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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 1,657 records · Page 92
All sourcesNASA NTRSDOE OSTI
NASA NTRS1987

Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) spectrometer design and performance

The development of the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) has been completed at JPL. This paper outlines the functional requirements of the spectrometer optics subsystem, and describes the spectrometer optical design. The optical subsystem performance is shown in terms of spectral modulation transfer functions, radial energy distributions, and system transmission at selected wavelengths for the four spectrometers. An outline of the spectrometer alignment is included.

Macenka, Steven A.↗
NASA NTRS1987

Spread-spectrum multiple access using wideband noncoherent MFSK

Two spread-spectrum multiple access systems which use wideband M-ary frequency shift keying (FSK) (MFSK) as the primary modulation are presented. A bit error rate performance analysis is presented and system throughput is calculated for sample C band and Ku band satellite systems. Sample link analyses are included to illustrate power and adjacent satellite interference considerations in practical multiple access systems.

Ha, Tri T.↗
NASA NTRS1988

Space Station user Servicing System architecture and operational aspects

The structure of the Space Station Servicing System architecture, operational aspects of the system, and the potential evolution of the servicing capabilities to accomodate a variety of missions are disscussed. Services to be performed include replacement or repair of failed modules, subsystems or parts, replacement or upgrading of spacecraft or instrument subsystems, replacement of limited lifetime subsystems or components, replenishment of consumables, and assembly of attached payloads and instruments. Elements of the system discussed include intravehicular servicing, the flight telerobotic servicer, and the mobile servicing center. Ground, preservicing, extravehicular and intravehicular servicing, and postservicing operations are examined. Also, a typical mission scenario for mature servicing operations is given.

Cline, Helmut P.↗
NASA NTRS1988

Airborne Visible/Infrared Imaging Spectrometer (AVIRIS)

The development of the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) has been completed at JPL. This paper outlines the functional requirements of the spectrometer optics subsystem, and describes the spectrometer optical design. The optical subsystem performance is shown in terms of spectral modulation transfer functions, radial energy distributions, and system transmission at selected wavelengths for the four spectrometers. An outline of the spectrometer alignment is included.

Macenka, Steven A.↗
NASA NTRS1992

Conceptual design study for the use of COBE rocket engines on the Tropical Rainfall Measuring Mission

The objective of this conceptual design study is to verify that the Cosmic Background Explorer (COBE) Hydrazine Propulsion Subsystem (HPS) Rocket Engine Assembly (REA) will satisfy the Tropical Rainfall Measuring Mission (TRMM) requirements and to develop a preliminary thruster module design using the existing REAs. The performance of the COBE HPS 5 lbf thrusters meet the TRMM mission requirements. The preliminary design consists of a single 5 lbf REA REM which is isolation mounted to a spacecraft interface angle bracket (5 or 10 deg angle). The REM incorporates a catalyst bed heater and sensor assembly, and propellant thermal control is achieved by thermostatically controlled heaters on the thruster valves. A ROM cost of approx. $950 K has been estimated for the phase 2 program to finalize the design, fabricate, and test the hardware using mechanical thermostats for thermal control. In the event that solid state thermostats are used, the cost is estimated to be $160 K higher. A ROM cost is approx. $145 K is estimated to study the effects of using Japanese manufactured hydrazine for the TRMM mission.

Source record↗
NASA NTRS1992

An image compression technique for use on token ring networks

A low complexity technique for compression of images for transmission over local area networks is presented. The technique uses the synchronous traffic as a side channel for improving the performance of an adaptive differential pulse code modulation (ADPCM) based coder.

Gorjala, B.↗
NASA NTRS1957

Summary of Scale-Model Thrust-Reverser Investigation

An investigation was undertaken to determine the characteristics of several basic types of thrust-reverser. Models of three types, target, tailpipe cascade, and ring cascade, were tested with unheated air. The effects of design variables on reverse-thrust performance, reversed-flow boundaries, and thrust modulation characteristics were determined.

Povolny, John H↗
NASA NTRS1993

Advanced microfabrication technologies for microspacecraft

Advanced microfabrication technologies offer the prospect of reducing the weight and size of spacecraft through the use of lighter and stronger materials in conjunction with new mechanical/structural design concepts and design optimization methods. At the same time, electronic components have been scaled down while increasing functional utility. A two-fold benefit is derived for space applications through the use of less expensive components and the lower launch costs associated with lighter components. GE-CRD is actively pursuing research in these key technologies for a wide range of applications including satellites. These key technologies will be reviewed and an update on GE progress will be given. The need to reduce weight and lower cost, while maintaining product quality and reliability are primary drivers in the design of satellites, in general, and microsatellites in particular. For the structural subsystem, these requirements pose a complex design problem unless new mechanical design concepts and computer-aided design optimization methods are employed. Several new concepts, such as battery packs doubling as panel reinforcements and fuel tanks as integral structural members, need to utilized. In addition, new viscoelastic material damping concepts for spacecraft components provide for lighter weight/lower cost designs, while satisfying the structural dynamics requirements. High density interconnect (HDI) technology permits the use of bare IC's on a ceramic substrate with 90 percent active area utilization. A copper/polyimide multilayer structure is the backbone of the technology, which has demonstrated a size/weight reduction of greater than 10x compared to printed circuit board with performance up to the GHz level. HDI modules have exceptional mechanical robustness as evidenced by survival of 180 kg rapid acceleration tests. Microelectromechanical systems (MEMS) are redefining sensors and actuators by miniaturization through micromachining techniques. Sharing many fabrication steps with HDI, we have developed a new technique for surface micromachining of copper/polyimide structures using computer-aided laser patterning.

Ghezzo, M.↗
NASA NTRS1995

PLATSIM: An efficient linear simulation and analysis package for large-order flexible systems

PLATSIM is a software package designed to provide efficient time and frequency domain analysis of large-order generic space platforms implemented with any linear time-invariant control system. Time domain analysis provides simulations of the overall spacecraft response levels due to either onboard or external disturbances. The time domain results can then be processed by the jitter analysis module to assess the spacecraft's pointing performance in a computationally efficient manner. The resulting jitter analysis algorithms have produced an increase in speed of several orders of magnitude over the brute force approach of sweeping minima and maxima. Frequency domain analysis produces frequency response functions for uncontrolled and controlled platform configurations. The latter represents an enabling technology for large-order flexible systems. PLATSIM uses a sparse matrix formulation for the spacecraft dynamics model which makes both the time and frequency domain operations quite efficient, particularly when a large number of modes are required to capture the true dynamics of the spacecraft. The package is written in MATLAB script language. A graphical user interface (GUI) is included in the PLATSIM software package. This GUI uses MATLAB's Handle graphics to provide a convenient way for setting simulation and analysis parameters.

Maghami, Periman↗
NASA NTRS2000

Biotechnology Facility: An ISS Microgravity Research Facility

The International Space Station (ISS) will support several facilities dedicated to scientific research. One such facility, the Biotechnology Facility (BTF), is sponsored by the Microgravity Sciences and Applications Division (MSAD) and developed at NASA's Johnson Space Center. The BTF is scheduled for delivery to the ISS via Space Shuttle in April 2005. The purpose of the BTF is to provide: (1) the support structure and integration capabilities for the individual modules in which biotechnology experiments will be performed, (2) the capability for human-tended, repetitive, long-duration biotechnology experiments, and (3) opportunities to perform repetitive experiments in a short period by allowing continuous access to microgravity. The MSAD has identified cell culture and tissue engineering, protein crystal growth, and fundamentals of biotechnology as areas that contain promising opportunities for significant advancements through low-gravity experiments. The focus of this coordinated ground- and space-based research program is the use of the low-gravity environment of space to conduct fundamental investigations leading to major advances in the understanding of basic and applied biotechnology. Results from planned investigations can be used in applications ranging from rational drug design and testing, cancer diagnosis and treatments and tissue engineering leading to replacement tissues.

Gonda, Steve R.↗
NASA NTRS2001

Regenerative pseudo-noise ranging for deep space applications

Currently, ranging for deep space missions is performed by turning around the uplink ranging modulation and remodulating it onto the downlink carrier. This method results in about 1.5 MHz of noise also being modulated onto the downlink, severely degrading the received ranging SNR on the ground. This degradation must be compensated for by either increasing the integration time of the received signal, which increases the length of time for the track, or increasing the downlink ranging signal's modulation index, which decreases the power available for the telemetry modulation. A method for the regeneration on the spacecraft of a pseudo noise (PN) ranging signal has been developed. This method allows for an increase of up to 30dB in the received downlink ranging power. The increased power can be used to decrease the measurement uncertainty, reduce the time of the measurement, or increase the power allocated to the downlink telemetry. This system was implemented in the Spacecraft Transponding Modem that was developed by JPL for NASA.

deep space ranging↗
NASA NTRS2002

Observations of the Performance of the U.S. Laboratory Architecture

The United States Laboratory Module "Destiny" was the product of many architectural, technology, manufacturing, schedule and cost constraints which spanned 15 years. Requirements for the Space Station pressurized elements were developed and baselined in the mid to late '80's. Although the station program went through several design changes the fundamental requirements that drove the architecture did not change. Manufacturing of the U.S. Laboratory began in the early 90's. Final assembly and checkout testing completed in December of 2000. Destiny was launched, mated to the International Space Station and successfully activated on the STS-98 mission in February of 2001. The purpose of this paper is to identify key requirements, which directly or indirectly established the architecture of the U.S. Laboratory. Provide an overview of how that architecture affected the manufacture, assembly, test, and activation of the module on-orbit. And finally, through observations made during the last year of operation, provide considerations in the development of future requirements and mission integration controls for space habitats.

Jones, Rod↗
NASA NTRS2011

Thermally Stabilized Transmit/Receive Modules

RF-hybrid technologies enable smaller packaging and mass reduction in radar instruments, especially for subsystems with dense electronics, such as electronically steered arrays. We are designing thermally stabilized RF-hybrid T/R modules using new materials for improved thermal performance of electronics. We are combining advanced substrate and housing materials with a thermal reservoir material, and develop new packaging techniques to significantly improve thermal-cycling reliability and performance stability over temperature.

thermal cycling stress↗
NASA NTRS2004

Scalable Multiprocessor for High-Speed Computing in Space

A report discusses the continuing development of a scalable multiprocessor computing system for hard real-time applications aboard a spacecraft. "Hard realtime applications" signifies applications, like real-time radar signal processing, in which the data to be processed are generated at "hundreds" of pulses per second, each pulse "requiring" millions of arithmetic operations. In these applications, the digital processors must be tightly integrated with analog instrumentation (e.g., radar equipment), and data input/output must be synchronized with analog instrumentation, controlled to within fractions of a microsecond. The scalable multiprocessor is a cluster of identical commercial-off-the-shelf generic DSP (digital-signal-processing) computers plus generic interface circuits, including analog-to-digital converters, all controlled by software. The processors are computers interconnected by high-speed serial links. Performance can be increased by adding hardware modules and correspondingly modifying the software. Work is distributed among the processors in a parallel or pipeline fashion by means of a flexible master/slave control and timing scheme. Each processor operates under its own local clock; synchronization is achieved by broadcasting master time signals to all the processors, which compute offsets between the master clock and their local clocks.

Lux, James↗
NASA NTRS2011

Optimized Biasing of Pump Laser Diodes in a Highly Reliable Metrology Source for Long-Duration Space Missions

Optical metrology system reliability during a prolonged space mission is often limited by the reliability of pump laser diodes. We developed a metrology laser pump module architecture that meets NASA SIM Lite instrument optical power and reliability requirements by combining the outputs of multiple single-mode pump diodes in a low-loss, high port count fiber coupler. We describe Monte-Carlo simulations used to calculate the reliability of the laser pump module and introduce a combined laser farm aging parameter that serves as a load-sharing optimization metric. Employing these tools, we select pump module architecture, operating conditions, biasing approach and perform parameter sensitivity studies to investigate the robustness of the obtained solution.

808 mm diode pumps↗
NASA NTRS2012

Plume-Free Stream Interaction Heating Effects During Orion Crew Module Reentry

During reentry of the Orion Crew Module (CM), vehicle attitude control will be performed by firing reaction control system (RCS) thrusters. Simulation of RCS plumes and their interaction with the oncoming flow has been difficult for the analysis community due to the large scarf angles of the RCS thrusters and the unsteady nature of the Orion capsule backshell environments. The model for the aerothermal database has thus relied on wind tunnel test data to capture the heating effects of thruster plume interactions with the freestream. These data are only valid for the continuum flow regime of the reentry trajectory. A Direct Simulation Monte Carlo (DSMC) analysis was performed to study the vehicle heating effects that result from the RCS thruster plume interaction with the oncoming freestream flow at high altitudes during Orion CM reentry. The study was performed with the DSMC Analysis Code (DAC). The inflow boundary conditions for the jets were obtained from Data Parallel Line Relaxation (DPLR) computational fluid dynamics (CFD) solutions. Simulations were performed for the roll, yaw, pitch-up and pitch-down jets at altitudes of 105 km, 125 km and 160 km as well as vacuum conditions. For comparison purposes (see Figure 1), the freestream conditions were based on previous DAC simulations performed without active RCS to populate the aerodynamic database for the Orion CM. Other inputs to the analysis included a constant Orbital reentry velocity of 7.5 km/s and angle of attack of 160 degrees. The results of the study showed that the interaction effects decrease quickly with increasing altitude. Also, jets with highly scarfed nozzles cause more severe heating compared to the nozzles with lower scarf angles. The difficulty of performing these simulations was based on the maximum number density and the ratio of number densities between the freestream and the plume for each simulation. The lowest altitude solutions required a substantial amount of computational resources (up to 1800 processors) to simulate approximately 2 billion molecules for the refined (adapted) solutions.

Marichalar, J.↗
NASA NTRS2007

Corrosion Protection for Space and Beyond

Florida is home to NASA's Launch Operations Center. Since its establishment in July 1962, the spaceport has served as the departure gate for every American manned mission and hundreds of advanced scientific spacecraft under the Launch Services Program. The center was renamed the John F. Kennedy Space Center in late 1963 to honor the president who put America on the path to the moon. Today, NASA is on the edge of a bold new chaIlenge: the ConsteIlation Program. ConsteIlation is a NASA program to create a new generation of spacecraft for human spaceflight, consisting primarily of the Ares I and Ares V launch vehicles, the Orion crew capsule, the Earth Departure stage and the Lunar access module. These spacecraft will be capable of performing a variety of missions, from Space Station resupply to lunar landings. The ambitious new endeavor caIls for NASA to return human explorers to the moon and then venture even farther, to Mars and beyond. As the nation's premier spaceport, Kennedy Space Center (KSC) will playa critical role in this new chapter in exploration, particularly in the conversion of the launch facilities to accommodate the new launch vehicles. To prepare for this endeavor, the launch site and facilities for the next generation of crew and cargo vehicles must be redesigned, assembled and tested. One critical factor that is being carefuIly considered during the renovation is protecting the new facilities and structures from corrosion and deterioration.

Calle, Luz Marina↗