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At least 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
NASA NTRS1990

Requirements for extravehicular activities on the lunar and Martian surfaces

Basic design reference requirements pertinent to EVA equipment on lunar and martian surfaces are provided. Environmental factors affecting surface EVA are analyzed including gravity, dust, atmospheric conditions, thermal gradients, lightning conditions, and radiation effects, and activities associated with surface EVA are outlined. Environmental and activity effects on EVA equipment are assessed, and emphasis is placed on planetary surface portable life support systems (PLSS), suit development, protection from micrometeoroids, dust, and radiation, food and water supplies, and the extravehicular mobility-unit thermal-control system. Environmental and activity impacts on PLSS design are studied, with focus on base self-sufficiency and reduction in resupply logistics.

Brown, Mariann F.↗
NASA NTRS1990

Design considerations for future planetary space suits

Manned extravehicular activity (EVA) operations will be major mission elements of planned future U.S. space operations. Whether designed for orbital operations or planetary surface exploration, the EVA system must be safe and reliable, and must provide a high degree of performance capabilities. An extravehicular mobility unit (EMU) consisting of a space suit, EVA gloves, and a portable life support system (PLSS) is central to the EVA system. A rugged, highly reliable, mobile, reusable, and easily maintained EVA suit and compact PLSS must meet the specific requirements of the intended mission. Additional requirements imposed by exposure to surface and gravitational environments are the need for lightweight, high-strength materials for fabricating EMUs to prevent astronaut fatigue and the need for dust protection measures and removal techniques to prevent contamination. Also, operational pressure for habitats should be chosen so as to maintain zero-prebreathe conditions while allowing for lower EMU operating pressure.

Kosmo, Joseph J.↗
NASA NTRS1990

Characterization of metal oxide absorbents for regenerative carbon dioxide and water vapor removal for advanced portable life support systems

Characterization of the performance of a silver-oxide-based absorbent in terms of its ability to remove both gaseous CO2 and water vapor in an astronaut portable life support systems (PLSS) is discussed. Attention is focused on regeneration of the absorbent from the carbonite state of the oxide state, preconditioning of the absorbent using a humidified gas stream, and absorption breakthrough testing. Based on the results of bench-scale experiments, a test plan is carried out to further characterize the silver-oxide-based absorbent on a larger scale; it calls for examination of the absorbent in both an adiabatic packed bed and a near-isothermal cooled bed configuration. It is demonstrated that the tested absorbent can be utilized in a way that removes substantial amounts of CO2 and water vapor during an 8-hour extravehicular activity mission, and that applying the absorbent to PLSS applications can simplify the ventilation loop.

Kast, Timothy P.↗
NASA NTRS1991

Metal oxide absorbents for regenerative carbon dioxide and water vapor removal for advanced portable life support systems

Recent studies of Allied Signal metal oxide based absorbents demonstrated that these absorbents offer a unique capability to regeneratively remove both metabolic carbon dioxide and water vapor from breathing air; previously, metal oxides were considered only for the removal of CO2. The concurrent removal of CO2 and H2O vapor can simplify the astronaut Portable Life Support System (PLSS) by combining the CO2 and humidity control functions into one regenerative component. The use of metal oxide absorbents for removal of both CO2 ad H2O vapor in the PLSS is the focus of an ongoing program. The full scale Metal Oxide Carbon dioxide and Humidity Remover (MOCHR) and regeneration unit is described.

Hart, Joan M.↗
NASA NTRS1991

Comparison of metal oxide absorbents for regenerative carbon dioxide and water vapor removal for advanced portable life support systems

Metal-oxide absorbents (MOAs) have a demonstrated capability for removal of both metabolic CO2 and H2O from breathing atmospheres, simplifying portable life support system (PLSS) design and affording reversible operation for regeneration. Attention is presently given to the comparative performance levels obtained by silver-oxide-based and silver/zinc-oxide-based systems, which also proved to be longer-lasting than the silver oxide-absorber system. The silver/zinc system is found to substantially simplify the ventilation loop of a prospective Space Station Freedom PLSS.

Stonesifer, Greg T.↗
NASA NTRS1992

Composite materials for the extravehicular mobility unit

The extravehicular mobility unit (EMU), commonly known as the astronaut space suit assembly (SSA) and primary life support system (PLSS), has evolved through the years to incorporate new and innovative materials in order to meet the demands of the space environment. The space shuttle program which is seeing an increasing level of extravehicular activity (EVA), also called space walks, along with interest in an EMU for Lunar-Mars missions means even more demanding conditions are being placed on the suit and PLSS. The project for this NASA-ASEE Summer Program was to investigate new materials for these applications. The focus was to emphasize the use of composite materials for every component of the EMU to enhance the properties while reducing the total weight of the EMU. To accomplish this, development of new materials called fullerene reinforced materials (FRM's) was initiated. Fullerenes are carbon molecules which when added to a material significantly reduce the weight of that material. The Faculty Fellow worked directly on the development of the fullerene reinforced materials. A chamber for fullerene production was designed and assembled and first generation samples were processed. He also supervised with the JSC Colleague, a study of composite materials for the EMU conducted by the student participant in the NASA-ASEE Program, Hector Tello a Rice University graduate student, and by a NASA Aerospace Technologist (Materials Engineer) Evelyne Orndoff, in the Systems Engineering Analysis Office (EC7), also a Rice University graduate student. Hector Tello conducted a study on beryllium and Be alloys and initiated a study of carbon and glass reinforced composites for space applications. Evelyne Orndoff compiled an inventory of the materials on the SSA. Ms. Orndoff also reviewed SSA material requirements and cited aspects of the SSA design where composite materials might be further considered. Hector Tello spent part of his time investigating the solar radiation sensitivity of anodic coatings. This project was directed toward the effects of ultra-violet radiation on high emissivity anodic coatings. The work of both Evelyne Orndoff and Hector Tello is of interest to the Engineering Directorate at NASA/JSC and is also directed toward their research as Rice University graduate students.

Barrera, Enrique V.↗
NASA NTRS1994

The embodiment design of the heat rejection system for the portable life support system

The Portable Life Support System (PLSS) provides a suitable environment for the astronaut in the Extravehicular Mobility Unit (EMU), and the heat rejection system controls the thermal conditions in the space suit. The current PLSS sublimates water to the space environment; therefore, the system loses mass. Since additional supplies of fluid must be available on the Space Shuttle, NASA desires a closed heat rejecting system. This document presents the embodiment design for a radiative plate heat rejection system without mass transfer to the space environment. This project will transform the concept variant into a design complete with material selection, dimensions of the system, layouts of the heat rejection system, suggestions for manufacturing, and financial viability.

Stuckwisch, Sue↗
NASA NTRS2004

New Lithium-ion Polymer Battery for the Extravehicular Mobility Unit Suit

The Extravehicular Mobility Unit (EMU) suit currently has a silver-zinc battery that is 20.5 V and 45 Ah capacity. The EMU's portable life support system (PLSS) will draw power from the battery during the entire period of an EVA. Due to the disadvantages of using the silver-zinc battery in terms of cost and performance, a new high energy density battery is being developed for future use, The new battery (Lithium-ion battery or LIB) will consist of Li-ion polymer cells that will provide power to the EMU suit. The battery design consists of five 8 Ah cells in parallel to form a single module of 40 Ah and five such modules will be placed in series to give a 20.5 V, 40 Ah battery. Charging will be accomplished on the Shuttle or Station using the new LIB charger or the existing ALPS (Air Lock Power Supply) charger. The LIB delivers a maximum of 3.8 A on the average, for seven continuous hours, at voltages ranging from 20.5 V to 16.0 V and it should be capable of supporting transient pulses during start up and once every hour to support PLSS fan and pump operation. Figure 1 shows the placement of the battery in the backpack area of the EMU suit. The battery and cells will undergo testing under different conditions to understand its performance and safety characteristics.

Jeevarajan, J. A.↗
NASA NTRS2006

Rapid Cycling CO2 and H2O Removal System for EMU

NASA's planned future missions set stringent demands on the design of the Portable Life Support Systems (PLSS), requiring dramatic reductions in weight, decreased reliance on supplies and greater flexibility on the types of missions. Use of regenerable systems that reduce weight and volume of the EMU is of critical importance to NASA, both for low orbit operations and for long duration manned missions. The CO2 and humidity control unit in the existing PLSS design is relatively large, since it has to remove 8 hours worth of CO2. If the sorbent regeneration can be carried out during the extravehicular activity (EVA) with a relatively high regeneration frequency, the size of the sorbent canister and weight can be significantly reduced. TDA Research, Inc. (TDA) is developing a compact, regenerable sorbent-based system to control CO2 and humidity in the space suit ventilation loop. The sorbent can be regenerated using space vacuum during the EVA, eliminating all duration-limiting elements in the life support system. This paper summarizes the results of the sorbent development and testing, and evaluation efforts. The results of a preliminary system analysis are also included, showing the size and volume reductions provided by the new system.

Alptekin, Gokhan↗
NASA NTRS2007

Demonstration of Metabolic Heat Regenerated Temperature Swing Adsorption Technology

Patent-pending Metabolic heat regenerated Temperature Swing Adsorption (MTSA) technology is currently being investigated for removal and rejection of CO2 and heat from a Portable Life Support System (PLSS) to a Martian environment. The metabolically-produced CO2 present in the vent loop gas is collected using a CO2 selective adsorbent that has been cooled via a heat exchanger to near CO2 sublimation temperatures (approx.195K) with liquid CO2 obtained from Martian resources. Once the adsorbent is fully loaded, fresh warm, moist vent loop (approx.300K) is used to heat the adsorbent via another heat exchanger. The adsorbent will then reject the collected CO2 to the Martian ambient. Two beds are used to achieve continuous CO2 removal by cycling between the cold and warm conditions for adsorbent loading and regeneration, respectively. Small experiments have already been completed to show that an adsorbent can be cycled between these PLSS operating conditions to provide adequate conditions for CO2 removal from a simulated vent loop. One of the remaining technical challenges is extracting enough heat from the vent loop to warm the adsorbent in an appreciable time frame to meet the required adsorb/desorb cycle. The other key technical aspect of the technology is employing liquid CO2 to achieve the appropriate cooling. A technology demonstrator has been designed, built and tested to investigate the feasibility of 1) warming the adsorbent using the moist vent loop, 2) cooling the adsorbent using liquid CO2, and 3) using these two methods in conjunction to successfully remove CO2 from a vent loop and reject it to Mars ambient. Both analytical and numerical methods were used to perform design calculations and trades. The demonstrator was built and tested. The design analysis and testing results are presented along with recommendations for future development required to increase the maturity of the technology.

Paul, Heather↗
NASA NTRS2007

Development of a Rapid Cycling CO2 and H2O Removal Sorbent

The National Aeronautics and Space Administration (NASA) planned future missions set stringent demands on the design of the Portable Life Support System (PLSS), requiring dramatic reductions in weight, decreased reliance on supplies and greater flexibility on the types of missions. Use of regenerable systems that reduce weight and volume of the Extravehicular Mobility Unit (EMU) is of critical importance to NASA, both for low orbit operations and for long duration manned missions. The carbon dioxide and humidity control unit in the existing PLSS design is relatively large, since it has to remove and store eight hours worth of carbon dioxide (CO2). If the sorbent regeneration can be carried out during the Extravehicular Activity (EVA) with a relatively high regeneration frequency, the size of the sorbent canister and weight can be significantly reduced. TDA Research, Inc. is developing compact, regenerable sorbent materials to control CO2 and humidity in the space suit ventilation loop. The sorbent can be regenerated using space vacuum during the EVA, eliminating all CO2 and humidity duration-limiting elements in the life support system. The material also has applications in other areas of space exploration including long duration exploration missions requiring regenerable technologies and possibly the Crew Exploration Vehicle (CEV) spacecraft. This paper summarizes the results of the sorbent development, testing, and evaluation efforts to date.

Alptekin, Gokhan↗
NASA NTRS2007

Collaborative Human Engineering Work in Space Exploration Extravehicular Activities (EVA)

A viewgraph presentation on extravehicular activities in space exploration in collaboration with other NASA centers, industries, and universities is shown. The topics include: 1) Concept of Operations for Future EVA activities; 2) Desert Research and Technology Studies (RATS); 3) Advanced EVA Walkback Test; 4) Walkback Subjective Results; 5) Integrated Suit Test 1; 6) Portable Life Support Subsystem (PLSS); 7) Flex PLSS Design Process; and 8) EVA Information System; 9)

DeSantis, Lena↗
NASA NTRS2007

Lithium Iron Phosphate Cell Performance Evaluations for Lunar Extravehicular Activities

Lithium-ion battery cells are being evaluated for their ability to provide primary power and energy storage for NASA s future Exploration missions. These missions include the Orion Crew Exploration Vehicle, the Ares Crew Launch Vehicle Upper Stage, Extravehicular Activities (EVA, the advanced space suit), the Lunar Surface Ascent Module (LSAM), and the Lunar Precursor and Robotic Program (LPRP), among others. Each of these missions will have different battery requirements. Some missions may require high specific energy and high energy density, while others may require high specific power, wide operating temperature ranges, or a combination of several of these attributes. EVA is one type of mission that presents particular challenges for today s existing power sources. The Portable Life Support System (PLSS) for the advanced Lunar surface suit will be carried on an astronaut s back during eight hour long sorties, requiring a lightweight power source. Lunar sorties are also expected to occur during varying environmental conditions, requiring a power source that can operate over a wide range of temperatures. Concepts for Lunar EVAs include a primary power source for the PLSS that can recharge rapidly. A power source that can charge quickly could enable a lighter weight system that can be recharged while an astronaut is taking a short break. Preliminary results of Al23 Ml 26650 lithium iron phosphate cell performance evaluations for an advanced Lunar surface space suit application are discussed in this paper. These cells exhibit excellent recharge rate capability, however, their specific energy and energy density is lower than typical lithium-ion cell chemistries. The cells were evaluated for their ability to provide primary power in a lightweight battery system while operating at multiple temperatures.

Reid, Concha↗
NASA NTRS2008

Helmet Exhalation Capture System (HECS) Sizing Evaluation for an Advanced Space Suit Portable Life Support System

As part of NASA s initiative to develop an advanced portable life support system (PLSS), a baseline schematic has been chosen that includes gaseous oxygen in a closed circuit ventilation configuration. Supply oxygen enters the suit at the back of the helmet and return gases pass over the astronaut s body to be extracted at the astronaut s wrists and ankles through the liquid cooling and ventilation garment (LCVG). The extracted gases are then treated using a rapid cycling amine (RCA) system for carbon dioxide and water removal and activated carbon for trace gas removal before being mixed with makeup oxygen and reintroduced into the helmet. Thermal control is provided by a suit water membrane evaporator (SWME). As an extension of the original schematic development, NASA evaluated several Helmet Exhalation Capture System (HECS) configurations as alternatives to the baseline. The HECS configurations incorporate the use of full contact masks or non-contact masks to reduce flow requirements within the PLSS ventilation subsystem. The primary scope of this study was to compare the alternatives based on mass and volume considerations; however other design issues were also briefly investigated. This paper summarizes the results of this sizing analysis task.

Paul, Heather L.↗
NASA NTRS2008

Spacesuit Water Membrane Evaporator Development for Lunar Missions

For future lunar extra-vehicular activities (EVA), one method under consideration for rejecting crew and electronics heat involves evaporating water through a hydrophobic, porous Teflon membrane. A Spacesuit Water Membrane Evaporator (SWME) prototype using the Teflon membrane was tested successfully by Ungar and Thomas (2001) with predicted performance matching test data well. The above referenced work laid the foundation for the design of the SWME development unit, which is being considered for service in the Constellation System Spacesuit Element (CSSE) Portable Life Support System (PLSS). Multiple PLSS SWME configurations were considered on the basis of thermal performance, mass, volume, and performance and manufacturing risk. All configurations were a variation of an alternating concentric water and vapor channel configuration or a stack of alternating rectangular water and vapor channels. Supporting thermal performance trades mapped maximum SWME heat rejection as a function of water channel thickness, vapor channel thickness, channel length, number of water channels, porosity of the membrane structural support, and backpressure valve throat area. Preliminary designs of each configuration were developed to determine total mass and volume as well as to understand manufacturing issues. Review of configurations led to the selection of a concentric annulus configuration that meets the requirements of 800 watts (W) of heat rejection. Detailed design of the SWME development unit will be followed by fabrication of a prototype test unit, with thermal testing expected to start in 2008.

Vogel, Matt R.↗
NASA NTRS2008

Results of the Trace Contaminant Control Trade Study for Space Suit Life Support Development

As the United States plans to return astronauts to the moon, designing the most effective and efficient life support systems is of extreme importance. The trace contaminant control system (TCCS) will be located within the Portable Life Support System (PLSS) of the Constellation Space Suit Element (CSSE), and is responsible for removing contaminants, which at increased levels can be hazardous to a crewmember s health. These contaminants come from several sources including metabolic production of the crewmember (breathing, sweating, etc.) and offgassing of the space suit material layers. This paper summarizes the results of a trade study that investigated TCC technologies used in NASA space suits and vehicles as well as commercial and academic applications, to identify the best technology options for the CSSE PLSS. The trade study also looked at the feasibility of regeneration of TCC technologies, specifically to determine the viability of vacuum regeneration for on-back, realtime EVA.

Jennings, Mallory A.↗
NASA NTRS2008

Development of a Compact Efficient Cooling Pump for Space Suit Life Support Systems

With the increasing demands placed on extravehicular activity (EVA) for the International Space Station (ISS) assembly and maintenance, along with planned lunar and Martian missions, the need for increased human productivity and capability becomes ever more critical. This is most readily achieved by reduction in space suit weight and volume, and increased hardware reliability, durability, and operating lifetime. Considerable progress has been made with each successive generation of space suit design; from the Apollo A7L suit, to the current Shuttle Extravehicular Mobile Unit (EMU) suit, and the next generation Constellation Space Suit Element (CSSE). However, one area of space suit design which has continued to lag is the fluid pump used to drive the water cooling loop of the Primary Life Support System (PLSS). The two main types of fluid pumps typically used in space applications are rotodynamic pumps (pumping is achieved through a rotary vaned impeller) and displacement pumps (which includes rotary and diaphragm pumps). The rotating and moving parts found in the pumps and electric motor add significantly to the susceptibility to wear and friction, thermal mismatch, and complexity of the pumps. Electric motor-driven pumps capable of achieving high operational reliability are necessarily large, heavy, and energy inefficient. This report describes a development effort conducted for NASA by Lynntech, Inc., who recently demonstrated the feasibility of an electrochemically-driven fluid cooling pump. With no electric motor and minimal lightweight components, an electrochemically-driven pump is expected to be significantly smaller, lighter and achieve a longer life time than conventional rotodynamic and displacement pumps. By employing sulfonated polystyrene-based proton exchange membranes, rather than conventional Nafion membranes, a significant reduction in the actuator power consumption was demonstrated. It was also demonstrated that these membranes possess the necessary mechanical strength, durability, and temperature range for long life space operation. The preliminary design for a Phase II prototype pump compares very favorably to the fluid cooling pumps currently used in space suit portable life support systems (PLSS). Characteristics of the electrochemically-driven pump are described and the benefits of the technology as a replacement for electric motor pumps in mechanically pumped single-phase fluid loops (MPFLs) is discussed.

vanBoeyen, Roger W.↗
NASA NTRS2009

Lunar Portable Life Support System Heat Rejection Study

Performing extravehicular activity (EVA) at various locations of the lunar surface presents thermal challenges that exceed those experienced in space flight to date. The lunar Portable Life Support System (PLSS) cooling unit must maintain thermal conditions within the space suit and reject heat loads generated by the crewmember and the PLSS equipment. The amount of cooling required varies based on the lunar location and terrain due to the heat transferred between the suit and its surroundings. A study has been completed which investigated the resources required to provide cooling under various lunar conditions, assuming three different thermal technology categories: 1. Spacesuit Water Membrane Evaporator (SWME) 2. Subcooled Phase Change Material (SPCM) 3. Radiators with and without heat pumps Results from the study are presented that show mass and power impacts on the cooling system as a function of the location and terrain on the lunar surface. Resources (cooling equipment mass and consumables) are greater at the equator and inside sunlit craters due to the additional heat loads on the cooling system. While radiator and SPCM technologies require minimal consumables, they come with carry-weight penalties and have limitations. A wider investigation is recommended to determine if these penalties and limitations are offset by the savings in consumables.

Conger, Bruce↗