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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 343 records · Page 19
All sourcesNASA NTRSDOE OSTI
NASA NTRS2004

A New Test Method for Material Flammability Assessment in Microgravity and Extraterrestrial Environments

The standard oxygen consumption (cone) calorimeter (described in ASTM E 1354 and NASA STD 6001 Test 2) is modified to provide a bench-scale test environment that simulates the low velocity buoyant or ventilation flow generated by or around a burning surface in a spacecraft or extraterrestrial gravity level. The Equivalent Low Stretch Apparatus (ELSA) uses an inverted cone geometry with the sample burning in a ceiling fire (stagnation flow) configuration. For a fixed radiant flux, ignition delay times for characterization material PMMA are shown to decrease by a factor of three at low stretch, demonstrating that ignition delay times determined from normal cone tests significantly underestimate the risk in microgravity. The critical heat flux for ignition is found to be lowered at low stretch as the convective cooling is reduced. At the limit of no stretch, any heat flux that exceeds the surface radiative loss at the surface ignition temperature is sufficient for ignition. Regression rates for PMMA increase with heat flux and stretch rate, but regression rates are much more sensitive to heat flux at the low stretch rates, where a modest increase in heat flux of 25 kW/m2 increases the burning rates by an order of magnitude. The global equivalence ratio of these flames is very fuel rich, and the quantity of CO produced in this configuration is significantly higher than standard cone tests. These results [2] demonstrate the ELSA apparatus allows us to conduct normal gravity experiments that accurately and quantifiably evaluate a material s flammability characteristics in the real-use environment of spacecraft or extra-terrestrial gravitational acceleration. These results also demonstrate that current NASA STD 6001 Test 2 (standard cone) is not conservative since it evaluates materials flammability with a much higher inherent buoyant convective flow.

Olson, S. L.↗
NASA NTRS2009

Circuit for Driving Piezoelectric Transducers

The figure schematically depicts an oscillator circuit for driving a piezoelectric transducer to excite vibrations in a mechanical structure. The circuit was designed and built to satisfy application-specific requirements to drive a selected one of 16 such transducers at a regulated amplitude and frequency chosen to optimize the amount of work performed by the transducer and to compensate for both (1) temporal variations of the resonance frequency and damping time of each transducer and (2) initially unknown differences among the resonance frequencies and damping times of different transducers. In other words, the circuit is designed to adjust itself to optimize the performance of whichever transducer is selected at any given time. The basic design concept may be adaptable to other applications that involve the use of piezoelectric transducers in ultrasonic cleaners and other apparatuses in which high-frequency mechanical drives are utilized. This circuit includes three resistor-capacitor networks that, together with the selected piezoelectric transducer, constitute a band-pass filter having a peak response at a frequency of about 2 kHz, which is approximately the resonance frequency of the piezoelectric transducers. Gain for generating oscillations is provided by a power hybrid operational amplifier (U1). A junction field-effect transistor (Q1) in combination with a resistor (R4) is used as a voltage-variable resistor to control the magnitude of the oscillation. The voltage-variable resistor is part of a feedback control loop: Part of the output of the oscillator is rectified and filtered for use as a slow negative feedback to the gate of Q1 to keep the output amplitude constant. The response of this control loop is much slower than 2 kHz and, therefore, does not introduce significant distortion of the oscillator output, which is a fairly clean sine wave. The positive AC feedback needed to sustain oscillations is derived from sampling the current through the piezoelectric transducer. This positive AC feedback, in combination with the slow feedback to the voltage-variable resistors, causes the overall loop gain to be just large enough to keep the oscillator running. The positive feedback loop includes two 16-channel multiplexers, which are not shown in the figure. One multiplexer is used to select the desired piezoelectric transducer. The other multiplexer, which is provided for use in the event that there are significant differences among the damping times of the 16 piezoelectric transducers, facilitates changing the value of one of the resistors in the positive-feedback loop to accommodate the damping time of the selected transducer.

Randall, David P.↗
NASA NTRS1998

The Growth of Protein Crystals Using McDUCK

Most of the current microgravity crystal growth hardware is optimized to produce crystals within the limited time available on orbit. This often results in the actual nucleation and growth process being rushed or the system not coming to equilibrium within the limited time available. Longer duration hardware exists, but one cannot readily pick out crystals grown early versus those which nucleated and grew more slowly. We have devised a long duration apparatus, the Multi-chamber Dialysis Unit for Crystallization Kinetics, or McDUCK. This apparatus-is a series of protein chambers, stacked upon a precipitant reservoir chamber. All chambers are separated by a dialysis membrane, which serves to pass small molecules while retaining the protein. The volume of the Precipitant chamber is equal to the sum of the volumes of the protein chamber. In operation, the appropriate chambers are filled with precipitant solution or protein solution, and the McDUCK is placed standing upright, with the precipitant chamber on the bottom. The precipitant diffuses upwards over time, with the time to reach equilibration a function of the diffusivity of the precipitant and the overall length of the diffusion pathway. Typical equilibration times are approximately 2-4 months, and one can readily separate rapid from slow nucleation and growth crystals. An advantage on Earth is that the vertical precipitant concentration gradient dominates that of the solute, thus dampening out solute density gradient driven convective flows. However, large Earth-grown crystals have so far tended to be more two dimensional. Preliminary X-ray diffraction analysis of lysozyme crystals grown in McDUCK have indicated that the best, and largest, come from the middle chambers, suggesting that there is an optimal growth rate. Further, the improvements in diffraction resolution have been better signal to noise ratios in the low resolution data, not an increase in resolution overall. Due to the persistently large crystals grown we are currently proposing McDUCK for the growth of macromolecule crystals for use in neutron diffraction studies.

Ewing, Felicia↗
NASA NTRS1982

Improved boundary lubrication with formulated C-ethers

A comparison of five recently developed C-ether-formulated fluids with an advanced formulated MIL-L-27502 candidate ester is described. Steady state wear and friction measurements were made with a sliding pin on disk friction apparatus. Conditions included disk temperatures up to 260 C, dry air test atmosphere, 1 kilogram load, 50 rpm disk speed, and test times to 130 minutes. Based on wear rates and coefficients of friction, three of the C-ether formulations as well as the C-ether base fluid gave better boundary lubrication than the ester fluid under all test conditions. The susceptibility of C-ethers to selective additive treatment (phosphinic esters or acids and other antiwear additives) was demonstrated when two of the formulations gave somewhat improved lubrication over the base fluid. The increased operating potential for this fluid was shown in relationship to bulk oil temperature limits for MIL-L-23699 and MIL-L-27502 type esters.

Loomis, W. R.↗
NASA NTRS1991

Compact Apparatus For Growth Of Protein Crystals

Compact apparatus proposed specifically for growth of protein crystals in microgravity also used in terrestrial laboratories to initiate and terminate growth at prescribed times automatically. Has few moving parts. Also contains no syringes difficult to clean, load, and unload and introduces contaminant silicon grease into crystallization solution. After growth of crystals terminated, specimens retrieved and transported simply.

Carter, Daniel C.↗
NASA NTRS1994

Atomic oxygen reactor having at least one sidearm conduit

An apparatus for treating a microporous structure with atomic oxygen is presented. The apparatus includes a main gas chamber for flowing gas in an axial direction and a source of gas, containing atomic oxygen, connected for introducing the gas into the main gas chamber. The apparatus employs at least one side arm extending from the main atomic oxygen-containing chamber. The side arm has characteristic relaxation times such that a uniform atomic oxygen dose rate is delivered to a specimen positioned transversely in the side arm spaced from the main gas chamber.

Koontz, Steven L.↗
NASA NTRS1995

Effect of microgravity on stress ethylene and carbon dioxide production in sweet clover (Melilotus alba L.)

The study of higher plant growth and development in the microgravity (micro-g) environment continues to be a challenge. This is in part a result of the available flight qualified hardware with restrictive closed gas environments. This point is underscored by considering that gas exchange of seedlings grown in microgravity may be further limited owing to a thicker layer of water wicked onto the roots and to the absence of convective mixing. We hypothesized that seedlings grown under such conditions will experience greater hypoxia in microgravity than at Earth gravity, and thus produce greater stress ethylene. We compared flight and ground samples of sweet clover seedlings grown in the Fluid Processing Apparatus (FPA) during STS-57 and found them to contain extremely high levels of carbon dioxide (CO2) and stress ethylene. There were time dependent increases for both gases, and seedling growth was greatly inhibited. We repeated these experiments aboard STS-60 using modified chambers which increased, by fifty fold, the air available to the developing seedlings. Sweet clover seed germination and subsequent seedling growth to eight days within the FPA modified with a gas permeable membrane is not compromised by the microgravity environment.

Gallegos, Gregory L.↗
NASA NTRS2003

Radio Frequency Telemetry System for Sensors and Actuators

The present invention discloses and teaches apparatus for combining Radio Frequency (RF) technology with novel micro-inductor antennas and signal processing circuits for RF telemetry of real time, measured data, from microelectromechanical system (MEMS) sensors, through electromagnetic coupling with a remote poweringheceiving device. Such technology has many applications, but is especially useful in the biomedical area.

Rainee N Simons↗
NASA NTRS2003

Specific Heat and Second Sound Measurements with the DYNAMIX Instrument

In addition to its primary role of studying non-linear heat transport effects near the lambda transition of He-4, the DYNAMX apparatus is suitable for measurements of the specific heat and the velocity of second sound. We plan to take advantage of available time on orbit to make measurements in these areas near to the lambda transition. The specific heat work would be similar to LPE, aimed at improving our knowledge of the singularity in the bulk heat capacity at the transition, but would provide more accurate results close to the transition. It would focus roughly equally on each side of the transition and would be synergistic with the CQ experiment, providing wider-range data at Q = 0. The second sound measurements are made possible by the fast time constant and high resolution of the DYNAMX thermometers, which allow accurate time-of-flight measurements of second sound pulses. It appears possible to measure the second sound velocity to about 1% at a reduced temperature of t = 5x10(exp -8) by averaging over a moderate number of pulses. The data would complement and extend earlier ground-based measurements, leading to improved tests of the theory of static critical phenomena at the lambda transition.

Nissen, Joel↗
NASA NTRS1991

Motion detection, novelty filtering, and target tracking using an interferometric technique with GaAs phase conjugate mirror

A method and apparatus for detecting and tracking moving objects in a noise environment cluttered with fast- and slow-moving objects and other time-varying background. A pair of phase conjugate light beams carrying the same spatial information commonly cancel each other out through an image subtraction process in a phase conjugate interferometer, wherein gratings are formed in a fast photorefractive phase conjugate mirror material. In the steady state, there is no output. When the optical path of one of the two phase conjugate beams is suddenly changed, the return beam loses its phase conjugate nature and the interferometer is out of balance, resulting in an observable output. The observable output lasts until the phase conjugate nature of the beam has recovered. The observable time of the output signal is roughly equal to the formation time of the grating. If the optical path changing time is slower than the formation time, the change of optical path becomes unobservable, because the index grating can follow the change. Thus, objects traveling at speeds which result in a path changing time which is slower than the formation time are not observable and do not clutter the output image view.

Cheng, Li-Jen↗
NASA NTRS2003

Radio frequency telemetry system for sensors and actuators

The present invention discloses and teaches apparatus for combining Radio Frequency (RF) technology with novel micro-inductor antennas and signal processing circuits for RF telemetry of real time, measured data, from microelectromechanical system (MEMS) sensors, through electromagnetic coupling with a remote powering/receiving device. Such technology has many applications, but is especially useful in the biomedical area.

Simons, Rainee N.↗
NASA NTRS2023

A Multi-Sensor, Low Volume, Automated Culture System for Space Biology Experiments

Optical density (absorbance) is commonly used in microbiology to measure cell concentration and other colorimetric indicators. It is the main type of bioscience data returned from the BioSentinel small spacecraft mission, which was recently launched as a secondary payload on Artemis I. The flight unit takes absorbance measurements of yeast cultures at 570 nm, 630 nm, and 850 nm to track cell concentration and oxidation-reduction (redox) state of the metabolic indicator dye alamarBlue over time [1]. Because the data returned from a small spacecraft mission is necessarily limited, BioSentinel uses a specialized ground-based experiment apparatus to map the absorbance data onto several other parameters. This culture apparatus is composed of a polycarbonate base and lid which contain ports for several commercial sensors, including a standard 12 mm dissolved oxygen probe, gaseous CO2, fluid pressure, and two micro-probes for measuring pH and redox potential. It also contains a pressure relief valve, a rubber membrane for culture interaction, and a 12mm port for the custom optical probe designed to match in-flight measurements. Modules in two corners expand the culture volume into narrow columns, enabling solid-state optical density measurement and dielectric spectroscopy. The apparatus can be fit to a plate for magnetic stirring. The apparatus’s optical probe allows mapping between the flight unit’s optical data and the additional parameters measured by the ground-based experiments. Within the probe, a linear actuator pulls a plunger, drawing culture volume into the optical path. The actuator then pushes out the plunger and culture volume, cleaning any stray yeast from the inside surface of the probe. The probe chassis is 3D-printed from biocompatible resin with the optoelectronics cured inside an optically clear conformal coat which functions as a lens. To optimize the probe’s dimensions, including optical path, a test harness was developed to manipulate and measure distance while the LED light sources and photodiode detector are in operation. The test harness was composed of two 3/64” thick polycarbonate plates mounted to a set of calipers. The LEDs and photodiode were mounted on the outside of each plate. A cuvette of sample fluid was then clamped between the plates in line between the LEDs and photodiode. The test harness generated a 78% signal change between water and a dye standard for the green (570 nm) LED, a 90% signal change for the red (630 nm) LED, and a 25% signal change between water and overgrown yeast for the infrared (850 nm) LED. The improvements to the ground experiment apparatus (culture volume reduction, inclusion of an optical probe to measure flight-like optical data, and magnetic stirring for culture homogeneity) allow for more flight-like measurements to be taken and more accurate mapping of these additional parameters to the optical data returned from the flight unit. This enhancement to mission science return will give insight into how deep space radiation may affect human biology for future long-term space exploration.

Multi-Sensor↗
NASA NTRS1979

EKG and ultrasonoscope display

A system is disclosed which permits simultaneous display of an EKG waveform in real time in conjunction with a two-dimensional cross-sectional image of the heart, so that the EKG waveform can be directly compared with dimensional changes in the heart. The apparatus of the invention includes an ultrasonoscope for producing a C-scan cross-sectional image of the heart. An EKG monitor circuit along with EKG logic circuitry is combined with the ultrasonoscope circuitry to produce on the same oscilloscope screen a continuous vertical trace showing the EKG waveform simultaneously with the heart image. The logic circuitry controls the oscilloscope display such that the display of both heart and EKG waveforms occurs on a real time basis.

Lee, Robert D.↗
DOE OSTI2026

First results of the NEXT-100 detector using $^{83m}$Kr decays

The NEXT collaboration is investigating the double beta decay of $ ^{136}\mathrm Xe$ using high-pressure gas electroluminescent time projection chambers, which provide excellent energy resolution together with a robust topological signature. Operating at the Laboratorio Subterráneo de Canfranc (LSC) and building on the success of the NEXT-White detector, the NEXT-100 apparatus began commissioning in May 2024 and started operation with xenon at a pressure of 4 bar in October 2024. We report here the first results obtained with NEXT-100 using low-energy calibration data from $^{83\text {m}}\textrm{Kr}$ decays, which allow mapping of the detector response in the active volume and monitoring of its stability over time. After homogenizing the light response, we achieve an energy resolution of 4.37% FWHM at 41.5 keV for $^{83\text {m}}\textrm{Kr}$ point-like energy deposits contained in a radius of 425 mm. In a fiducial region representing the operating conditions of NEXT-100 at 10 bar we obtain an improved energy resolution of 4.16% FWHM. These results are in good agreement with that obtained in NEXT-White, and an $E^{-1/2}$ extrapolation to $Q_{\beta \beta }$ yields an energy resolution close to 0.5% FWHM, well below the 1% FWHM design target.

Martínez-Lema, G. [Donostia Intl. Phys. Ctr., San ↗
NASA NTRS1973

Ophthalmic method and apparatus

A method and apparatus for removing material and components such as the lens from an eye is described. High speed rotary cutting members at one end of a rod macerate the lens while an annular tubing disposed around the cutting members vibrates ultrasonically to coact with the cutting members in macerating the lens. At the same time, a liquid is supplied to the chamber behind the cornea of the eye. Spiral grooves extending along the rotating rod from the cutting members evacuate the liquid and the macerated material from the eye. An alternate embodiment of the apparatus includes a tube through which liquid is supplied to the operative site of the ultrasonically vibrating tube and the cutting members in the area of the lens.

Evvard, J. C.↗
NASA NTRS1984

Experimental results for the rapid determination of the freezing point of fuels

Two methods for the rapid determination of the freezing point of fuels were investigated: an optical method, which detected the change in light transmission from the disappearance of solid particles in the melted fuel; and a differential thermal analysis (DTA) method, which sensed the latent heat of fusion. A laboratory apparatus was fabricated to test the two methods. Cooling was done by thermoelectric modules using an ice-water bath as a heat sink. The DTA method was later modified to eliminate the reference fuel. The data from the sample were digitized and a point of inflection, which corresponds to the ASTM D-2386 freezing point (final melting point), was identified from the derivative. The apparatus was modifified to cool the fuel to -60 C and controls were added for maintaining constant cooling rate, rewarming rate, and hold time at minimum temperature. A parametric series of tests were run for twelve fuels with freezing points from -10 C to -50 C, varying cooling rate, rewarming rate, and hold time. Based on the results, an optimum test procedure was established. The results showed good agreement with ASTM D-2386 freezing point and differential scanning calorimetry results.

Mathiprakasam, B.↗
NASA NTRS1988

Simulation of launch and re-entry acceleration profiles for testing of Shuttle and unmanned microgravity research payloads

A procedure was developed for the simulation of the launch and reentry acceleration profiles of the Space Shuttle (3.3 and 1.7 g maximum, respectively) and of two versions of NASA's proposed materials research Reusable Reentry Satellite (RRS) (8 and 4 g maximum, respectively). With a 7-m centrifuge, the time dependence of five different acceleration episodes was simulated for payload masses up to 59 kg. Test results obtained for the Materials Dispersion Apparatus, a commercial low-cost payload device, are presented.

Cassanto, J. M.↗