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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 415 records · Page 23
All sourcesNASA NTRSDOE OSTI
NASA NTRS2011

GOES Type III Loop Heat Pipe Life Test Results

The GOES Type III Loop Heat Pipe (LHP) was built as a life test unit for the loop heat pipes on the GOES N-Q series satellites. This propylene LHP was built by Dynatherm Corporation in 2000 and tested continuously for approximately 14 months. It was then put into storage for 3 years. Following the storage period, the LHP was tested at Swales Aerospace to verify that the loop performance hadn t changed. Most test results were consistent with earlier results. At the conclusion of testing at Swales, the LHP was transferred to NASA/GSFC for continued periodic testing. The LHP has been set up for testing in the Thermal Lab at GSFC since 2006. A group of tests consisting of start-ups, power cycles, and a heat transport limit test have been performed every six to nine months since March 2006. Tests results have shown no change in the loop performance over the five years of testing. This presentation will discuss the test hardware, test set-up, and tests performed. Test results to be presented include sample plots from individual tests, along with conductance measurements for all tests performed.

Ottenstein, Laura↗
NASA NTRS2011

Spacesuit Portable Life Support System Breadboard (PLSS 1.0) Development and Test Results

A multi-year effort has been carried out at NASA-JSC to develop an advanced Extravehicular Activity (EVA) PLSS design intended to further the current state of the art by increasing operational flexibility, reducing consumables, and increasing robustness. Previous efforts have focused on modeling and analyzing the advanced PLSS architecture, as well as developing key enabling technologies. Like the current International Space Station (ISS) Extravehicular Mobility Unit (EMU) PLSS, the advanced PLSS comprises of three subsystems required to sustain the crew during EVA including the Thermal, Ventilation, and Oxygen Subsystems. This multi-year effort has culminated in the construction and operation of PLSS 1.0, a test rig that simulates full functionality of the advanced PLSS design. PLSS 1.0 integrates commercial off the shelf hardware with prototype technology development components, including the primary and secondary oxygen regulators, ventilation loop fan, Rapid Cycle Amine (RCA) swingbed, and Spacesuit Water Membrane Evaporator (SWME). Testing accumulated 239 hours over 45 days, while executing 172 test points. Specific PLSS 1.0 test objectives assessed during this testing include: confirming key individual components perform in a system level test as they have performed during component level testing; identifying unexpected system-level interactions; operating PLSS 1.0 in nominal steady-state EVA modes to baseline subsystem performance with respect to metabolic rate, ventilation loop pressure and flow rate, and environmental conditions; simulating nominal transient EVA operational scenarios; simulating contingency EVA operational scenarios; and further evaluating individual technology development components. Successful testing of the PLSS 1.0 provided a large database of test results that characterize system level and component performance. With the exception of several minor anomalies, the PLSS 1.0 test rig performed as expected; furthermore, many system responses trended in accordance with pre-test predictions.

Vogel, Matt R.↗
NASA NTRS2012

Spacesuit Portable Life Support System Breadboard (PLSS 1.0) Development and Test Results

A multi-year effort has been carried out at the Johnson Space Center to develop an advanced EVA PLSS design intended to further the current state of the art by increasing operational flexibility, reducing consumables, and increasing robustness. This multi-year effort has culminated in the construction and operation of PLSS 1.0, a test rig that simulates full functionality of the advanced PLSS design. PLSS 1.0 integrates commercial off-the-shelf hardware with prototype technology development components, including the primary and secondary oxygen regulators, ventilation loop fan, Rapid Cycle Amine (RCA) swingbed, and Spacesuit Water Membrane Evaporator (SWME). PLSS 1.0 was tested from June 17th through September 30th, 2011. Testing accumulated 233 hours over 45 days, while executing 119 test points. An additional 164 hours of operational time were accrued during the test series, bringing the total operational time for PLSS 1.0 testing to 397 hours. Specific PLSS 1.0 test objectives assessed during this testing include: (1) Confirming prototype components perform in a system level test as they have performed during component level testing, (2) Identifying unexpected system-level interactions (3) Operating PLSS 1.0 in nominal steady-state EVA modes to baseline subsystem performance with respect to metabolic rate, ventilation loop pressure and flow rate, and environmental conditions (4) Simulating nominal transient EVA operational scenarios (5) Simulating contingency EVA operational scenarios (6) Further evaluating prototype technology development components Successful testing of the PLSS 1.0 provided a large database of test results that characterize system level and component performance. With the exception of several minor anomalies, the PLSS 1.0 test rig performed as expected. Documented anomalies and observations include: (1) Ventilation loop fan controller issues at high fan speeds (near 70,000 rpm, whereas the fan speed during nominal operations would be closer to 35,000 rpm) (2) RCA performance at boundary conditions, including carbon dioxide and water vapor saturation events, as well as reduced vacuum quality (3) SWME valve anomalies (4 documented cases where the SWME failed to respond to a control signal or physically jammed, preventing SWME control) (4) Reduction of SWME hollow fiber hydrophobicity and significant reduction of the SWME degassing capability after significant accumulated test time.

Watts, Carly A.↗
NASA NTRS1994

An analysis of carrier phase jitter in an MPSK receiver utilizing map estimation

The use of 8 and 16 PSK TCM to support satellite communications in an effort to achieve more bandwidth efficiency in a power-limited channel has been proposed. This project addresses the problem of carrier phase jitter in an M-PSK receiver utilizing the high SNR approximation to the maximum aposteriori estimation of carrier phase. In particular, numerical solutions to the 8 and 16 PSK self-noise and phase detector gain in the carrier tracking loop are presented. The effect of changing SNR on the loop noise bandwidth is also discussed. These data are then used to compute variance of phase error as a function of SNR. Simulation and hardware data are used to verify these calculations. The results show that there is a threshold in the variance of phase error versus SNR curves that is a strong function of SNR and a weak function of loop bandwidth. The M-PSK variance thresholds occur at SNR's in the range of practical interest for the use of 8 and 16-PSK TCM. This suggests that phase error variance is an important consideration in the design of these systems.

Osborne, William P.↗
NASA NTRS2003

An Internet Protocol-Based Software System for Real-Time, Closed-Loop, Multi-Spacecraft Mission Simulation Applications

A mission simulation prototype for Distributed Space Systems has been constructed using existing developmental hardware and software testbeds at NASA s Goddard Space Flight Center. A locally distributed ensemble of testbeds, connected through the local area network, operates in real time and demonstrates the potential to assess the impact of subsystem level modifications on system level performance and, ultimately, on the quality and quantity of the end product science data.

Burns, Richard D.↗
NASA NTRS2018

Human in the Loop Tests: Experiences in Space Suit Testing

What is a space suit? Space suit testing; How and why we test them; hardware design vs. user functionality; Data collection lessons learned; Challenges of objective and subjective data; Personal experience from 2 perspectives: test director and test subject

Ross, Amy J.↗
NASA NTRS1987

Hardware fault insertion and instrumentation system: Mechanization and validation

Automated test capability for extensive low-level hardware fault insertion testing is developed. The test capability is used to calibrate fault detection coverage and associated latency times as relevant to projecting overall system reliability. Described are modifications made to the NASA Ames Reconfigurable Flight Control System (RDFCS) Facility to fully automate the total test loop involving the Draper Laboratories' Fault Injector Unit. The automated capability provided included the application of sequences of simulated low-level hardware faults, the precise measurement of fault latency times, the identification of fault symptoms, and bulk storage of test case results. A PDP-11/60 served as a test coordinator, and a PDP-11/04 as an instrumentation device. The fault injector was controlled by applications test software in the PDP-11/60, rather than by manual commands from a terminal keyboard. The time base was especially developed for this application to use a variety of signal sources in the system simulator.

Benson, J. W.↗
NASA NTRS1978

Deployable heat-pipe radiator

Loop temperatures are controlled effectively under varying load conditions. Radiator has four separate pieces of hardware: heat-pipe panel, flexible heat-pipe leader, heat exchanger, fluid header. Single-fluid transport capacities of about 850 watts, corresponding to 51,000 watt-inches, have been achieved in 90 degree bend orientation of heat-pipe header.

Edelstein, F.↗
NASA NTRS1979

Implementing a bubble memory hierarchy system

This paper reports on implementation of a magnetic bubble memory in a two-level hierarchial system. The hierarchy used a major-minor loop device and RAM under microprocessor control. Dynamic memory addressing, dual bus primary memory, and hardware data modification detection are incorporated in the system to minimize access time. It is the objective of the system to incorporate the advantages of bipolar memory with that of bubble domain memory to provide a smart, optimal memory system which is easy to interface and independent of user's system.

Segura, R.↗
NASA NTRS1981

Experimental demonstration of static shape control

Results of a microprocessor-controlled implementation of static shape control using a specially constructed flexible beam facility are presented. The discussion covers the development of shape control algorithms, adaptation of the algorithms for use with finite element models, construction of a flexible beam, characterization and calibration of the facility, development of a finite element model for the beam, and the development of computer hardware and software. It is shown that feedback control yields better results than open-loop control, and that the use of more than two sensors in the control loop has little effect on the system performance.

Eldred, D.↗
NASA NTRS1993

Terminal Sliding Modes In Nonlinear Control Systems

Control systems of proposed type called "terminal controllers" offers increased precision and stability of robotic operations in presence of unknown and/or changing parameters. Systems include special computer hardware and software implementing novel control laws involving terminal sliding modes of motion: closed-loop combination of robot and terminal controller converge, in finite time, to point of stable equilibrium in abstract space of velocity and/or position coordinates applicable to particular control problem.

Venkataraman, Subramanian T.↗
NASA NTRS2019

Hydrogen Recovery by Methane Pyrolysis to Elemental Carbon

Use of a Sabatier reactor to recover the oxygen from the carbon dioxide exhaled by the crew on the International Space Station has been limited by the loss of the hydrogen contained in the methane it generates. Maximizing the oxygen recovered requires the hydrogen to be recovered from the methane product and recycled back to the Sabatier reactor. We describe the use of a tailored methane pyrolysis reactor to completely recover this hydrogen. The carbon-containing byproduct is elemental carbon, which is generated in the form of easily handled, non-sooty material that may have various uses. The process of creating this tailored carbon vapor deposition process involved exploration of the effects of temperature, pressure, substrate design and other variables to develop a high yield process that cleanly generates the desired products. Reaction kinetics and kinetics modelling were used to specify the temperature, pressure and reactor volume required to achieve the target conversion and to assure that the final average density was as high as possible. Reactor design included the selection of materials that will survive the high temperatures and environment in the pyrolysis reactor, and thermal modeling to achieve the required temperatures with minimum power consumption. The successful construction and demonstration of a brassboard prototype will allow the results of the chemical, thermal and mechanical models to be validated and should provide a useful alternative for a completely closed loop ECLS system. Integration of this technology with state-of-the-art (SOA) Sabatier hardware on ISS requires a complete understanding of the effects of impurities in the product hydrogen on the Sabatier catalyst. SOA Sabatier catalyst was evaluated over short and long-term exposure to anticipated contaminants to identify effects.

Yates, Stephen F.↗
NASA NTRS2019

Hydrogen Recovery by Methane Pyrolysis to Elemental Carbon

Use of a Sabatier reactor to recover the oxygen from the carbon dioxide exhaled by the crew on the International Space Station has been limited by the loss of the hydrogen contained in the methane it generates. Maximizing the oxygen recovered requires the hydrogen to be recovered from the methane product and recycled back to the Sabatier reactor. We describe the use of a tailored methane pyrolysis reactor to completely recover this hydrogen. The carbon-containing byproduct is elemental carbon, which is generated in the form of easily handled, non-sooty material that may have various uses. The process of creating this tailored carbon vapor deposition process involved exploration of the effects of temperature, pressure, substrate design and other variables to develop a high yield process that cleanly generates the desired products. Reaction kinetics and kinetics modelling were used to specify the temperature, pressure and reactor volume required to achieve the target conversion and to assure that the final average density was as high as possible. Reactor design included the selection of materials that will survive the high temperatures and environment in the pyrolysis reactor, and thermal modeling to achieve the required temperatures with minimum power consumption. The successful construction and demonstration of a brassboard prototype will allow the results of the chemical, thermal and mechanical models to be validated and should provide a useful alternative for a completely closed loop ECLS system. Integration of this technology with state-of-the-art (SOA) Sabatier hardware on ISS requires a complete understanding of the effects of impurities in the product hydrogen on the Sabatier catalyst. SOA Sabatier catalyst was evaluated over short and long-term exposure to anticipated contaminants to identify effects.

Yates, Stephen F.↗
NASA NTRS2010

Parallel Processing of Broad-Band PPM Signals

A parallel-processing algorithm and a hardware architecture to implement the algorithm have been devised for timeslot synchronization in the reception of pulse-position-modulated (PPM) optical or radio signals. As in the cases of some prior algorithms and architectures for parallel, discrete-time, digital processing of signals other than PPM, an incoming broadband signal is divided into multiple parallel narrower-band signals by means of sub-sampling and filtering. The number of parallel streams is chosen so that the frequency content of the narrower-band signals is low enough to enable processing by relatively-low speed complementary metal oxide semiconductor (CMOS) electronic circuitry. The algorithm and architecture are intended to satisfy requirements for time-varying time-slot synchronization and post-detection filtering, with correction of timing errors independent of estimation of timing errors. They are also intended to afford flexibility for dynamic reconfiguration and upgrading. The architecture is implemented in a reconfigurable CMOS processor in the form of a field-programmable gate array. The algorithm and its hardware implementation incorporate three separate time-varying filter banks for three distinct functions: correction of sub-sample timing errors, post-detection filtering, and post-detection estimation of timing errors. The design of the filter bank for correction of timing errors, the method of estimating timing errors, and the design of a feedback-loop filter are governed by a host of parameters, the most critical one, with regard to processing very broadband signals with CMOS hardware, being the number of parallel streams (equivalently, the rate-reduction parameter).

Gray, Andrew↗
NASA NTRS1987

FLUINT - General fluid system analysis with SINDA '85

This paper introduces FLUINT (FLUid INTegrator), a general fluid system simulation program that works in conjunction with SINDA '85 (Systems Improved Numerical Differencing Analyzer, 1985 version). FLUINT solves arbitrary networks representing internal fluid systems while SINDA '85 simultaneously solves traditional thermal networks. This transportable program is intended to provide spacecraft thermal management engineers with the analytic tools needed to simulate single- and two-phase coolant loops. The fundamental concepts for fluid system modeling are described, and methods of modeling complex, hardware-specific components are outlined. Underlying correlations and solution methods are briefly discussed. Example analyses and comparisons to test data are provided.

Cullimore, B. A.↗
NASA NTRS1988

The flight robotics laboratory

The Flight Robotics Laboratory of the Marshall Space Flight Center is described in detail. This facility, containing an eight degree of freedom manipulator, precision air bearing floor, teleoperated motion base, reconfigurable operator's console, and VAX 11/750 computer system, provides simulation capability to study human/system interactions of remote systems. The facility hardware, software and subsequent integration of these components into a real time man-in-the-loop simulation for the evaluation of spacecraft contact proximity and dynamics are described.

Tobbe, Patrick A.↗
NASA NTRS2002

Preliminary Investigation of the Thermal Behavior of High-Speed Helical Gear Trains

A preliminary experimental investigation of the thermal behavior of high-speed helical gears will be presented. A full-scale torque regenerative test stand has been built to test a representative helical gear train as that used in tiltrotor aircraft. Power loss and temperature data from a wide range of operating conditions were measured. Loop power ranged up to 3730 kW (5000 hp). Drive system components representative of flight quality hardware were used in the test program. The results attained in this initial study indicated that windage losses due to the high rotational speeds that were tested were far more important than the losses due to the gear meshing losses.

Handschuh, Robert F.↗
NASA NTRS2002

Flight Testing of the Capillary Pumped Loop 3 Experiment

The Capillary Pumped Loop 3 (CAPL 3) experiment was a multiple evaporator capillary pumped loop experiment that flew in the Space Shuttle payload bay in December 2001 (STS-108). The main objective of CAPL 3 was to demonstrate in micro-gravity a multiple evaporator capillary pumped loop system, capable of reliable start-up, reliable continuous operation, and heat load sharing, with hardware for a deployable radiator. Tests performed on orbit included start-ups, power cycles, low power tests (100 W total), high power tests (up to 1447 W total), heat load sharing, variable/fixed conductance transition tests, and saturation temperature change tests. The majority of the tests were completed successfully, although the experiment did exhibit an unexpected sensitivity to shuttle maneuvers. This paper describes the experiment, the tests performed during the mission, and the test results.

Ottenstein, Laura↗