Engineering topics

Hoehn, A.

Publications and source records attributed to Hoehn, A..

9 records

NASA NTRS2001

Modeling of two-phase flow in membranes and porous media in microgravity as applied to plant irrigation in space

In traditional applications in soil physics it is convention to scale porous media properties, such as hydraulic conductivity, soil water diffusivity, and capillary head, with the gravitational acceleration. In addition, the Richards equation for water flux in partially saturated porous media also contains a gravity term. With the plans to develop plant habitats in space, such as in the International Space Station, it becomes necessary to evaluate these properties and this equation under conditions of microgravitational acceleration. This article develops models for microgravity steady state two-phase flow, as found in irrigation systems, that addresses critical design issues. Conventional dimensionless groups in two-phase mathematical models are scaled with gravity, which must be assigned a value of zero for microgravity modeling. The use of these conventional solutions in microgravity, therefore, is not possible. This article therefore introduces new dimensionless groups for two-phase models. The microgravity models introduced here determined that in addition to porous media properties, important design factors for microgravity systems include applied water potential and the ratio of inner to outer radii for cylindrical and spherical porous media systems.

Plant Roots/growth & development↗

NASA NTRS2000

Approaches in the determination of plant nutrient uptake and distribution in space flight conditions

The effective growth and development of vascular plants rely on the adequate availability of water and nutrients. Inefficiency in either the initial absorption, transportation, or distribution of these elements are factors which impinge on plant structure and metabolic integrity. The potential effect of space flight and microgravity conditions on the efficiency of these processes is unclear. Limitations in the available quantity of space-grown plant material and the sensitivity of routine analytical techniques have made an evaluation of these processes impractical. However, the recent introduction of new plant cultivating methodologies supporting the application of radionuclide elements and subsequent autoradiography techniques provides a highly sensitive investigative approach amenable to space flight studies. Experiments involving the use of gel based 'nutrient packs' and the radionuclides calcium-45 and iron-59 were conducted on the Shuttle mission STS-94. Uptake rates of the radionuclides between ground and flight plant material appeared comparable.

manned↗

NASA NTRS1998

Approaches in the Determination of Plant Nutrient Uptake and Distribution in Space Flight Conditions

The effective growth and development of vascular plants rely on the adequate availability of water and nutrients. Inefficiency in either the initial absorption, transportation, or distribution of these elements are factors which may impinge on plant structure and metabolic integrity. The potential effect of space flight and microgravity conditions on the efficiency of these processes is unclear. Limitations in the available quantity of space-grown plant material and the sensitivity of routine analytical techniques have made an evaluation of these processes impractical. However, the recent introduction of new plant cultivating methodologies supporting the application of radionuclide elements and subsequent autoradiography techniques provides a highly sensitive investigative approach amenable to space flight studies. Experiments involving the use of gel based 'nutrient packs' and the nuclides Ca45 and Fe59 were conducted on the Shuttle mission STS-94. Uptake rates of the radionuclides between ground and flight plant material appeared comparable.

Heyenga, A. G.↗

NASA NTRS1998

The Utilization of a Space Flight Plant Growth Chamber in the Cultivation of Salad Crop Species: A Prelude to a Salad Machine

The application of bioregenerative life support systems provides an attractive approach to minimize resupply requirement and ultimate self-sufficiency on long duration manned missions in space. The on-board cultivation of salad-type vegetables for crew consumption has been proposed as a first step approach towards reducing a total reliance on the resupply of food. The recent advances in the development of space flight plant growth facilities such as the Plant Generic Bioprocessing Apparatus (PGBA) have established a firm technical basis upon which the implementation of a 'salad machine' concept may be achieved. A presentation on ground based studies will be made evaluating (a) the operational performance of the PGBA facility in a crop production mode and (b) the qualitative and quantitative value of salad plant material produced within the chamber.

Heyenga, A. G.↗

NASA NTRS1997

On-Orbit and Ground Performance of the PGBA Plant Growth Facility

PGBA, a plant growth facility developed for commercial space biotechnology research, successfully grew a total of 30 plants (6 species) for 10 days on board the Space Shuttle Endeavour (STS-77) and is scheduled for reflight on board MSL-1 (STS-83) for a 16 day flight. The PGBA life support systems provide atmospheric, thermal, and humidity control as well as lighting and nutrient supply in a 23.6 liter chamber. Atmosphere treatment includes ethylene and other hydrocarbon removal, CO2 replenishment, and O2 control. The normally closed system uses controlled CO2 replenishment from the crew cabin as required by the plants. Temperature is controlled (1 C) at user-specified setpoints between 20-32 C, using water-filled coolant loops, solid state Peltier thermoelectric devices, and liquid heat exchangers. The thermoelectric cooling systems were optimized for low power consumption and high cooling efficiencies. Relative humidity is maintained between 60-100% using a cooled porous metal plate to remove water vapor from the air stream without cooling the bulk air below the dew point. The lighting system utilizes three compact fluorescent bi-axial lights with variable lighting control and light intensity (PAR) between 220 and 330 micromol/sq m/s at a distance of 20 cm in spaceflight configuration (on orbit power limited to 230 Watt for entire payload). A ground, up to 550 micromol/sq m/s light intensity can be achieved with 330 Watt payload power consumption. Plant water and nutrient support is sustained via the 'Nutrient Pack' system including the passive or active 'Water Replenishable Nutrient Pack.' The root matrix material (soil or Agar) and nutrient formulation of each pack is prepared according to plant species and experimental requirements. These systems were designed by NASA Ames personnel. Data acquisition and control systems provide 32 channels of environmental data as well as digitized or analog video signals for downlink.

Hoehn, A.↗

NASA NTRS1994

Plant-module for autonomous space-support (p-mass).

A wide variety of technical and science questions arise when attempting to envision the long-term support of plants, algae and bacteria in space. Currently, spaceflight data remain elusive since there are no U.S. carriers for investigating either the germane technical or scientific issues. The first flight of the Commercial Experiment Transporter (COMET) will provide a nominal 30 day orbital opportunity to evlauate such issues. The P-Mass is a small payload that is designed to meet the mass (40 lbs), Volume (1.5cu. ft.), and power (120 W0 constraints of one of several COMET payloads while enabling flight evaluations of plants, algae and bacteria. Various biological sub-systems have been similarly evaluated. Through a variety of sensors coupled with color video, the P-Mass performance and the supported biological systems will be compared for terrestrial controls versus spaceflight materials. This small, low cost payload should return valuable regarding the requirements for hardware and biological systems needed to move toward biogenerative life support systems in space. In addition, it should be possible to accurately identify major unresolved difficulties that may arise in the long-term, this generic spaceflight capability should enable a variety of plant research programs focused on the use of microgravity to modulate and exploit plant products for commercial applications ranging from new agricultural products to pharmacological feedstocks and new controlled agricultural strategies.

Luttges, M. W.↗

NASA NTRS1992

Design and evaluation of a payload to support plant growth onboard COMET 1

The paper describes the design and the operation principles of the Plant Module for Autonomous Space Support (P-MASS), designed to provide life support for a variety of plants, algae, and bacteria in low earth orbit during the maiden flight of COMET-1, scheduled for 1993. During flight (scheduled to continue for 30 days), both color video images and collected environmental data (including light intensity, temperature, relative humidity, CO2 and O2 concentrations, soil moisture, and nutrients released) will be downlinked to earth several times a day. These data will also be stored within the payload and retrieved from it after reentry and recovery.

Hoehn, A.↗

NASA NTRS1991

A lunar base reference mission for the phased implementation of bioregenerative life support system components

Previous design efforts of a cost effective and reliable regenerative life support system (RLSS) provided the foundation for the characterization of organisms or 'biological processors' in engineering terms and a methodology was developed for their integration into an engineered ecological LSS in order to minimize the mass flow imbalances between consumers and producers. These techniques for the design and the evaluation of bioregenerative LSS have now been integrated into a lunar base reference mission, emphasizing the phased implementation of components of such a BLSS. In parallel, a designers handbook was compiled from knowledge and experience gained during past design projects to aid in the design and planning of future space missions requiring advanced RLSS technologies. The lunar base reference mission addresses in particular the phased implementation and integration of BLS parts and includes the resulting infrastructure burdens and needs such as mass, power, volume, and structural requirements of the LSS. Also, operational aspects such as manpower requirements and the possible need and application of 'robotics' were addressed.

Dittmer, Laura N.↗

NASA NTRS1989

CIS-lunar space infrastructure lunar technologies: Executive summary

Technologies necessary for the creation of a cis-Lunar infrastructure, namely: (1) automation and robotics; (2) life support systems; (3) fluid management; (4) propulsion; and (5) rotating technologies, are explored. The technological focal point is on the development of automated and robotic systems for the implementation of a Lunar Oasis produced by Automation and Robotics (LOAR). Under direction from the NASA Office of Exploration, automation and robotics were extensively utilized as an initiating stage in the return to the Moon. A pair of autonomous rovers, modular in design and built from interchangeable and specialized components, is proposed. Utilizing a buddy system, these rovers will be able to support each other and to enhance their individual capabilities. One rover primarily explores and maps while the second rover tests the feasibility of various materials-processing techniques. The automated missions emphasize availability and potential uses of Lunar resources, and the deployment and operations of the LOAR program. An experimental bio-volume is put into place as the precursor to a Lunar environmentally controlled life support system. The bio-volume will determine the reproduction, growth and production characteristics of various life forms housed on the Lunar surface. Physicochemical regenerative technologies and stored resources will be used to buffer biological disturbances of the bio-volume environment. The in situ Lunar resources will be both tested and used within this bio-volume. Second phase development on the Lunar surface calls for manned operations. Repairs and re-configuration of the initial framework will ensue. An autonomously-initiated manned Lunar oasis can become an essential component of the United States space program.

Faller, W.↗