Performance of the CELSS Antarctic Analog Project (CAAP) crop production system.

Regenerative life support systems potentially offer a level of self-sufficiency and a decrease in logistics and associated costs in support of space exploration and habitation missions. Current state-of-the-art in plant-based, regenerative life support requires resources in excess of allocation proposed for candidate mission scenarios. Feasibility thresholds have been identified for candidate exploration missions. The goal of this paper is to review recent advances in performance achieved in the CELSS Antarctic Analog Project (CAAP) in light of the likely resource constraints. A prototype CAAP crop production chamber has been constructed and operated at the Ames Research Center. The chamber includes a number of unique hardware and software components focused on attempts to increase production efficiency, increase energy efficiency, and control the flow of energy and mass through the system. Both single crop, batch production and continuous cultivation of mixed crops production studies have been completed. The crop productivity as well as engineering performance of the chamber are described. For each scenario, energy required and partitioned for lighting, cooling, pumping, fans, etc. is quantified. Crop production and the resulting lighting efficiency and energy conversion efficiencies are presented. In the mixed-crop scenario, with 27 different crops under cultivation, 17 m2 of crop area provided a mean of 515 g edible biomass per day (85% of the approximate 620 g required for one person). Enhanced engineering and crop production performance achieved with the CAAP chamber, compared with current state-of-the-art, places plant-based life support systems at the threshold of feasibility.     

Teratogenic effects of gravitational changes.

In investigating the effect of gravitational changes on development, it is instructive to think of altered gravity (delta g) as a teratogen--that is, an environmental factor influencing development. Observed effects on skeletal development include: suppression of morphogenesis in centrifuged mouse limb buds; advanced fusion stages in centrifuged mouse palates; smaller crown rump lengths (CRL) and decreased number of pregnancies in centrifuged rats and mice; altered differentiation of growth plates in young growing rats in space; and decreased length of calcified long bone regions in fetal rats exposed to microgravity in utero. These studies show that delta g is able to alter development in vivo and in vitro and suggest that delta g operates, at least in part, at the cellular level.     

ROSA Rotorcraft Open Systems Avionics

Commercial standards adopted from the volume-driven electronics markets provide improved processing capacities over those widely used military standards and at reduced cost. Desired future capabilities and advanced functions, such as RPA, require the throughput, bandwidth, and memory provided by commercial processors and data buses. The primary issues needing resolution prior to implementation are related to operations in military rotorcraft environment, reliability, redundancy management, and fault and battle damage tolerance. In addition, some required network components presently do not exist in the preferred form factors. The ROSA project is providing effective laboratory demonstrations of COTS products and open systems specifications and standards to rotorcraft avionics. Preliminary cost estimates forecast large potential savings and create a compelling business case for follow-on research and transition to production systems. In addition, the project is developing a Rotorcraft Technical Architecture with the participation of many industry partners and will promote the resulting documentation as background materials for the JTA-A     

The passenger aircraft cargo hold environment: the implications of a fire on lithium-ion battery shipments

Although very rare events, fires in aircraft cargo holds are a concern for regulators, aircraft operators, and passengers. Lithium-ion cells and batteries are often shipped as cargo aboard passenger aircraft. This paper provides an overview of cargo hold configurations and fire suppression systems in passenger aircraft. Next, ways in which a cargo hold fire might affect a shipment of lithium-ion cells or batteries, and the degree to which the cells or batteries might interact with a fire are discussed. Finally, the results of FAA simulated cargo hold fire testing are presented and discussed in the context of lithium-ion cell or battery shipments.     

Fly-by-wire T & E challenge [aircraft test pilot handling compensation]

Systems developers and testers have always assumed that human compensation is measurable, or, at least, that a cognizant and trained tester is able to identify and detect compensation. More than one study conducted at the Wright-Patterson large amplitude multi-mode aerospace research simulator (LAMARS) facility indicates that this is not necessarily true. Test pilots were able to compensate sufficiently to fly and meet defined performance standards on intentionally crippled aircraft flight control designs. These flight control systems were designed to trigger pilot-induced oscillations, but, in most cases, test pilots could compensate sufficiently to prevent pilot-induced oscillations and to control the simulated aircraft. Anecdotally, this points to a colossal deficiency in the test of highly augmented aircraft systems that has been borne out by multiple aircraft accidents in actual aircraft designs: natural pilot compensation is sufficient to allow faulty designs to reach production and operational service while hiding critical handling qualities cliffs that can lead to loss of an aircraft. This observation, if applied across the gamut of human factors experimentation, has vast ramifications for test and evaluation and development of all human interface systems.     

Successful deployment of commercial ATE to an Air Force I-level (back-shop) repair facility

In today's world of constrained budgets, one of the problems the military faces is the challenge of trying to maintain organic maintenance capabilities. Historically, the US Air Force has desired to achieve an autonomous capability to maintain the equipment it uses. This has been achieved, traditionally, by setting-up three levels of maintenance: organizational; intermediate (back-shop); and depot. The I-level back-shops often utilize militarized automatic test equipment (ATE) and test program sets (TPSs) to test today's complex aircraft line replaceable units (LRUs). And even though this is still a cost-effective maintenance philosophy, it has become costly to develop militarized ATE. The Department of Defense (DoD) has been very active in trying to reduce the total ownership cost of ATE in the government inventory. One approach is to utilize commercial, instead of Mil-Spec, ATE. However, utilizing commercial ATE at an USAF back-shop is not without its tradeoffs and challenges as it represents a significant deviation from the way the USAF maintenance squadrons are accustomed to "doing business." This paper documents the current success story of replacing the legacy C-17 I-level ATE with a commercial ATE.     

Induction of hypoxic root metabolism results from physical limitations in O2 bioavailability in microgravity.

Numerous spaceflight experiments have noted changes in the roots that are consistent with hypoxia in the root zone. These observations include general ultrastructure analysis and biochemical measurements to direct measurements of stress specific enzymes. In experiments that have monitored alcohol dehydrogenase (ADH), the data shows this hypoxically responsive gene is induced and is associated with increased ADH activity in microgravity. These changes in ADH could be induced either by spaceflight hypoxia resulting from inhibition of gravity mediated O2 transport, or by a non-specific stress response due to inhibition of gravisensing. We tested these hypotheses in a series of two experiments. The objective of the first experiment was to determine if physical changes in gravity-mediated O2 transport can be directly measured, while the second series of experiments tested whether disruption of gravisensing can induce a non-specific ADH response. To directly measure O2 bioavailability as a function of gravity, we designed a sensor that mimics metabolic oxygen consumption in the rhizosphere. Because of these criteria, the sensor is sensitive to any changes in root O2 bioavailability that may occur in microgravity. In a KC-135 experiment, the sensor was implanted in a moist granular clay media and exposed to microgravity during parabolic flight. The resulting data indicated that root O2 bioavailability decreased in phase with gravity. In experiments that tested for non-specific induction of ADH, we compared the response of transgenic Arabidopsis plants (ADH promoted GUS marker gene) exposed to clinostat, control, and waterlogged conditions. The plants were grown on agar slats in a growth chamber before being exposed to the experimental treatments. The plants were stained for GUS activity localization, and subjected to biochemical tests for ADH, and GUS enzyme activity. These tests showed that the waterlogging treatment induced significant increases in GUS and ADH enzyme activities, while the control and clinostat treatments showed no response. This work demonstrates: (1) the inhibition of gravity-driven convective transport can reduce the O2 bioavailability to the root tip, and (2) the perturbation of gravisensing by clinostat rotation does not induce a nonspecific stress response involving ADH. Together these experiments support the microgravity convection inhibition model for explaining changes in root metabolism during spaceflight.     

Proposed optical observations of Comet Halley

A comprehensive programme is proposed for optical observations of Comet Halley based on the wide range of available facilities such as photometers, monochromators, interferometers and a polarimeter. Feasibility study of the proposed investigations with reference to existing facilities is carried out for each technique and needs for additional instrumentation are established. Conclusions for optimum utilization of existing facilities are presented.     

Relative biological effectiveness and microdosimetry of a mixed energy field of protons up to 200 MeV.

We have studied radiation effects utilizing the new 250 MeV Synchrotron at Loma Linda University Medical Center. In this paper we present the data collected for the survival of Chinese hamster lung (V79) cells, that were irradiated with a beam of mixed energy protons up to 200 MeV. The RBE for protons, when compared to 60Co gamma rays, ranged from a low of 1.2 at the high energy portion of the field to 1.3+ at the low energy portion of the field. These results are consistent with the measured lineal energy (microdosimetric) spectra.     

Using interchangeable virtual instrument (IVI) drivers to increasetest system performance

Instrument driver technology has evolved tremendously over the last decade. Initiatives such as SCPI and VXIplug&play have simplified remote instrument programming with standardized command messages and high-level utility functions. The latest initiative is the Interchangeable Virtual Instrument (IVI) Foundation. IVI defines standards for instrument drivers that offer benefits to provide higher performance. These benefits include instrument interchangeability, instrument simulation, and instrument state-caching. Because instrument drivers are an integral part of a modern test system, IVI promises to provide developers with the tools to increase their system performance significantly. This paper reviews the technical aspects of the IVI specification and the TVI architecture and describes how IVI can help the test system developer improve performance and lower long-term software maintenance costs