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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 NTRS1981

Mission concepts for Venus surface investigation

Mission concepts for the in situ investigation of the Venus atmosphere and surface in the period following the VOIR mission are discussed. The science issues in Venus exploration and possible means of meeting the scientific objectives are considered, including global mapping, surface composition determination, atmospheric composition determination and surface-atmosphere interactions. Particular attention is then given to the feasibility of buoyant stations for atmospheric observation, balloon-tether combinations for surface observations, and the active thermal control by a reversed Brayton cycle or a vapor compression cycle of a long-lived Venus lander. Of the concepts examined, it is found that only the balloon-tether system would be impractical for the mission outlined for it, while the other two concepts appear feasible.

Hoffman, S. J.↗
NASA NTRS1982

The mechanical design of a vapor compressor for a heat pump to be used in space

A heat pump developed for use in Spacelab as a stand-alone refrigeration unit as well as within a fluid loop system is discussed. It will provide an active thermal control for payloads. Specifications for the heat pump were established: (1) heat removal rates at the source; (2) heat source temperatures from room temperature; (3) heat-sink fluid temperatures at condenser inlet; and (4) minimum power consumption. A reversed Carnot cycle heat pump using Freon 12 as working fluid incorporating a one-cylinder reciprocating compressor was selected. The maximum crankshaft speed was fixed relatively high at 100 rpm. The specified cooling rates then made it necessary to select a cylinder volume of 10 cu cm, which was obtained with a bore of 40 mm and a stroke of 8 mm.

Berner, F.↗
NASA NTRS1982

Shuttle orbiter flash evaporator operational flight test performance

The Flash evaporator System (FES is part of the Shuttle Orbiter Active Thermal Control Subsystem. The FES provides total heat rejection for the vehicle Freon Coolant Loops during ascent and entry and supplementary heat rejection during orbital mission phases. This paper reviews the performance of the FES during the first two Shuttle orbital missions (STS-1 and STS-2). A comparison of actual mission performance against design requirements is presented. Mission profiles (including Freon inlet temperature and feedwater pressure transients), control temperature, and heat load variations are evaluated. Anomalies that occurred during STS-2 are discussed along with the procedures conducted, both in-flight and post-flight, to isolate the causes. Finally, the causes of the anomalies and resulting corrective action taken for STS-3 and subsequent flights are presented.

Nason, J. R.↗
NASA NTRS1985

Cryogenic Fluid Management Facility

The Cryogenic Fluid Management Facility is a reusable test bed which is designed to be carried within the Shuttle cargo bay to investigate the systems and technologies associated with the efficient management of cryogens in space. Cryogenic fluid management consists of the systems and technologies for: (1) liquid storage and supply, including capillary acquisition/expulsion systems which provide single-phase liquid to the user system, (2) both passive and active thermal control systems, and (3) fluid transfer/resupply systems, including transfer lines and receiver tanks. The facility contains a storage and supply tank, a transfer line and a receiver tank, configured to provide low-g verification of fluid and thermal models of cryogenic storage and transfer processes. The facility will provide design data and criteria for future subcritical cryogenic storage and transfer system applications, such as Space Station life support, attitude control, power and fuel depot supply, resupply tankers, external tank (ET) propellant scavenging, and ground-based and space-based orbit transfer vehicles (OTV).

Eberhardt, R. N.↗
NASA NTRS1987

Space ten-meter telescope (STMT) - Structural and thermal feasibility study of the primary mirror

The structural and thermal behavior of a ten-meter primary mirror for a space optical/near-IR telescope in geosynchronous orbit is studied. The glass-type lightweighted mirror is monolithic, of the double arch type, and is supported at only three points. The computer programs SSPTA (thermal), NASTRAN (finite element), and ACCOS V (optical) are used in sequence to determine the temperature, deformation, and optical performance of the mirror. A mirror temperature of 130 K or less appears to be obtainable by purely passive means. With a fused silica or standard Zerodur blank, thermally-induced deformation is unacceptable and cannot be fully corrected by an active secondary mirror over the desired field. Either active thermal control or a blank of lower thermal expansion coefficient would be required.

Bely, Pierre Y.↗
NASA NTRS1988

Independent Orbiter Assessment (IOA): CIL issues resolution report, volume 1

The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) are presented. This report contains IOA assessment worksheets showing resolution of outstanding IOA CIL issues that were summarized in the IOA FMEA/CIL Assessment Interim Report, dated 9 March 1988. Each assessment worksheet has been updated with CIL issue resolution and rationale. The NASA and Prime Contractor post 51-L FMEA/CIL documentation assessed is believed to be technically accurate and complete. No assessment issues remain that has safety implications. Volume 1 contain worksheets for the following sybsystems: Landing and Deceleration Subsystem; Purge, Vent and Drain Subsystem; Active Thermal Control and Life Support Systems; Crew Equipment Subsystem; Instrumentation Subsystem; Data Processing Subsystem; Atmospheric Revitalization Pressure Control Subsystem; Hydraulics and Water Spray Boiler Subsystem; and Mechanical Actuation Subsystem.

Urbanowicz, Kenneth J.↗
NASA NTRS1991

Heat pump evaluation for Space Station ATCS evolution

A preliminary feasibility assessment of the application of a vapor compression heat pump to the Active Thermal Control System (ATCS) of SSF is presented. This paper focuses on the methodology of raising the surface temperature of the radiators for improved heat rejection. Some of the effects of the vapor compression cycle on SSF examined include heat pump integration into ATCS, constraints on the heat pump operating parameters, and heat pump performance enhancements.

Ames, Brian E.↗
NASA NTRS1992

Aerospace applications of SINDA/FLUINT at the Johnson Space Center

SINDA/FLUINT has been found to be a versatile code for modeling aerospace systems involving single or two-phase fluid flow and all modes of heat transfer. Several applications of SINDA/FLUINT are described in this paper. SINDA/FLUINT is being used extensively to model the single phase water loops and the two-phase ammonia loops of the Space Station Freedom active thermal control system (ATCS). These models range from large integrated system models with multiple submodels to very detailed subsystem models. An integrated Space Station ATCS model has been created with ten submodels representing five water loops, three ammonia loops, a Freon loop and a thermal submodel representing the air loop. The model, which has approximately 800 FLUINT lumps and 300 thermal nodes, is used to determine the interaction between the multiple fluid loops which comprise the Space Station ATCS. Several detailed models of the flow-through radiator subsystem of the Space Station ATCS have been developed. One model, which has approximately 70 FLUINT lumps and 340 thermal nodes, provides a representation of the ATCS low temperature radiator array with two fluid loops connected only by conduction through the radiator face sheet. The detailed models are used to determine parameters such as radiator fluid return temperature, fin efficiency, flow distribution and total heat rejection for the baseline design as well as proposed alternate designs. SINDA/FLUINT has also been used as a design tool for several systems using pressurized gasses. One model examined the pressurization and depressurization of the Space Station airlock under a variety of operating conditions including convection with the side walls and internal cooling. Another model predicted the performance of a new generation of manned maneuvering units. This model included high pressure gas depressurization, internal heat transfer and supersonic thruster equations. The results of both models were used to size components, such as the heaters and gas bottles and also to point to areas where hardware testing was needed.

Ewert, Michael K.↗
NASA NTRS1993

Causal modeling and event-driven simulation for monitoring of continuous systems

We describe extensions to the traditional techniques for anomaly detection, as well as new anomaly detection techniques based on alternate models of what distinguishes normal from abnormal behavior. Some of these techniques are designed to capture anomalies at individual sensors; some detect anomalies across collections of sensors. To assist in reasoning about complex global behaviors, we construct and simulate a causal model of the physical system being monitored. These techniques have been tested on data from the ECLSS of Space Station Freedom (SSF) and are being applied in advanced monitoring prototypes for the SSF External Active Thermal Control System of SSF and the Environmental Emergency and Consumables Management subsystem of the Space Shuttle.

Doyle, Richard↗
NASA NTRS1995

Thermal control on the lunar surface

For a mission to the Moon which lasts more than a few days, thermal control is a challenging problem because of the Moon's wide temperature swings and long day and night periods. During the lunar day it is difficult to reject heat temperatures low enough to be comfortable for either humans or electronic components, while excessive heat loss can damage unprotected equipment at night. Fluid systems can readily be designed to operate at either the hot or cold temperature extreme but it is more difficult to accomodate both extermes within the same system. Special consideration should be given to sensitive systems, such as optics and humans, and systems that generate large amounts of waste heat, such as lunar bases or manufacturing facilities. Passive thermal control systems such as covers, shades and optical coatings can be used to mitigate the temperature swings experienced by components. For more precise thermal control active systems such as heaters or heat pumps are required although they require more power than passive systems.

Walker, Sherry T.↗
NASA NTRS1993

Evaluation of space station ATCS evolution growth paths

This paper determines the feasibility of potential Active Thermal Control System (ATCS) growth paths by assessing thermal, integration, and implementation impacts. Thermal Radiation Analysis System/Infrared Radiation Transfer (TRASYS/IRTRAN) models were used to evaluate the effects of increased radiator temperature, increased radiator area, and radiator wing addition on Space Station Freedom (SSF) elements, including energy reflected back to the ATCS. Systems Improved Numerical Differencing Analyzer/Fluid Integrator (SINDA/FLUINT) models were used to determine the heat rejection capability of an ATCS loop with an integrated heat pump that operates with Electric Power System (EPS) peak power. The effects of upgrading the ATCS by advanced technology Orbital Replacement Unit (ORU) implementation during maintenance replacements was also evaluated. The study results presented lead to conclusions on which paths are best suited for different growth scenarios.

Ames, Brian E.↗
NASA NTRS1999

Die Attachment for -120 C to +20 C Thermal Cycling of Microelectronics for Future Mars Rovers: An Overview

Active thermal control for electronics on Mars Rovers imposes a serious penalty in weight, volume, power consumption, and reliability. Thus, we propose that thermal control be eliminated for future Rovers. From a functional standpoint there is no reason that the electronics could not operate over the entire temperature range of the Martian environment, which can vary from a low of approximately equal -90 C to a high of approximately equal +20 C during the Martian night and day. The upper end of this range is well within that for conventional electronics. Although the lower end is considerably below that for which conventional--even high-reliability electronics is designed or tested, it is well established that electronic devices can operate to such low temperatures. The primary concern is reliability of the overall electronic system, especially in regard to the numerous daily temperature cycles that it would experience over the duration of a mission on Mars. Accordingly, key reliability issues have been identified for elimination of thermal control on future Mars Rovers. One of these is attachment of semiconductor die onto substrates and into packages. Die attachment is critical since it forms a mechanical, thermal and electrical interface between the electronic device and the substrate or package. This paper summarizes our initial investigation of existing information related to this issue, in order to form an opinion whether die attachment techniques exist, or could be developed with reasonable effort, to withstand the Mars thermal environment for a mission duration of approximately I year. Our conclusion, from a review of literature and personal contacts. is that die attachment can be made sufficiently reliable to satisfy the requirements of future Mars Rovers. Moreover, it appears that there are several possible techniques from which to choose and that the requirements could be met by judicious selection from existing methods using hard solders, soft solders, or organic adhesives. Thus from the standpoint of die attachment. it appears feasible to eliminate thermal control for Rover electronics. We recommend that this be further investigated and verified for the specific hardware and thermal conditions appropriate to Mars Rovers.

Kirschman, Randall K.↗
NASA NTRS1999

Two-Phase Technology at NASA/Johnson Space Center

Since the baseline International Space Station (ISS) External Active Thermal Control System (EATCS) was changed from a two-phase mechanically pumped system to a single phase cascade system in the fall of 1993, two-phase EATCS research has continued at a low level at JSC. One of-the lessons of the ISS EATCS selection was that two-phase thermal control systems must have significantly lower power than comparable single phase systems to overcome their larger radiator area, larger line and fluid mass, and perceived higher technical risk. Therefore, research at JSC has concentrated on low power mechanically pumped two-phase EATCSs. In the presentation, the results of a study investigating the trade of single and two-phase mechanically pumped EATCSs for space vehicles will be summarized. The low power two-phase mechanically pumped EATCS system under development at JSC will be described in detail and the current design status of the subscale test unit will be reviewed. Also, performance predictions for a full size EATCS will be presented. In addition to the discussion of two-phase mechanically pumped EATCS development at JSC, two-phase technologies under development for biological water processing will be discussed. These biological water processor technologies are being prepared for a 2001 flight experiment and subsequent usage on the TransHab module on the International Space Station.

Ungar, Eugene K.↗
NASA NTRS1999

Studies on Normal and Microgravity Annular Two Phase Flows

Two-phase gas-liquid flows occur in a wide variety of situations. In addition to normal gravity applications, such flows may occur in space operations such as active thermal control systems, power cycles, and storage and transfer of cryogenic fluids. Various flow patterns exhibiting characteristic spatial and temporal distribution of the two phases are observed in two-phase flows. The magnitude and orientation of gravity with respect to the flow has a strong impact on the flow patterns observed and on their boundaries. The identification of the flow pattern of a flow is somewhat subjective. The same two-phase flow (especially near a flow pattern transition boundary) may be categorized differently by different researchers. Two-phase flow patterns are somewhat simplified in microgravity, where only three flow patterns (bubble, slug and annular) have been observed. Annular flow is obtained for a wide range of gas and liquid flow rates, and it is expected to occur in many situations under microgravity conditions. Slug flow needs to be avoided, because vibrations caused by slugs result in unwanted accelerations. Therefore, it is important to be able to accurately predict the flow pattern which exists under given operating conditions. It is known that the wavy liquid film in annular flow has a profound influence on the transfer of momentum and heat between the phases. Thus, an understanding of the characteristics of the wavy film is essential for developing accurate correlations. In this work, we review our recent results on flow pattern transitions and wavy films in microgravity.

Balakotaiah, V.↗
NASA NTRS2002

Design and Performance of the Vegetation Canopy Lidar (VCL) Laser Transmitter

The Vegetation Canopy Lidar (VCL) laser is a Nd:YAG Q-switched, diode side-pumped, zig-zag slab design producing 10 ns, 15 mJ pulses at 1064 nm. It employs an unstable resonator as well as a graded reflectivity output coupler with a Gaussian reflectivity profile. In order to conserve power, a conductively cooled design is employed and is designed to operate over a range of 25 C without active thermal control. The laser is an oscillator-only design and equipped with an 15X beam expander to limit the output divergence to less than 60 microrad. Thermal lensing compensation in the side-pumped slab was performed with different treatments of the x and y portions of the z-directed beam. Performance data as a function of temperature are given.

Coyle, D. Barry↗
NASA NTRS2007

Lessons Learned from the Aquarius Radiometer Engineering Model

The Aquarius instrument is a combination microwave radiometer and scatterometer operating in the L-band for the measurement of sea surface salinity (SSS) over the open-ocean. "The Aquarius science goals are to observe and model the processes that relate salinity variations to climatic changes in the global cycling of water and to understand how these variations influence the general ocean circulation. By measuring salinity globally and synoptically every month for 3 years, Aquarius will provide an unprecedented new view of the ocean's role in climate." (http://aquarius.asfc.nasa.gov on Jan. 4, 2007). To launch in 2009, Aquarius will provide 8-day global coverage and monthly-averaged salinity maps at approx.120-km spatial resolution. Because the microwave emissivity of the ocean surface is weakly dependent upon salinity, the Aquarius radiometer remain sufficiently stable to provide accurate salinity measurements. An engineering model (EM) of one radiometer receiver was developed and tested for functionality and performance at NASA's Goddard Space Flight Center. It was tested for long-term stability starting July 27,2006. Two discrepancies where found at the start of testing and a four-month correction process ensued. This paper covers the testing and debugging of the EM radiometer through resolution of the problems. The radiometer is required to have calibration stability of less than or equal to 0.15 K over 7 days. The radiometer is in a three-beam push-broom configuration with each beam being an independent three-state Dicke radiometer (antenna, reference load, and additive noise). Internal noise diodes and reference loads provide periodic and rapid calibration of the receiver. Front-end loss contributions must be corrected as the lossy components are outside the calibration loop. A key design feature for obtaining stability is active thermal control of the front-end lossy components and the RF receiver. The thermal stability is predicted to be about 0.1 C over an orbit and no more than 1 C over a year. The radiometric stability requirement is 0.13 K rms 1 7 days without using temperature corrections. Temperature corrections and post-launch calibration are expected to extend the stability period through the life of the mission.

Piepmeier, Jeffrey↗
NASA NTRS2010

Thermal Analysis of the Advanced Technology Large Aperture Space Telescope (ATLAST) 8 Meter Primary Mirror

The Advanced Technology Large Aperture Space Telescope (ATLAST) preliminary design concept consists of an 8 meter diameter monolithic primary mirror enclosed in an insulated, optical tube with stray light baffles and a sunshade. ATLAST will be placed in orbit about the Sun-Earth L2 and will experience constant exposure to the sun. The insulation on the optical tube and sunshade serve to cold bias the telescope which helps to minimize thermal gradients. The primary mirror will be maintained at 280K with an active thermal control system. The geometric model of the primary mirror, optical tube, sun baffles, and sunshade was developed using Thermal Desktop(R) SINDA/FLUINT(R) was used for the thermal analysis and the radiation environment was analyzed using RADCAD(R). A XX node model was executed in order to characterize the static performance and thermal stability of the mirror during maneuvers. This is important because long exposure observations, such as extra-solar terrestrial planet finding and characterization, require a very stable observatory wave front. Steady state thermal analyses served to predict mirror temperatures for several different sun angles. Transient analyses were performed in order to predict thermal time constant of the primary mirror for a 20 degree slew or 30 degree roll maneuver. This paper describes the thermal model and provides details of the geometry, thermo-optical properties, and the environment which influences the thermal performance. All assumptions that were used in the analysis are also documented. Parametric analyses are summarized for design parameters including primary mirror coatings and sunshade configuration. Estimates of mirror heater power requirements are reported. The thermal model demonstrates results for the primary mirror heated from the back side and edges using a heater system with multiple independently controlled zones.

Hornsby, Linda↗