Agricultural and other experiments relating to the development of a controlled ecological life support system (CELSS) were proposed. The engineering feasibility of each proposal was investigated by a CELSS experiment concept met study group. The CELSS experiment concept to clarify the goals of CELSS and to determine three phases to achieve the goals. The resulting phases, or missions, and preliminary proposals and studies needed to develop a CELSS are described

Nitta, K.

Ohya, H.

Oshima, T.

English

NASA Technical Reports Server

SURVEY OF CELSS CONCEPTS AND PRELIMINARY RESEARCH IN JAPAN 
Haruhiko Ohya·, Tairo Oshima •• and Keiji Nitta ••• 
·Department of Chemical Engineering, Yokohama National University, Hodogaya, 
Yokohama 240, Japan, ··Laboratory of Chemistry for Natural Products, Tokyo 
Institute of Technology, Nagatsuda, Yokohama 227, Japan, ••• Space Technology 
Research Group, National Aerospace Laboratory, Chofu, Tokyo 182, Japan 
ABSTRACT 
Many agricultural and other experiments relating to the development of a Controlled 
Ecological Life Support System (CELSS) were proposed by scientists throughout Japan in the 
fall of 1982. To develop concrete experimental concepts from these proposals, the 
engineering feasibility of each proposal was investigated by a CELSS experiment concept 
study group under the support of the National Aerospace Laboratory. The conclusions of the 
group were described in two documents, /1/, /2/. Originally, the study group did not 
clearly define necessary missions leading to the goal of an operational CELSS for 
spaceflight. Therefore, the CELSS experiment concept study group met again to clarify the 
goals of CELSS and to determine three phases to achieve the goals. The resulting phases, or 
missions, and preliminary proposals and studies needed to develop a CELSS are described 
herein. 
INTRODUCTION 
Since 1982 a study group in Japan examined proposals for the development of a CELSS, and the 
problems regarding the stability of the CELSS experiment model 12/. The general conclusions 
from the discussions were as follows: 
1) The final targets of three necessary phases, or missions, should be more clearly 
defined to provide guidelines for technology development. 
2) A water recycle system for urine and waste water purification should be developed to 
save water transportation costs. 
3) A gas recycle system, containing gas separation capabilities, gas reservoirs, and 
pressure regulators, should be introduced to maintain air composition and pressure. 
4) Waste management systems should reduce methane gas and organic sludge produced from 
a microbial waste management system. Therefore, incineration and wet oxidation methods are 
preferable to other methods as the primary waste processor for CELSS systems. 
Based on these considerations and on an assessment of state of the art, three phases, or 
missions, are suggested, /1/, /2/. 
THREE MISSIONS 
The most essential parts of CELSS are the systems for food production and for gas conversion 
from carbon dioxide to oxygen by plants and algae through photosynthesis. However, data on 
the morphogenesis and physiology of higher plants and algae in the space environment are not 
complete at the present time. Three missions are suggested to establish an operational 
CELSS for spaceflight. (' 
The first mission should be conducted during 1991-1995. The purpose of this phase is to 
evaluate plant and algae cultivation methods and to summarize available data about the 
stability of photosynthesis in space. The problems of propagation in a microgravity 
environment is also to be studied during this phase. 
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The second mission, a CELSS-dedicated missio~, should be conducted during 1995-1998. The 
purpose of this phase is to check the feasibility of a micro closed ecology using animal and 
aquatic subjects instead of human beings. In this mission, non-biological waste management 
and recycling systems should also be tested and evaluated in the space environment. 
The third mission should demonstrate the feasibility of a complete CELSS system. This phase 
should be conducted in a CELSS-dedicated module after 1999 and is intended to develop the 
future technology needed for construction of a lunar base or an advanced space station. In 
this mission, the main food supply and gas conversion from C02 to 02 for one man will be 
based on the photosynthesis of plants and algae. Necessary animal protein could be produced 
by small animal and fish breeding colonies. A microbial waste management experiment, an 
immobilized-enzyme bio-reactor experiment, and plant cell (or tissue) CUltivation 
experiments for future food production should also be conducted in this dedicated module. 
Plant species which grow well and are stable should be selected for the third mission from 
the results of the first and second phase missions. 
ARCHITECTURE OF EACH MISSION 
The First Mission 
Two kinds of experimental equipment: (1) A phytotron (for plant cultivation), and (2) an 
algae cultivator (for algae cultivation), are essential to conduct the first phase, or 
mission. (Fig. 1). In addition, an artificial light supply system is needed to maintain 
control over light intensity and duration, and thereby control photosynthetic productivity. 
Other equipment such as a data management system, an enclosed work bench (a zero-gravity 
fume hood), a refrigerator, and a solar light supply system are required for this mission. 
This equipment is also required for other life science missions. 
Second Mission 
In this phase a closed ecological system experiment should be composed of gas and water 
recycling systems, in addition to the algae cultivator, and the phytotron for cultivation of 
higher plants. 
1) In the zero-gravity field small animals, plants and algae will be used as the 
bio-species in the micro ecology system (Fig. 2-A). A sufficient food supply for animals 
may not be possible by plant cultivation. However, this experiment should require complete 
gas recycling between the respiration of small animals and the photosynthetic gas conversion 
of algae and plants. Feces and urine will be processed by the waste management and water 
recycling systems. Food will be supplied from outside the experimental system. 
2) In an artificial gravity field produced by a rotating drum, higher plant cultivation 
equipment (a phytotron) should be installed for investigating the behavior of plants. (Fig. 
2-B) • 
The Third Mission 
To demonstrate the one-man life support capability of CELSS, a large area is required for 
food production by a plant cultivator. Therefore, a large-scale facility in a 
CELSS-dedicated module must be used for this mission. 
For this demonstration (Fig. 3), a waste management system will be added with gas and water 
recycling systems in the environment control section of the module. The biological species 
section of the module will contain a large-scale plantation facility, algae cultivation 
equipment, and small-animal and fish vivariums. Solar light can supply the light source for 
photosynthesis. 
The experimental and support equipment and systems for each of the three missions are listed 
in Table 1. 
TABLE Devices Required for Each CELSS Mission 
Mission 
Mission 2 
Mission 3 
Phytotron 
Algae Cultivator 
Data Management System 
(including TV/VTR Equipment) 
Artificial Light Supply System 
Phytotron 
Algae Cultivator 
Fish Breeding Equipment 
Small Animal Vivarium 
Rotating. Drum 
Data Management System 
(including TV/VTR Equipment) 
Solar Light Supply System (possibly) 
Waste Management System 
Water Recycle System 
Gas Recycle System 
Enclosed Work Bench 
Refrigerator 
Large Scale Rotating Plantation Facility 
Callus Cultivator 
Algae Cultivator 
Fish Breeding Equipment 
Small Animal Vivarium 
Human Subject 
Rotating Drum 
Data Management System 
(including TV/VTR Equipment) 
Solar Light Supply System (possibly) 
Waste Management System 
Water Recycle System 
Gas Recycle System 
Microbial Waste Management Equipment 
Immobilized Enzyme Bioreactor 
Galley 
Shower 
Toilet 
PRELIMINARY DESIGN WORK AND SYSTEM INTEGRATION FOR EACH MISSION 
The requirements for experimental devices and systems were deduced by the CELSS concept 
study group considering the developmental steps of CELSS technology and the need to limit 
initial development costs. Based on these requirements, systems were designed by four 
manufacturers: Hitachi Ltd., Mitsubishi Electric Ltd., Kawasaki Heavy Industry, and 
Mitsubishi Heavy Industry. These companies were asked to determine the measuring 
instruments required on the mission, and to estimate the weight, size, shape and electric 
power requirements for each experimental device or system. 
The experimental equipment should be installed and integrated in the experimental module as 
easily as possible. Therefore the location of each device must be determined with the 
following considerations in mind: 
1) Experimental procedures 
2) Functions of each device 
3) Weight of each device 
12 
13 
4) Power consumption 
5) Size of each device. 
An example of equipment integration in a typical Spacelab or space station module is shown 
in Fig. 4. 
PROPOSALS AND PRELIMINARY STUDIES MADE BY INDIVIDUAL RESEARCH GROUPS 
The following is a summary of CELSS-related studies in Japan. 
1) An example of a biological recycling system is shown in Fig. 5. This system, 
proposed by Prof. Yatazawa of Nagoya University, consists of various living organisms and a 
number of biological subsystems (S/S). Attention should be paid to the inclusion of the 
following: 
a) Biological nitrogen fixation by Azolla-Anabaena symbiosis (S/S 2) 
b) Sodium extraction by edible halophytes, plants native to salt marshes or 
alkaline soils (S/S 5) 
c) Cellulolytic food production by mushroom fungi (S/S 4). 
2) Dr. I. Endo of the Chemical Engineering Laboratory, Institute for Physical and 
Chemical Research, has proposed the use of algae (Spirulina sp.) for the production of 
oxygen and foods. Dr. Endo and his collaborators have carefully considered zero gravity 
and other environmental conditions in the space station. His system includes many 
experimental and measuring devices requiring very few operators for control. Computer 
hardware and software has been developed for monitoring cultivation of Spirulina sp. A 
computer model has calculated the size of a fermentor, the volume of the gas reservoir, the 
size of the tank for the medium, the size of the waste water tank, methods for cultivation, 
light supply characteristics, fermentor agitation, separation methods for algae, methods of 
oxygen removal, and the characteristics of automatic monitoring and control of the system. 
One of the most difficult problems is contamination by bacteria in a space environment. 
These studies are continuing with the collaboration of the Institute of Physical and 
Chemical Research and the National Aerospace Laboratory. 
3) To study the suitability of various crop species and their nutrient balance, 
scientists affiliated with Japan's Ministry of Agriculture and the Departments of Forestry 
and Fisheries have investigated a wide range of crop species for nutrition and ease of 
planting in space. As an example, the relative advantages of growing the sweet potato in 
space follows. 
The sweet potato provides a lower moisture content and greater food energy than the 
white potato. Two kg of sweet potato supplies 2400 Kcalj various nutrients such as 24 g 
protein, 4 g fat, 600 mg calcium, 10 mg iron, 0.2 mg carotine, 2 mg Vitamin Bl, 1 mg Vitamin 
B2, 600 mg Vitamin C, and about 1400 g of water. Although protein, fat and carotine vary 
with species variety and cultivation methods, it may be possible, through selective breeding 
in space, to increase the nutritive value of the crop. 
The sweet potato also has the advantage of having edible leaves and vines, as well as 
the tuber. If a variety of sweet potato with good cultivation characteristics under the 
weightlessness of low gravity can be selected, it may well become the "First Crop in Space." 
4) As a possible life support system in space, a biochemical oxygen and carbon 
recycling apparatus has been proposed by Prof. T. Oshima of Tokyo Institute of Technlogy. 
This apparatus is intended to replace living plants or algae. The first unit in the 
bioreactor is for photoreaction and oxygen generation. It is composed of a chloroplast 
suspension (a film of immobilized chloroplast particles), used to produce molecular oxygen, 
ATP and NADPH under sunlight. The second unit is composed of immobilized enzymes, or 
possibly whole cells which fix C02 into organic compounds using the supply of ATP and 
NADPH from the first unit. The advantages of the bioreactor system over living organisms 
are: 
a) Bioreactors are easier to control and more stable than living organisms 
b) Weightlessness may not seriously affect the reactors. 
In cooperation with Mitsubishi Electric Company (Drs. 
model experiment is being designed for space station. Fig. 
bioreactor system. 
s. Isoda and M. Maeda), a 
6 shows a rough sketch of the 
Production of oxygen and reduced compo~d(s), especially molecular hydrogen, from 
chloroplast particles has been studied by many researchers, Therefore Dr. Oshima and his 
colleagues have focused their attention on the second reactor in the system. Based on 
stabilized enzyme systems from thermophilic algae (Synechococcus lividus), isolated from a 
hot spring and grown at 55 0 C, is immobilized in an agarose matrix and then treated at cold 
temperatures to damage the cell envelopes. The immobilized cells are incubated in the 
presence of ATP, NADPH and carbonate ion. Theoretically, glucose will be produced from 18 
ATP and 12 NADPH according to the following formula: 
Hydrogen bacteria, especially a thermophilic strain, is also considered as an enzyme source 
for the"second unit. A preliminary design for this bioreactor is shown in Fig. 7. 
REFERENCES 
1. Mission Model Study for Space Station. MSS-SS-01. Report -- Japan Space Station Task" 
Force, National Aerospace Lab., Tokyo, Japan, 1981. 
2. Preliminary Concepts of Space Station Missions. MS-SS-02. 
Concept Study Group, National Aerospace Lab., Tokyo, Japan. 
Nutrient 
Solution 
Nutrient 
Solut ion 
Report -- CELSS Experiment 
1981. 
Fig .1. First phase experimental concept 
Feces 
Urine 
Water Recycle 
SY' tem 
Fig.2. Second phase experimental concept 
14 
15 
111 CO2 
I 
J Gas Recycle Syslem ~ 102 
Water ICOZ I Human 8"n9 J r-I Water Reclc,e System I 
I Primace) 
1 I Enviro mentol Conlrol W Waste Monagement System I CO2 Section I Urine 
I Feces 
I 
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:Foad Planti n9 Seetio n 
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I 
I D2 I 
t:S I I Anlmol Vivarium CO:> 1----- -
I 
I 
I 02 I 
L..---__ Fish Breeding Equipment I CO2 
Fig.3. Third phase experimental concept 
LOW GR"VITY 
~EN£RA7ING 
SYSTEM 
~. STORAGE 
LOW-G 
COHTROLLER 
WATER 
RECYCLE 
SYSTEM 
ARTlfIClAl. 
LIGHTING 
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STOR"G£ 
ALGA E 
FIBER AND V'fR HANAGEHENT RECYCLE CULTIVATION 
SMALL SYSTEM SYSTEM EQUIPHENT 
ANIMAL 
VIVARIUM 
Fig.4. The second time phase mission experiment integration 
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Fig.5. Proposed scheme of controlled 
ecological life support system 
Fig.6. Schematic diagram of a 
bioreactor system using 
immobilized enzymes 
Membrl;ne 
RUC10r 
Pump 
Mlcroprocessor-
Controller 
, t 
PteaUI'e Bome 
Flow Melef 
,:&1~ 
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Enzyme [mmobilzing Bioreoctor Equipment 
ATPaNAQPH "-
reserving column 
column 
washing 
reservoir 
glucose seporaTion column 
enzyme reactor 
terrperature a spin rote a:rnroller 
elution buffer cylinder 
CO. a buffer cylinder 
o. reservoir a water cylinder 
chloroplast membrane reactor 
gas exchange unit 
light supply unit 
:":;;:::::;'~;-system controller 
200 
emperature a 
spin rare control \er 
Fig. 1. A proposed design for the bioreactor experiment using immobilized enzymes. 
16 


Survey of CELSS Concepts and Preliminary Research in Japan

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