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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 325 records · Page 18
All sourcesNASA NTRSDOE OSTI
NASA NTRS2016

Levitation Technology in International Space Station Research

The International Space Station (ISS) is a unique multidisciplinary orbiting laboratory for science and technology research, enabling discoveries that benefit life on Earth and exploration of the universe. ISS facilities for containerless sample processing in Materials Science experiments include levitation devices with specimen positioning control while reducing containment vessel contamination. For example, ESA's EML (ElectroMagnetic Levitator), is used for melting and solidification of conductive metals, alloys, or semiconductors in ultra-high vacuum, or in high-purity gaseous atmospheres. Sample heating and positioning are accomplished through electromagnetic fields generated by a coil system. EML applications cover investigation of solidification and microstructural formation, evaluation of thermophysical properties of highly reactive metals (whose properties can be very sensitive to contamination), and examination of undercooled liquid metals to understand metastable phase convection and influence convection on structural changes. MSL utilization includes development of novel light-weight, high-performance materials. Another facility, JAXA's ELF (Electrostatic Levitation Furnace), is used to perform high temperature melting while avoiding chemical reactions with crucibles by levitating a sample through Coulomb force. ELF is capable of measuring density, surface tension, and viscosity of samples at high temperatures. One of the initial ELF investigations, Interfacial Energy-1, is aimed at clarification of interfacial phenomena between molten steels and oxide melts with industrial applications in control processes for liquid mixing. In addition to these Materials Science facilities, other ISS investigations that involve levitation employ it for biological research. For example, NASA's "Magnetic 3D Culturing and Bioprinting" investigation uses magnetic levitation for three-dimensional culturing and positioning of magnetized cells to generate spheroid assemblies for biomedical applications. Levitation is also used as a modeled microgravity ground analog in the NASA OsteoOmics ISS investigation, which tests whether magnetic levitation accurately simulates microgravity conditions by studying gravitational regulation of osteoblast and osteoclast genomics and metabolism. Elucidating the cellular mechanisms of bone loss in microgravity contributes to the understanding of bone loss in medical disorders on Earth, which may lead to development of preventive or therapeutic countermeasures. Thus, the ISS state-of-the-art laboratory offers various levitation capability platforms with applications for innovative research in Materials and Life Sciences disciplines, with benefits for humanity.

Guinart-Ramirez, Y.↗
NASA NTRS1976

Theory and applications of sampled analog recursive CTD comb filters

Sampled analog comb filter using a recursive filter implementation was studied. Charge transfer device delay lines were used as the delay elements. The similarities and differences between sampled analog recursive filter and digital recursive filter were pointed out. Both canceller type and integrator type comb filter using the first order or the second order canonical circuits were studied. Experimental results of frequency response are presented to show their difference from that of digital filters. A theoretical analysis was presented based essentially on the digital filter theory but modified to take into account the differences described above. The usefulness of this theory in analyzing the comb filter characteristics was discussed. Several applications of both the canceller type comb filter and the integrator type comb filter were demonstrated.

Tao, T. F.↗
NASA NTRS1990

Electro-optic network analyzer

The bandwidth of frequency domain measurement methods of electrical signals has usually been far greater than the bandwidth of time domain methods. The primary limits of the time domain approach have been the 20 to 30 GHz bandwidth limit for electronic waveform acquisition instrumentation, and the lack of usable electrical pulse generators for excitation of a test device. The bandwidth of frequency domain network analysis appears to have reached a plateau of between 100 to 200 GHz, while time domain measurement have improved markedly in both bandwidth and sensitivity with the introduction of the pulsed laser based electro-optic sampling approach. Network analysis or the measurement of device scattering parameters provides information necessary to the design of electronic network such as high frequency amplifiers, mixers, and phase shifter. The bandwidth of frequency domain network analysis is currently being exceeded by the next generations of high frequency transistors and devices. Thus the electro-optic approach is a natural means of extending network analysis into the range above 100 GHz by employing time domain methods. In this approach, a suitable electrical excitation pulse is generated and propagated along a transmission line toward a test device. In the picosecond domain, laser driven photoconductive switches provide a unique method of generating electrical transients. Several materials were studied for generating short electrical pulses using photoconductive switches. The various semiconductive materials tested for photoconductive switching, and the electro-optic measurement technique used to characterize the material performance are described.

Jackson, Todd A.↗
NASA NTRS2011

Distributed Capacitive Sensor for Sample Mass Measurement

Previous robotic sample return missions lacked in situ sample verification/ quantity measurement instruments. Therefore, the outcome of the mission remained unclear until spacecraft return. In situ sample verification systems such as this Distributed Capacitive (DisC) sensor would enable an unmanned spacecraft system to re-attempt the sample acquisition procedures until the capture of desired sample quantity is positively confirmed, thereby maximizing the prospect for scientific reward. The DisC device contains a 10-cm-diameter pressure-sensitive elastic membrane placed at the bottom of a sample canister. The membrane deforms under the weight of accumulating planetary sample. The membrane is positioned in close proximity to an opposing rigid substrate with a narrow gap. The deformation of the membrane makes the gap narrower, resulting in increased capacitance between the two parallel plates (elastic membrane and rigid substrate). C-V conversion circuits on a nearby PCB (printed circuit board) provide capacitance readout via LVDS (low-voltage differential signaling) interface. The capacitance method was chosen over other potential approaches such as the piezoelectric method because of its inherent temperature stability advantage. A reference capacitor and temperature sensor are embedded in the system to compensate for temperature effects. The pressure-sensitive membranes are aluminum 6061, stainless steel (SUS) 403, and metal-coated polyimide plates. The thicknesses of these membranes range from 250 to 500 m. The rigid substrate is made with a 1- to 2-mm-thick wafer of one of the following materials depending on the application requirements glass, silicon, polyimide, PCB substrate. The glass substrate is fabricated by a microelectromechanical systems (MEMS) fabrication approach. Several concentric electrode patterns are printed on the substrate. The initial gap between the two plates, 100 m, is defined by a silicon spacer ring that is anodically bonded to the glass substrate. The fabricated proof-of-concept devices have successfully demonstrated tens to hundreds of picofarads of capacitance change when a simulated sample (100 g to 500 g) is placed on the membrane.

Toda, Risaku↗
NASA NTRS1971

The Viking mission to Mars.

In 1975 the National Aeronautics and Space Administration will launch two unmanned scientific payloads to make soft landings on Mars in 1976. They will be placed in orbit around the planet to perform a reconnaissance before landing. The spacecraft will be separated into an orbiter, which is sent to the surface. During the entry into the Martian atmosphere, Viking will make measurements of the composition and atmospheric structure. After landing, two cameras will be used to visually characterize the site. A device will be deployed to obtain a sample of the Mars surface, which will be returned to the lander for biological tests and for chemical analysis. The atmosphere at the surface will be chemically analyzed as well as the wind velocity, the humidity, and changes in temperature and pressure.

Soffen, G. A.↗
NASA NTRS1979

Automated array assembly, phase 2

Tasks of scaling up the tandem junction cell (TJC) from 2 cm x 2 cm to 6.2 cm and the assembly of several modules using these large area TJC's are described. The scale-up of the TJC was based on using the existing process and doing the necessary design activities to increase the cell area to an acceptably large area. The design was carried out using available device models. The design was verified and sample large area TJCs were fabricated. Mechanical and process problems occurred causing a schedule slippage that resulted in contract expiration before enough large-area TJCs were fabricated to populate the sample tandem junction modules (TJM). A TJM design was carried out in which the module interconnects served to augment the current collecting buses on the cell. No sample TJMs were assembled due to a shortage of large-area TJCs.

Carbajal, B. G.↗
NASA NTRS1981

Germanium accumulation-mode charge-injection-device process

Gallium doped germanium is suitable for applications in the detection of far infrared radiation. Measurements were made on experimental photoconductors (PCs), accumulation mode charge injection devices (AMCIDs), and the SSPC (a switched, sampled PC alternative to the AMCID). The results indicate that the SSPC, which had a responsivity near 1.5 amp/watt, is desirable for use in two dimensional detector arrays.

Moore, T. G.↗
NASA NTRS1984

Automated Mercury Dilatometer

Task of reading and recording indications of mercury dilatometer simplified by automatic system. Volume change of sample under test converted into electrical signal. Device modified by addition of resistance wire to mercury column. Height of column read indirectly by measuring resistance between terminals. Signal suitable for strip-chart recording or other processing.

Hong, S. D.↗
NASA NTRS1982

Electrophoresis device

A device for separating cellular particles of a sample substance into fractionated streams of different cellular species includes a casing having a distribution chamber, a separation chamber, and a collection chamber. The electrode chambers are separated from the separation chamber interior by means of passages such that flow variations and membrane variations around the slotted portion of the electrode chamber do not enduce flow perturbations into the laminar buffer curtain flowing in the separation chamber. The cellular particles of the sample are separated under the influence of the electrical field and the separation chamber into streams of different cellular species. The streams of separated cells enter a partition array in the collection chamber where they are fractionated and collected.

Rhodes, P. H.↗
NASA NTRS1986

Partial-Transmission Scintillation Detector for Ions

Only outer portion of ion beam sampled to prevent unnecessary energy losses. Measurement device allows only periphery of beam to pass through scintillation material. Total flux in uniform beam inferred from peripheral flux. Device provides readings without reducing energy of ions in middle of beam. Measurement device developed for ion beams used in studies of how fast heavy ions affect integrated-circuit chips.

Malone, C. J.↗
NASA NTRS1986

Solar cell reliability testing

The progress and initial data on accelerated stress tests on small amorphous silicon test samples from several manufacturers are reported. The test samples include both single and tandem junction devices.

Lathrop, J.↗
NASA NTRS1986

Measurement of the thermal conductivity of composites using heat flow sensors

A thermal conductivity measuring apparatus that uses heat flow sensors to measure the heat flux through samples was constructed of inexpensive materials. This device was used to measure the thermal conductivity (k) of two composites used in the space program that consist of fibrous or granular components embedded in a resin matrix. The k-values that were determined ranged from 0.035 to 0.059 Btu/h sq ft-F/ft (-163 to 553 F) and 0.029 to 0.035 Btu/h-sq ft-F/ft (77 to 212 F). Thermal conductivity values of the composites conformed to the rule of mixture. The accuracy of the system was found to be comparable to the guarded hotplate and it requires neither a skilled operator nor extensive maintenance.

Penn, B. G.↗
NASA NTRS1997

Statistical Evaluation of Molecular Contamination During Spacecraft Thermal Vacuum Test

The purpose of this paper is to evaluate the statistical molecular contamination data with a goal to improve spacecraft contamination control. The statistical data was generated in typical thermal vacuum tests at the National Aeronautics and Space Administration, Goddard Space Flight Center (GSFC). The magnitude of material outgassing was measured using a Quartz Crystal Microbalance (QCM) device during the test. A solvent rinse sample was taken at the conclusion of the each test. Then detailed qualitative and quantitative measurements were obtained through chemical analyses. All data used in this study encompassed numerous spacecraft tests in recent years.

Chen, Philip↗
NASA NTRS1998

Statistical Evaluation of Molecular Contamination During Spacecraft Thermal Vacuum Test

The purpose of this paper is to evaluate the statistical molecular contamination data with a goal to improve spacecraft contamination control. The statistical data was generated in typical thermal vacuum tests at the National Aeronautics and Space Administration, Goddard Space Flight Center (GSFC). The magnitude of material outgassing was measured using a Quartz Crystal Microbalance (QCM) device during the test. A solvent rinse sample was taken at the conclusion of each test. Then detailed qualitative and quantitative measurements were obtained through chemical analyses. All data used in this study encompassed numerous spacecraft tests in recent years.

Chen, Philip↗
NASA NTRS1999

Statistical Evaluation of Molecular Contamination During Spacecraft Thermal Vacuum Test

The purpose of this paper is to evaluate the statistical molecular contamination data with a goal to improve spacecraft contamination control. The statistical data was generated in typical thermal vacuum tests at the National Aeronautics and Space Administration, Goddard Space Flight Center (GSFC). The magnitude of material outgassing was measured using a Quartz Crystal Microbalance (QCNO device during the test. A solvent rinse sample was taken at the conclusion of each test. Then detailed qualitative and quantitative measurements were obtained through chemical analyses. All data used in this study encompassed numerous spacecraft tests in recent years.

Chen, Philip↗
NASA NTRS2002

Microelectric Heterogeneous Hybrid Devices for Space Applications

The existing projects designated as SACA (Sample Ampoule Cartridge/Container Assembly) and QMI (Quench Module Insert) at NASA's MSFC (Marshall Space Flight Center) involve development of high-temperature coating materials. A number of material systems need to be evaluated for this purpose. The requirement of these coating materials included high emissivity (approaching unity), sufficient physical strength, appropriate thermal conductivity to dissipate heat, and above all high temperature (T is equal to or greater than 2000 C) withstanding capability. Potential materials for applications considered were non-oxide based materials such as tungsten carbide, tantalum carbide, compounds of niobium, etc.

Mohammad A. Alim↗
NASA NTRS2003

Device Control Using Gestures Sensed from EMG

In this paper we present neuro-electric interfaces for virtual device control. The examples presented rely upon sampling Electromyogram data from a participants forearm. This data is then fed into pattern recognition software that has been trained to distinguish gestures from a given gesture set. The pattern recognition software consists of hidden Markov models which are used to recognize the gestures as they are being performed in real-time. Two experiments were conducted to examine the feasibility of this interface technology. The first replicated a virtual joystick interface, and the second replicated a keyboard.

Wheeler, Kevin R.↗