Star tracking reticles

A method for the production of reticles, particularly those for use in outer space, where the product is a quartz base coated with highly adherent layers of chromium, chromium-silver, and silver vacuum deposited through a mask, and then coated with an electrodeposit of copper from a copper sulfate solution followed by an electrodeposit of black chromium is described. The masks are produced by coating a beryllium-copper alloy substrate with a positive working photoresist, developing the photoresist, according to a pattern to leave a positive mask, plating uncoated areas with gold, removing the photoresist, coating the substrate with a negative working photoresist, developing the negative working photoresist to expose the base metal of the pattern, and chemically etching the unplated side of the pattern to produce the mask

Process for the production of star-tracking reticles

Reticles designed with quartz bases are masked with desired pattern and then are coated with highly adherent layers of chromium, chromium silver alloy, silver, copper, and black chromium (mixture of chromium and chromium oxides). Black chromium final layer produces required nonreflective surface

Formation of star tracking reticles

The present application is directed towards a process for producing high resolution, substantially non-reflective reticles or choppers suitable for use for transmitting in both the visible and near ultra-violet regions, able to withstand reasonable handling and extreme environmental conditions, and capable of operating at speeds of from 2800 to about 9000 revolutions per minute without distortion. In particular, the present invention is directed towards the production or reticles having a quartz base vacuum coated with chromium, chromium-silver alloy, and silver with electrodeposited copper and black chromium thereon, respectively, in the form of a reticle pattern. The quartz permits the transmission of light while the pattern is opaque to light. The reticles of the present invention are intended for use in optical trackers, such as star trackers used in outer space

The effects of estimation of censoring, truncation, transformation and partial data vectors

The purpose of this research was to attack statistical problems concerning the estimation of distributions for purposes of predicting and measuring assembly performance as it appears in biological and physical situations. Various statistical procedures were proposed to attack problems of this sort, that is, to produce the statistical distributions of the outcomes of biological and physical situations which, employ characteristics measured on constituent parts. The techniques are described

An experimental investigation of leading-edge vortex augmentation by blowing

A wind tunnel test was conducted to determine the effects of over-the-wing blowing as a means of augmenting the leading-edge vortex flow of several pointed-tip, sharp-edged planforms. Arrow, delta, and diamond wings with leading-edge sweeps of 30 and 45 degrees were mounted on a body-of-revolution fuselage and tested in a low-speed wind tunnel at a Mach number of 0.2. Nozzle location data, pitch data, and flow-visualization pictures were obtained for a range of blowing rates. Results show pronounced increases in vortex lift due to the blowing

A Revised Geometry for the Magnetic Wind of theta^1 Orionis C

Theta^1 Ori is thought to be a hot analog of Bp variables because its optical and UV line and X-ray continuum fluxes modulate regularly over the magnetic/rotational period. A flattened magnetosphere surrounding co-rotates with these stars, producing a periodic modulation of emission and absorption components of the UV resonance lines, as well as of optical H and He lines. In this paper we examine these modulations in detail and point out that the far-blue and near-red wings of C IV and N V resonance lines exhibit anticorrelated modulations, causing mild flux elevations at moderate redshifts at edge-on phase (phi=0.5). However, the lines do not exhibit rest-frame absorption features, the usual signatures of cool static disks surrounding Bp stars. We suggest that this behavior can be explained by the existence of two geometrically distinct wind regions separated by the local magnetic Alfven radius. Wind streams emerging outside this point are forced outward by radiative forces and eventually expand outward radially to infinity - this matter produces the far-blue wing absorptions at phi=0.5. Interior streams follow closed loops and collide at the magnetic equator with counterstreams. There they coalesce and fall back to the star along their original field lines - these are responsible for mild emissions at this same phase. The rapid circulation of the interior wind component back to the star is responsible for the absence of static disk features.Comment: 7 figure

Frog foams and natural protein surfactants

Foams and surfactants are relatively rare in biology because of their potential to harm cell membranes and other delicate tissues. However, in recent work we have identified and characterized a number of natural surfactant proteins found in the foam nests of tropical frogs and other unusual sources. These proteins, and their associated foams, are relatively stable and bio-compatible, but with intriguing molecular structures that reveal a new class of surfactant activity. Here we review the structures and functional mechanisms of some of these proteins as revealed by experiments involving a range of biophysical and biochemical techniques, with additional mechanistic support coming from more recent site-directed mutagenesis studies

Atmospheric constraint statistics for the Space Shuttle mission planning

The procedures used to establish statistics of atmospheric constraints of interest to the Space Shuttle mission planning are presented. The statistics considered are for the frequency of occurrence, runs, and time conditional probabilities of several atmospheric constrants for each of the Space Shuttle mission phases. The mission phases considered are (1) prelaunch, (2) launch, (3) return to launch site, (4) abort once around landing, and (5) end of mission landing

Some properties of a 5-parameter bivariate probability distribution

A five-parameter bivariate gamma distribution having two shape parameters, two location parameters and a correlation parameter was developed. This more general bivariate gamma distribution reduces to the known four-parameter distribution. The five-parameter distribution gives a better fit to the gust data. The statistical properties of this general bivariate gamma distribution and a hypothesis test were investigated. Although these developments have come too late in the Shuttle program to be used directly as design criteria for ascent wind gust loads, the new wind gust model has helped to explain the wind profile conditions which cause large dynamic loads. Other potential applications of the newly developed five-parameter bivariate gamma distribution are in the areas of reliability theory, signal noise, and vibration mechanics