Tech Briefs

Advanced Metal Foam Structures for Outer Space

A document discusses a proposal to use advanced materials — especially bulk metallic glass (BMG) foams — in structural components of spacecraft, lunar habitats, and the like. BMG foams, which are already used on Earth in some consumer products, are superior to conventional metal foams: BMG foams have exceptionally low mass densities and high strength-to-weight ratios and are more readily processable into strong, lightweight objects of various sizes and shapes. These and other attractive properties of BMG foams would be exploited, according to the proposal, to enable in situ processing of BMG foams for erecting and repairing panels, shells, containers, and other objects. The in situ processing could include (1) generation of BMG foams inside prefabricated deployable skins that would define the sizes and shapes of the objects thus formed and (2) thermoplastic deformation of BMG foams. Typically, the generation of BMG foams would involve mixtures of precursor chemicals that would be subjected to suitable pressure and temperature schedules. In addition to serving as structural components, objects containing or consisting of BMG foams could perform such functions as thermal management, shielding against radiation, and shielding against hypervelocity impacts of micrometeors and small debris particles.

Posted in: Briefs, TSP, Materials


Improved Small-Particle Powders for Plasma Spraying

Minimum layer thicknesses needed for complete coverage are reduced. Improved small-particle powders and powder-processing conditions have been developed for use in plasma spray deposition of thermal-barrier and environmentalbarrier coatings. Heretofore, plasmasprayed coatings have typically ranged in thickness from 125 to 1,800 µm. As explained below, the improved powders make it possible to ensure complete coverage of substrates at unprecedentedly small thicknesses — of the order of 25 µm.

Posted in: Briefs, TSP, Materials


Wipes, Coatings, and Patches for Detecting Hydrazines

With suitable reformulation, other hazardous substances could also be detected. Three color-indicating devices have been conceived as simple, rapid, inexpensive means of detecting hazardous liquid and gaseous substances in settings in which safety is of paramount concern and it would be too time-consuming or otherwise impractical to perform detection by use of such instruments as mass spectrometers. More specifically, these devices are designed for detecting hypergolic fuels (in particular, hydrazines) and hypergolic oxidizers in spacecraft settings, where occasional leakage of these substances in liquid or vapor form occurs and it is imperative to take early corrective action to minimize adverse health effects. With suitable redesign, including reformulation of their color indicator chemicals, these devices could be adapted to detection of other hazardous substances in terrestrial settings (e.g., industrial and military ones).

Posted in: Briefs, Materials


Flexible, Carbon-Based Ohmic Contacts for Organic Transistors

These contacts are printed using an inexpensive, low temperature process. A low-temperature process for fabricating flexible, ohmic contacts for use in organic thin-film transistors (OTFTs) has been developed. Typical drainsource contact materials used previously for OTFTs include (1) vacuum deposited noble metal contacts and (2) solution deposited intrinsically conducting molecular or polymeric contacts. Both of these approaches, however, have serious drawbacks.

Posted in: Briefs, TSP, Semiconductors & ICs


Tool Measures Depths of Defects on a Case Tang Joint

Precise measurements can be made consistently.A special-purpose tool has been developed for measuring the depths of defects on an O-ring seal surface. The surface lies in a specially shaped ringlike fitting, called a “capture feature tang,” located on an end of a cylindrical segment of a case that contains a solid-fuel booster rocket motor for launching a space shuttle. The capture feature tang is a part of a tang-and-clevis, O-ring joint between the case segment and a similar, adjacent cylindrical case segment. When the segments are joined, the tang makes an interference fit with the clevis and squeezes the O-ring at the side of the gap.

Posted in: Briefs, Mechanical Components, Mechanics


Stability-Augmentation Devices for Miniature Aircraft

Passive mechanical devices help miniature aircraft fly in adverse weather. Non-aerodynamic mechanical devices are under consideration as means to augment the stability of miniature autonomous and remotely controlled aircraft. Such aircraft can be used for diverse purposes, including military reconnaissance, radio communications, and safety-related monitoring of wide areas. The need for stability-augmentation devices arises because adverse meteorological conditions generally affect smaller aircraft more strongly than they affect larger aircraft: Miniature aircraft often become uncontrollable under conditions that would not be considered severe enough to warrant grounding of larger aircraft. The need for the stability augmentation devices to be non-aerodynamic arises because there is no known way to create controlled aerodynamic forces sufficient to counteract the uncontrollable meteorological forces on miniature aircraft.

Posted in: Briefs, Mechanical Components


Predicting Numbers of Problems in Development of Software

A method has been formulated to enable prediction of the amount of work that remains to be performed in developing flight software for a spacecraft. The basic concept embodied in the method is that of using an idealized curve (specifically, the Weibull function) to interpolate from (1) the numbers of problems discovered thus far to (2) a goal of discovering no new problems after launch (or six months into the future for software already in use in orbit). The steps of the method can be summarized as follows:

Posted in: Briefs, Information Sciences


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