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At least 19 records

Potential of a New Lunar Surface Radiator Concept for Hot Lunar Thermal Environments

The optimum radiator configuration in hot lunar thermal environments is one in which the radiator is parallel to the ground and has no view to the hot lunar surface. However, typical spacecraft configurations have limited real estate available for top-mounted radiators, resulting in a desire to use the spacecraft s vertically oriented sides. Vertically oriented, flat panel radiators will have a large view factor to the lunar surface, and thus will be subjected to significant incident lunar infrared heat. Consequently, radiator fluid temperatures will need to exceed approx.325 K (assuming standard spacecraft radiator optical properties) in order to provide positive heat rejection at lunar noon. Such temperatures are too high for crewed spacecraft applications in which a heat pump is to be avoided. A recent study of vertically oriented radiator configurations subjected to lunar noon thermal environments led to the discovery of a novel radiator concept that yielded positive heat rejection at lower fluid temperatures. This radiator configuration, called the Upright Lunar Terrain Radiator Assembly (ULTRA), has exhibited superior performance to all previously analyzed concepts in terms of heat rejection in the lunar noon thermal environment. A key benefit of the ULTRA is the absence of louvers or other moving parts and its simple geometry. Analysis of the ULTRA for a lunar extravehicular activity (EVA) portable life support system (PLSS) is shown to provide moderate heat rejection, on average, at all solar incident angles assuming an average radiator temperature of 294 K, whereas prior concepts exhibited insignificant heat rejection or heat absorption at higher incident angles. The performance of the ULTRA for a lunar lander is also discussed and compared to the performance of a vertically oriented, flat panel radiator at various lunar latitudes.

Ochoa, Dustin A.↗

Optimized Radiator Geometries for Hot Lunar Thermal Environments

The optimum radiator configuration in hot lunar thermal environments is one in which the radiator is parallel to the ground and has no view to the hot lunar surface. However, typical spacecraft configurations have limited real estate available for top-mounted radiators, resulting in a desire to use the spacecraft's vertically oriented sides. Vertically oriented, flat panel radiators will have a large view factor to the lunar surface, and thus will be subjected to significant incident lunar infrared heat. Consequently, radiator fluid temperatures will need to exceed approximately 325 K (assuming standard spacecraft radiator optical properties) in order to provide positive heat rejection at lunar noon. Such temperatures are too high for crewed spacecraft applications in which a heat pump is to be avoided. A recent study of vertically oriented radiator configurations subjected to lunar noon thermal environments led to the discovery of a novel radiator concept that yielded positive heat rejection at lower fluid temperatures. This radiator configuration, called the Intense Thermal Infrared Reflector (ITIR), has exhibited superior performance to all previously analyzed concepts in terms of heat rejection in the lunar noon thermal environment. A key benefit of ITIR is the absence of louvers or other moving parts and its simple geometry (no parabolic shapes). ITIR consists of a specularly reflective shielding surface and a diffuse radiating surface joined to form a horizontally oriented V-shape (shielding surface on top). The point of intersection of these surfaces is defined by two angles, those which define the tilt of each surface with respect to the local horizontal. The optimum set of these angles is determined on a case-by-case basis. The idea assumes minimal conductive heat transfer between shielding and radiating surfaces, and a practical design would likely stack sets of these surfaces on top of one another to reduce radiator thickness.

Ochoa, Dustin↗

Lunar thermal environment

Quantitative data on photometric, luminescence, light polarization, color, infrared temperature, and microwave temperature properties of moon

THERMAL ENVIRONMENT↗

Simulating the Lunar Thermal Environment for the Surface-Deployed LEMS Artemis III TVAC Test

The Lunar Environment Monitoring Station (LEMS) is an autonomous, survive-the lunar-night seismic suite to be deployed on the Lunar surface by the Artemis III crew and designed to operate continuously for two years. It will see the extremes of the Lunar south pole thermal environment where surface temperatures range from -200°C to +20°C and where nighttime duration is at least 354 hours. Given power and mass constraints, the thermal system is limited to 2.5 Watts of heat during the lunar night. Presented is the system thermal vacuum test plan and configuration to validate the thermal control system performance in a flight-like environment. The test will measure the nighttime heat leaks for the bus and 18 seismometers to ensure lunar night survival and operability.

Thermal↗

Simulating the Lunar Thermal Environment for the Surface-Deployed LEMS Artemis III TVAC Test

The Lunar Environment Monitoring Station (LEMS) is an autonomous, survive-the lunar-night seismic suite to be deployed on the Lunar surface by the Artemis III crew and designed to operate continuously for two years. It will see the extremes of the Lunar south pole thermal environment where surface temperatures range from -200°C to +20°C and where nighttime duration is at least 354 hours. Given power and mass constraints, the thermal system is limited to 2.5 Watts of heat during the lunar night. Presented is the system thermal vacuum test plan and configuration to validate the thermal control system performance in a flight-like environment. The test will measure the nighttime heat leaks for the bus and 18 seismometers to ensure lunar night survival and operability.

Thermal↗

Simulating the Lunar Thermal Environment for the Surface-Deployed LEMS Artemis III TVAC Test

The Lunar Environment Monitoring Station (LEMS) is an autonomous, survive-the lunar-night seismic suite to be deployed on the Lunar surface by the Artemis III crew and designed to operate continuously for two years. It will see the extremes of the Lunar south pole thermal environment where surface temperatures range from -200°C to +20°C and where nighttime duration is at least 354 hours. Given power and mass constraints, the thermal system is limited to 2.5 Watts of heat during the lunar night. Presented is the system thermal vacuum test plan and configuration to validate the thermal control system performance in a flight-like environment. The test will measure the nighttime heat leaks for the bus and 18 seismometers to ensure lunar night survival and operability.

TVAC↗

Planetary and Lunar Environment Thermal Toolbox Elements (PALETTE) Project Year One Results

This paper summarizes the technology development progress made during year one of the three-year JPL PALETTE project, which is funded by the NASA STMD Game Changing Development (GCD) Program. The project goal is to ensure that a full “palette” of flight-ready (high TRL) thermal “toolbox” elements is available so that engineers can create passive, ultra-isolative thermal designs for science instruments on a variety of carriers in lunar/planetary extreme environments. PALETTE is structured to meet the need via four design/build/test tasks and four analysis/study tasks. This paper focuses on Tasks 1-4, the four design/build/test tasks. Task 1 involves the development of nested thermally-switched enclosures featuring a reverse-operation DTE thermal switch (ROD-TSW) in series with a propylene miniaturized loop heat pipe (mini-LHP). Task 2 involves the development of a parabolic reflector radiator (PRR) for low latitude lunar sites. Task 3 involves the development of a low effective emissivity (e*) multilayer insulation (MLI) known as “spacerless” MLI. Finally, Task 4 involves the development of low conductance (G) thermal isolators. Available test results for all four tasks will be summarized in the paper, as will the plans for the remainder of the PALETTE project.

Britton, Shawn R↗

Thermal Vacuum Testing of a Modified COTS Camera for Lunar Environments

The primary objective of this study was to simulate lunar thermal environments to qualify a modified Commercial-Off-The-Shelf (COTS) camera for potential flight applications. A comprehensive testing regimen was developed, including both vacuum and thermal vacuum testing. The tests subjected the camera to temperatures corresponding to expected extrema, and thermal performance was recorded throughout the process. The testing demonstrated that both the camera and its thermal protection systems were able to maintain operational functionality under most of the simulated conditions. The results of the testing indicate that the implemented thermal protection system is effective for the expected lunar environments. Despite the decrease in operational time in comparison with terrestrial usage, the camera's overall performance supports its suitability for use in both flight and lunar missions.

Thermal↗

Lunar Thermal Analysis Guidebook (L-TAG): Thermo-physical and Optical Properties of Lunar Regolith

The purpose of the Human Landing System (HLS) Lunar Thermal Analysis Guidebook (L-TAG) is to provide guidance to experienced thermal engineering personnel on how to conduct worst-case hot and cold lunar thermal analyses for the design of HLS hardware in both lunar orbit and lunar surface environments. The HLS L-TAG will include pointers to the Cross-Program Design Specification for Natural Environments (DSNE), SLS-SPEC-159, and best practices/approaches for interpreting and complying with the DSNE lunar thermal environments in the analysis of HLS spacecraft, vehicles and systems. The HLS L-TAG is a reference document that is available to all HLS thermal analysts. In the event of a conflict with the descriptions provided herein, the DSNE takes precedence. This document represents the best available information at the time of publication and will undergo updates as the HLS program evolves. Feedback from the user community is encouraged to support further refinement of the Guidebook.

Thermal Analysis↗

Lunar Thermal Analysis Guidebook (L-TAG)

The purpose of the Human Landing System (HLS) Lunar Thermal Analysis Guidebook (L-TAG) is to provide guidance to experienced thermal engineering personnel on how to conduct worst-case hot and cold lunar thermal analyses for the design of HLS hardware in both lunar orbit and lunar surface environments. The HLS L-TAG will include pointers to the Cross-Program Design Specification for Natural Environments (DSNE), SLS-SPEC-159, and best practices/approaches for interpreting and complying with the DSNE lunar thermal environments in the analysis of HLS spacecraft, vehicles and systems. The HLS L-TAG is a reference document that is available to all HLS thermal analysts. In the event of a conflict with the descriptions provided herein, the DSNE takes precedence. This document represents the best available information at the time of publication and will undergo updates as the HLS program evolves. Feedback from the user community is encouraged to support further refinement of the Guidebook.

Thermal Analysis↗

Lunar Thermal Analysis Guidebook (L-TAG)

The purpose of the Human Landing System (HLS) Lunar Thermal Analysis Guidebook (L-TAG) is to provide guidance to experienced thermal engineering personnel on how to conduct worst-case hot and cold lunar thermal analyses for the design of HLS hardware in both lunar orbit and lunar surface environments. The HLS L-TAG will include pointers to the Cross-Program Design Specification for Natural Environments (DSNE), SLS-SPEC-159, and best practices/approaches for interpreting and complying with the DSNE lunar thermal environments in the analysis of HLS spacecraft, vehicles and systems. The HLS L-TAG is a reference document that is available to all HLS thermal analysts. In the event of a conflict with the descriptions provided herein, the DSNE takes precedence. This document represents the best available information at the time of publication and will undergo updates as the HLS program evolves. Feedback from the user community is encouraged to support further refinement of the Guidebook.

Thermal Analysis↗

Human Landing System Lunar Thermal Analysis Guidebook

The purpose of the Human Landing System (HLS) Lunar Thermal Analysis Guidebook (L-TAG) is to provide guidance to experienced thermal engineering personnel on how to conduct worst-case hot and cold lunar thermal analyses for the design of HLS hardware in both lunar orbit and lunar surface environments. The HLS L-TAG will include pointers to the Cross-Program Design Specification for Natural Environments (DSNE), SLS-SPEC-159, and best practices/approaches for interpreting and complying with the DSNE lunar thermal environments in the analysis of HLS spacecraft, vehicles and systems. The HLS L-TAG is a reference document that is available to all HLS thermal analysts. In the event of a conflict with the descriptions provided herein, the DSNE takes precedence. This document represents the best available information at the time of publication and will undergo updates as the HLS program evolves. Feedback from the user community is encouraged to support further refinement of the Guidebook.

Thermal Analysis↗

Development of Thermal Control Devices for Extreme Lunar Environments at Marshall Space Flight Center

NASA’s return to the moon brings many challenges, including issues with sustainable survival on the Lunar surface. One of the key challenges with sustainability is designing adequate thermal control systems that allow for surface systems to survive both during the day and the Lunar Night. The extreme thermal environments on the Lunar surface are a challenging design space for thermal engineers. At equatorial regions, the Lunar noon can be very hot, requiring systems with high heat rejection to the environment. At polar regions, such as those targeted by the return to the moon, the Lunar night temperatures plummet to -200 degrees Celsius or lower. Such temperatures are formidable and require specialized thermal control systems to allow surface assets to surface the long night.

Will Johnson↗

Lunar Reconnaissance Orbiter (LRO) Rapid Thermal Design Development

The Lunar Reconnaissance Orbiter (LRO) project had a rapid development schedule starting with project conception in spring of 2004, instrument and launch vehicle selection late in 2005 and then launch in early 2009. The lunar thermal environment is one of the harshest in our solar system with the heavy infrared loading of the moon due to low albedo, lack of lunar atmosphere, and low effective regolith conduction. This set of constraints required a thermal design which maximized performance (minimized radiator area and cold control heater power) and minimized thermal hardware build at the orbiter level (blanketing, and heater service). The orbiter design located most of the avionics on an isothermalized heat pipe panel called the IsoThermal Panel (ITP). The ITP was coupled by dual bore heat pipes to an Optical Solar Reflector (OSR) covered heat pipe radiator. By coupling all of the avionics to one system, the hardware was simplified. The seven instruments were mainly heritage instruments which resulted in their desired radiators being located by their heritage design. This minimized instrument redesigns and therefore allowed them to be delivered earlier, though it resulted in a more complex orbiter level blanket and heater service design. Three of the instruments were mounted on a tight pointing M55J optical bench that needed to be covered in heaters to maintain pointing. Two were mounted to spacecraft controlled radiators. One was mounted to the ITP Dual Bores. The last was mounted directly to the bus structure on the moon facing panel. The propulsion system utilized four-20 pound insertion thrusters and eight-5 pound attitude control thrusters (ACS) in addition to 1000 kg of fuel in two large tanks. The propulsion system had a heater cylinder and a heated mounting deck for the insertion thrusters which coupled most of the propulsion design together simplifying the heater design. The High Gain Antenna System (HGAS) and Solar Array System (SAS) used dual axis actuator gimbal systems. HGAS required additional boom heaters to cool the approximately 10 W of RF losses thru the rotary joints and wave guides from the 40 W Ka system. By design this module needed a fair amount of heater, blanketing, and radiator complexity. The SAS system required a separate cable wrap radiator to help cool the Solar Array harness which dissipated 30 W thru the actuators and cable wraps. This module also was complex.

Baker, Charles↗

Development of a Cold-Walled Molten Regolith Electrolysis Reactor for Lunar Oxygen Production

On the lunar surface, production of commodi-ties to support human presence, such as water, food and oxygen, and sustain the growth of a per-manent outpostwill likely require the use oflocal resources. The moon is covered almost entirely withfragmented oxide minerals known as regolithhundreds of meter thick.As a resource, it is rich in oxygen (> 42 wt.%) bound in a solid state with a variety of metals. The molten regolith electrolysis (MRE)reactor is a promising technology for the production of gaseous oxygen from the lunar reg-olithin a simple, single-stepreaction that requires minimalconsumable materials, produces oxygen and metals with high electrical efficiency and high yields from any regolithcomposition.This process involvesmelting regolith to~1600°C then electro-lyzing the molten pool to separate metal and oxy-gen ions that are then collected as liquid metal and gaseous oxygen at the respective electrodes. Lab-scale demonstrations of the MRE technology have previously reliedon external heating sources to bring the entirety of the reactor up to the operating temperaturewhich creates corrosive interfaces be-tween the molten regolith and the containment ma-terial in the reactor, limiting the overall lifespan of a reactor[1]. The Gaseous Lunar Oxygen from Regolith Electrolysis (GaLORE) project is focused on the development of a “cold-walled” or “Joule-heated” reactor design in which an internal heating source is used to selectively melt a pool of regolith between the electrodes of the reactor, leaving a shell of solidified regolith between the molten pool and the containment vessel of the reactor. This next generation reactor concept has been under development as molten oxide electrolysis (MOE) by MIT and Boston Metal for the production of iron from pure ores for terrestrial application [2]. The GaLORE project in engaged in early development of the technology for use with varying lunar regolith compositionsin the lunar environment. Thermal modelling of a proposed cold-walledreac-tor design were used as a scaffold to develop pa-rameters for a feasible reactor shape and size as well as target energy consumption[3]. The current development effort for the cold-walled reactor de-sign will be presented as a trade study of the most promising techniques for melting regolithwithin the constraints imposed by the lunar environment.Heater devices are designed to accommodate lim-ited electrical power availabilityon the moon, a wide range of regolith compositions that may be seen on the moon, limited metals available for re-placing consumed parts,and the low thermal con-ductivity of granular regolith in vacuum.Heater de-vices will be down-selectedbased on performance measurements within the above operationalcon-straints,and selected devices will be integrated into a reactor with electrodes to begin producing oxygen. [1]Sibille,L.,Sadoway, D.R.,Sirk, A., Tripathy,P.,Melendez, O., Standish, E., Dominguez, J. A., Stefanescu, D.M.,Curreri, P.A., Poizeau,S.,2009. “Recent Advancesin Scale-up Development of Molten Regolith Electrolysis for Oxygen Production in support of a Lunar Base.”AIAA 2009-659, 47th AIAA Aerospace Sciences Meeting, 5 -8 January 2009, Orlando, FL. [2] Boston Metal, https://www.boston-metal.com/moe-technology/#moe-process[3]Schreiner, S.S.,Sibille, L., Dominguez, J.A., Hoffman, J.A., 2016. "A parametric sizing model for Molten Regolith Electrolysis reactors to pro-duce oxygen on the Moon." Advances in Space Research 57.,7,1585-1603.

K D Grossman↗