Neil A. Armstrong Test Facility

Red‐winged Blackbirds Agelaius phoeniceus , the most abundant bird in North America, annually destroy over 360 000 tonnes of field corn and substantial amounts of sweet corn. This loss, representing <1% of North American corn production, is localized within 8 km of wetlands where Red‐winged Blackbirds roost in late summer. Red‐winged Blackbirds are often initially attracted to corn fields to feed on insect pests during the 2–3 week period between silking and kernel development. An ideal resolution of the conflict between corn farmers and Red‐winged Blackbirds is to couple the birds' beneficial feeding habits in silking‐stage corn with management techniques to reduce subsequent damage to kernels. Once birds switch from feeding on insects to feeding on corn, protective measures to reduce damage are more critical in the early (milk) stages of kernel development than later because the damage potential is much higher at this time. Birds must eat three times more kernels at 20 days after silking than at 40 days in order to receive the same corn biomass. The use of bird‐resistant cultivars of corn, the deployment of frightening devices during the critical damage period, and the provision of alternative feeding sites are important components of an integrated management programme. The goal is to accommodate Red‐winged Blackbirds as a part of the wetland‐agricultural complex in North America.

ABSTRACT We examined food habits and scale annuli of freshwater drum (Aplodinotus grunniens) from western Lake Erie to determine whether increasing predation on zebra mussels (Dreissena polymorpha) had affected growth of freshwater drum. The volume of zebra mussels in drum guts was greater in older fish. Growth of age classes 3–4, which consumed few zebra mussels, was greater in the most productive year for zebra mussels, July 1990–August 1991, than in three prior years. The total lengths of 5-year-old drum changed little. The mean total length of 6-year-old females has declined since the zebra mussel invaded Lake Erie, even through mussels comprised more than two-thirds of gut samples in these fish. These studies suggest that zebra mussels may not benefit freshwater drum when serving as a staple in the diet.

The U.S. Environmental Protection Agency and Environment Canada are supporting the development of indicators of ecosystem health that can be used to report on progress in restoring and maintaining the Great Lakes ecosystem, as called for in the Great Lakes Water Quality Agreement between the United States and Canada. One indicator under development is based on burrowing mayflies (Hexagenia: Ephemeroptera: Ephemeridae). We sampled in western Lake Erie, Saginaw Bay (Lake Huron), and Green Bay (Lake Michigan) in spring 2001 at 117 stations covering about 1,870 km2 of lake bed, to determine the status of nymphal populations of Hexagenia, and to provide information that would further the technical development of an indicator of ecosystem health based on Hexagenia. In western Lake Erie, density and biomass of nymphs were generally highest on fine-grained substrate in offshore waters and were lower on coarser substrates in near shore waters. Nymphs were virtually absent from Saginaw Bay, where only one nymph was collected at 28 stations. Nymphs were collected at only 6 of 48 stations in Green Bay, and density and biomass were highest at the northern end of the bay. Polluted sediments are likely responsible for the absence or low density and biomass of nymphs observed on fine-grained substrates in western Lake Erie, Saginaw Bay, and Green Bay, all of which historically supported abundant populations.

Concerns about climate change have encouraged significant interest in concepts for ultralow or “zero”-emissions power generation systems. In a concept proposed by Clean Energy Systems, Inc., nitrogen is removed from the combustion air and replaced with steam diluent. In this way, formation of nitrogen oxides is prevented, and the exhaust stream can be separated into concentrated CO2 and water streams. The concentrated CO2 stream could then serve as input to a CO2 sequestration process. In this study, experimental data are reported from a full-scale combustion test using steam as the diluent in oxy-fuel combustion. This combustor represents the “reheat” combustion system in a steam cycle that uses a high and low-pressure steam expansion. The reheat combustor serves to raise the temperature of the low-pressure steam turbine inlet, similar to the reheat stage of a conventional steam power cycle. Unlike a conventional steam cycle, the reheat enthalpy is actually generated by oxy-fuel combustion in the steam flow. This paper reports on the unique design aspects of this combustor, as well as initial emissions and operating performance.

A section of retrieved Hubble Space Telescope (HST) bi-stem thermal shields (BSTS), which experienced 8.25 years of space exposure, was analyzed for space environmental durability. The shields were comprised of 2 mil (0.051 mm) aluminized-Teflon® fluorinated ethylene propylene (Al-FEP) rings fused together into a circular bellows shape. As the circular thermal shields had solar, anti-solar and solar-grazing surfaces and were exposed to the space environment for a long duration, it provided a unique opportunity to study solar effects on the environmental degradation of Al-FEP, a commonly used spacecraft thermal control material. Therefore, the objective of this research was to characterize the degradation of retrieved HST BSTS Al-FEP with particular emphasis on solar effects. Data obtained included tensile properties, density (as-retrieved and after 200 3 C heating), solar absorptance, and surface morphology and chemistry. The solar-facing surfaces of the thermal shields were found to be extremely embrittled and contained numerous through-thickness cracks. Tensile testing verified that near solar-facing surfaces lost their mechanical strength and elasticity, whereas the anti-solar-facing surfaces maintained their ductility. The density of the as-retrieved BSTS insulation was similar to pristine FEP. Heating at 200 3 C resulted in significant increases in density for the solar-facing BSTS indicating chain scission damage, consistent with the loss of mechanical strength and elongation. The solar absorptance of the solar-grazing and the anti-solar-facing surfaces were found to be similar to pristine BSTS, whereas the solar-facing surfaces were found to have significantly increased solar absorptance. Both solar- and anti-solar-facing surfaces were microscopically textured from sweeping atomic oxygen erosion with the solar-facing surface appearing to have a more pronounced texture in spite of being exposed to a lower atomic oxygen fluence indicating a possible solar/atomic oxygen synergistic effect. These results provide valuable information on space environmental degradation of Al-FEP, particularly with respect to solar radiation effects on embrittlement.

We conducted studies from 1994 to 1999 in eastern South Dakota to determine the best strategy for baiting spring-migrating blackbirds. From 26 March to 14 April, male and female red-winged blackbirds made-up 61% and 17% of the roost population, respectively. After the 14th of April, the population consisted of 32% male and 49% female red-winged blackbirds. Blackbird migration in eastern South Dakota generally ended by late April. Habitat use studies conducted in March and April 1994, 1995, and 1998 showed that blackbirds used corn stubble for foraging and woodlots/shelterbelts for loafing. We concluded that bait plots located in corn stubble adjacent to wooded areas could attract large numbers of red-winged blackbirds during spring migration.

Facility, commonly referred to as B-2, is NASA's third largest thermal vacuum facility. It is the largest designed to store and transfer large quantities of liquid hydrogen and liquid oxygen, and is perfectly suited to support developmental testing of upper stage chemical propulsion systems as well as fully integrated stages. The facility is also capable of providing thermal-vacuum simulation services to support testing of large lightweight structures, Cryogenic Fluid Management (CFM) systems, electric propulsion test programs, and other In-Space propulsion programs.

Four unique, world class propulsion testing facilities are located at NASA Lewis Research Center's Plum Brook Station in northern Ohio, USA. These facilities include the world's largest thermal vacuum chamber which can be used for testing future nuclear rocket propulsion systems or solar thermal upper stages; the world's largest upper stage launch vehicle test facility wherein liquid rocket engines or complete vehicles can be system tested, including hot firing, under simulated space conditions; the world's largest slush hydrogen batch production facility for conducting full scale densified fuels development testing; and one of the world's largest clean air hypersonic wind tunnels capable of advanced propulsion system development in the Mach 5 through 7 range. During the past seven years, all four of these world class test facilities were reactivated and were recently used in partnership by NASA, other government agencies, and the private sector. This paper focuses on one of these facilities, the Spacecraft Propulsion Research Facility (B-2). Some of the cutting edge technology development work recently conducted in this facility is also being reported at this propulsion conference (see References Section of this report).

Development of method of direct correlation of radiation damage with time-integrated activation of neutron dosimeters

A digital computer control and abort system which is used at NASA-Lewis research center is described. The system was designed to control test operations such as rocket engine testing, structure testing, and wind tunnel tests. Because of the nature of spacecraft system testing, particularly rocket engine testing, the unique features of the system are, control function updating at a 20 millisecond rate, continuous abort monitoring and a software system designed for short duration tests rather than continuous on-line control. To accomplish these system requirements, special hardware was designed. The presentation includes a description of the computer system and special interface hardware as well as a general description of the software used.

The NASA Glenn Research Center’s (GRC’s) Plum Brook Station has a complement of unique, highly capable facilities that can test space flight hardware ranging from development testing at the component, subsystem and system levels up to environmental qualification of very large spacecraft and extraterrestrial surface systems. The facilities can simulate the conditions of free space or the surfaces of the Moon or Mars, including atmospheric pressure and content, temperature and day/night cycles. This paper presents information on the facilities at the Plum Brook Station as they apply to the development of space systems that support the Vision for Space Exploration, and cites specific examples of testing to illustrate those capabilities.

Tungsten-184 is a useful dosimeter for thermal neutrons, particularly for high temperature applications. Correlation of neutron flux with 59Co activation and 235U fission density for short-term irradiations is shown. The 184W thermal-neutron capture cross-section in the Plum Brook Reactor was found to be 1.94 ± 0.08 b. Cadmium ratios for 184W are ~⅕ of the value found for 59Co in differing spectral regions of the reactor. The radiochemistry and counting techniques for 185W are described.

Electric field emissions at frequencies of (n + 1/2) times the electron cyclotron frequency have been generated in a large-scale electron beam experiment in a vacuum facility. These emissions arise when a contrastreaming beam configuration exists, the primary beam consisting of monoenergetic electrons (50 eV to 5 keV) and the other beam of lower-energy backscattered secondary electrons. It is suggested that the same mechanism could also be the source of the observed 3/2 times the electron cyclotron frequency emissions at auroral latitudes. In the absence of the beam-beam instability, weak oscillations were observed at the plasma frequency. In the latter case no significant modifications of the primary beam velocity distribution occurred, and the beam configuration is adequately described by single-particle motion in the ambient magnetic field.

A way to vary the source to microphone distance and obtain noise measurements over a reflecting plane adhering to the spherical spreading law is achieved by adjusting the microphone height to maintain the ground interference pattern. Vehicle noise radiation mechanisms are re-examined. The study shows how to devise a stationary test procedure which could be expected to correlate with a given passby vehicle noise test procedure. An example shows how a motorcycle passby test is transformed into a correlatable stationary test with five times as short a measurement distance. The noise testing costs and complexity can be significantly reduced by methods discussed here.

In the design of irradiation experiments, prediction of the perturbation of the thermal-neutron flux by the experiment test specimens is frequently a problem. In order to obtain a model for calculating these perturbation effects, an experimental study was performed. A cylindrical shape was selected as being most typical of irradiation test specimens, and measurements of perturbation effects were made for several cylinders having different dimensions and made from different materials.Regression analysis was used to obtain polynomials from these measurements. These polynomials can be used to predict the flux perturbation, depression, and self-shielding factors as functions of cylinder materials and dimensions and control-rod position. The polynomials include a wide range of sizes and materials so that almost any cylindrical specimen that might be found in a typical irradiation capsule can be evaluated. In general, the error at the fitted points was only a few percent over the range of variables corresponding to most common materials and dimensions.In many cases, the polynomials have several distinct advantages over numerical models or mockup measurements. They are general (insofar as a cylinder is a typical shape for reactor test specimens), and they are simple to use since they require no computer calculations or reactor time. Also, their uncertainty can be established quantitatively (excluding the uncertainty due to reactor differences).These measurements were made in the Plum Brook test reactor. Because this is a typical reactor configuration (light-water moderated, MTR-type fuel elements with metal-to-water ratio of 0.75) much like many other reactors that can be found in industry and government today, these results should be generally useful. For reactors differing from this typical configuration, the results can be used to estimate flux perturbation effects after consideration is given to basic reactor differences. Also, we feel that the success we have experienced with this approach to the perturbation problem will be of interest to others confronted with this problem and having the facilities to repeat these measurements for their reactor.

The space power facility is located at NASA's Glenn Research Center Plum Brook Station in Sandusky, Ohio. It is the world's largest space simulation test facility with a test chamber that is 30.5m (100ft) in diameter by 37.2m (122ft) high. It has been used to test a variety of large space flight hardware and space systems for NASA, other government agencies, and the private sector over the last 20 years. Most of the design features of the facility provide unique characteristics that are ideally suited to meet the requirements of large space optical system thermal/vacuum testing. This paper describes the space power facility's unique characteristics and systems and how they meet these requirements. Future large space optical systems require a facility that can handle large, delicate hardware in a clean environment. Large high bay clean rooms are needed for pre-test build-up and checkout activities. A large test chamber with easy access is needed near the build-up area to minimize the risk of transporting the hardware into the chamber for thermal/vacuum testing. The space power facility's unique architecture with large high bays on each side of the test chamber is ideal for handling and processing large hardware and systems. Large space optical system testing requires a test environment that is as quiet as possible from a vibration standpoint. By nature of the construction of the space power facility, the vibration environment has been found to be extremely stable. Additionally, large space optical system testing must be performed at high-vacuum (< 1/spl times/10-5 Torr) conditions and many future systems require testing at cryogenic temperatures. The facility's high-vacuum system for pumping the test chamber has recently been upgraded with cryopumps and high-vacuum isolation valves to provide a contaminant-free, clean testing environment. To ensure that the facility upgrades has meet the demands of future test programs, an integrated systems test was performed to assess the operation and performance of the chamber and the new vacuum pumping system.