Weapons System Open Architecture - a bridge between "embedded" and "off-board"

A demonstration program is described: Weapons System Open Architecture (WSOA) - funded jointly by the Air Force Research Laboratory (AFRL), DARPA, and the Open Systems Joint Task Force (OSJTF). WSOA provides an open systems "bridge" between legacy embedded mission systems and off-board C3I sources and systems. This "bridge" is used to support Internet-like connectivity between command and attack nodes. The foundation of this bridge is the creation of a Common Object Request Broker Architecture (CORBA) layer over Link 16. In addition, application of quality of service techniques and resource management technologies will ensure the timely exchange and processing of mission critical information by both attack and command nodes in even the most time-sensitive situations.     

Atmospheric dynamics in the "Laboratory Biosphere" with wheat and sweet potato crops.

Laboratory Biosphere is a 40-m3 closed life system equipped with 12,000 W of high pressure sodium lamps over planting beds with 5.37 m2 of soil. Atmospheric composition changes due to photosynthetic fixation of carbon dioxide and corresponding production of oxygen or the reverse, respiration, are observed in short timeframes, e.g., hourly. To focus on inherent characteristics of the crop as distinct from its area or the volume of the chamber, we report fixation and respiration rates in mmol h-1 m-2 of planted area. An 85-day crop of USU Apogee wheat under a 16-h lighted/8-h dark regime peaked in fixation rate at about 100 mmol h-1 m-2 approximately 24 days after planting. Light intensity was about 840 micromoles m-2 s-1. Dark respiration peaked at about 31 mmol h-1 m-2 at the same time. Thereafter, both fixation and respiration declined toward zero as harvest time approached. A residual soil respiration rate of about 1.9 mmol h-1 m-2 was observed in the dark closed chamber for 100 days after the harvest. A 126-day crop of Tuskegee TU-82-155 sweet potato behaved quite differently. Under a 680 micromoles m-2 s-1, 18-h lighted/6-h dark regime, fixation during lighted hours rose to a plateau ranging from about 27 to 48 mmol h-1 m-2 after 42 days and dark respiration settled into a range of 12-23 mmol h-1 m-2. These rates continued unabated until the harvest at 126 days, suggesting that tuber biomass production might have continued at about the same rate for some time beyond the harvest time that was exercised in this experiment. In both experiments CO2 levels were allowed to range widely from a few hundred to about 3000 ppm, which permitted observation of fixation rates both at varying CO2 concentrations and at each number of days after planting. This enables plotting the fixation rate as a function of both variables. Understanding the atmospheric dynamics of individual crops will be essential for design and atmospheric management of more complex CELSS which integrate the simultaneous growth of several crops as in a sustainable remote life support system.     

Space Station power requirements and issues

This paper provides an overview of the Space Station configuration and summarizes the requirements, architecture, and significant challenges associated with the electrical power system (EPS). The Space Station configuration was baselined during the systems design review (SDR) process in March, 1994. The current configuration includes the addition of Russia as an international partner, resulting in major changes to the assembly sequence, pressurized module complement, and overall power architecture. The Russian contributions to the power system architecture, as well as an-overview and development status of the US provided elements is presented. Finally, a planned flight demonstration of solar dynamic power system on the Mir as part of the first phase of US/Russian cooperation in human space flight is described     

Physiological, biochemical and molecular processes associated with gravitropism in roots of maize.

This research aims to characterize regulation of the principal cytosolic protein kinases in maize, cultivar 'Merit' root tips, since much evidence indicates that stimuli which modulate the gravitropic response in this system act through regulation of activity of these enzymes. To this end, we have cloned a maize protein kinase belonging to a group of plant protein kinases with a catalytic domain similar in primary structure to the second messenger-regulated protein kinases known in animal and fungal systems. However, both the unique structural features conserved among plant protein kinases in this group, and lack of evidence for cyclic nucleotide signalling in plants point to operation of a novel protein kinase regulatory mechanism in plants. In order to test effects of possible regulators on protein kinase activity, we developed a sensitive method for detecting regulation of autophosphoryl labelling of protein kinases in unfractionated maize protein extracts. Regulation of protein kinase autophosphorylation in these extracts was different from that known in animals and fungi, further suggesting operation of unique protein kinase regulatory mechanisms in plants. Previous research has shown that light, or factors modulated by light, regulate plant protein kinase activity. We found that protein kinase activity was co-immunoprecipitated with the plant photoreceptor phytochrome, and was associated with phytochrome by high-affinity chemical interactions. Far-red reversibility of red-light regulation of phytochrome phosphorylation by the associated protein kinase indicates that it may modulate or transduce the light signals which lead to gravitropic sensitivity in 'Merit' maize.     

Performance and reliability of the NASA Biomass Production Chamber.

The Biomass Production Chamber (BPC) at the Kennedy Space Center is part of the Controlled Ecological Life Support System (CELSS) Breadboard Project. Plants are grown in a closed environment in an effort to quantify their contributions to the requirements for life support. Performance of this system is described. Also, in building this system, data from component and subsystem failures are being recorded. These data are used to identify problem areas in the design and implementation. The techniques used to measure the reliability will be useful in the design and construction of future CELSS. Possible methods for determining the reliability of a green plant, the primary component of a CELSS, are discussed.     

Long-term modulation of Galactic Cosmic Radiation and its model for space exploration.

As the human exploration of space has received new attention in the United States, studies find that exposure to space radiation could adversely impact the mission design. Galactic Cosmic Radiation (GCR), with its very wide range of charges and energies, is particularly important for a mission to Mars, because it imposes a stiff mass penalty for spacecraft shielding. Dose equivalent versus shielding thickness calculations, show a rapid initial drop in exposure with thickness, but an asymptotic behavior at a higher shielding thickness. Uncertainties in the radiobiology are largely unknown. For a fixed radiation risk, this leads to large uncertain ties in shielding thickness for small uncertainties in estimated dose. In this paper we investigate the application of steady-state, spherically-symmetric diffusion-convection theory of solar modulation to individual measurements of differential energy spectra from 1954 to 1989 in order to estimate the diffusion coefficient, kappa (r,t), as a function of time. We have correlated the diffusion coefficient to the Climax neutron monitor rates and show that, if the diffusion coefficient can be separated into independent functions of space and time: kappa (-r,t)=K(t)kappa 0 beta P kappa 1(r), where beta is the particle velocity and P the rigidity, then (i) The time dependent quantity 1/K(t), which is proportional to the deceleration potential, phi(r,t), is linearly related to the Climax neutron monitor counting rate. (ii) The coefficients obtained from hydrogen or helium intensity measurements are the same. (iii) There are different correlation functions for odd and even solar cycles. (iv) The correlation function for the Climax neutron monitor counting rate for given time, t, can be used to estimate mean deceleration parameter phi(t) to within +/- 15% with 90% confidence. We have shown that kappa(r,t) determined from hydrogen and/or helium data, can be used to fit the oxygen and iron differential energy spectra with a root mean square error of about +/- 10%, and essentially independent of the particle charge or energy. We have also examined the ion chamber and 14C measurements which allow the analysis to be extended from the year 1906 to 1990. Using this model we have defined reference GCR spectra at solar minimum and solar maximum. These can be used for space exploration studies and provide a quantitative estimate of the error in dose due to changes in GCR intensities.     

Models of CNS radiation damage during space flight.

The primary structural and functional arrangement of the different cell types within the CNS are reviewed. This was undertaken with a view to providing a better understanding of the complex interrelationships that may contribute to the pathogenesis of lesions in this tissue after exposure to ionizing radiation. The spectrum of possible CNS radiation-induced syndromes are discussed although not all have an immediate relevance to exposure during space flight. The specific characteristics of the lesions observed would appear to be dose related. Very high doses may produce an acute CNS syndrome that can cause death. Of the delayed lesions, selective coagulation necrosis of white matter and a later appearing vascular microangiopathy, have been reported in patients after cancer therapy doses. Lower doses, perhaps very low doses, may produce a delayed generalised CNS atrophy; this effect and the probability of the induction of CNS tumors could potentially have the greatest significance for space flight.     

Fuel cell status, 1994

The high efficiency environmental benefits and other attributes of fuel cells have attracted world-wide attention to the technology. Approximately 250 phosphoric acid fuel cell (PAFC) power units, 35 molten carbonate fuel cell (MCFC) stacks, and 12 solid oxide fuel cell (SOFC) modules have been or are being operated. Total capacity installed or operating is close to 45 MW. Fuel cell development has progressed to where complete power plants have reached nearly 16,000 operating hours and this continues to increase. Developers in the U.S. and Japan have embarked on extensive government and private programs to commercialize the technology in those countries and abroad. By mid-1994, the U.S. sold and shipped to other countries at least 33 PAFC 200 kW plants, 20 675 kW PAFC stacks, two SOFC 25 kW modules, and one MCFC system. Additional units have been produced for the domestic market. There is intense interest in Japan where there are very stringent environmental regulations and fuel prices are high. The fuel cell can respond with its combined attributes of low emissions and relative high efficiency. In Europe, the environmental cleanliness of fuel cell power units holds the promise of preserving the quality of life, motivating support and development of the technology. Canada and Australia have spawned important development programs. Interest continues to increase in other parts of the world. The author reviews the 1994 status and outlines the future development trends in this area     

Galactic cosmic ray radiation levels in spacecraft on interplanetary missions.

Using the Langley Research Center galactic cosmic ray (GCR) transport computer code (HZETRN) and the computerized anatomical man (CAM) model, crew radiation levels inside manned spacecraft on interplanetary missions are estimated. These radiation-level estimates include particle fluxes, LET (linear energy transfer) spectra, absorbed dose, and dose equivalent within various organs of interest in GCR protection studies. Changes in these radiation levels resulting from the use of various different types of shield materials are presented.     

Energy and charge localization in irradiated DNA.

The relation between the site of energy deposition and the site of its biological action is an important question in radiobiology. Even at 77 degrees K, evidence is clear that these two sites must be separated since energy deposition is random but specific products are formed. Several processes that may contribute to this separation are: 1) hole migration and stabilization through deprotonation to give neutral oxidation product radicals; 2) electron trapping and transfer to form specific radical anions, possibly followed by protonation to give neutral reduction product radicals; and 3) recombination of spatially separated charges or radicals. These microscopic processes will be reviewed critically in an analysis using electron paramagnetic resonance spectroscopy (EPR) evidence for and against long-range transfer of energy and/or charge in frozen, hydrated DNA.