Magazine

A thermoelectric contact cooler/ freezer is designed to utilize thermal conduction to rapidly freeze blood and urine samples in test tubes and syringes. This apparatus is dependable, wastes little energy, contains no moving parts other than a fan, can operate in a wide temperature range and in any orientation...

Electrochemical cells in which molten carbonates would serve as electrolytes have been proposed for use in electrolyzing CO2. The proposal was made in an effort to implement a concept of in situ resource utilization (ISRU) for the exploration of Mars; the basic idea is to generate CO (if needed as...

An improved spherical energy analyzer (a type of electrostatic mass spectrometer) is under development for use in analyzing a beam of ions generated by a Hall thruster. The major improvement, relative to a commercial spherical energy analyzer, is the addition of a quadrupole stage (with refocusing electron optics)...

An oxygen-deficiency monitoring system (ODMS) has been developed for a ten-room facility in which the use of large amounts of nitrogen and helium could cause an oxygen deficiency severe enough to be hazardous to personnel. The ODMS comprises three subsystems, of which two monitor three rooms...

A report presents the mathematical basis of a method of controlling multiple spacecraft flying in formation, subject to control constraints. The spacecraft are assumed to be equipped with relative-position-sensing, relative-velocity-sensing, and communication infrastructure, and with...

A report presents a theoretical study of communication among intelligent agents in the presence of quantum entanglement and the absence of classical (in the sense of non-quantum) communication channels. Several paradigms of self-organization based on quantum entanglement are introduced and...

A report proposes a technique for onboard updating of the orbital period of an aerobraking spacecraft in order to estimate the time of the next periapsis. The time of periapsis is nearly centered in the middle of the drag pass, and provides a convenient reference time for events in the...

A report briefly describes a user's guide for a computer program that constructs vector wind profiles on the basis of a statistical model. The monthly vector wind profiles are meant to be used (1) to estimate wind-dispersion-related dispersions of critical aerodynamic loads and...

A report describes an experimental study undertaken to verify a finite-element mathematical model used to predict residual stresses and stress-induced failures in the adhesive interfacial layers (bondlines) that join phenolic liners to interior surfaces of metal housings of reusable...

A report describes an improved micromachined vaporizing-liquid microthruster (VLM), now under development as a prototype of thrusters for microspacecraft. This thruster is of the resistojet type: the energy for vaporization and expansion of a propellant liquid is provided through...

A report describes an experimental study of the sizes and concentrations of capped (buried) and surface In0.6Ga0.4As/GaAs quantum dots that were grown by metal-organic vapor deposition under the same conditions except for the inclusion or exclusion of capping. [InxGa1-xAs/GaAs quantum dots...

A report proposes the development of a thin-film fuel cell that would generate electric power from two minor constituents of the Martian atmosphere — O2 and CO. These compounds are generated continuously by photolysis of CO2, the major constituent. The fuel cell would include a cathode...

A proposed x-ray instrument - a Fourier-transform x-ray microscope - would enable high-resolution imaging of objects with sizes of the order of 20 nm. (This size range is typical of cell organelles.) The instrument would also offer a spectroscopic capability for the sensitive detection and identification of...

AMPERES is a prototype computer program that implements the algorithm, described in the preceding article, for optimizing designs of diffractive optics. Several other programs for designing refractive optics are commercially available, but they offer very limited capabilities with respect to...

An algorithm for optimizing the designs of diffractive optics is based on constrained dynamics and the reciprocity of electromagnetic propagation. This algorithm can contribute to realization of the potential of diffractive optics, which offer capabilities greater than those of refractive...

Sensors based on microscopic optical resonators and arrays of such resonators have been proposed for detecting trace amounts of specific molecules in small gaseous, liquid, and solid samples. In addition to compactness, these sensors would offer ultrahigh sensitivity - in some cases, enough...

Solar heating has been proposed as a means of deployment of structures of the type described in "Cold Hibernated Elastic Memory (CHEM) Expandable Structures," (NPO-20394), NASA Tech Briefs, Vol. 23, No. 2 (February 1999), page 56. A few examples of structures that would be amenable to the CHEM...

Some experiments directed toward the development of improved hard, lubricious coating materials have involved direct fluorination of proprietary diamondlike coats on various substrates. The idea is to retain the hardness of the diamondlike material while adding surface molecular structures that impart the...