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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 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
NASA NTRS1992

Project APEX: Advanced Phobos Exploration. Manned mission to the Martian moon Phobos

The manned exploration of Mars is a massive undertaking which requires careful consideration. A mission to the moon of Mars called Phobos as a prelude to manned landings on the Martian surface offers some advantages. One is that the energy requirements, in terms of delta 5, is only slightly higher than going to the Moon's surface. Another is that Phobos is a potential source of water and carbon which could be extracted and processed for life support and cryogenic propellants for use in future missions; thus, Phobos might serve as a base for extended Mars exploration or for exploration of the outer planets. The design of a vehicle for such a mission is the subject of our Aerospace System Design course this year. The materials and equipment needed for the processing plant would be delivered to Phobos in a prior unmanned mission. This study focuses on what it would take to send a crew to Phobos, set up the processing plant for extraction and storage of water and hydrocarbons, conduct scientific experiments, and return safely to Earth. The size, configuration, and subsystems of the vehicle are described in some detail. The spacecraft carries a crew of five and is launched from low Earth orbit in the year 2010. The outbound trajectory to Mars uses a gravitational assisted swing by of Venus and takes eight months to complete. The stay at Phobos is 60 days at which time the crew will be engaged in setting up the processing facility. The crew will then return to Earth orbit after a total mission duration of 656 days. Both stellar and solar observations will be conducted on both legs of the mission. The design of the spacecraft addresses human factors and life science; mission analysis and control; propulsion; power generation and distribution; thermal control; structural analysis; and planetary, solar, and stellar science. A 0.5 g artificial gravity is generated during transit by spinning about the lateral body axis. Nuclear thermal rockets using hydrogen as fuel are selected to reduce total launch mass and to shorten the duration of the mission. The nuclear systems also provide the primary electrical power via dual mode operation. The overall spacecraft length is 110 meters and the total mass departing from low Earth orbit is 900 metric tons.

Source record↗
NASA NTRS1982

Solar drum positioner mechanisms

The need for additional power on spinning satellites required development of deployable solar arrays activated, as on a 3-axis vehicle, after separation from a booster or shuttle orbiter. Mechanisms were developed for telescopically extending a secondary 36.3 kg (80 lb.), 2.13 m (84 in.) diameter spinning solar drum for a distance of 2.0 m (80 in.) or more along the spin axis. After extension, the system has the capability of dynamically controlling the drum tilt angle about the spin axis to provide precision in-orbit balancing of the spacecraft. This approach was selected for the SBS, ANIK C, ANIK D, WESTAR B and PALAPA B satellites. It was successfully demonstrated during the in orbit deployment of the aft solar panels of the SBS F-3 and F-1 satellites, subsequent to the November 1980 and September 1981 launches.

Briggs, L. W.↗
NASA NTRS1986

Low-speed aerodynamic characteristics of a 1/8-scale X-29A airplane model at high angles of attack and sideslip

A 1/8-scale model of the X-29A airplane was tested in the Ames 12-Foot Pressure Wind Tunnel at a Mach number of 0.20 and Reynolds numbers of 0.13 x 10 to the 6th power to 2.00 x 10 to the 6th power based on a fuselage forebody depth of 0.4 ft, For the test series presented herein, the angle of attack ranged from 40 deg. to 90 deg. and the angle of sideslip ranged from -10 deg. to 30 deg. for the erect attitude. Tests with the model inverted covered angles of attack from -40 deg. to -90 deg. and angles of sideslip from -30 deg. to 10 deg. Data were obtained for the basic design and for several forebody strakes. An alternate forebody design was also tested. The results provided information for selection of forebody strakes for compensation of Reynolds number effect on the 1/25-scale free-spinning model tested in the Langley Spin Tunnel.

Whipple, R. D.↗
NASA NTRS1992

The spin vector of Venus determined from Magellan data

A control network of the north polar region of Venus has been established by selecting and measuring control points on full-resolution radar strips. The measurements were incorporated into a least-squares adjustment program that improved initial estimates of the coordinates of the control points, pole direction, and rotation rate of Venus. The current dataset contains 4206 measurements of 606 points on 619 radar strips. The accuracy of the determination is driven by spacecraft ephemeris errors. An accurate estimate of the rotation period of Venus was obtained by applying an ephemeris improvement technique. The second cycle closure orbits improved ephemeris solutions for 40 orbits (376-384, 520-528, 588-592, 658-668, 1002-1010, 1408-1412, 1746-1764, and 2166-2170) are included and fixed in the geodetic control computations, thus trying the network to the J2000 coordinate system.

Davies, M. E.↗
NASA NTRS2013

Parameter Estimation for Compact Binary Coalescence Signals with the First Generation Gravitational-Wave Detector Network

Compact binary systems with neutron stars or black holes are one of the most promising sources for ground-based gravitational-wave detectors. Gravitational radiation encodes rich information about source physics; thus parameter estimation and model selection are crucial analysis steps for any detection candidate events. Detailed models of the anticipated waveforms enable inference on several parameters, such as component masses, spins, sky location and distance, that are essential for new astrophysical studies of these sources. However, accurate measurements of these parameters and discrimination of models describing the underlying physics are complicated by artifacts in the data, uncertainties in the waveform models and in the calibration of the detectors. Here we report such measurements on a selection of simulated signals added either in hardware or software to the data collected by the two LIGO instruments and the Virgo detector during their most recent joint science run, including a blind injection where the signal was not initially revealed to the collaboration. We exemplify the ability to extract information about the source physics on signals that cover the neutron-star and black-hole binary parameter space over the component mass range 1M25M and the full range of spin parameters. The cases reported in this study provide a snapshot of the status of parameter estimation in preparation for the operation of advanced detectors.

Aasi, J.↗
NASA NTRS1976

Wind-tunnel testing with a rotary-balance apparatus to simulate aircraft spin motions

Experiments have been conducted in the Ames 12-Foot Pressure Wind Tunnel on a simple airplane-like model using a rotary-balance apparatus to simulate a steady spin motion at high angles of attack. Tests were run at Mach numbers of 0.1 and 0.25 over a wide Reynolds number range with the angle of attack varying from 45 to 90 deg. During previous tests of the same research model, some difficulties were experienced with measurement accuracy in the low-to-medium range of Reynolds number because of limitations in the sensitivity of selected force balances. For the present tests, special balances were built to provide accurate measurements of the nose and tail contributions to spin motions and improvements were made to the overall test apparatus. The results of this test, including some interesting hysteresis effects with spin rate, are described. Some of the problems associated with rotary-balance tests at high Reynolds numbers are discussed. A new large-scale rotary apparatus now nearing completion for use in the Ames 12-Foot and 11- by 11-Foot Wind Tunnels is described briefly.

Malcolm, G. N.↗
NASA NTRS1976

Proton magnetic relaxation and internal rotations in tetramethylammonium cadmium chloride

Nuclear magnetic resonance (NMR) and relaxation studies of the proton spin-lattice relaxation time (PSLRT) and proton second moment (PSM) are reported. Tetramethylammonium cadmium chloride (TMCC) was selected as a diamagnetic member of the isomorphic series, and hence proton data relate directly to the motion of the tetramethylammonium ion in the absence of paramagnetic ions. In the model adopted, the correlation time for hindered motion of one of the methyl groups differs from that of the other three groups in the low-temperature phase below 104 K. PSLRT and PSM values agree closely with experimental data with this model. Crystallographic phase transitions in TMCC occur at 104 K and 119 K according to the PSLRT measurements. Dipolar interactions between adjacent protons account for the PSLR rates below 104 K.

Tsang, T.↗
NASA NTRS1988

Material growth and characterization for solid state devices

During the period of this research grant, the process of liquid phase electroepitaxy (LPEE) was used to grow ternary and quaternary alloy III-V semiconductor thin films. Selective area growth of InGaAs was performed on InP substrates using a patterned sputtered quartz or spin-on glass layer. The etch back and growth characteristics with respect to substrate orientation were investigated. The etch back behavior is somewhat different from wet chemical etching with respect to the sidewall profiles which are observed. LPEE was also employed to grow epitaxial layers of InGaAsP alloys on InP substrates. The behavior of Mn as an acceptor dopant was investigated with low temperature Hall coefficient and photoluminescence measurements. A metal-organic vapor phase epitaxy system was partially complete within the grant period. This atmospheric pressure system will be used to deposit III-V compound and alloy semiconductor layers in future research efforts.

Collis, Ward J.↗
NASA NTRS1996

Dynamic modelling and simulation study for the Galileo spacecraft pulsed-mode spinup/400 N main engine burn/spindown maneuvers

Two Galileo dynamic models were developed to simulate the spinup, the main engine burn and the spindown maneuvers for the critical events of the Jupiter orbit insertion and perijove raise maneuver. The dynamic interaction between the spin thruster pulsing frequency, the science magnetometer boom flexible modes and the propellant slosh modes were studied. The prediction of safe orbit insertion was validated in flight. For the perijove raise maneuver, the simulation results indicated that propellant unporting would occur if the original spin thruster duty cycle was not updated. Based on further simulation results, a new duty cycle was selected to prevent propellant unporting. Subsequent Galileo flight data indicated that the perijove raise maneuver was successfully executed.

Ih, Che-Hang Charles↗
NASA NTRS2010

Propulsion Health Monitoring of a Turbine Engine Disk Using Spin Test Data

This paper considers data collected from an experimental study using high frequency capacitive sensor technology to capture blade tip clearance and tip timing measurements in a rotating turbine engine-like-disk-to predict the disk faults and assess its structural integrity. The experimental results collected at a range of rotational speeds from tests conducted at the NASA Glenn Research Center s Rotordynamics Laboratory are evaluated using multiple data-driven anomaly detection techniques to identify abnormalities in the disk. Further, this study presents a select evaluation of an online health monitoring scheme of a rotating disk using high caliber sensors and test the capability of the in-house spin system.

Abdul-Aziz, Ali↗
NASA NTRS1979

Pointing and control of planetary spacecraft - The next 20 years

Four basic categories of spacecraft pointing and control systems are discussed: (1) spin stabilized, (2) dual spin, (3) three-axis, and (4) momentum bias. Goals, mission requirements, and payloads should be considered for selection of control systems. A set of representative requirements, including life and environmental, vehicle/payload orientation and accuracy requirements, and control-system operational and functional requirements are discussed. Attention is given to design constraints imposed by the system selection. It is noted that sensitivity of any system design to increasing accuracy and flexibility in science-mission reprogramming will be major cost factors.

Mcglinchey, L. F.↗
NASA NTRS2001

Development of a fully integrated analysis system for ions based on ion-selective optodes and centrifugal microfluidics

A fully integrated, miniaturized analysis system for ions based on a centrifugal microfluidics platform and ion-selective optode membranes is described. The microfluidic architecture is composed of channels, five solution reservoirs, a measuring chamber, and a waste reservoir manufactured onto a disk-shaped substrate of poly(methyl methacrylate). Ion-selective optode membranes, composed of plasticized poly(vinyl chloride) impregnated with an ionophore, a proton chromoionophore, and a lipophilic anionic additive, were cast, with a spin-on device, onto a support layer and then immobilized on the disk. Fluid propulsion is achieved by the centrifugal force that results from spinning the disk, while a system of valves is built onto the disk to control flow. These valves operate based on fluid properties and fluid/substrate interactions and are controlled by the angular frequency of rotation. With this system, we have been able to deliver calibrant solutions, washing buffers, or "test" solutions to the measuring chamber where the optode membrane is located. An analysis system based on a potassium-selective optode has been characterized. Results indicate that optodes immobilized on the platform demonstrate theoretical responses in an absorbance mode of measurement. Samples of unknown concentration can be quantified to within 3% error by fitting the response function for a given optode membrane using an acid (for measuring the signal for a fully protonated chromoionophore), a base (for fully deprotonated chromoionophore), and two standard solutions. Further, the ability to measure ion concentrations by employing one standard solution in conjunction with acid and base and with two standards alone were studied to delineate whether the current architecture could be simplified. Finally, the efficacy of incorporating washing steps into the calibration protocol was investigated.

NASA Discipline Life Sciences Technologies↗
NASA NTRS1973

System design of the Pioneer Venus spacecraft. Volume 4: Probe bus and orbiter spacecraft vehicle studies

The requirements, trades, and design descriptions for the probe bus and orbiter spacecraft configurations, structure, thermal control, and harness are defined. Designs are developed for Thor/Delta and Atlas/Centaur launch vehicles with the latter selected as the final baseline. The major issues examined in achieving the baseline design are tabulated. The importance of spin axis orientation because of the effect on science experiments and earth communications is stressed.

Bozajian, J. M.↗
NASA NTRS1986

Rotary Joints With Electrical Connections

Power and data transmitted on many channels. Two different rotary joints equipped with electrical connections between rotating and stationary parts. One joint transmits axial thrust and serves as interface between spinning and nonspinning parts of Galileo spacecraft. Other is scanning (limitedrotation) joint that aims scientific instruments from nonspinning part. Selected features of both useful to designers of robots, advanced production equipment, and remotely controlled instruments.

Osborn, F. W.↗
NASA NTRS2000

A Flexible Statechart-to-Model-Checker Translator

Many current-day software design tools offer some variant of statechart notation for system specification. We, like others, have built an automatic translator from (a subset of) statecharts to a model checker, for use to validate behavioral requirements. Our translator is designed to be flexible. This allows us to quickly adjust the translator to variants of statechart semantics, including problem-specific notational conventions that designers employ. Our system demonstration will be of interest to the following two communities: (1) Potential end-users: Our demonstration will show translation from statecharts created in a commercial UML tool (Rational Rose) to Promela, the input language of Holzmann's model checker SPIN. The translation is accomplished automatically. To accommodate the major variants of statechart semantics, our tool offers user-selectable choices among semantic alternatives. Options for customized semantic variants are also made available. The net result is an easy-to-use tool that operates on a wide range of statechart diagrams to automate the pathway to model-checking input. (2) Other researchers: Our translator embodies, in one tool, ideas and approaches drawn from several sources. Solutions to the major challenges of statechart-to-model-checker translation (e.g., determining which transition(s) will fire, handling of concurrent activities) are retired in a uniform, fully mechanized, setting. The way in which the underlying architecture of the translator itself facilitates flexible and customizable translation will also be evident.

Rouquette, Nicolas↗
NASA NTRS2014

GMI Instrument Spin Balance Method, Optimization, Calibration, and Test

The Global Microwave Imager (GMI) instrument must spin at a constant rate of 32 rpm continuously for the 3 year mission life. Therefore, GMI must be very precisely balanced about the spin axis and CG to maintain stable scan pointing and to minimize disturbances imparted to the spacecraft and attitude control on-orbit. The GMI instrument is part of the core Global Precipitation Measurement (GPM) spacecraft and is used to make calibrated radiometric measurements at multiple microwave frequencies and polarizations. The GPM mission is an international effort managed by the National Aeronautics and Space Administration (NASA) to improve climate, weather, and hydro-meteorological predictions through more accurate and frequent precipitation measurements. Ball Aerospace and Technologies Corporation (BATC) was selected by NASA Goddard Space Flight Center to design, build, and test the GMI instrument. The GMI design has to meet a challenging set of spin balance requirements and had to be brought into simultaneous static and dynamic spin balance after the entire instrument was already assembled and before environmental tests began. The focus of this contribution is on the analytical and test activities undertaken to meet the challenging spin balance requirements of the GMI instrument. The novel process of measuring the residual static and dynamic imbalances with a very high level of accuracy and precision is presented together with the prediction of the optimal balance masses and their locations.

Ayari, Laoucet↗
NASA NTRS1979

Design, fabrication and spin testing of ceramic blade metal disk attachment

A ceramic turbine blade-metal disk attachment was designed for small, non man-rated turbine engine applications. The selected design consisted of a hot pressed silicon nitride blade having a skewed dovetail attachment with a compliant interlayer between the disk and the blade. Two-dimensional and three-dimensional analyses predicted that life goals could be achieved, considering both NDE limitations and crack growth rates for the ceramic material. Twenty ceramic blades were fabricated to closely-held manufacturing tolerances. New fracture mechanics data at elevated temperature are presented.

Calvert, G.↗
NASA NTRS2014

GMI Instrument Spin Balance Method, Optimization, Calibration and Test

The Global Microwave Imager (GMI) instrument must spin at a constant rate of 32 rpm continuously for the 3-year mission life. Therefore, GMI must be very precisely balanced about the spin axis and center of gravity (CG) to maintain stable scan pointing and to minimize disturbances imparted to the spacecraft and attitude control on-orbit. The GMI instrument is part of the core Global Precipitation Measurement (GPM) spacecraft and is used to make calibrated radiometric measurements at multiple microwave frequencies and polarizations. The GPM mission is an international effort managed by the National Aeronautics and Space Administration (NASA) to improve climate, weather, and hydro-meteorological predictions through more accurate and frequent precipitation measurements. Ball Aerospace and Technologies Corporation (BATC) was selected by NASA Goddard Space Flight Center to design, build, and test the GMI instrument. The GMI design has to meet a challenging set of spin balance requirements and had to be brought into simultaneous static and dynamic spin balance after the entire instrument was already assembled and before environmental tests began. The focus of this contribution is on the analytical and test activities undertaken to meet the challenging spin balance requirements of the GMI instrument. The novel process of measuring the residual static and dynamic imbalances with a very high level of accuracy and precision is presented together with the prediction of the optimal balance masses and their locations.

Ayari, Laoucet↗