Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “Thermal performance”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 847 records · Page 47
All sourcesNASA NTRSDOE OSTI
NASA NTRS2018

Landsat 9 Thermal Infrared Sensor 2 Pre-Launch Characterization: Initial Imaging & Spectral Performance Results

The Thermal Infrared Sensor-2 (TIRS-2) scheduled to launch in December 2020 aboard Landsat 9 will continue Landsat's four decade-long legacy of providing moderate resolution thermal imagery from low earth orbit (at 705 km) for environmental applications. Like the Thermal Infrared Sensor aboard Landsat 8, it is a pushbroom sensor with a cross-track field of view of 15 and provides two spectral channels at 10.8 and 12 um. To ensure radiometric, spatial, and spectral performance, a comprehensive pre-launch testing program is being conducted at NASA Goddard Space Flight Center at the component, subsystem, and instrument level. This effort will focus on the results from the subsystem level testing to assess TIRS-2 imaging performance including focus, spatial performance, and stray light rejection. It is also used to provide a preliminary assessment of spectral performance. The TIRS-2 subsystem is placed in a thermal vacuum chamber with the calibration ground support equipment, which provides a flexible blackbody illumination source and optics to assess imaging performance. Spectral performance is tested using a spectral response test setup with its own illumination source outside the chamber that propagates through the calibration ground support equipment in an optical configuration designed for this purpose. The results show that TIRS-2 performance is expected to meet all of its performance requirements with few waivers and deviations.

scatter↗
NASA NTRS1988

Long-term performance of the passive thermal control systems of the IRAS spacecraft

Degradation of passive thermal control systems in space is a matter of serious concern and has been observed in many missions. The performance of the passive thermal control systems of the Infrared Astronomical Satellite (IRAS) over a period of three years is reported here. An exterior temperature of 200 K and a sunshade temperature of approximately 100 K were maintained over this period without significant degradation. The temperature of the telescope contained in the IRAS cryostat was also observed for two years after expenditure of the helium cryogen. It remained at 100 K with no degradation.

Mason, P. V.↗
NASA NTRS2013

Rover Low Gain Antenna Qualification for Deep Space Thermal Environments

A method to qualify the Rover Low Gain Antenna (RLGA) for use during the Mars Science Laboratory (MSL) mission has been devised. The RLGA antenna must survive all ground operations, plus the nominal 670 Martian sol mission that includes the summer and winter seasons of the Mars thermal environment. This qualification effort was performed to verify that the RLGA design, its bonding, and packaging processes are adequate. The qualification test was designed to demonstrate a survival life of three times more than all expected ground testing, plus a nominal 670 Martian sol missions. Baseline RF tests and a visual inspection were performed on the RLGA hardware before the start of the qualification test. Functional intermittent RF tests were performed during thermal chamber breaks over the course of the complete qualification test. For the return loss measurements, the RLGA antenna was moved to a test area. A vector network analyzer was calibrated over the operational frequency range of the antenna. For the RLGA, a simple return loss measurement was performed. A total of 2,010 (3 670 or 3 times mission thermal cycles) thermal cycles was performed. Visual inspection of the RLGA hardware did not show any anomalies due to the thermal cycling. The return loss measurement results of the RLGA antenna after the PQV (Package Qualification and Verification) test did not show any anomalies. The antenna pattern data taken before and after the PQV test at the uplink and downlink frequencies were unchanged. Therefore, the developed design of RLGA is qualified for a long-duration MSL mission.

Ramesham, Rajeshuni↗
NASA NTRSDate not supplied

Lunar Surface Crater Thermal Effects on Lander Radiator Performance

Lunar surface craters smaller than the spatial resolution of surface meshes used in typical Lunar surface thermal models (10 to 60 meters per pixel) may impact the accuracy of thermal model extrema predictions. The goal of this study is to investigate the thermal sensitivity of representative lander systems with realistic thermal surface orientations in bare and cratered terrain environments at relevant Artemis mission locations. This thermal analysis task investigates the impact of lunar surface craters on lander radiator performance by comparing heat rejection capability results between bare and cratered terrain environments. This study examines external body-mounted lander radiator thermal performance across varying lander heights (5.5m, 20m, 50m) and radiator orientations (horizontal, 45º tilted, and vertical) at two representative Artemis mission latitudes (-89.5ºS and -82.5ºS), spanning from the Shackleton Connecting Ridge to Mons Mouton Plateau.

Lunar Surface↗
NASA NTRS1993

Performance of silvered Teflon (trademark) thermal control blankets on spacecraft

Silverized Teflon (Ag/FEP) is a widely used passive thermal control material for space applications. The material has a very low alpha/e ratio (less than 0.1) for low operating temperatures and is fabricated with various FEP thicknesses (as the Teflon thickness increases, the emittance increases). It is low outgassing and, because of its flexibility, can be applied around complex, curved shapes. Ag/FEP has achieved multiyear lifetimes under a variety of exposure conditions. This has been demonstrated by the Long Duration Exposure Facility (LDEF), Solar Max, Spacecraft Charging at High Altitudes (SCATHA), and other flight experiments. Ag/FEP material has been held in place on spacecraft by a variety of methods: mechanical clamping, direct adhesive bonding of tapes and sheets, and by Velcro(TM) tape adhesively bonded to back surfaces. On LDEF, for example, 5-mil blankets held by Velcro(TM) and clamping were used for thermal control over 3- by 4-ft areas on each of 17 trays. Adhesively bonded 2- and 5-mil sheets were used on other LDEF experiments, both for thermal control and as tape to hold other thermal control blankets in place. Performance data over extended time periods are available from a number of flights. The observed effects on optical properties, mechanical properties, and surface chemistry will be summarized in this paper. This leads to a discussion of performance life estimates and other design lessons for Ag/FEP thermal control material.

Pippin, Gary↗
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↗
NASA NTRS2018

Landsat 9 Thermal Infrared Sensor 2 Pre-Launch Characterization: Initial Imaging and Spectral Performance Results

The Thermal Infrared Sensor-2 (TIRS-2) scheduled to launch in December 2020 aboard Landsat 9 will continue Landsat's four decade-long legacy of providing moderate resolution thermal imagery from low earth orbit (at 705 km) for environmental applications. Like the Thermal Infrared Sensor aboard Landsat 8, it is a pushbroom sensor with a cross-track field of view of 15 and provides two spectral channels at 10.8 and 12 micrometers. To ensure radiometric, spatial, and spectral performance, a comprehensive pre-launch testing program is being conducted at NASA Goddard Space Flight Center at the component, subsystem, and instrument level. This effort will focus on the results from the subsystem level testing to assess TIRS-2 imaging performance including focus, spatial performance, and stray light rejection. It is also used to provide a preliminary assessment of spectral performance. The TIRS-2 subsystem is placed in a thermal vacuum chamber with the calibration ground support equipment, which provides a flexible blackbody illumination source and optics to assess imaging performance. Spectral performance is tested using a spectral response test setup with its own illumination source outside the chamber that propagates through the calibration ground support equipment in an optical configuration designed for this purpose. The results show that TIRS-2 performance is expected to meet all of its performance requirements with few waivers and deviations.

Landsat 9↗
NASA NTRS1993

Prototype test article verification of the Space Station Freedom active thermal control system microgravity performance

To verify the on-orbit operation of the Space Station Freedom (SSF) two-phase external Active Thermal Control System (ATCS), a test and verification program will be performed prior to flight. The first system level test of the ATCS is the Prototype Test Article (PTA) test that will be performed in early 1994. All ATCS loops will be represented by prototypical components and the line sizes and lengths will be representative of the flight system. In this paper, the SSF ATCS and a portion of its verification process are described. The PTA design and the analytical methods that were used to quantify the gravity effects on PTA operation are detailed. Finally, the gravity effects are listed, and the applicability of the 1-g PTA test results to the validation of on-orbit ATCS operation is discussed.

Chen, I. Y.↗
NASA NTRS1989

Infrared thermal imaging figures of merit

Commercially available types of infrared thermal imaging instruments, both viewers (qualitative) and imagers (quantitative) are discussed. The various scanning methods by which thermal images (thermograms) are generated will be reviewed. The performance parameters (figures of merit) that define the quality of performance of infrared radiation thermometers will be introduced. A discussion of how these parameters are extended and adapted to define the performance of thermal imaging instruments will be provided. Finally, the significance of each of the key performance parameters of thermal imaging instruments will be reviewed and procedures currently used for testing to verify performance will be outlined.

Kaplan, Herbert↗
NASA NTRS2010

Mission Performance of the GLAS Thermal Control System - 7 Years In Orbit

ICESat (Ice, Cloud and land Elevation Satellite) was launched in 2003 carrying a single science instrument - the Geoscience Laser Altimeter System (GLAS). Its primary mission was to measure polar ice thickness. The GLAS thermal control architecture utilized propylene Loop Heat Pipe (LHP) technology to provide selectable and stable temperature control for the lasers and other electronics over a widely varying mission thermal environment. To minimize expected degradation of the radiators, Optical Solar Reflectors (OSRs) were used for both LHP radiators to minimize degradation caused by UV exposure in the various spacecraft attitudes necessary throughout the mission. Developed as a Class C mission, with selective redundancy, the thermal architecture was single st ring, except for temperature sensors used for heater control during normal operations. Although originally planned for continuous laser operations over the nominal three year science mission, laser anomalies limited operations to discrete measurement campaigns repeated throughout the year. For trending of the science data, these periods were selected to occur at approximately the same time each year, which resulted in operations during similar attitudes and beta angles. Despite the laser life issues, the LHPs have operated nearly continuously over this time, being non-operational for only brief periods. Using mission telemetry, this paper looks at the performance of the thermal subsystem during these periods and provides an assessment of radiator degradation over the mission lifetime.

Grob, Eric W.↗
NASA NTRS1988

Transient performance evaluation of an integrated heat pipe-thermal storage system

Transient performance tests of an integrated heat pipe-thermal storage system have been conducted. This system was developed as a part of an Organic Rankine Cycle-Solar Dynamic Power System receiver for future power systems. The integrated system consists of potassium heat pipe elements that incorporate thermal energy storage canisters within the vapor space and an organic fluid (toluene) heater tube used as the condenser region of the heat pipe. The transient performance tests determined the operating characteristics and power input limits of the integrated heat pipe-thermal storage unit under conditions corresponding to re-acquisition of the sun during emergence from eclipse conditions and to the initial start-up of the solar dynamic power system. The tests demonstrated that the heat pipe-thermal storage element is not limited under conditions corresponding to emergence from eclipse during normal orbital operations and the heat pipe will successfully start-up from the frozen condition with full input power at the onset. Details of the test procedures and results of the tests are presented in this paper.

Keddy, E.↗
NASA NTRS1973

Photoheliograph thermal concepts study. Volume 1: Summary

The performances of thermal subsystem concepts for each of three photoheliograph designs oriented toward unique solar observation missions are defined. These designs and missions may be categorized as: (1) A 150-centimeter photoheliograph for large Solar Observatory (LSO) missions; (2) a 100-centimeter photoheliograph for shuttle sorties; and (3) a 100-centimeter photoheliograph for balloon missions. For each of these photoheliograph designs are the basic thermal environments, boundary conditions, and applicable thermal control concepts defined, the interactions between concepts and environments determined, and a baseline thermal control concept for the three classes of photoheliographs selected. A set of experimental work plans describing the major efforts required to further the detailed design and to confirm analytical performance predictions is included.

Source record↗
NASA NTRS2010

Thermal Deformation and RF Performance Analyses for the SWOT Large Deployable Ka-Band Reflectarray

A large deployable antenna technology for the NASA Surface Water and Ocean Topography (SWOT) Mission is currently being developed by JPL in response to NRC Earth Science Tier 2 Decadal Survey recommendations. This technology is required to enable the SWOT mission due to the fact that no currently available antenna is capable of meeting SWOT's demanding Ka-Band remote sensing requirements. One of the key aspects of this antenna development is to minimize the effect of the on-orbit thermal distortion to the antenna RF performance. An analysis process which includes: 1) the on-orbit thermal analysis to obtain the temperature distribution; 2) structural deformation analysis to get the geometry of the antenna surface; and 3) the RF performance with the given deformed antenna surface has been developed to accommodate the development of this antenna technology. The detailed analysis process and some analysis results will be presented and discussed by this paper.

thermal distorsion↗
NASA NTRS1980

Life and stability testing of packaged low-cost energy storage materials

Thermal cycling and performance tests, performed to verify the package integrity, life, and stability of the chub packaged materials system for storage coolness with application to residential air conditioning, are described. The moisture vapor retention characteristics of the laminate film for long term chub performance was determined. The stability, mechanical integrity, and thermal performance of chubs following mechanical shock, vibration, and temperature extremes is reported.

Frysinger, G. R.↗
NASA NTRS1979

A two-dimensional thermal analysis of a new high-performance tubular solar collector

The first of two articles are presented which describe and analyze the thermal performance of a vacuum tube solar collector. The assumptions and mathematical modeling are presented. The problem is reduced to the formulation of two simultaneous linear differential equations characterizing the collector thermal behavior. After applying the boundary conditions, a general solution is obtained which is found similar to the general Hottel, Whillier and Bliss form but with a complex flow factor.

Lansing, F. L.↗