Requirements for emittance measurements of thermal control surfaces of spacecraft
Emittance measurement techniques and required properties for spacecraft thermal control surfaces
SPACECRAFT CONTROL↗
SEARCH · Search NASA
Results for “spacecraft thermal”
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.
Thermal scale modeling of a manned spacecraft
A manned spacecraft thermal scale modeling program is described. The program consisted of the design, construction, instrumentation, testing, data correlation, and associated analysis of a transient thermal scale model (TSM) of the Subsystem Test Bed (STB). The STB was chosen as a representative manned spacecraft for which detailed thermal vacuum test data were available. The STB is a cylindrical vehicle (15 ft diameter by 8.3 ft high) with four docking hatches and six windows. The pressure shell is insulated with multilayer insulation and protected by meteoroid shields. Four truss assemblies were used to support the STB during testing. It was concluded that thermal scale modeling can be used as an effective thermal design/verification tool for manned spacecraft. Thermal analysis can be used in conjunction with scale model testing to provide a verified math model that can be applied to the prototype manned spacecraft.
Shannon, R. L.↗
Evaluation of Low-Earth-Orbit Environmental Effects on International Space Station Thermal Control Materials
Many spacecraft thermal control coatings in low Earth orbit (LEO) can be affected by solar ultraviolet radiation and atomic oxygen. Ultraviolet radiation can darken some polymers and oxides commonly used in thermal control materials. Atomic oxygen can erode polymer materials, but it may reverse the ultraviolet-darkening effect on oxides. Maintaining the desired solar absorptance for thermal control coatings is important to assure the proper operating temperature of the spacecraft. Thermal control coatings to be used on the International Space Station (ISS) were evaluated for their performance after exposure in the NASA Lewis Research Center's Atomic Oxygen-Vacuum Ultraviolet Exposure (AO-VUV) facility. This facility simulated the LEO environments of solar vacuum ultraviolet (VUV) radiation (wavelength range, 115 to 200 nanometers (nm)) and VUV combined with atomic oxygen. Solar absorptance was measured in vacuo to eliminate the "bleaching" effects of ambient oxygen on VUV-induced degradation. The objective of these experiments was to determine solar absorptance increases of various thermal control materials due to exposure to simulated LEO conditions similar to those expected for ISS. Work was done in support of ISS efforts at the requests of Boeing Space and Defense Systems and Lockheed Martin Vought Systems.
Dever, Joyce A.↗
Role of Flight Experiments in the Study of Thermal-Control Coatings for Spacecraft
Spacecraft thermal control coating experiments, discussing unreliability of degradation results due to failure to measure radiation properties, UV wavelength dependence and micrometeroid damage
Neel, C. B.↗
Kinds and Amounts of Decomposition Products in the Thermal Degradation of Spacecraft Materials
Thermal degradation profile of 25 selected polymeric spacecraft materials
Rudloff, W. K.↗
Thermal sterilization of spacecraft structures.
Thermal sterilization environment as significant design condition for planetary lander entry-shield bond-structure combination
THERMAL ENVIRONMENT↗
Theory of thermal similitude with applications to spacecraft - A survey.
Mathematical theory of dimensional analysis and similitude, application to spacecraft thermal design and experimental results
MATRIX ALGEBRA↗
Assessment of the Use of Nanofluids in Spacecraft Active Thermal Control Systems
The addition of metallic nanoparticles to a base heat transfer fluid can dramatically increase its thermal conductivity. These nanofluids have been shown to have advantages in some heat transport systems. Their enhanced properties can allow lower system volumetric flow rates and can reduce the required pumping power. Nanofluids have been suggested for use as working fluids for spacecraft Active Thermal Control Systems (ATCSs). However, there are no studies showing the end-to-end effect of nanofluids on the design and performance of spacecraft ATCSs. In the present work, a parametric study is performed to assess the use of nanofluids in a spacecraft ATCSs. The design parameters of the current Orion capsule and the tabulated thermophysical properties of nanofluids are used to assess the possible benefits of nanofluids and how their incorporation affects the overall design of a spacecraft ATCS. The study shows that the unique system and component-level design parameters of spacecraft ATCSs render them best suited for pure working fluids. The addition of nanoparticles to typical spacecraft thermal control working fluids actually results in an increase in the system mass and required pumping power.
Ungar, Eugene K.↗
Criteria for thermal regulation for manned spacecraft cabins
Thermal comfort criteria for manned spacecraft cabin atmosphere
SPACE CABIN ATMOSPHERE↗
Recent advances in spacecraft thermal-control materials research.
The state-of-the-art of spacecraft thermal-control materials technology has been significantly advanced during the past 4 years. Selective black coatings are discussed together with black paints, dielectric films on metal surfaces, and white radiator coatings. Criteria for the selection of thermal-control surfaces are considered, giving attention to prelaunch protection, the capability of being measured, reproducibility, simulator response, and aspects of a nonindigenous space environment. Progress in space simulation is related to vacuum technology, ultraviolet sources, solar wind simulation, and the production of protons. Advances have been made in the protection against space environmental effects, and in the development of thermal-control surfaces and pigments.
Zerlaut, G. A.↗
Scale modeling considerations for thermal control coatings
Spacecraft thermal control coatings scale models, discussing temperature errors due to energy transport along surfaces
Macgregor, R. K.↗
High Speed Bearing Wear Rate Measurements for Spacecraft Active Thermal Control Fluid Pumps with a Novel Pin on Disk Apparatus
A novel pin on disc tribometer was designed and constructed to generate a high-speed, wear coefficient database for hydrodynamic bearings that are typically used in canned motors found in the active thermal control circuits of robotic and inhabited spacecraft. The primary motivation for this work was the premature failure of the active external thermal control pump on the International Space Station in 2010. During the failure investigation of this incident, the root cause was postulated to be high speed wear of the bearings. Although a detailed forensic analysis gave credibility to this theory, the lack of wear coefficient data at relevant conditions prevented validation of this finding. The database generated from the new Extreme Environment Tribometer (EET) enabled a closure calculation within 5% of the observed wear from inspections of the failed hardware. Testing in anhydrous ammonia and surrogate fluid was performed to provide a means for simplified testing in the future and to populate a preliminary database for the design of future active thermal control systems on spacecraft. The EET and test techniques developed for the measurement of high-speed wear coefficients are available to future system designers.
thermal control↗
Small Spacecraft Active Thermal Control: Micro-Vascular Composites Enable Small Satellite Cooling
The Small Spacecraft Integrated Power System with Active Thermal Control project endeavors to achieve active thermal control for small spacecraft in a practical and lightweight structure by circulating a coolant through embedded micro-vascular channels in deployable composite panels. Typically, small spacecraft rely on small body mounted passive radiators to discard heat. This limits cooling capacity and leads to the necessity to design for limited mission operations. These restrictions severely limit the ability of the system to dissipate large amounts of heat from radios, propulsion systems, etc. An actively pumped cooling system combined with a large deployable radiator brings two key advantages over the state of the art for small spacecraft: capacity and flexibility. The use of a large deployable radiator increases the surface area of the spacecraft and allows the radiation surface to be pointed in a direction allowing the most cooling, drastically increasing cooling capacity. With active coolant circulation, throttling of the coolant flow can enable high heat transfer rates during periods of increased heat load, or isolate the radiator during periods of low heat dissipation.
Deployable radiator↗
Significance of Landsat-7 Spacecraft Level Thermal Balance and Thermal Test for ETM+Instrument
The thermal design and the instrument thermal vacuum (T/V) test of the Landsat-7 Enhanced Thematic Mapper Plus (ETM+) instrument were based on the Landsat-4, 5 and 6 heritage. The ETM+ scanner thermal model was also inherited from Landsat-4, 5 and 6. The temperature predictions of many scanner components in the original thermal model had poor agreement with the spacecraft and instrument integrated sun-pointing safehold (SPSH) thermal balance (T/B) test results. The spacecraft and instrument integrated T/B test led to a change of the Full Aperture Calibrator (FAC) motor stack "solar shield" coating from MIL-C-5541 to multi-layer insulation (MLI) thermal blanket. The temperature predictions of the Auxiliary Electronics Module (AEM) in the thermal model also had poor agreement with the T/B test results. Modifications to the scanner and AEM thermal models were performed to give good agreement between the temperature predictions and the test results. The correlated ETM+ thermal model was used to obtain flight temperature predictions. The flight temperature predictions in the nominal 15-orbit mission profile, plus margins, were used as the yellow limits for most of the ETM+ components. The spacecraft and instrument integrated T/B and TN test also revealed that the standby heater capacity on the Scan Mirror Assembly (SMA) was insufficient when the Earth Background Simulator (EBS) was 1 50C or colder, and the baffle heater possibly caused the coherent noise in the narrow band data when it was on. Also, the cooler cool-down was significantly faster than that in the instrument T/V test, and the coldest Cold Focal Plane Array (CFPA) temperature achieved was colder.
Choi, Michael K.↗
Cryogenics and Fluids at NASA-Goddard Space Flight Center
Abstract: Spacecraft thermal design presents unique thermal and fluid challenges caused by a variety of harsh spacecraft thermal environments. In addition, at cryogenic temperatures (i.e., less than 123 K (-150° C), and sometimes as low as 50 milliKelvin), more challenges arise, such as the increasing importance of mitigating thermal radiation, the effects of coefficient of thermal expansion mismatches between different materials, changes in the physics behavior of materials, and increasing thermodynamic difficulty of lifting heat up large temperature gradients. In this talk, Dr. Rueger will present a broad overview of spacecraft thermal environments; cryogenic design practices; components of interest for the Cryogenics and Fluids Branch (e.g., cryocoolers, adiabatic demagnetization refrigerators, heat switches, and superconducting leads); cryogenic considerations in some current NASA mission examples (e.g., the DragonFly mission to Titan and the X-ray Imaging and Spectroscopy Mission); and capabilities of the Cryogenics and Fluids Branch at NASA.
Paul Rueger↗
Temperature control. A case history of the Mariner spacecraft
Thermal design considerations for Mariner family of interplanetary probes
TEMPERATURE CONTROL↗
Spacecraft active thermal control subsystem design and operation considerations
Future spacecraft missions will be characterized by high electrical power requiring active thermal control subsystems for acquisition, transport, and rejection of waste heat. These systems will be designed to operate with minimum maintenance for up to 10 years, with widely varying externally-imposed environments, as well as the spacecraft waste heat rejection loads. This paper presents the design considerations and idealized performance analysis of a typical thermal control subsystem with emphasis on the temperature control aspects during off-design operation. The selected thermal management subsystem is a cooling loop for a 75-kWe fuel cell subsystem, consisting of a fuel cell heat exchanger, thermal storage, pumps, and radiator. Both pumped-liquid transport and two-phase (liquid/vapor) transport options are presented with examination of similarities and differences of the control requirements for these representative thermal control options.
Sadunas, J. A.↗
Development and Validation of a High-Vacuum Thermal Conductivity Testbed for Aerospace Interface Materials
Spacecraft thermal margins depend on the temperature penalty of installed interfaces, yet catalog conductivity omits bondline thickness, mating surfaces, preload, and environment. The Testbed for Advanced Interface Materials in Vacuum (TAIMV) addresses this engineering-data gap by converting ambient/vacuum temperature fields from a four-coupon stack into quantities usable in spacecraft thermal models. Its 17-node steady-state model resolves axial conduction, parasitic fixture paths, grease-filled contact, radiation, and ambient convection. Four monolithic checks gave axial heat-rate ratios of 0.90–1.02, and Braycote calibration self-recovery gave 2.20% casewise mean absolute percentage error (MAPE) and 2.85% maximum difference. With transferable fixture terms frozen, Krytox LVP tested cross-material transfer against a manufacturer-derived external relation. The six Krytox cases gave 2.28% MAPE, 5.10% maximum difference, and full-field residual root-mean-square values of 0.553 °C ambient and 1.306 °C vacuum. Installed-joint resistance spanned 6.39–7.15 × 10⁻⁴ m²·K/W for Braycote and 4.09–4.49 × 10⁻⁴ m²·K/W for Krytox, corresponding to 2.33–6.66 K per modeled interface over the tested heat-flux range. TAIMV therefore supplies directly usable installed-joint resistance and conductance, plus apparent installed conductivity and explicitly model-conditioned grease conductivity/contact terms.
heat transfer↗