology Center, Graduate School of Advanced Integrated Studies in Human Survivability#1,1

1.

Three “Core” Concepts and Terrawindows

When planning planetary migration, it's essential to develop self-sufficient systems on other planets without
relying on Earth for resources like food or construction materials. This system, known as the "core biomecomplex," includes both the life-support system and the global ecosystem. The necessary technology for
maintaining life is termed "core technology." Together, these form the "core society," a self-sufficient systemvital for establishing a "space society."
Figure 3 Terraforming vs terrawindowsThe"core biome complex" simplifies the Earth's ecosystem by focusing on essential functions and is categorized
into "Standard Biome," "Extreme Biome," and "Habitable Biome." To support human life in space, key
technologies include space radiation protection
and artificial gravity, which are integral once lifesupporting systems are established. Additionally,
space law, sociology, and space medicine are
crucial for sustaining relocated societies.
Maintaining a space ecosystem raises challenges,
such as controlling pests and managing
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pathogenic microorganisms. Introducing Earth's ecosystem to another planet is akin to an alien species
invasion, raising concerns about Planetary Quarantine. Reproducing Earth's environment on a target planet
may be best achieved through a completely enclosed dome structure, termed "Terrawindows," which isdistinct from "Terraforming."
2.

Natural capital classification & Life supporting classification
The idea of bringing an ecosystem into space was firstLong-term Life Support System in Space
Combining Phy,s Chem/Bio, ECLSS, &, Core Biomes

Maintain
Oxygen level
Biodiversity

ForestEstuary
BayStreamPhys
ChemECLSS

StableMechanical
Needs maintenance

BIO
ECLSS

Unstable
BiologicalLess maintenance*

Earth's nature. This division is called "natural capitalclassification." In contrast, "life supporting classification"
focuses on essential functions for human survival, such as

Sunlightzone

SpaceCity
Mangrove

Pond
Lake

like ocean, forest, savanna, and estuary, representing

Backup system forSpace Survivability
By ECLSSCore Biome SelectedDesert

realized in Biosphere 2, which was divided into modules

food production and oxygen generation.

Coralreef

RiverBlue
green
algae

Producing Recycling Removing
Rockyarea

Water

OxygenSpace station construction and almost all current space

CO2

manned mission systems are being designed based on "lifesupporting classification." However, for planetary migration, the "natural capital classification" will needconsideration. At the same time, challenges with this approach include maintaining oxygen levels andnecessary biomass, as untouched nature cannot sustain the current population in space due to the low
efficiency of each compartment of a natural system. Therefore, integrating "life supporting classification" iscrucial, and resolving this contradiction is key to constructing a core biome in space.
1.1 Natural Capital Classification
In the "natural capital classification," as seen in Biosphere

Three core concepts
Purpose-oriented classification2, each ecosystem is classified similarly to Earth's. The
Ocean, Forest, Savanna, and Estuary modules wereTo increase
efficiency forfoodproduction

Space
Agriculture

To increase
efficiency forfood
production

DesertForest

To improve
efficiency for
Oxygenproductionhydrologically connected. However, maintaining thisconnection in Biosphere 2 altered the salinity of the Ocean
Space
Aquaculture

module,highlighting

thechallengeofaccurately

replicating Earth's 70% ocean and 30% land ratio

Ocean(ocean/rand ratio equals to 2.4). This imbalance and theBIO
ECLSS

scarcity of water make it difficult to maintain such a ratio
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in space – which makes it difficult to maintain and“artificial” hydrological system with correct salinity in a small ocean. As a compromise, Biosphere 2, whereocean/land ratio is just 0.2, focused on coastal ecosystems, but this led to the separation of land and ocean
water cycles. The rainforest module, with its high biomass productivity, was separated from other modules tomaintain temperature and humidity. Initially, 300 tree species coexisted, but now only around 100 species
remain. Insects were introduced instead of animals due to their lower biomass consumption, but pollination
has not been fully studied.
The ocean module was independent, featuring a wave-making device (artificial waves are essential for marine
2 of 3ecosystems), 7m water depth, and aeration. These features are crucial because water circulation doesn't occur
naturally in the artificial ocean, necessitating constant energy input to maintain water quality and oxygen
levels.
In these ecosystems, creating a mass balance is essential, particularly in modeling and monitoring the oxygen,carbon, nitrogen, and phosphorus cycles. This ensures the oxygen concentration necessary for the survival of
aerobic organisms, including humans.
Even if we try to "bring in an ecosystem" or "simulate the Earth's ecosystem," engineering technology is stillrequired to ensure human survival in a confined space. However, we should note that sometimes “engineeringtechnologies” and “human favorable” nature does not fit for the “ideal” natural ecosystem where“biodiversity” become an essential parameter for its existence.

References1)
2)

Yamashiki Yosuke et al.: Human Spaceology, three “core” concept for the space migration, 1 st Ed. Kyoto University
Press (2023)
Zabel Bernd et al. Construction and engineering of a created environment: Overview of the Biosphere 2 closedecosystem. Ecological Engineering 13 43-63. (1999)© 2024 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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