Development of a two axis motion simulation system for thermal/vacuum satellite testing

A two-axis motion simulation system for thermal vacuum testing of large satellites in a space simulation chamber was developed. Satellites as large as 3000 kilograms with a 4-meter diameter and a 5-meter length can be tested. This motion simulator (MS) incorporates several unique features which result in a less complicated design with improved performance when compared to previous satellite motion simulators. The design of the simulator is discussed in detail

Lower Respiratory Tract Infection Induced by a Genetically Modified Picornavirus in Its Natural Murine Host

Infections with the picornavirus, human rhinovirus (HRV), are a major cause of wheezing illnesses and asthma exacerbations. In developing a murine model of picornaviral airway infection, we noted the absence of murine rhinoviruses and that mice are not natural hosts for HRV. The picornavirus, mengovirus, induces lethal systemic infections in its natural murine hosts, but small genetic differences can profoundly affect picornaviral tropism and virulence. We demonstrate that inhalation of a genetically attenuated mengovirus, vMC0, induces lower respiratory tract infections in mice. After intranasal vMC0 inoculation, lung viral titers increased, peaking at 24 h postinoculation with viral shedding persisting for 5 days, whereas HRV-A01a lung viral titers decreased and were undetectable 24 h after intranasal inoculation. Inhalation of vMC0, but not vehicle or UV-inactivated vMC0, induced an acute respiratory illness, with body weight loss and lower airway inflammation, characterized by increased numbers of airway neutrophils and lymphocytes and elevated pulmonary expression of neutrophil chemoattractant CXCR2 ligands (CXCL1, CXCL2, CXCL5) and interleukin-17A. Mice inoculated with vMC0, compared with those inoculated with vehicle or UV-inactivated vMC0, exhibited increased pulmonary expression of interferon (IFN-α, IFN-β, IFN-λ), viral RNA sensors [toll-like receptor (TLR)3, TLR7, nucleotide-binding oligomerization domain containing 2 (NOD2)], and chemokines associated with HRV infection in humans (CXCL10, CCL2). Inhalation of vMC0, but not vehicle or UV-inactivated vMC0, was accompanied by increased airway fluid myeloperoxidase levels, an indicator of neutrophil activation, increased MUC5B gene expression, and lung edema, a sign of infection-related lung injury. Consistent with experimental HRV inoculations of nonallergic, nonasthmatic human subjects, there were no effects on airway hyperresponsiveness after inhalation of vMC0 by healthy mice. This novel murine model of picornaviral airway infection and inflammation should be useful for defining mechanisms of HRV pathogenesis in humans

Atmospheric budget implications of the temporal and spatial trends in methyl bromide concentraton

Methyl bromide (CH3Br) is an important ozone-depleting gas for which 20th century trends of the atmospheric concentration have recently been derived from air trapped in Antarctic firn. In this paper, a two-dimensional (2-D) global model, with a coupled atmosphere and ocean, is used to examine this historical trend, analyzing its implication for the various source strengths and the lifetime of CH3Br. The results illustrate that not only is the current understanding of the present-day atmospheric budget of CH3Br incomplete but so too is our understanding of the budget of CH3Br prior to major industrial emissions and anthropogenic changes to it. This difference cannot be explained by the overall error in the model results as determined from the uncertainties in the major source and sink terms. Either the estimate of the sink strength is too large or there is an underestimate of a known “nonindustrial” source or an unaccounted “nonindustrial” source, or some combination of these. Further, the results imply that the increase in the “anthropogenically influenced” sources during the 20th century is underestimated or that the sink strength is too strong. Since this applies to both before and after 1950, this suggests that the increase in nonfumigant sources and possibly fumigant sources is underestimated, assuming the sinks not to be overestimated. A longer lifetime has the effect of not only increasing the absolute concentrations but also increasing the rate of growth in concentrations and thus improving the agreement with the firn data. The sensitivity of the results to the uncertainties in the individual source and sink terms is assessed. The budget is also examined in terms of the properties of an artificial source necessary to provide balance. Other data sets of observed CH3Br concentration are also used to evaluate the modeled source and sink scenarios in terms of seasonal and latitudinal variations