Mars Astrobiology: Recent Status and Progress - Planetary Exploration and Science: Recent Results and Advances - page 229

was launched on Space Shuttle Endeavour during the STS-130 mission and was
performed on the ISS during Expedition 22. Frozen plant samples from the TROPI
experiment were returned on the landing of the STS-131 mission on Space Shuttle
Discovery.
Arabidopsis thaliana seeds (thale cress, the genome of which has been DNA
sequenced as a reference organism for the study of plant biology and genetics)
were germinated and grown under various lighting and gravity conditions, using
centrifugal gravity simulation and LEDs of various wavelengths (colors) and
intensities to model lighting conditions. The specific aim of this project was to
investigate phototropism in plants grown in microgravity conditions without the
complications of a 1-g environment. Experiments performed were used to explore
the mechanisms of both blue-light- and red-light-induced phototropism in plants.
John Z. Kiss of Miami University (Oxford OH) is the principal investigator;
Richard E. Edelmann of Miami University and Melanie J. Correll of the University
of Florida are coinvestigators; Kenny Vassigh of NASA is the project manager,
and Marianne Steele of NASA is the project scientist. The payload was developed
by the NASA Ames Research Center, Moffett Field, California. The experiment
was performed in the European Modular Cultivation System (EMCS) built by the
European Space Agency (ESA). The Norwegian User Support Operation Centre
(N-USOC), located in Trondheim, Norway, controlled the EMCS during the TROPI
experiments on the ISS.
In the long term, the results from TROPI will help in the development of future
space, Moon, and Mars life-support systems, in which plants are used to help
remove carbon dioxide and generate oxygen via photosynthesis for maintenance
of atmospheric and other conditions, reducing the need for very expensive resupply
from Earth.
Zero-g strong effects became apparent when plants were germinated and grown
in space: plants do grow under microgravity conditions but not normally and the
problems become more severe the longer the duration. When plants are grown
during space flight, roots are typically disoriented while shoots may orient to a light
source. Root and shoot growth is often less in space, but the rate of development
and aging may be faster. Deterioration and death of plants are common. Lignin and
cellulose are reduced with thinner cell walls resulting. And there is altered flow of
water and minerals around the roots and through the plant and out the leaves (Raven
et al. 1986 ). But those studies are only through 0 g (de Morais 2004 ).
All influent characteristics of Mars, except its gravity, can be simulated on
Earth's ground. There are no ways for doing these fundamentally necessary long-
term studies with 0.38 g using the present-day space vehicles; the only capable one is
the ISS, which accommodates two biological facilities built by ESA - the European
Modular Cultivation System (EMCS) and the Biological Experiment Laboratory
(BioLab) (de Morais 2004 ).
EMCS was launched to the ISS on the STS-121 mission in July 2006. BioLab
was pre-installed inside the Columbus laboratory, and Space Shuttle Atlantis on ISS
Assembly Flight 1E, mission STS-122, successfully delivered the Columbus module
to the ISS on February 9, 2008.