TY - JOUR
T1 - Modeling gravity effects on water retention and gas transport characteristics in plant growth substrates
AU - Chamindu, Deepagoda
AU - Jones, Scott B.
AU - Tuller, Markus
AU - De Jonge, Lis Wollesen
AU - Kawamoto, Ken
AU - Komatsu, Toshiko
AU - Moldrup, Per
PY - 2014
Y1 - 2014
N2 - Growing plants to facilitate life in outer space, for example on the International Space Station (ISS) or at planned deep-space human outposts on the Moon or Mars, has received much attention with regard to NASA’s advanced life support system research. With the objective of in situ resource utilization to conserve energy and to limit transport costs, native materials mined on Moon or Mars are of primary interest for plant growth media in a future outpost, while terrestrial porous substrates with optimal growth media characteristics will be useful for onboard plant growth during space missions. Due to limited experimental opportunities and prohibitive costs, liquid and gas behavior in porous substrates under reduced gravity conditions has been less studied and hence remains poorly understood. Based on ground-based measurements, this study examined water retention, oxygen diffusivity and air permeability characteristics of six plant growth substrates for potential applications in space, including two terrestrial analogs for lunar and Martian soils and four particulate substrates widely used in reduced gravity experiments. To simulate reduced gravity water characteristics, the predictions for ground-based measurements (1 _ g) were scaled to two reduced gravity conditions, Martian gravity (0.38 _ g) and lunar gravity (0.16 _ g), following the observations in previous reduced gravity studies. We described the observed gas diffusivity with a recently developed model combined with a new approach that estimates the gas percolation threshold based on the pore size distribution. The model successfully captured measured data for all investigated media and demonstrated the implications of the poorly-understood shift in gas percolation threshold with improved gas percolation in reduced gravity. Finally, using a substrate-structure parameter related to the gaseous phase, we adequately described the air permeability under reduced gravity conditions.
AB - Growing plants to facilitate life in outer space, for example on the International Space Station (ISS) or at planned deep-space human outposts on the Moon or Mars, has received much attention with regard to NASA’s advanced life support system research. With the objective of in situ resource utilization to conserve energy and to limit transport costs, native materials mined on Moon or Mars are of primary interest for plant growth media in a future outpost, while terrestrial porous substrates with optimal growth media characteristics will be useful for onboard plant growth during space missions. Due to limited experimental opportunities and prohibitive costs, liquid and gas behavior in porous substrates under reduced gravity conditions has been less studied and hence remains poorly understood. Based on ground-based measurements, this study examined water retention, oxygen diffusivity and air permeability characteristics of six plant growth substrates for potential applications in space, including two terrestrial analogs for lunar and Martian soils and four particulate substrates widely used in reduced gravity experiments. To simulate reduced gravity water characteristics, the predictions for ground-based measurements (1 _ g) were scaled to two reduced gravity conditions, Martian gravity (0.38 _ g) and lunar gravity (0.16 _ g), following the observations in previous reduced gravity studies. We described the observed gas diffusivity with a recently developed model combined with a new approach that estimates the gas percolation threshold based on the pore size distribution. The model successfully captured measured data for all investigated media and demonstrated the implications of the poorly-understood shift in gas percolation threshold with improved gas percolation in reduced gravity. Finally, using a substrate-structure parameter related to the gaseous phase, we adequately described the air permeability under reduced gravity conditions.
KW - Gas diffusivity
KW - Percolation threshold
KW - Plant growth media
KW - Reduced gravity
U2 - 10.1016/j.asr.2014.04.018
DO - 10.1016/j.asr.2014.04.018
M3 - Journal article
AN - SCOPUS:84904048266
SN - 0273-1177
VL - 54
SP - 797
EP - 808
JO - Advances in Space Research
JF - Advances in Space Research
IS - 4
ER -