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Technical Paper

Rapid Microbial Analysis during Simulated Surface EVA at Meteor Crater: Implications for Human Exploration of the Moon and Mars

Procedures for rapid microbiological analysis were performed during simulated surface extra-vehicular activity (EVA) at Meteor Crater, Arizona. The fully suited operator swabbed rock (‘unknown’ sample), spacesuit glove (contamination control) and air (negative control). Each swab sample was analyzed for lipopolysaccharide (LPS) and β-1, 3-glucan within 10 minutes by the handheld LOCAD PTS instrument, scheduled for flight to ISS on space shuttle STS-116. This simulated a rapid and preliminary ‘life detection’ test (with contamination control) that a human could perform on Mars. Eight techniques were also evaluated for their ability to clean and remove LPS and β-1, 3-glucan from five surface materials of the EVA Mobility Unit (EMU). While chemical/mechanical techniques were effective at cleaning smooth surfaces (e.g. RTV silicon), they were less so with porous fabrics (e.g. TMG gauntlet).
Technical Paper

Fluid Behavior Under Microgravity Conditions Within Plant Nutrient Delivery Systems: Parabolic Flight Investigations

We report here on a series of KC-135 parabolic flight studies investigating various aspects of water distribution in plant nutrient delivery systems being developed for spaceflight applications. Several types of porous tubes were evaluated. Under microgravity conditions, fluid was observed to creep up the end walls of polycarbonate substrate compartments. Capillary mats wrapped around the porous tubes wetted up in a uniform fashion regardless of the level of gravity to which they were being exposed, and they were found to eliminate the end-wall creep wetting-up pattern. Results from observations using 1-2 mm glass beads and 1-2 mm Turface substrates are presented. The Turface’s absorption of water effectively minimized fluid redistribution as the compartment alternated between microgravity and 1-1.8g conditions.
Technical Paper

Examining Dehydration and Hypoxic Stress in Wheat Plants Using a Porous Tube Plant Nutrient Delivery System Developed for Microgravity

The Porous Tube Plant Nutrient Delivery System (PTPNDS) was designed for NASA to grow plants in microgravity of space. The system utilizes a controlled fluid loop to supply nutrients and water to plant roots growing on a ceramic surface moistened by capillary action. Utilizing remote sensing systems, spectral analyses procedures, gas-exchange, and fluorescence measurements, we examined differences in plant water status for wheat plants (Triticum aestivum, cv. Perigee). These plants were grown in a modified growth chamber during the summers of 2003 and 2004. Some differences in plant performance were detectable in the gas-exchange and fluorescence measurements. For instance, in both years the plants grown with the most available water had the lowest rates of photosynthesis and exhibited higher proportions of non-photochemical quenching, particularly under low light levels.
Technical Paper

Evaluation of a Pulse Fertilization Strategy for the Cultivation of Plants in Space

The recycling of water will be critical for the successful long-term cultivation of plants in space. The capture of transpired water via humidity control systems and subsequent refilling of water reservoirs feeding into plant nutrient delivery systems is an approach that accomplishes this objective, but results in a progressive dilution of the nutrient levels initially present. As part of pre-spaceflight protocol development efforts for the Water Offset Nutrient Delivery ExpeRiment (WONDER), we have evaluated the reestablishment of reservoir nutrient concentration levels via the periodic injection of 60 and 90 mL pulses of concentrated (10x) Hoaglands nutrient solution. In space this will involve crew-facilitated injections via a quick disconnect port on the payload's front panel. A study demonstrating the efficacy of this approach is presented using wheat grown on porous tubes.
Technical Paper

Evaluation of Two Soil Moisture Sensor Designs for Spaceflight Applications

A study was conducted evaluating the Temperature and Moisture Acquisition System (TMAS; Orbital Technologies, Madison, WI) and the Specific Heat Sensor (Thermal Logic, Pullman, WA) for root zone moisture level monitoring. Each design used a heat pulse and measured the transient temperature response to determine soil moisture changes. The sensors were placed in a polycarbonate compartment filled with oven-dried 1-2 mm Turface. Data was collected from the dry media, then the media was saturated with water and evaporation was monitored using the sensors and a digital balance. Generally, the TMAS sensors tended to over-estimate, while the Thermal Logic sensors under-estimated changes in soil moisture.
Technical Paper

Comparison Studies of Candidate Nutrient Delivery Systems for Plant Cultivation in Space

A reliable nutrient delivery system is essential for long-term cultivation of plants in space. At the Kennedy Space Center, a series of ground-based tests are being conducted to compare candidate plant nutrient delivery systems for space. To date, our major focus has concentrated on the Porous Tube Plant Nutrient Delivery System, the ASTROCULTURE™ System, and a zeoponic plant growth substrate. The merits of each system are based upon the performance of wheat supported over complete growth cycles. To varying degrees, each system supported wheat biomass production and showed distinct patterns for plant nutrient uptake and water use.
Technical Paper

A More Completely Defined CELSS

A CELSS has been defined based on current or near-term technology. The CELSS was sized to support the metabolic load of four people on the Moon for ten years. A metabolic load of 14 MJ/person/day is assumed, including an average of 2.6 hr of EVA/person/day. Close to 100% closure of water, and oxygen, and 85% closure of the food loop is assumed. With 15% of the calories supplied from Earth, this should provide adequate dietary variety for the crew along with vitamin and mineral requirements. Other supply and waste removal requirements are addressed. The basic shell used is a Space Station Freedom 7.3 m (24 ft) module. This is assumed to be buried in regolith to provide protection from radiation, meteoroids, and thermal extremes. A solar dynamic power system is assumed, with a design life of 10 years delivering power at 368 kWh/kg. Initial estimates of size are that 73 m2 of plant growth area are required, giving a plant growth volume of about 73 m3.