Environmental Engineering Reference
In-Depth Information
5 Bioregenerative Life-Support Systems
The nexus approach is applicable in bioregenerative life-support systems. Recy-
cling and utilizing the waste is integral to space agriculture for providing the life
support system through exploitation of the food-waste nexus on extraterrestrial
bodies (e.g., moon and Mars). The space agriculture technology is critical to
developing a Lunar Outpost for any space exploration initiative (Hossner et al.
1991 ). The goal of a nexus approach is to design a bioregenerative life-support
NASA developed a Controlled Ecological Life-Support System or CELSS for
long-duration human habitation on the moon or Mars. Salisbury ( 1992 ) outlined
some challenges and researchable priorities in designing a Lunar or Martian
microgravity CELSS. Technological challenges listed by Salisbury included: (1)
creation and control of gas composition (CO 2 ), light and the rooting media, (2)
equipment for waste recycling, (3) techniques for environmental monitoring and
control, and (4) identifying appropriate species, cultivars and optimal growing
conditions. Several life-support systems have been designed and technologies tested
for growing plants in space (Morrow et al. 1994 ) and for manned space missions
(Aydogan-Cremashi et al. 2009 ; Nelson et al. 2008 ). Simulation modelling has been
used to assess mass balance for a biological life-support system (Volk and Rummel
1987 ), the C balance in bioregenative life-support systems (Wheeler 2003 ), and
equipment for composting on Mars (Finstein et al. 1999a , b ), by the use of hyper-
thermic aerobic composting bacteria (Kanazewa et al. 2008 ). The
rst space veg-
etables were grown under the CELSS project by means of controlled environmental
conditions (Ivanova et al. 1992 ).
Principal researchable challenges include understanding the pedological,
microbiological and physiological processes under microgravity conditions (Hoson
et al. 2000 ; Maggi and Pallud 2010a , b ). It is important to understand the bio-
physical limitations in physiological transport and exchange processes of plants
growing in microgravity (Porterfield 2002 ). There is a need to understand the effects
of hypogravity on transpiration of plant leaves (Hirai and Kitaya 2009 ), water
distribution and
ow (Jones and Or 1999 ; Helnse et al. 2007 ), capillarity in porous
soil (Podolsky and Mashinsky 1994 ; Jones and Or 1998 ), water supply and sub-
strate properties in porous root matrix systems (Bingham et al. 2000 ), and mod-
elling heat and mass transfer for human habitation on Mars (Yamashita et al. 2006 ).
Since the discovery of water on the moon (Hand 2009 ) and Mars (Grotzinger
2009 ), there has been a growing interest in space agriculture. Using the principles of
bioregenerative strategies for long-term life support in extraterrestrial conditions,
soil-based cropping is considered a more effective approach for waste decompo-
sition, C sequestration, oxygen production and water bio-
ltration than those of
hydroponics and aeroponics cropping (Maggi and Pallud 2010a , b ). Silverstone
et al. ( 2003 ) proposed soil-based bioregenerative agriculture. The proposed closed
system included a wetland wastewater treatment system similar to that of the
Biosphere 2.
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