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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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NASA NTRSDate not supplied

Space Launch System Core Stage Green Run Base Heating: Anomaly, Mitigation and Flight Redesign

The NASA Space Launch System (SLS) vehicle is composed of four RS-25 liquid oxygen and hydrogen rocket engines in the Core Stage (CS). The SLS Core Stage went through Green Run hotfire testing at NASA Stennis Space Center’s B-2 test facility in 2021. The main goal of this testing was to confirm Core Stage tanking, propulsion and thrust vector control systems operations and performance to verify with predicted models. Two hot-fire (HF) test sequences were performed with the first one (HF1) in January for a test duration of 70 seconds and the second (HF2) testing completed in March for a test duration of 500 seconds. This paper focuses on the base heating anomalies observed during HF1 and HF2 where an extensive fire was observed along the Core Stage base heat shield during test operations. This environment was not anticipated and led to extensive unplanned damage to the thermal protection system which was augmented for flight. Green Run observations also led to a reassessment of flight environments for Artemis I. This paper discusses the potential cause of the anomalies, the flow physics, the reconstructed base environments, and mitigation plans for HF2 and flight.

aerothermodynamics↗
NASA NTRS1971

Detailed Test Plan Redundant Sensor Strapdown IMU Evaluation Program

The test plan for a redundant sensor strapdown inertial measuring unit evaluation program is presented. The subjects discussed are: (1) test philosophy and limitations, (2) test sequence, (3) equipment specifications, (4) general operating procedures, (5) calibration procedures, (6) alignment test phase, and (7) navigation test phase. The data and analysis requirements are analyzed.

Hartwell, T.↗
NASA NTRS1972

Extended life testing evaluation of complementary MOS integrated circuits

The purpose of the extended life testing evaluation of complementary MOS integrated circuits was twofold: (1) To ascertain the long life capability of complementary MOS devices. (2) To assess the objectivity and reliability of various accelerated life test methods as an indication or prediction tool. In addition, the determination of a suitable life test sequence for these devices was of importance. Conclusions reached based on the parts tested and the test results obtained was that the devices were not acceptable.

Brosnan, T. E.↗
NASA NTRS1997

Mir Cooperative Solar Array Flight Performance Data and Computational Analysis

The Mir Cooperative Solar Array (MCSA) was developed jointly by the United States (US) and Russia to provide approximately 6 kW of photovoltaic power to the Russian space station Mir. The MCSA was launched to Mir in November 1995 and installed on the Kvant-1 module in May 1996. Since the MCSA photovoltaic panel modules (PPMs) are nearly identical to those of the International Space Station (ISS) photovoltaic arrays, MCSA operation offered an opportunity to gather multi-year performance data on this technology prior to its implementation on ISS. Two specially designed test sequences were executed in June and December 1996 to measure MCSA performance. Each test period encompassed 3 orbital revolutions whereby the current produced by the MCSA channels was measured. The temperature of MCSA PPMs was also measured. To better interpret the MCSA flight data, a dedicated FORTRAN computer code was developed to predict the detailed thermal-electrical performance of the MCSA. Flight data compared very favorably with computational performance predictions. This indicated that the MCSA electrical performance was fully meeting pre-flight expectations. There were no measurable indications of unexpected or precipitous MCSA performance degradation due to contamination or other causes after 7 months of operation on orbit. Power delivered to the Mir bus was lower than desired as a consequence of the retrofitted power distribution cabling. The strong correlation of experimental and computational results further bolsters the confidence level of performance codes used in critical ISS electric power forecasting. In this paper, MCSA flight performance tests are described as well as the computational modeling behind the performance predictions.

Kerslake, Thomas W.↗
NASA NTRS2003

Brayton Power Conversion Unit Tested: Provides a Path to Future High-Power Electric Propulsion Missions

Closed-Brayton-cycle conversion technology has been identified as an excellent candidate for nuclear electric propulsion (NEP) power conversion systems. Advantages include high efficiency, long life, and high power density for power levels from about 10 kWe to 1 MWe, and beyond. An additional benefit for Brayton is the potential for the alternator to deliver very high voltage as required by the electric thrusters, minimizing the mass and power losses associated with the power management and distribution (PMAD). To accelerate Brayton technology development for NEP, the NASA Glenn Research Center is developing a low-power NEP power systems testbed that utilizes an existing 2- kWe Brayton power conversion unit (PCU) from previous solar dynamic technology efforts. The PCU includes a turboalternator, a recuperator, and a gas cooler connected by gas ducts. The rotating assembly is supported by gas foil bearings and consists of a turbine, a compressor, a thrust rotor, and an alternator on a single shaft. The alternator produces alternating-current power that is rectified to 120-V direct-current power by the PMAD unit. The NEP power systems testbed will be utilized to conduct future investigations of operational control methods, high-voltage PMAD, electric thruster interactions, and advanced heat rejection techniques. The PCU was tested in Glenn s Vacuum Facility 6. The Brayton PCU was modified from its original solar dynamic configuration by the removal of the heat receiver and retrofitting of the electrical resistance gas heater to simulate the thermal input of a steady-state nuclear source. Then, the Brayton PCU was installed in the 3-m test port of Vacuum Facility 6, as shown. A series of tests were performed between June and August of 2002 that resulted in a total PCU operational time of about 24 hr. An initial test sequence on June 17 determined that the reconfigured unit was fully operational. Ensuing tests provided the operational data needed to characterize PCU performance over its full operating range. The primary test variables used in operating the Brayton PCU were heater input power and rotor speed. Testing demonstrated a maximum steady-state alternating-current power output of 1835 W at a gas heater power of 9000 W and a rotor speed of 52000 rpm. The corresponding measured turbine inlet gas temperature was 1076 K, and the compressor inlet gas temperature was 282 K. When insulation losses from the gas heater were neglected, the Brayton cycle efficiency for the maximum power point was calculated to be 24 percent. The net direct-current power output was 1750 W, indicating a PMAD efficiency of about 95 percent.

Mason, Lee S.↗
NASA NTRS1980

Effectiveness of spacecraft testing programs

The need for testing under simulated mission operational conditions is discussed and the results of such tests are reviewed from the point of view of the user. A brief overview of the usal test sequences for high reliability long life spacecraft is presented and the effectiveness of the testing program is analyzed in terms of the defects which are discovered by such tests. The need for automation, innovative mechanical test procedures, and design for testability is discussed.

Krausz, A.↗
NASA NTRS2013

Small Radioisotope Power System Testing at NASA Glenn Research Center

In April 2009, NASA Glenn Research Center (GRC) formed an integrated product team (IPT) to develop a Small Radioisotope Power System (SRPS) utilizing a single Advanced Stirling Convertor (ASC) with passive balancer. A single ASC produces approximately 80 We making this system advantageous for small distributed lunar science stations. The IPT consists of Sunpower, Inc., to provide the single ASC with a passive balancer, The Johns Hopkins University Applied Physics Laboratory (JHUAPL) to design an engineering model Single Convertor Controller (SCC) for an ASC with a passive balancer, and NASA GRC to provide technical support to these tasks and to develop a simulated lunar lander test stand. The single ASC with a passive balancer, simulated lunar lander test stand, and SCC were delivered to GRC and were tested as a system. The testing sequence at GRC included SCC fault tolerance, integration, electromagnetic interference (EMI), vibration, and extended operation testing. The SCC fault tolerance test characterized the SCCs ability to handle various fault conditions, including high or low bus power consumption, total open load or short circuit, and replacing a failed SCC card while the backup maintains control of the ASC. The integrated test characterized the behavior of the system across a range of operating conditions, including variations in cold-end temperature and piston amplitude, including the emitted vibration to both the sensors on the lunar lander and the lunar surface. The EMI test characterized the AC and DC magnetic and electric fields emitted by the SCC and single ASC. The vibration test confirms the SCCs ability to control the single ASC during launch. The extended operation test allows data to be collected over a period of thousands of hours to obtain long term performance data of the ASC with a passive balancer and the SCC. This paper will discuss the results of each of these tests.

Vibration↗
NASA NTRSDate not supplied

A Summary of the NEXT-C Flight Thruster Proto-flight Testing

Aerojet Rocketdyne (AR), under contract to NASA Glenn Research Center, built, tested and delivered the first flight version of the NEXT-C (NASA Evolutionary Xenon Thruster – Commercial) engine system. This system is comprised of a 7 kW thruster and power processing unit which are the commercial variants of the NEXT prototype thruster and power processing unit. In addition to developing the NEXT-C engine system for potential future NASA science missions, AR is dedicated to ensuring that this propulsion system is viable for commercial users and a wider variety of commercial applications. This paper will focus on the performance of the first flight model thruster, SN001, and presents an overview of the proto-flight testing environments and data obtained. For this first flight thruster, the proto-flight test sequence involved characterizing the performance of the thruster, in addition to vibration and thermal vacuum testing of the thruster. Between each of these environmental tests, the performance of the thruster was verified, ensuring that the environmental exposures, i.e. vibration and TVAC, did not affect the thruster performance. Specifically, the proto-flight data obtained included discharge chamber, optics and neutralizer performance. Faraday probe and ExB data obtained in the regions downstream of the thruster are presented and used to calculate thrust, and therefore specific impulse and total efficiency. Lastly, data are presented showing how the centroid of the ion beam, assumed to be indicative of the thrust vector location, varies throughout the entire proto-flight test campaign. The proto-flight testing of the NEXT-C PPU is documented in a previously published paper by Bontempo4. Following the proto-flight testing of the thruster, the thruster and its PPU successfully completed a System Integrated Test (SIT) tailored to the DART Mission. After the completion of the proto-flight testing, the SN001 thruster and SN002 PPU were delivered to APL for use on the DART mission.

Ion thruster↗
NASA NTRS2022

Pre-Installation Acceptance (PIA) Functional Performance of the Design Verification Test (DVT) Exploration Extra-vehicular Mobility Unit (xEMU)

In an effort that began with technology investment by NASA in a few key components during the Constellation Program and then evolved to demonstrate a packaged Portable Life Support System (PLSS) as part of the Advanced Exploration Systems (AES) Program, the next evolution of the PLSS is now a key component of the Exploration Extra-vehicular Mobility Unit (xEMU) and is assembled as a Design Verification Test (DVT) unit. The xEMU has been detailed with respect to completing a demonstration on the International Space Station (ISS) with support of units for initial lunar capability. The xEMU completed the Preliminary Design Review (PDR) with subsequent Safety Review Panel (SRP) Phase I reviews in 2019-2020. The objectives for DVT are to validate requirements, train the team, learn how to fabricate the hardware with appropriate process controls, assemble the hardware, test the hardware, determine the failure mechanisms/limits of the hardware design and buy down the most risk possible for the qualification and flight phases of the development. With completion of the assembly and initial functional testing of the DVT PLSS in laboratory ambient conditions and vacuum conditions the xEMU has progressed significantly into the DVT objectives. A key part of the test sequences for DVT and all future phases is the Pre-Installation Acceptance (PIA) functional testing which validates the performance of integrated systems including: primary thermal control, auxiliary thermal control, suit ventilation, primary oxygen, secondary oxygen, power distribution, as well as caution and warning all with respect to the applied requirements. This discussion will include an overview of the assembly, summary of the PIA functional testing, lessons learned, and corrective actions implemented moving forward into the remainder of the DVT phase for xEMU.

Colin Campbell↗
NASA NTRS1989

Distributed integrated instrumentation and control system

The operation and capabilities of a new integrated instrumentation and control system are described. The system will, under one main program, both acquire data from a conducted test and automatically control the test sequence. The system layout has a multiplexer front end and control-function electronics at the test area, while the system control computer, recording devices, and monitors are located remotely. The system's data, control, and communication signals are transmitted via fiber-optic lines. Diagrams are presented illustrating the control and data displays.

Hagood, Don↗
NASA NTRS1993

Long Duration Exposure Facility (LDEF) low temperature Heat Pipe Experiment Package (HEPP) flight results

The Low Temperature Heat Pipe Flight Experiment (HEPP) is a fairly complicated thermal control experiment that was designed to evaluate the performance of two different low temperature ethane heat pipes and a low-temperature (182 K) phase change material. A total of 390 days of continuous operation with an axially grooved aluminum fixed conductance heat pipe and an axially grooved stainless steel heat pipe diode was demonstrated before the data acquisition system's batteries lost power. Each heat pipe had approximately 1 watt applied throughout this period. The HEPP was not able to cool below 188.6 K during the mission. As a result, the preprogrammed transport test sequence which initiates when the PCM temperature drops below 180 K was never exercised, and transport tests with both pipes and the diode reverse mode test could not be run in flight. Also, because the melt temperature of the n-heptane PCM is 182 K, its freeze/thaw behavior could not be tested. Post-flight thermal vacuum tests and thermal analyses have indicated that there was an apparent error in the original thermal analyses that led to this unfortunate result. Post-flight tests have demonstrated that the performance of both heat pipes and the PCM has not changed since being fabricated more than 14 years ago. A summary of HEPP's flight data and post-flight test results are presented.

Mcintosh, Roy↗
NASA NTRS1995

Preliminary Design Program: Vapor Compression Distillation Flight Experiment Program

This document provides a description of the results of a program to prepare a preliminary design of a flight experiment to demonstrate the function of a Vapor Compression Distillation (VCD) Wastewater Processor (WWP) in microgravity. This report describes the test sequence to be performed and the hardware, control/monitor instrumentation and software designs prepared to perform the defined tests. the purpose of the flight experiment is to significantly reduce the technical and programmatic risks associated with implementing a VCD-based WWP on board the International Space Station Alpha.

Schubert, F. H.↗
NASA NTRS2008

Contamination Sources Effects Analysis (CSEA) - A Tool to Balance Cost/Schedule While Managing Facility Availability

A CSEA is similar to a Failure Modes Effects Analysis (FMEA). A CSEA tracks risk, deterrence, and occurrence of sources of contamination and their mitigation plans. Documentation is provided spanning mechanical and electrical assembly, precision cleaning, thermal vacuum bake-out, and thermal vacuum testing. These facilities all may play a role in contamination budgeting and reduction ultimately affecting test and flight. With a CSEA, visibility can be given to availability of these facilities, test sequencing and trade-offs. A cross-functional team including specialty engineering, contamination control, electrostatic dissipation, manufacturing, testing, and material engineering participate in an exercise that identifies contaminants and minimizes the complexity of scheduling these facilities considering their volatile schedules. Care can be taken in an efficient manner to insure correct cleaning processes are employed. The result is reduction in cycle time ("schedule hits"), reduced cost due to rework, reduced risk and improved communication and quality while achieving adherence to the Contamination Control Plan.

Wilcox, Margaret↗
NASA NTRS1989

Optical test unit design for the direct detection laser tranceiver program

The Optical Test Unit (OTU) for the NASA Direct Detection Laser Tranceiver (DDLT) Experiment was designed to perform a wide variety of electrical and optical tests with minimum cost and risk. Choosing instruments that could do their own processing and carefully examining each step of the integration and test sequence helped reduce the cost and complexity of the system, allowing us to meet a very ambitious schedule. For some tests, less elegant schemes can be used than the traditional system test methods, while still maintaining the integrity of the test system. This paper explores the problems encountered and options that were available in designing the system test equipment for this optical communication system.

Reed, Patricia A.↗
NASA NTRS1998

Use of SX Series Devices and IEEE 1149.1 JTAG Circuitry

This report summarizes the use of SX series devices and their JTAG 1149.1 circuitry. 'JTAG' circuitry was originally designed to standardize testing of boards via a simple control port interface electrically without having to use devices such as a bed of nails tester. JTAG is also used for other functions such as executing built-in-test sequences, identifying devices, or, through custom instructions, other functions designed in by the chip designer. The JTAG circuitry is designed for test only; it has no functional use in the integrated circuit during normal operations. The JTAG circuitry and the mode of the device is controlled by a circuit block known as the 'TAP controller,' which is a sixteen-state state machine along with various registers. The controller is normally in an operational state known as TEST-LOGIC-RESET. In this state, the device is held in a fully functional, operating mode. However, a Single Event Upset (SEU) may remove the TAP controller from this state, causing a loss of control of the integrated circuit, unless certain precautions are taken, such as grounding the optional JTAG TRST signal.

Katz, Richard B.↗
NASA NTRS1998

Use of SX Series Devices and IEEE 1149.1 JTAG Circuitry

This report summarizes the use of SX series devices and their JTAG 1149.1 circuitry. 'JTAG' circuitry was originally designed to standardize testing of boards via a simple control port interface electrically without having to use devices such as a bed of nails tester. JTAG is also used for other functions such as executing built-in-test sequences, identifying devices, or, through custom instructions, other functions designed in by the chip designer. The JTAG circuitry is designed for test only; it has no functional use in the integrated circuit during normal operations. The JTAG circuitry and the mode of the device is controlled by a circuit block known as the 'TAP controller,' which is a sixteen-state state machine along with various registers. The controller is normally in an operational state known as TEST-LOGIC-RESET. In this state, the device is held in a fully functional, operational mode. However, a Single Event Upset (SEU) may remove the TAP controller from this state, causing a loss of control of the integrated circuit, unless certain precautions are taken, such as grounding the optional JTAG TRST signal.

Katz, Richard B.↗
NASA NTRS2010

Incorporating Vibration Test Results for the Advanced Stirling Convertor into the System Dynamic Model

The U.S. Department of Energy (DOE), Lockheed Martin Corporation (LM), and NASA Glenn Research Center (GRC) have been developing the Advanced Stirling Radioisotope Generator (ASRG) for use as a power system for space science missions. As part of the extended operation testing of this power system, the Advanced Stirling Convertors (ASC) at NASA GRC undergo a vibration test sequence intended to simulate the vibration history that an ASC would experience when used in an ASRG for a space mission. During these tests, a data system collects several performance-related parameters from the convertor under test for health monitoring and analysis. Recently, an additional sensor recorded the slip table position during vibration testing to qualification level. The System Dynamic Model (SDM) integrates Stirling cycle thermodynamics, heat flow, mechanical mass, spring, damper systems, and electrical characteristics of the linear alternator and controller. This Paper presents a comparison of the performance of the ASC when exposed to vibration to that predicted by the SDM when exposed to the same vibration.

Meer, David W.↗