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NASA NTRS1998

Development of High Conductivity Lithium-Ion Electrolytes for Low Temperature Cell Applications

NASA has continued interest in developing power sources which are capable of operating at low temperatures (-20 C and below) to enable future missions, such as the Mars Rover and Lander. Thus, under a program sponsored by the Mars Exploration Program, we have been involved in developing Li-ion batteries with improved low temperature performance. To accomplish this task, the focus of the research has been upon the development of advanced electrolyte systems with improved low temperature properties. This had led to the identification of a carbonate-based electrolyte, consisting of 1.0 M LiPF6 in EC + DEC + DMC (33:33:34), which has been shown to have excellent performance at -20 C in Li-ion AA-size prototype cells. Other groups are also actively engaged in developing electrolytes which can result in improved low temperature performance of Li-ion cells, including Polystor, Yardney, and Covalent. In addition to developing cells capable of operation at -20 C, there is continued interest in systems which can successfully operate at even lower temperatures (less than -30 C) and at high discharge rates (greater than C/2). Thus, we are currently focusing upon developing advanced electrolytes which are highly conductive at low temperatures and will result in cells capable of operation at -40 C. One approach to improve the low temperature conductivity of ethylene carbonate-based electrolytes involves adding co-solvents which will decrease the viscosity and extend the liquid range. Candidate solvent additives include formates, acetates, cyclic and aliphatic ethers, lactones, as well as other carbonates. Using this approach, we have prepared a number of electrolytes which contain methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), ethyl proprionate (EP), and 1,2-dimethoxyethane (DME), some of which have been characterized and reported. Other groups have also reported electrolytes based on mixtures of carbonates and acetates. In the present study, electrolytes which have been identified to have good low temperature conductivity and stability were incorporated into lithium-graphite cells for evaluation. Using various electrochemical methods, including ac impedence and DC micropolarization techniques, the film formation characteristics of graphite electrodes in contact with various lectrolyte formulations was investigated.

Smart, M. C.↗

NASA NTRS2000

Highlights of Nanosatellite Development Program at NASA-Goddard Space Flight Center

Currently the GN&C's Propulsion Branch of the NASA's Goddard Space Flight Center (GSFC) is conducting a broad technology development program for propulsion devices that are ideally suited for nanosatellite missions. The goal of our program is to develop nanosatellite propulsion systems that can be flight qualified in a few years and flown in support of nanosatellite missions. The miniature cold gas thruster technology, the first product from the GSFC's propulsion component technology development program, will be flown on the upcoming ST-5 mission in 2003. The ST-5 mission is designed to validate various nanosatellite technologies in all major subsystem areas. It is a precursor mission to more ambitious nanosatellite missions such as the Magnetospheric Constellation mission. By teaming with the industry and government partners, the GSFC propulsion component technology development program is aimed at pursuing a multitude of nanosatellite propulsion options simultaneously, ranging from miniaturized thrusters based on traditional chemical engines to MEMS based thruster systems. After a conceptual study phase to determine the feasibility and the applicability to nanosatellite missions, flight like prototypes of selected technology are fabricated for testing. The development program will further narrow down the effort to those technologies that are considered "mission-enabling" for future nanosatellite missions. These technologies will be flight qualified to be flown on upcoming nanosatellite missions. This paper will report on the status of our development program and provide details on the following technologies: Low power miniature cold gas thruster Nanosatellite solid rocket motor. Solid propellant gas generator system for cold gas thruster. Low temperature hydrazine blends for miniature hydrazine thruster. MEMS mono propellant thruster using hydrogen peroxide.

Rhee, Michael S.↗

NASA NTRS2000

Flight Control System Development for the BURRO Autonomous UAV

Developing autonomous flying vehicles has been a growing field in aeronautical research within the last decade and will continue into the next century. With concerns about safety, size, and cost of manned aircraft, several autonomous vehicle projects are currently being developed; uninhabited rotorcraft offer solutions to requirements for hover, vertical take-off and landing, as well as slung load transportation capabilities. The newness of the technology requires flight control engineers to question what design approaches, control law architectures, and performance criteria apply to control law development and handling quality evaluation. To help answer these questions, this paper documents the control law design process for Kaman Aerospace BURRO project. This paper will describe the approach taken to design control laws and develop math models which will be used to convert the manned K-MAX into the BURRO autonomous rotorcraft. With the ability of the K-MAX to lift its own weight (6000 lb) the load significantly affects the dynamics of the system; the paper addresses the additional design requirements for slung load autonomous flight. The approach taken in this design was to: 1) generate accurate math models of the K-MAX helicopter with and without slung loads, 2) select design specifications that would deliver good performance as well as satisfy mission criteria, and 3) develop and tune the control system architecture to meet the design specs and mission criteria. An accurate math model was desired for control system development. The Comprehensive Identification from Frequency Responses (CIFER(R)) software package was used to identify a linear math model for unloaded and loaded flight at hover, 50 kts, and 100 kts. The results of an eight degree-of-freedom CIFER(R)-identified linear model for the unloaded hover flight condition are presented herein, and the identification of the two-body slung-load configuration is in progress.

Colbourne, Jason D.↗

NASA NTRS2000

Space Resources Development: The Link Between Human Exploration and the Long-Term Commercialization of Space

In a letter to the NASA Administrator, Dan Goldin, in January of 1999, the Office of Management and Budget (OMB) stated the following . OMB recommends that NASA consider commercialization in a broader context than the more focused efforts to date on space station and space shuttle commercialization. We suggest that NASA examine architectures that take advantage of a potentially robust future commercial infrastructure that could dramatically lower the cost of future human exploration." In response to this letter, the NASA Human Exploration and Development of Space (HEDS) Enterprise launched the BEDS Technology & Commercialization Initiative (HTCI) to link technology and system development for human exploration with the commercial development of space to emphasize the "D" (Development) in BEDS. The development of technologies and capabilities to utilize space resources is the first of six primary focus areas in this program. It is clear that Space Resources Development (SRD) is key for both long-term human exploration of our solar system and to the long-term commercialization of space since: a) it provides the technologies, products, and raw materials to support efficient space transportation and in-space construction and manufacturing, and b) it provides the capabilities and infrastructure to allow outpost growth, self-sufficiency, and commercial space service and utility industry activities.

Sanders, Gerald B.↗

NASA NTRS2000

Development of a Reference Dose for Perchlorate: Current Issues and Status

The perchlorate anion (ClO4) is typically manufactured as the ammonium salt. The most common use of ammonium perchlorate is in the aerospace program as a component of solid rocket fuel. The perchlorate anion is exceedingly stable under environmental conditions and has been found in ground and surface waters in CA, NV, UT, AZ, TX, AK, NY, MD, WV and FL. The National Center for Environmental Assessment (NCEA) of the U.S. Environmental Protection Agency (US EPA) is in the process of developing an oral reference dose (RfD) for perchlorate. An oral RfD is a body-weight-adjusted dose that can be consumed daily over an entire lifetime with the expectation of no adverse health effects. Once developed, the new RfD will be used by US EPA as the basis of a safe-drinking-water level (SDWL) guideline. US EPA and regional regulatory agencies will then jointly or separately propose clean-up action levels for ground and surface waters at contaminated sites. The toxicological database on CIO4- as of March 1997 was determined by an expert peer-review panel to be inadequate for the purpose of deriving an oral RfD. For example, little or no experimental data existed on the subchronic, reproductive, or developmental toxicity of perchlorate. To fill gaps in the toxicological database, eight animal studies were designed by a government-industry consortium that included US EPA and AFRL. These studies were performed in 1997-1998. It has been known for many years that in the thyroid, high doses of perchlorate block the function of iodide by competing for iodide binding sites. Perchlorate was used in the 1950s-60s as a treatment for Graves' disease (a hyperthyroid condition). Because of what was already known about the pharmacological mode of action of perchlorate, specific concerns addressed in the design of the recent animal studies included the potential for developmental toxicity, notably neurological development. Upon review of complete study reports from four of the studies and incomplete data from the other two, US EPA/NCEA issued a document in December 1998 stating that the critical effects were hormone and histology data from the neurodevelopmental/behavioral toxicity study that had been performed in rats; an RfD was proposed based upon the observation of thyroid-follicular-cell hypertrophy in the 5-day-old pups (PND) of dams given perchlorate in drinking water at 0.1 mg/kg-day (the lowest dose tested) in this study. US EPA/NCEA also focused attention on a nonsignificant increase in motor activity observed in 14-day-old male pups in the same study at the same dose. In February 1999, a public workshop was convened at which an external peer-review panel determined that there was still insufficient data to support the development of a RfD. Additional studies were recommended. Since that time a clinical study revealed significant depression of thyroidal uptake of iodide in volunteers receiving potassium perchlorate at 10 mg/day for 14 days. Follow-up studies currently underway include a pathology working-group review of histology slides from the all of the previous studies, a motor activity study similar to the first behavioral study, an additional immunotoxicity study, male and female rat kinetic studies, a hormone interlaboratory study, and an effects study for thyroid and brain in developing rats. These studies are expected to be complete by mid-2000. A clinical study is planned to determine inhibition of iodide uptake and kinetic parameters in humans following 14-day perchlorate ingestion. The kinetics studies will provide data for developing physiologically based pharmacokinetic (PBPK) models for rats and humans needed to establish the RfD.

Pleus, R. C.↗

NASA NTRS2000

Development and Application of Computational/In Vitro Toxicological Methods for Chemical Hazard Risk Reduction of New Materials for Advanced Weapon Systems

The development of quantitative structure-activity relationship (QSAR) is essential for reducing the chemical hazards of new weapon systems. The current collaboration between HEST (toxicology research and testing), MLPJ (computational chemistry) and PRS (computational chemistry, new propellant synthesis) is focusing R&D efforts on basic research goals that will rapidly transition to useful products for propellant development. Computational methods are being investigated that will assist in forecasting cellular toxicological end-points. Models developed from these chemical structure-toxicity relationships are useful for the prediction of the toxicological endpoints of new related compounds. Research is focusing on the evaluation tools to be used for the discovery of such relationships and the development of models of the mechanisms of action. Combinations of computational chemistry techniques, in vitro toxicity methods, and statistical correlations, will be employed to develop and explore potential predictive relationships; results for series of molecular systems that demonstrate the viability of this approach are reported. A number of hydrazine salts have been synthesized for evaluation. Computational chemistry methods are being used to elucidate the mechanism of action of these salts. Toxicity endpoints such as viability (LDH) and changes in enzyme activity (glutahoione peroxidase and catalase) are being experimentally measured as indicators of cellular damage. Extrapolation from computational/in vitro studies to human toxicity, is the ultimate goal. The product of this program will be a predictive tool to assist in the development of new, less toxic propellants.

Frazier, John M.↗

NASA NTRS1999

Development of a Portable, Ground-based Ozone Lidar Instrument for Tropospheric Ozone Research and Educational Training

The objective of this research project is to develop a portable, eye-safe, ground-based ozone lidar instrument specialized for ozone differential absorption lidar (DIAL) measurements in the troposphere. This research project directly supports the goal of NASA's Earth Science Enterprise to understand the distribution and budget of tropospheric ozone (objective 1.5 of the Earth Science Strategic Enterprise Plan, 1998-2002). It can participate in ground validation experiments for TES, a tropospheric ozone satellite mission due to be launched in 2002. It can also be utilized for correlative ground measurements in future GTE (Global Tropospheric Experiment) and space-based ozone lidar missions, such as ORACLE. Multiple ground-based ozone lidar systems would improve the data obtained through current ozone-sonde networks. This prototype instrument could to serve as the basic unit for these and other future monitoring projects requiring multi-instrument networks, such as that proposed for the Global Tropospheric Ozone Project (GTOP). GTOP is currently being formulated by a scientific panel of the International Global Atmospheric Chemistry Project to meet its goal to better understand the processes that control the global distribution of tropospheric ozone. In order for the lidar to be widely deployed in networks, it must be fairly easy to use and maintain as well as being cost-competitive with a ground station launching ozonesondes several times a day. A second 2-year grant to continue this effort with students participating in ground tests and system improvements has been awarded by the Office of Equal Employment Opportunities (OEOP). This project also supports existing NASA lidar missions through its development of advanced, compact lidar technology. Innovations in both transmitters and receivers have been made in this project. Finally, this system could be modified in the future to probe more deeply into the stratosphere. This could be accomplished by increasing the emitted energy or optimizing the wavelengths for this purpose. In addition to NASA, this system has applications to the EPA, NOAA, and the DOD. An AFOSR grant has been awarded based on the results of this effort to fund advanced transmitter development at medium (20-40 mJ) energies. A second proposal to the DOD with a letter of support from Air Force Research Laboratory, has been submitted to extend this uv laser technology to 100 mJ levels. Thus, this project has enabled students and faculty at Hampton University to begin to develop research efforts in support of the mission of the DOD. This instrument will be based at Hampton University (HU) to meet our educational goal to train students in lidar technology as well as atmospheric ozone data analysis and interpretation. It will be also available for off-site measurement campaigns and will serve as a test bed for further instrument development. Later development beyond this grant to extend the scientific usefulness of the instrument may include incorporation of an aerosol channel and upgrading the laser to make stratospheric ozone measurements. Seven undergraduates, three graduate students, and one postdoctoral. researcher (formerly an HU student) have been active participants in this research effort.

Chyba, Thomas↗

NASA NTRS1994

Flight Testing of Hypersonic Airbreathing Propulsion for Developing Computational Design Technology

The objective of this paper is to present and discuss a scenario and the requirements for flight testing of hypersonic airbreathing propulsion leading to the development of computational design technology. Flight Testing for this development is a significant part of a triad/synergistic, design approach which integrates computations, flight testing, and ground testing. These three complementary, design developmental tools have various capabilities and limitations. An incremental approach is necessary to use and to develop these tools effectively and efficiently. This computational technology must be developed keeping in focus the aerospace plane that is to be developed. The criteria for selecting the right plane are presented and consequently, the appropriate flight tests are identified. Two conceptual, flight-test systems are suggested considering the following: (1) the relevant, lessons learned from previous and current United States hypersonic programs, from the Apollo program, from the Space Shuttle program, and from the space station program; (2) the current need for a low risk, affordable access to space; and (3) the design challenge for hypersonic airbreathing propulsion testing. How these systems may be used for developing the computational design technology is described. The requirements for conducting propulsion- design computations, sources of uncertainties in these computations, and a guide for establishing the credibility of these computations are also presented.

Mehta, Unmeel B.↗

NASA NTRS2002

Software Development for the Hobby-Eberly Telescope's Segment Alignment Maintenance System using LABView

The software development for an upgrade to the Hobby-Eberly Telescope (HET) was done in LABView. In order to improve the performance of the HET at the McDonald Observatory, a closed-loop system had to be implemented to keep the mirror segments aligned during periods of observation. The control system, called the Segment Alignment Maintenance System (SAMs), utilized inductive sensors to measure the relative motions of the mirror segments. Software was developed in LABView to tie the sensors, operator interface, and mirror-control motors together. Developing the software in LABView allowed the system to be flexible, understandable, and able to be modified by the end users. Since LABView is built using block diagrams, the software naturally followed the designed control system's block and flow diagrams, and individual software blocks could be easily verified. LABView's many built-in display routines allowed easy visualization of diagnostic and health-monitoring data during testing. Also, since LABView is a multi-platform software package, different programmers could develop the code remotely on various types of machines. LABView s ease of use facilitated rapid prototyping and field testing. There were some unanticipated difficulties in the software development, but the use of LABView as the software "language" for the development of SAMs contributed to the overall success of the project.

Hall, Drew P.↗

NASA NTRS2003

NASA GRC Stirling Technology Development Overview

The Department of Energy, Lockheed Martin (LM), Stirling Technology Company, and NASA Glenn Research Center (GRC) are developing a high-efficiency Stirling Radioisotope Generator (SRG) for potential NASA Space Science missions. The SRG is being developed for multimission use, including providing spacecraft onboard electric power for NASA deep space missions and power for unmanned Mars rovers. NASA GRC is conducting an in- house supporting technology project to assist in developing the Stirling convertor for space qualification and mission implementation. Preparations are underway for a thermalhacuum system demonstration and unattended operation during endurance testing of the 55-We Technology Demonstration Convertors. Heater head life assessment efforts continue, including verification of the heater head brazing and heat treatment schedules and evaluation of any potential regenerator oxidation. Long-term magnet aging tests are continuing to characterize any possible aging in the strength or demagnetization resistance of the permanent magnets used in the linear alternator. Testing of the magnet/lamination epoxy bond for performance and lifetime characteristics is now underway. These efforts are expected to provide key inputs as the system integrator, LM, begins system development of the SRG. GRC is also developing advanced technology for Stirling convertors. Cleveland State University (CSU) is progressing toward a multi-dimensional Stirling computational fluid dynamics code, capable of modeling complete convertors. Validation efforts at both CSU and the University of Minnesota are complementing the code development. New efforts have been started this year on a lightweight convertor, advanced controllers, high-temperature materials, and an end-to-end system dynamics model. Performance and mass improvement goals have been established for second- and third-generation Stirling radioisotope power systems.

Thieme, Lanny G.↗

NASA NTRS2003

Early Development of Gravity-Sensing Organs in Microgravity

Most animals have organs that sense gravity. These organs use dense stones (called otoliths or statoconia), which rest on the sensitive hairs of specialized gravity- and motion-sensing cells. The weight of the stones bends the hairs in the direction of gravitational pull. The cells in turn send a coded representation of the gravity or motion stimulus to the central nervous system. Previous experiments, in which the eggs or larvae of a marine mollusk (Aplysia californica, the sea hare) were raised on a centrifuge, demonstrated that the size of the stones (or test mass) was reduced in a graded manner as the gravity field was increased. This suggests that some control mechanism was acting to normalize the weight of the stones. The experiments described here were designed to test the hypothesis that, during their initial development, the mass of the stones is regulated to achieve a desired weight. If this is the case, we would expect a larger-than-normal otolith would develop in animals reared in the weightlessness of space. To test this, freshwater snails and swordtail fish were studied after spaceflight. The snails mated in space, and the stones (statoconia) in their statocysts developed in microgravity. Pre-mated adult female swordtail fish were flown on the Space Shuttle, and the developing larvae were collected after landing. Juvenile fish, where the larval development had taken place on the ground, were also flown. In snails that developed in space, the total volume of statoconia forming the test mass was 50% greater than in size-matched snails reared in functionally identical equipment on the ground. In the swordtail fish, the size of otoliths was compared between ground- and flight-reared larvae of the same size. For later-stage larvae, the growth of the otolith was significantly greater in the flight-reared fish. However, juvenile fish showed no significant difference in otolith size between flight- and ground-reared fish. Thus, it appears that fish and snails reared in space do produce larger-than-normal otoliths (or their analogs), apparently in an attempt to compensate for the reduced weight of the stones in space. The fish data suggest that there is a critical period during which altered gravity can affect the size of the test mass, since the larval, but not the juvenile, fish showed the changes.

Wiederhold, Michael L.↗

NASA NTRS2003

Neural Development Under Conditions of Spaceflight

One of the key tasks the developing brain must learn is how to navigate within the environment. This skill depends on the brain's ability to establish memories of places and things in the environment so that it can form cognitive maps. Earth's gravity defines the plane of orientation of the spatial environment in which animals navigate, and cognitive maps are based on this plane of orientation. Given that experience during early development plays a key role in the development of other aspects of brain function, experience in a gravitational environment is likely to be essential for the proper organization of brain regions mediating learning and memory of spatial information. Since the hippocampus is the brain region responsible for cognitive mapping abilities, this study evaluated the development of hippocampal structure and function in rats that spent part of their early development in microgravity. Litters of male and female Sprague-Dawley rats were launched into space aboard the Space Shuttle Columbia on either postnatal day eight (P8) or 14 (P14) and remained in space for 16 days. Upon return to Earth, the rats were tested for their ability to remember spatial information and navigate using a variety of tests (the Morris water maze, a modified radial arm maze, and an open field apparatus). These rats were then tested physiologically to determine whether they exhibited normal synaptic plasticity in the hippocampus. In a separate group of rats (flight and controls), the hippocampus was analyzed using anatomical, molecular biological, and biochemical techniques immediately postlanding. There were remarkably few differences between the flight groups and their Earth-bound controls in either the navigation and spatial memory tasks or activity-induced synaptic plasticity. Microscopic and immunocytochemical analyses of the brain also did not reveal differences between flight animals and ground-based controls. These data suggest that, within the developmental window studied, microgravity has minimal long-term impact on cognitive mapping function and cellular substrates important for this function. Any differences due to development in microgravity were transient and returned to normal soon after return to Earth.

Kosik, Kenneth S.↗

NASA NTRS2003

Creation and Implementation of a Workforce Development Pipeline Program at MSFC

Within the context of NASA's Education Programs, this Workforce Development Pipeline guide describes the goals and objectives of MSFC's Workforce Development Pipeline Program as well as the principles and strategies for guiding implementation. It is designed to support the initiatives described in the NASA Implementation Plan for Education, 1999-2003 (EP-1998-12-383-HQ) and represents the vision of the members of the Education Programs office at MSFC. This document: 1) Outlines NASA s Contribution to National Priorities; 2) Sets the context for the Workforce Development Pipeline Program; 3) Describes Workforce Development Pipeline Program Strategies; 4) Articulates the Workforce Development Pipeline Program Goals and Aims; 5) List the actions to build a unified approach; 6) Outlines the Workforce Development Pipeline Programs guiding Principles; and 7) The results of implementation.

Hix, Billy↗

NASA NTRS2001

Evaluation Criteria for Solid Waste Processing Research and Technology Development

A preliminary list of criteria is proposed for evaluation of solid waste processing technologies for research and technology development (R&TD) in the Advanced Life Support (ALS) Program. Completion of the proposed list by current and prospective ALS technology developers, with regard to specific missions of interest, may enable identification of appropriate technologies (or lack thereof) and guide future development efforts for the ALS Program solid waste processing area. An attempt is made to include criteria that capture information about the technology of interest as well as its system-wide impacts. Some of the criteria in the list are mission-independent, while the majority are mission-specific. In order for technology developers to respond to mission-specific criteria, critical information must be available on the quantity, composition and state of the waste stream, the wast processing requirements, as well as top-level mission scenario information (e.g. safety, resource recovery, planetary protection issues, and ESM equivalencies). The technology readiness level (TRL) determines the degree to which a technology developer is able to accurately report on the list of criteria. Thus, a criteria-specific minimum TRL for mandatory reporting has been identified for each criterion in the list. Although this list has been developed to define criteria that are needed to direct funding of solid waste processing technologies, this list processes significant overlap in criteria required for technology selection for inclusion in specific tests or missions. Additionally, this approach to technology evaluation may be adapted to other ALS subsystems.

Levri, Julie A.↗

NASA NTRS2003

CFD Code Development for Combustor Flows

During the lifetime of this grant, work has been performed in the areas of model development, code development, code validation and code application. For model development, this has included the PDF combustion module, chemical kinetics based on thermodynamics, neural network storage of chemical kinetics, ILDM chemical kinetics and assumed PDF work. Many of these models were then implemented in the code, and in addition many improvements were made to the code, including the addition of new chemistry integrators, property evaluation schemes, new chemistry models and turbulence-chemistry interaction methodology. Validation of all new models and code improvements were also performed, while application of the code to the ZCET program and also the NPSS GEW combustor program were also performed. Several important items remain under development, including the NOx post processing, assumed PDF model development and chemical kinetic development. It is expected that this work will continue under the new grant.

Norris, Andrew↗

NASA NTRS2003

Early development of fern gametophytes in microgravity

Dormant spores of the fern Ceratopteris richardii were flown on Shuttle mission STS-93 to evaluate the effects of micro-g on their development and on their pattern of gene expression. Prior to flight the spores were sterilized and sown into one of two environments: (1) Microscope slides in a video-microscopy module; and (2) Petri dishes. All spores were then stored in darkness until use. Spore germination was initiated on orbit after exposure to light. For the spores on microscope slides, cell level changes were recorded through the clear spore coat of the spores by video microscopy. After their exposure to light, spores in petri dishes were frozen in orbit at four different time points during which on earth gravity fixes the polarity of their development. Spores were then stored frozen in Biological Research in Canister units until recovery on earth. The RNAs from these cells and from 1-g control cells were extracted and analyzed on earth after flight to assay changes in gene expression. Video microscopy results revealed that the germinated spores developed normally in microgravity, although the polarity of their development, which is guided by gravity on earth, was random in space. Differential Display-PCR analyses of RNA extracted from space-flown cells showed that there was about a 5% change in the pattern of gene expression between cells developing in micro-g compared to those developing on earth. c2002 Published by Elsevier Science Ltd on behalf of COSPAR.

manned↗

NASA NTRS2000

Ceratopteris richardii: a productive model for revealing secrets of signaling and development

Ceratopteris richardii is an aquatic fern grown in tropical and subtropical regions of the world. It is proven to be a productive model system for studies in the genetics, biochemistry, and cell biology of basic biologic processes that occur in early gametophytic development. It provides several advantages to biologists, especially those interested in gravitational biology, polarity development, and in the genetics of sexual development. It is easy to culture, has a relatively short life cycle, and offers an array of attractive features that facilitate genetic studies. The germination and early development of large populations of genetically identical spores are easy to synchronize, and both the direction of polarity development and cell-level gravity responses can be measured and readily manipulated within the first 24 h of spore development. Although there is no reliable transformation system available yet in Ceratopteris, recent studies suggest that the technique of RNA interference can be used to block translation of specific genes in a related fern, Marsilea, and current studies will soon reveal the applicability of this approach, as well as of other transformation approaches, in Ceratopteris. A recently completed expressed sequence tag (EST) sequencing project makes available the partial sequence of more than 2000 cDNAs, representing a significant percentage of the genes being expressed during the first 24 h of spore germination, when many developmentally interesting processes are occurring. A microarray of these ESTs is being constructed, so especially for those scientists interested in basic cellular phenomena that occur early in spore germination, the availability of the ESTs and of the microarray will make Ceratopteris an even more attractive model system.

NASA Discipline Plant Biology↗

NASA NTRS1994

Development of the brine shrimp Artemia is accelerated during spaceflight

Developmentally arrested brine shrimp cysts have been reactivated during orbital spaceflight on two different Space Shuttle missions (STS-50 and STS-54), and their subsequent development has been compared with that of simultaneously reactivated ground controls. Flight and control brine shrimp do not significantly differ with respect to hatching rates or larval morphology at the scanning and transmission EM levels. A small percentage of the flight larvae had defective nauplier eye development, but the observation was not statistically significant. However, in three different experiments on two different flights, involving a total of 232 larvae that developed in space, a highly significant difference in degree of flight to control development was found. By as early as 2.25 days after reactivation of development, spaceflight brine shrimp were accelerated, by a full instar, over ground control brine shrimp. Although developing more rapidly, flight shrimp grew as long as control shrimp at each developmental instar or stage.

Flight Experiment↗