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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 199 records · Page 11
All sourcesNASA NTRSDOE OSTI
NASA NTRS2022

The Psyche Planning Software Subsystem: Creating a Robust Toolset for a Discovery-class Mission

Psyche is a Discovery-class mission to the small metal-rich asteroid (16) Psyche, and is slated to launch in 2022. Psyche, like many missions, requires low-cost activity planning and sequence generation that serves as the backbone to overall uplink design. Such tools must be maintainable over long periods of operations, and powerful enough to solve complex issues that deep-space one-off missions encounter. In this paper we introduce cost-effective solutions that leverage inner- and open-source principles to meet a variety of common and novel use cases.The uplink process that was designed to meet these challenges is presented, as well as the data-flow through the high-level architecture of the planning software subsystem. The user-facing planning tools are described, particularly the Science Opportunity Analyzer, the Plan Editor, Psyche’s planning automation in the Blackbird framework, and Psyche Simulation Reports. All these applications are either new or have been substantially revamped to meet Psyche’s concept of operations. In particular, ensuring the entire toolchain can correctly process epoch-relative activities is discussed. Underlying the main applications are a common set of dependencies developed and maintained by a new cross-mission association of planning developers. In this way, Psyche can inherit well-tested functionality which saves effort and ensures its developers can focus on solving domain challenges. Quality control of the applications and libraries is ensured with a code-review and unit-test based novel ‘CM lite’ process. Collaboration with international industry and academia using the open-source modules is already occurring.The planning and scheduling software is designed to maximize operator awareness of the integrated plan at every step of the process and use common interfaces and file formats to easily transfer information. Design choices plus the team’s test-driven development process enables more expansive capabilities compared to the decentralized planning and sequence generation functions typical of Discovery-class orbiters without significant development cost increases. Benefits and drawbacks of Psyche’s approach are discussed, including comparison to other missions and tools where appropriate.

Ramanathan, Keshav↗
NASA NTRSDate not supplied

PACE OCI Pre-launch ETU Spectral Characterization and Performance

The Ocean Color Instrument (OCI) is the primary sensor on the upcoming Plankton, Aerosol, Cloud ocean Ecosystem (PACE) mission. OCI is a new type of sensor compared to NASA’s ocean color heritage sensors VIIRS, MODIS, and SeaWiFs. Unlike its heritage sensors, OCI has two slit grating hyperspectral spectrographs in addition to a fiber-coupled multiband filter spectrograph. The two hyperspectral spectrographs provide continuous coverage from 340nm to 885nm in the UV to NIR range. These spectrographs use programmable CCD detectors that aggregate multiple CCD pixels that can effectively provide various spectral resolutions. The fiber-coupled multiband filter spectrograph provides seven discrete spectral bands from 940nm to 2260nm. OCI completed system level testing of the Engineering Test Unit (ETU) in June 2021 at the Goddard Space Flight Center (GSFC). The ETU contains one of the slit grating spectrographs (600nm to 885nm) and the fiber-coupled spectrograph. The ETU was tested in thermal vacuum (TVAC) in February 2020 and January 2021 to assess characterization and performance compliance to design requirements. This paper presents an overview of the spectral performance of the OCI ETU for relative spectral response (RSR), integrated Out-of-Band response (IOOB), system gain, band centers, and bandwidths.

PACE↗
NASA NTRS1976

High Temperature Strain Gage Calibration Fixture

An apparatus and method are described for calibrating high temperature strain gases which serve for both dead weight and constant deflection measurements. A cantilever support arm allows the test unit to slide into a furnace while one end is subjected to bending strain either by hanging weights upon it or by deflecting it with a push rod. The dual nature of the fixture permits both tests to be run without change of the test specimen or removal from the furnace.

Vranas, T.↗
NASA NTRSDate not supplied

Edge Wear of the Advanced Electric Propulsion System Pole Covers

This work summarizes a wear test focused on characterizing the erosion of the edges and side walls of the 12-kW Advanced Electric Propulsion System (AEPS) pole covers as well as the impact of magnetic field strength on component erosion for operation at a discharge voltage of 600 V. Testing was performed with the AEPS Engineering Test Unit 2 (ETU-2) thruster and accumulated approximately 325 hours of operation at the 600 V/12 kW condition with the magnetic field strength set to 75% of its nominal value. Thruster performance was invariant throughout the wear test for all thruster throttle conditions and matched previous measurements at the nominal magnetic field strength. Contrary to past results, inner front pole cover erosion rates were invariant to magnetic field strength at the 600 V/12 kW condition and no erosion was measured on the outer front pole cover. The erosion profile of the downstream inner front pole cover faces was continuous across the cover, indicating no significant change in erosion processes at the pole cover edges. Side wall erosion was only detected on the cathode-facing surfaces of the inner front pole cover and was equal in magnitude to the rates measured on the adjacent downstream edges. Taken together, these results suggest that erosion of the pole cover edges and sidewalls is driven by cathode-borne ions and will ultimately not impact AEPS life estimates.

Hall thrusters↗
NASA NTRSDate not supplied

Edge Wear of the Advanced Electric Propulsion System Pole Covers

This work presents a summary of the first wear test of the 12 kW Advanced Electric Propulsion System (AEPS) focused on characterizing the erosion of the edges and side walls of the thruster pole covers. Testing was performed with the AEPS Engineering Test Unit 2 (ETU-2) thruster and accumulated approximately 325 hours of operation at the 600 V/12 kW condition with the magnetic field strength set to 75% of its nominal value. Thruster performance was invariant throughout the wear test for all thruster throttle conditions and was found to be equal to previous measurements. Contrary to past results, inner front pole cover erosion rates were invariant to magnetic field strength at the 600 V/12 kW condition and no erosion was measured on the outer front pole cover. The erosion profile of the downstream inner front pole cover faces was continuous across the cover indicating no significant change in erosion process at the pole cover edges. Side wall erosion was only detected on the cathode-facing surfaces of the inner front pole cover and was equal in magnitude to the rates measured on the adjacent downstream edges. Taken together, these results suggest that erosion of the pole cover edges and sidewalls is driven by cathode-borne ions and will ultimately not impact AEPS life estimates.

Hall thrusters↗
NASA NTRS1989

Lessons learned in the transition to Ada from FORTRAN at NASA/Goddard

Two dynamics satellite simulators are developed from the same requirements, one in Ada and the other in FORTRAN. The purpose of the research was to find out how well the prescriptive Ada development model worked to develop the Ada simulator. The FORTRAN simulator development, as well as past FORTRAN developments, provided a baseline for comparison. Since this was the first simulator developed, the prescriptive Ada development model had many similarities to the usual FORTRAN development model. However, it was modified to include longer design and shorter testing phases, which is generally expected with Ada developments. One result was that the percentage of time the Ada project spent in the various development activities was very similar to the percentage of time spent in these activities when doing a FORTRAN project. Another finding was the difficulty the Ada team had with unit testing as well as with integration. It was realized that adding additional steps to the design phase, such as an abstract data type analysis, and certain guidelines to the implementation phase, such as to use primarily library units and nest sparingly, would have made development easier. These are among the recommendations made to be incorporated in a new Ada development model next time.

Brophy, Carolyn Elizabeth↗
NASA NTRS1989

Lessons learned in the transition to ADA from FORTRAN at NASA/Goddard

A case study was done at Goddard Space Flight Center, in which two dynamics satellite simulators are developed from the same requirements, one in Ada and the other in FORTRAN. The purpose of the research was to find out how well the prescriptive Ada development model worked to develop the Ada simulator. The FORTRAN simulator development, as well as past FORTRAN developments, provided a baseline for comparison. Since this was the first simulator developed here, the prescriptive Ada development model had many similarities to the usual FORTRAN development model. However, it was modified to include longer design and shorter testing phases, which is generally expected with Ada development. One surprising result was that the percentage of time the Ada project spent in the various development activities was very similar to the percentage of time spent in these activities when doing a FORTRAN project. Another surprising finding was the difficulty the Ada team had with unit testing as well as with integration. In retrospect it is realized that adding additional steps to the design phase, such as an abstract data type analysis, and certain guidelines to the implementation phase, such as to use primarily library units and nest sparingly, would have made development much easier.

Brophy, Carolyn Elizabeth↗
NASA NTRS1981

Develop and test fuel cell powered on-site integrated total energy systems. Phase 3: Full-scale power plant development

A schematic and physical layout is given for the 5kW integrated system and the development status of individual components is described. The results of using a one dimensional mathematical model of the 5kW reformer are presented. Plans for a single-tube reformer test unit for the acquisition of temperature profile data are described. Tentative specifications for a 50kW dc-to-ac inverter are listed. Performance data are given on two 3-cell stacks incorporating semiautomatic acid replenishment systems and improved electrocatalysts. A qualification test on methanol/steam reforming catalyst T2107RS is reported, including a portion in which the catalyst was deliberately poisoned with 800 ppm ethanol in the feed.

Source record↗
NASA NTRS1994

Software interface verifier

A Telos study of 40 recent subsystem deliveries into the DSN at JPL found software interface testing to be the single most expensive and error-prone activity, and the study team suggested creating an automated software interface test tool. The resulting Software Interface Verifier (SIV), which was funded by NASA/JPL and created by Telos, employed 92 percent software reuse to quickly create an initial version which incorporated early user feedback. SIV is now successfully used by developers for interface prototyping and unit testing, by test engineers for formal testing, and by end users for non-intrusive data flow tests in the operational environment. Metrics, including cost, are included. Lessons learned include the need for early user training. SIV is ported to many platforms and can be successfully used or tailored by other NASA groups.

Soderstrom, Tomas J.↗
NASA NTRS1981

Gortler vortices and transition in wall boundary layers of two Mach 5 nozzles

The onset of transition in the wall boundary layers of two axisymmetric Mach 5 wind-tunnel nozzles has been measured under conditions of extremely low incident disturbance levels. The range of test unit Reynolds numbers, based on conditions at the nozzle exit, was from 6 x 10 to the 6th power m to 2.5 x 10 to the 7th power m. When the nozzle walls were maintained in a polished and clean condition, transition moved gradually upstream as the test Reynolds number was increased. When transition occurred in the supersonic concave wall region, the values of the local Gortler parameter at transition varied from about 5 to 6, whereas the momentum thickness Reynolds number varied from about 750 to 1050. Oil flow patterns obtained near the exit of the nozzles indicated that Gortler vortices were always present when the wall boundary layers were laminar. Calculations for the growth of Gortler vortices based on new results from linear theory for supersonic flat-plate profiles gave amplification ratios to transition from e to the 4th power to e to the 15th power. Possible reasons for this wide range in amplification ratios are discussed, but no definite conclusions are yet possible regarding the values of n in a simple e to the nth power type theory for the assumed linear amplification of Gortler vortices to transition in supersonic nozzles.

Beckwith, I. E.↗
NASA NTRS2018

Space-and Ground-Based Non-Accelerated Long Lifetime Data for Ruggedized Commercial Non-Planar Ring Oscillator (NPRO) Lasers

Lifetime data is presented for ruggedized commercial NPRO lasers used in the Tropospheric Emission Spectrometer (TES) Instrument on NASA’s Aura Earth-orbiting spacecraft, including 20 years of data from two life test units on the ground, 12 years of on-orbit data from TES Laser A, and 2 years of on-orbit data from TES Laser B. The TES lasers are diode-pumped Non-Planar Ring Oscillator (NPRO) lasers using Nd:YAG crystals. Since accelerated life testing was not possible on the complete laser, early prototype lasers that had gone through thermal cycling and vibration testing were placed on non-accelerated life tests with the hope of gathering at least a couple of years of data before launch. Long-term lifetime data for hybrid laser systems in space applications is not abundant, and out of necessity, accelerated reliability testing is usually done over a relatively short time with a large number of devices. The data presented in this paper is unique as it tracks the optical power output over time of a total of four lasers on the order of decades rather than months or years. Two of the lasers have each been on life test for over 20 years on the ground and are still operating, and the other two lasers have been on-orbit for 14 years. TES Laser A was still operating when the TES Instrument was decommissioned in January 2018. Therefore, the data presented covers over 450,000 non-accelerated device-hours, with 23% of those hours being in space.

Kane, T.J.↗
NASA NTRS1998

Development and Testing of the CRYOTSU Flight Experiment

This paper describes the development and ground testing of the CRYOTSU thermal management flight experiment. CRYOTSU incorporates three cryogenic temperature experiments and one ambient temperature experiment into a Hitchhiker (HH) Get Away Special (GAS) Canister that is currently scheduled to fly on STS-95 in October 1998. The cryogenic experiments consist of a nitrogen triple-point cryogenic thermal storage unit (CTSU), a nitrogen cryogenic capillary pumped loop (CCPL), and a hydrogen gas-gap cryogenic thermal switch (CTSW). The ambient experiment is a carbon-fiber core, paraffin-filled thermal storage unit. Test results of integrated flight canister testing are provided herein for the CTSU and CCPL experiments. Pre-integration laboratory test results are provided for the CTSW. Design information and test results for the ambient experiment are not included.

Bugby, David C.↗
NASA NTRS1998

Development and Testing of the CRYOTSU Flight Experiment

This paper describes the development and ground testing of the CRYOTSU thermal management flight experiment. CRYOTSU incorporates three cryogenic temperature experiments and one ambient temperature experiment into a Hitchhiker (HH) Get Away Special (GAS) Canister that is currently scheduled to fly on STS-95 in October 1998. The cryogenic experiments consist of a nitrogen triple-point cryogenic thermal storage unit (CTSU), a nitrogen cryogenic capillary pumped loop (CCPL) and a hydrogen gas-gap cryogenic thermal switch (CTSW). The ambient experiment is a carbon-fiber core, paraffin-filled thermal storage unit. Test results of integrated flight canister testing are provided herein for the CTSU and CCPL experiments. Pre-integration laboratory test results are provided for the CTSW. Design information and test results for the ambient experiment are not included.

Bugby, David C.↗
NASA NTRS2007

Operational Results From a High Power Alternator Test Bed

The Alternator Test Unit (ATU) in the Lunar Power System Facility (LPSF) located at the NASA Glenn Research Center (GRC) in Cleveland, Ohio was used to simulate the operating conditions and evaluate the performance of the ATU and its interaction with various LPSF components in accordance with the current Fission Surface Power System (FSPS) requirements. The testing was carried out at the breadboard development level. These results successfully demonstrated excellent ATU power bus characteristics and rectified user load power quality during steady state and transient conditions. Information gained from this work could be used to assist the design and primary power quality considerations for a possible future FSPS. This paper describes the LPSF components and some preliminary test results.

Birchenough, Arthur↗
NASA NTRS1981

The development of an 85-kW (thermal) steam Rankine solar receiver

The receiver is a once-through monotube boiler designed for steam/electric and process steam applications at pressures up to 17.24 MPa (2500 psia) and temperatures up to 704 C (1300 F). The unit is 76.2 cm (30.0 in.) in diameter and 95.8 cm (37.7 in.) in length; it weighs 220 kg (485 lb). Its heat transfer surface, which is 45.7 cm (18 in.) in diameter by 57 cm (22.4 in.) long, is an Inconel 625, cylindrical, tube-coil assembly composed of primary and reheat sections. A test unit was successfully operated at up to 6.9 MPa (1000 psia) and 704 C (1300 F) with solar input from a 11-m-dia parabolic dish concentrator.

Wright, C. C.↗
NASA NTRS2001

Further Investigations of Control Surface Seals for the X-38 Re-Entry Vehicle

NASA is currently developing the X-38 vehicle that will be used to demonstrate the technologies required for a potential crew return vehicle (CRV) for the International Space Station. This vehicle would serve both as an ambulance for medical emergencies and as an evacuation vehicle for the Space Station. Control surfaces on the X-38 (body flaps and rudder/fin assemblies) require high temperature seals to limit hot gas ingestion and transfer of heat to underlying low-temperature structures to prevent over-temperature of these structures and possible loss of the vehicle. NASAs Johnson Space Center (JSC) and Glenn Research Center (GRC) are working together to develop and evaluate seals for these control surfaces. This paper presents results for compression. flow, scrub, and arc jet tests conducted on the baseline X-38 rudder/fin seal design. Room temperature seal compression tests were performed at low compression levels to determine load versus linear compression, preload. contact area, stiffness. and resiliency characteristics under low load conditions. For all compression levels that were tested, unit loads and contact pressures for the seals were below the 5 lb/in. and 10 psi limits required to limit the loads on the adjoining Shuttle thermal tiles that the seals will contact. Flow rates through an unloaded (i.e. 0% compression) double arrangement were twice those of a double seal compressed to the 20% design compression level. The seals survived an ambient temperature 1000 cycle scrub test over relatively rough Shuttle tile surfaces. The seals were able to disengage and re-engage the edges of the rub surface tiles while being scrubbed over them. Arc jet tests were performed to experimentally determine anticipated seal temperatures for representative flow boundary conditions (pressures and temperatures) under simulated vehicle re-entry conditions. Installation of a single seat in the gap of the test fixture caused a large temperature drop (1710 F) across the seal location as compared to an open gap condition (140 F) confirming the need for seals in the rudder/fin gap location. The seal acted as an effective thermal barrier limiting heat convection through the seal gap and minimizing temperature increases downstream of the seal during maximum heating conditions.

Dunlap, Patrick H., Jr.↗
NASA NTRS1975

Test procedures, AN/AIC-27 system and component units

The AN/AIC-27 (v) intercommunication system is a 30-channel audio distribution which consists of: air crew station units, maintenance station units, and a central control unit. A test procedure for each of the above units and also a test procedure for the system are presented. The intent of the test is to provide data for use in shuttle audio subsystem design.

Reiff, F. H.↗
NASA NTRS1974

Design of H2-O2 space shuttle APU. Volume 1: APU design

The H2-O2 space shuttle auxiliary power unit (APU) program is a NASA-Lewis effort aimed at hardware demonstration of the technology required for potential use on the space shuttle. It has been shown that a hydrogen-oxygen power unit (APU) system is an attractive alternate to the space shuttle baseline hydrazine APU system for minimum weight. It has the capability for meeting many of the heat sink requirements for the space shuttle vehicle, thereby reducing the amount of expendable evaporants required for cooling in the baseline APU. Volume 1 of this report covers preliminary design and analysis of the current reference system and detail design of the test version of this reference system. Combustor test results are also included. Volume 2 contains the results of the analysis of an initial version of the reference system and the computer printouts of system performance. The APU consists of subsystems for propellant feed and conditioning, turbopower, and control. Propellant feed and conditioning contains all heat exchangers, valves, and the combustor. The turbopower subsystem contains a two-stage partial-admission pressure-modulated, 400-hp, 63,000-rpm turbine, a 0-to 4-g lubrication system, and a gearbox with output pads for two hydraulic pumps and an alternator (alternator not included on test unit). The electronic control functions include regulation of speed and system temperatures; and start-and-stop sequences, overspeed (rpm) and temperature limits, failsafe provisions, and automatic shutdown provisions.

Harris, E.↗