Search Results

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.

This project sought to develop a photocatalytic oxidation (PCO) based total organic carbon (TOC) analyzer for real time monitoring of air quality in spacecraft. Specific requirements for this application were to convert volatile organic contaminants (VOC) into CO2 stoichiometrically in a single pass through a small reactor with low power requirement. One of the greatest challenges of this TiO2-mediated PCO was the incomplete oxidation of some recalcitrant VOCs leading to less reactive intermediates that deactivate the catalyst over time. Dichloromethane (DCM) is one of these VOCs. The effect of some design factors (e.g. TiO2 catalyst surface area to volume ratio and UV photon flux field) as well as operating conditions of an annular reactor (e.g. VOC residence time and relative humidity) on the efficiency in converting DCM to CO2 were investigated.

The first spaceflight opportunities for Advanced Life Support (ALS) Project testing with plants will likely occur with missions on vehicles in Low Earth Orbit, such as the International Space Station (ISS). In these settings, plant production systems would likely be small chambers with limited electrical power. Such systems are adequate for salad-type crops that provide moderate quantities of fresh, flavorful foods to supplement the crew diet. Successful operation of salad crop systems in the space environment requires extensive ground-based testing with horticultural methodologies that meet expected mission constraints. At Kennedy Space Center, cultivars of radish, onion, and lettuce are being compared for performance under these “flight-like” conditions.

Use of the local resources on Mars could reduce the cost of life support significantly. Theoretically, Closed Ecological Systems (CES) isolated from surroundings and functioning on the basis of a closed cycle of matter transformation are the most reliable systems for life support in open space or on the surface of non-terrestrial bodies such as the Moon or Mars. But these systems require a relatively high initial mass (which is a critical factor in space flight) in comparison to supply-based systems. In addition CESs are a useful scientific abstraction though they have never been reached in reality. To minimize the cost of life support on Mars, we need to find scenarios and technologies such as a Martian Greenhouse (MG) which are based on use of the planet’s indigenous sources of energy and materials (natural illumination, carbon dioxide, water, nutrient elements for plants in the planetary soil). Our initial analysis shows that such approaches are possible and cost effective.

The ASTROCULTURE™ flight unit flown as part of the SPACEHAB-03 mission on STS-63 was a complete plant growth system providing plant lighting, temperature control, humidity control, water and nutrient delivery, a CO2 control system, nutrient control using the NASA Zeoponics system, an ethylene photocatalysis unit, a control and data acquisition system, and plant video. The objective of the ASTROCULTURE™-4 experiment was to continue technological assessment of these environmental control subsystems. Plants were included in this package for the first time. Two plant species were flown, rapid cycling ‘Wisconsin Fast Plants’ (Brassica rapa), and dwarf wheat (Triticum aestivum cv. ‘Super Dwarf’). Growth and development of both plant species on orbit appeared normal and similar to that of plants grown under terrestrial conditions.

A BRIC (Biological Research In a Canister) experiment to investigate the effects of reduced gravity at the molecular level using Arabidopsis has been initiated. To ensure an efficient BRIC experiment, a series of ground-based studies have been conducted. These studies were designed to determine: 1) the ideal seed density to obtain enough plant tissue from a single canister; 2) optimum germination surface for tissue recovery after freezing in liquid nitrogen; 3) yield and quality of mRNA from small amounts of tissue; 4) time point to freeze the seedlings; and 5) changes in gene expression that may be caused by stresses during launch.

The candidate crops that have been considered by NASA for providing moderate quantities of supplemental food for crew's consumption during near term or long duration missions include minimally processed “salad” species. Lettuce (cv. Flandria), radish (cv. Cherry Bomb II) and green onion (cv. Kinka) plants were grown under cool-white fluorescent (CWF) lamps with light intensities of 8.6, 17.2, or 25.8 mol m−2 d−1, at air temperatures of 25 and 28 °C, 50% relative humidity, and 1200 µmol mol−1 CO2. Following 35 days growth, final edible mass yields were recorded. All three species grown at 25 °C showed an increase in edible fresh mass and growth rates as light intensity increased. When grown at 28 °C however, the edible fresh mass and crop growth rate of radish, lettuce and onion was significantly reduced at all light intensities when compared to yields at 25 °C. Overall, results indicated that all three crops were sensitive to changes in light intensity and temperature.

Radish (Raphanus sativus L.), green onion (Allium fistulosum L.), and lettuce (Lactuca sativa L.) are among several “salad” crop species suggested for use on the International Space Station (ISS) as a supplement to the crew’s diet. Among the more important factors affecting the crop yields will be the light intensity or photosynthetic photon flux (PPF) used to grow the plants. Radish (cv. Cherry Bomb), green onion (cv. Kinka), and lettuce (cv. Flandria) plants were grown for 35 days in growth chambers at 8.6, 17.2, and 26 mol m−2 d−1 (150, 300, or 450 μmol m−2 s−1 PPF, respectively) with a 16 hr photoperiod and cool-white fluorescent lamps and either 400 or 1200 μmol mol−1 CO2. Final (35-day) edible yields were taken for the treatments under ambient or supplemented CO2. Results showed a response of growth to incident PPF that indicated a strong influence of lighting on yields.

Nitrate concentration in spinach and lettuce is known to be influenced by light quantity. The enzyme nitrate reductase is regulated by phytochrome in some species, and in the presence of light, electrons that reduce nitrite to ammonium come from photosynthetic electron transport. It was hypothesized that light quality as well as light quantity may be used to manipulate nitrate concentration in spinach. To test this, narrow-band wavelength light-emitting diode (LED) sources (670 nm and 735 nm peak emission) were utilized in combination with cool white fluorescent (CWF) lamps. Nitrate concentration was compared in spinach seedlings grown for four weeks under CWF, followed by one of three 5-day pre-harvest light treatments. The three different light quality regimes were 1) CWF, 2) CWF + RED (670 nm) LED, and 3) CWF + FR (735 nm LED).

The main principles of artificial atmospheric design for a Martian Greenhouse (MG) are described based on: 1. Cost-effective approach to MG realization; 2. Using in situ resources (e.g. CO2, O2, water); 3. Controlled greenhouse gas exchange by using independent pump in and pump out technologies. We show by mathematical modeling and numerical estimates based on reasonable assumptions that this approach for Martian deployable greenhouse (DG) implementation could be viable. A scenario of MG realization (in terms of plant biomass/photosynthesis, atmospheric composition, and time) is developed. A list is given of technologies (natural water collection, MG inflation, oxygen collection and storage, etc.) that are used in the design. The conclusions we reached are: 1. Initial stocks of oxygen and water probably would be required to initiate plant germination and growth; 2. Active control of MG ventilation could provide proper atmospheric composition for each period of plant growth; 3.