The possibility of substituting helium for nitrogen in the cabins of spacecraft
Helium substitution for nitrogen in spacecraft cabins
SPACE CABIN ATMOSPHERE↗
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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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Results of experiments carried out in satellites
Biological & physiological investigations carried out on dogs in pressurized space cabin during space flight
DOG↗
EVA-Compatible Microbial Swab Tool
When we send humans to search for life on Mars, we'll need to know what we brought with us versus what may already be there. To ensure our crewed spacecraft meet planetary protection requirements—and to protect our science from human contamination—we'll need to know whether micro-organisms are leaking/venting from our ships and spacesuits. This is easily done by swabbing external vents and suit surfaces for analysis, but requires a specialized tool for the job. Engineers at the National Aeronautics and Space Administration (NASA) recently developed an Extravehicular Activity (EVA)-compatible swab tool that can be used to sample current space suits and life support systems. Data collected now will influence Mars life support and EVA hardware early in the planning process, before design changes become difficult and expensive.NASA’s EVA swab tool pairs a Space Shuttle-era tool handle with a commercially available swab tip mounted into a custom-designed end effector. A glove-compatible release mechanism allows the handle to quickly switch between swab tips, much like a shaving razor handle can snap onto a disposable blade cartridge. Swab tips are stowed inside individual sterile containers, each fitted with a microbial filter that allows the container to equalize atmospheric pressure, but prevents cabin contaminants from rushing into the container when passing from the EVA environment into a pressurized cabin. A bank of containers arrayed inside a tool caddy allows up to six individual samples to be collected during a given spacewalk.NASA plans to use the tool in 2016 to collect samples from various spacesuits during ground testing to determine what (if any) human-borne microbial contamination leaks from the suit under simulated thermal vacuum conditions. Next, the tool will be used on board the International Space Station to assess the types of microbial contaminants found on external environmental control and life support system vents. Data will support advanced EVA and life support system maturation studies, helping to answer questions such as “how close can an EVA-suited crew member approach an area of scientific interest without compromising the science?”
Rucker, Michelle A.↗
In situ measurements of particulate number density and size distribution from an aircraft
Two different commercial particulate measuring instruments were flown aboard the NASA Convair 990. A condensation nuclei monitor was utilized to measure particles larger than approximately 0.003 micron in diameter. A specially designed pressurization system was used with this monitor at cabin altitude pressure. A near-forward light scattering counter was used to measure the number and size distribution particles in the size range from 0.5 to 5 microns and greater in diameter. Considerable variation in number density was encountered for both classes of particles at the test altitudes ranging from 5 to 12 km. Presence of clouds could be detected by the light scattering instrument because large numbers of particles would then be registered by the instrument, especially in the size range above 5.0 microns in diameter.
Briehl, D.↗
Evaluation of Heritage Hardware for Use in Cabin Environments with Reduced Pressure and Increased Oxygen Concentration
Explore the source record for details and available documents.
Morgan B Abney↗
Evaluation of Heritage Hardware for Use in Cabin Environments with Reduced Pressure and Increased Oxygen Concentration
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Morgan B Abney↗
International Space Station (ISS) Gas Logistics Planning in the Post Shuttle Era
Over its life the International Space Station (ISS) has received gas (nitrogen, oxygen, and air) from various sources. Nitrogen and oxygen are used in the cabin to maintain total pressure and oxygen partial pressures within the cabin. Plumbed nitrogen is also required to support on-board experiments and medical equipment. Additionally, plumbed oxygen is required to support medical equipment as well as emergency masks and most importantly EVA support. Gas are supplied to ISS with various methods and vehicles. Vehicles like the Progress and ATV deliver nitrogen (both as a pure gas and as air) and oxygen via direct releases into the cabin. An additional source of nitrogen and oxygen is via tanks on the ISS Airlock. The Airlock nitrogen and oxygen tanks can deliver to various users via pressurized systems that run throughout the ISS except for the Russian segment. Metabolic oxygen is mainly supplied via cabin release from the Elektron and Oxygen Generator Assembly (OGA), which are water electrolyzers. As a backup system, oxygen candles (Solid Fuel Oxygen Generators-SFOGs) supply oxygen to the cabin as well. In the past, a major source of nitrogen and oxygen has come from the Shuttle via both direct delivery to the cabin as well as to recharge the ISS Airlock tanks. To replace the Shuttle capability to recharge the ISS Airlock tanks, a new system was developed called Nitrogen/Oxygen Recharge System (NORS). NIORS consists of high pressure (7000 psi) tanks which recharge the ISS Airlock tanks via a blowdown fill for both nitrogen and oxygen. NORS tanks can be brought up on most logistics vehicles such as the HTV, COTS, and ATV. A proper balance must be maintained to insure sufficient gas resources are available on-orbit so that all users have the required gases via the proper delivery method (cabin and/or plumbed).
Leonard, Daniel J.↗
Operational Philosophy Concerning Manned Spacecraft Cabin Leaks
The last thirty years have seen the Space Shuttle as the prime United States spacecraft for manned spaceflight missions. Many lessons have been learned about spacecraft design and operation throughout these years. Over the next few decades, a large increase of manned spaceflight in the commercial sector is expected. This will result in the exposure of commercial crews and passengers to many of the same risks crews of the Space Shuttle have encountered. One of the more dire situations that can be encountered is the loss of pressure in the habitable volume of the spacecraft during on orbit operations. This is referred to as a cabin leak. This paper seeks to establish a general cabin leak response philosophy with the intent of educating future spacecraft designers and operators. After establishing a relative definition for a cabin leak, the paper covers general descriptions of detection equipment, detection methods, and general operational methods for management of a cabin leak. Subsequently, all these items are addressed from the perspective of the Space Shuttle Program, as this will be of the most value to future spacecraft due to similar operating profiles. Emphasis here is placed upon why and how these methods and philosophies have evolved to meet the Space Shuttle s needs. This includes the core ideas of: considerations of maintaining higher cabin pressures vs. lower cabin pressures, the pros and cons of a system designed to feed the leak with gas from pressurized tanks vs. using pressure suits to protect against lower cabin pressures, timeline and consumables constraints, re-entry considerations with leaks of unknown origin, and the impact the International Space Station (ISS) has had to the standard Space Shuttle cabin leak response philosophy. This last item in itself includes: procedural management differences, hardware considerations, additional capabilities due to the presence of the ISS and its resource, and ISS docking/undocking considerations with a cabin leak occurring. The paper also offers a look at how different equipment configurations on future spacecraft impact the previously defined cabin leak operational philosophy and includes additional operational methods and considerations that result due to various configurations. The intent is to showcase these various considerations and highlight the variability they allow. The paper concludes with a selection of the author s personal observations from a spacecraft operator's point of view and recommendations with the goal of improving the design and operations of future spacecraft.
DeSimpelaere, Edward↗
Development of a Contingency Gas Analyzer for the Orion Crew Exploration Vehicle
NASA's experience with electrochemical sensors in a hand-held toxic gas monitor serves as a basis for the development of a fixed on-board instrument, the Contingency Gas Analyzer (CGA), for monitoring selected toxic combustion products as well as oxygen and carbon dioxide on the Orion Crew Exploration Vehicle (CEV). Oxygen and carbon dioxide are major components of the cabin environment and accurate measurement of these compounds is critical to maintaining a safe working environment for the crew. Fire or thermal degradation events may produce harmful levels of toxic products, including carbon monoxide (CO), hydrogen cyanide (HCN), and hydrogen chloride (HCl) in the environment. These three components, besides being toxic in their own right, can serve as surrogates for a panoply of hazardous combustion products. On orbit monitoring of these surrogates provides for crew health and safety by indicating the presence of toxic combustion products in the environment before, during and after combustion or thermal degradation events. Issues identified in previous NASA experiences mandate hardening the instrument and components to endure the mechanical and operational stresses of the CEV environment while maintaining high analytical fidelity. Specific functional challenges involve protecting the sensors from various anticipated events- such as rapid pressure changes, low cabin pressures, and extreme vibration/shock exposures- and extending the sensor lifetime and calibration periods far beyond the current state of the art to avoid the need for on-orbit calibration. This paper focuses on lessons learned from the earlier NASA hardware, current testing results, and engineering solutions to the identified problems. Of particular focus will be the means for protecting the sensors, addressing well known cross-sensitivity issues and the efficacy of a novel self monitoring mechanism for extending sensor calibration periods.
Niu, Bill↗
Orion ECLSS/Suit System - Ambient Pressure Integrated Suit Test
The Ambient Pressure Integrated Suit Test (APIST) phase of the integrated system testing of the Orion Vehicle Atmosphere Revitalization System (ARS) technology was conducted for the Multipurpose Crew Vehicle (MPCV) Program within the National Aeronautics and Space Administration (NASA) Exploration Systems Mission Directorate. Crew and Thermal Systems Division performed this test in the eleven-foot human-rated vacuum chamber at the NASA Johnson Space Center. This testing is the first phase of suit loop testing to demonstrate the viability of the Environmental Control and Life Support System (ECLSS) being developed for Orion. APIST is the first in a series, which will consist of testing development hardware including the Carbon dioxide and Moisture Removal Amine Swing-bed (CAMRAS) and the air revitalization loop fan with human test subjects in pressure suits at varying suit pressures. Follow-on testing, to be conducted in 2013, will utilize the CAMRAS and a development regulator with human test subjects in pressure suits at varying cabin and suit pressures. This paper will discuss the results and findings of APIST and will also discuss future testing.
Barido, Richard A.↗
Suitport Feasibility: Development and Test of a Suitport and Space Suit for Human Pressurized Space Suit Donning Tests
The suitport concept has been recently implemented as part of the small pressurized lunar rover (Currently the Space Exploration vehicle, or SEV) and the Multi-Mission Space Exploration Vehicle (MMSEV) concept demonstrator vehicle. Suitport replaces or augments the traditional airlock function of a spacecraft by providing a bulkhead opening, capture mechanism, and sealing system to allow ingress and egress of a space suit while the space suit remains outside of the pressurized volume of the spacecraft. This presents significant new opportunities to EVA exploration in both microgravity and surface environments. The suitport concept will enable three main improvements in EVA by providing reductions in: pre-EVA time from hours to less than thirty minutes; airlock consumables; contamination returned to the cabin with the EVA crewmember. To date, the first generation suitport has been tested with mockup suits on the rover cabins and pressurized on a bench top engineering unit. The work on the rover cabin has helped define the operational concepts and timelines, and has demonstrated the potential of suitport to save significant amounts of crew time before and after EVAs. The work with the engineering unit has successfully demonstrated the pressurizable seal concept including the ability to seal after the introduction and removal of contamination to the sealing surfaces. Using this experience, a second generation suitport was designed. This second generation suitport has been tested with a space suit prototype on the second generation MMSEV cabin, and testing is planned using the pressure differentials of the spacecraft. Pressurized testing will be performed using the JSC B32 Chamber B, a human rated vacuum chamber. This test will include human rated suitports, a suitport compatible prototype suit, and chamber modifications. This test will bring these three elements together in the first ever pressurized donning of a rear entry suit through a suitport. This paper presents the design of a human rated second generation suitport, the design of a suit capable of supporting pressurized human donning through a suitport, ambient pressure testing of the suit with the suitport, and modifications to the JSC human rated chamber B to accept a suitport. Design challenges and solutions, as well as compromises required to develop the system, are presented. Initial human testing results are presented.
Boyle, Robert M.↗
Prediction of light aircraft interior sound pressure level from the measured sound power flowing in to the cabin
The validity of the room equation of Crocker and Price (1982) for predicting the cabin interior sound pressure level was experimentally tested using a specially constructed setup for simultaneous measurements of transmitted sound intensity and interior sound pressure levels. Using measured values of the reverberation time and transmitted intensities, the equation was used to predict the space-averaged interior sound pressure level for three different fuselage conditions. The general agreement between the room equation and experimental test data is considered good enough for this equation to be used for preliminary design studies.
Atwal, Mahabir S.↗
In situ measurement of particulate number density and size distribution from an aircraft
Commercial particulate measuring instruments were flown aboard the NASA Convair 990. A condensation nuclei monitor was utilized to measure particles larger than approximately 0.003 micrometers in diameter. A specially designed pressurization system was used with this counter so that the sample could be fed into the monitor at cabin altitude pressure. A near-forward light scattering counter was used to measure the number and size distribution particles in the size range from 0.5 to 5 micrometers and greater in diameter.
Briehl, D.↗
Structure-borne noise estimates for the PTA aircraft
Estimates of the level of in-flight structure-borne noise transmission in the Propfan Test Assessment Aircraft were carried out for the first three blade passage frequencies. The procedure used combined the frequency response functions of wing strain to cabin sound pressure level (SPL) response obtained during ground test with in-flight measured wing strain response data. The estimated cabin average in-flight structure-borne noise levels varied from 64 to 84 dB, with an average level of 74 dB. The estimates showed little dependence on engine/propeller power, flight altitude, or flight Mach number. In general, the bare cabin noise levels decreased with increasing propeller tone, giving rise to a plausible structure-borne noise transmission problem at the higher blade passage tones. Without knowledge of the effects of a high insertion loss side wall treatment on structure-borne noise transmission, no quantitative conclusions could be made.
Unruh, James F.↗
Sizing a Common Habitat for Multiple Environments and Mission Durations
A human mission to Mars and other deep space destinations will require a consistent habitation strategy that applies to disparate environments preferably using multiples of identical hardware. The crew will endure high-g forces during launch, microgravity during transit, and various partial gravities on the destination planet, moon, or asteroid. Habitable volume will likely need to be broken up into smaller modules that do not exceed the capacity of launch vehicles and entry-descent-landing technologies. Though it may be possible to design a different unique, optimized habitat for each environment that the crew may encounter, it is more likely that space agencies and other mission sponsors will only have the resources to develop and produce single multi-use hardware that can be used equally well in all environments, with minimal adaptation by the crew. When sizing habitable volume, mission duration and number of crew become important factors to consider. For example, a pressurized rover cabin may only need to support two crew members for a few days at a time, requiring less volume than a habitat that must support the same number of persons for an entire year. In this study the authors consider constraining factors such as launch vehicle capacity, mission duration, crew size, and Mars lander capacity and study how to divide total pressurized volume, subsystems, equipment, consumables, and supplies into multiple manifests. Preference has been given to solutions that use multiples of identical modules over unique optimized volumes. For example at one extreme, can all the habitat pressure vessels, logistic modules, Mars ascent stage cabins, rover cabins, and airlocks be constructed from multiples of the same small-diameter cylindrical modules? On the other extreme, can logistics, habitation volume, mobility, all be enclosed in a single monolithic volume habitat design? Though there may be advantages and disadvantages to either extreme, the conclusion of this study is that most functions can be distilled into two sizes for hardware: multiples of large diameter modules that generally stay in one place, and multiples of smaller volume cabins that can be moved around or function as cockpits for ascent stages, support vehicles, rovers, airlocks, and logistics delivery.
Howe, A Scott↗
Porous media matric potential and water content measurements during parabolic flight
Control of water and air in the root zone of plants remains a challenge in the microgravity environment of space. Due to limited flight opportunities, research aimed at resolving microgravity porous media fluid dynamics must often be conducted on Earth. The NASA KC-135 reduced gravity flight program offers an opportunity for Earth-based researchers to study physical processes in a variable gravity environment. The objectives of this study were to obtain measurements of water content and matric potential during the parabolic profile flown by the KC-135 aircraft. The flight profile provided 20-25 s of microgravity at the top of the parabola, while pulling 1.8 g at the bottom. The soil moisture sensors (Temperature and Moisture Acquisition System: Orbital Technologies, Madison, WI) used a heat-pulse method to indirectly estimate water content from heat dissipation. Tensiometers were constructed using a stainless steel porous cup with a pressure transducer and were used to measure the matric potential of the medium. The two types of sensors were placed at different depths in a substrate compartment filled with 1-2 mm Turface (calcined clay). The ability of the heat-pulse sensors to monitor overall changes in water content in the substrate compartment decreased with water content. Differences in measured water content data recorded at 0, 1, and 1.8 g were not significant. Tensiometer readings tracked pressure differences due to the hydrostatic force changes with variable gravity. The readings may have been affected by changes in cabin air pressure that occurred during each parabola. Tensiometer porous membrane conductivity (function of pore size) and fluid volume both influence response time. Porous media sample height and water content influence time-to-equilibrium, where shorter samples and higher water content achieve faster equilibrium. Further testing is needed to develop these sensors for space flight applications.
Parabolic Flight↗
Preliminary structural evaluation and design of the HL-20
Several concepts have been proposed to meet the requirements of a Personnel Launch System. A lifting body concept, the HL-20, was designed at NASA Langley Research Center. A structural analysis of a proposed HL-20 configuration with a cylindrical pressurized crew cabin is presented in this paper. Loads for the vehicle are assembled from mission loading conditions such as abort, on-orbit pressurization, blast overpressure, aerodynamic maneuver, and touchdown. The critical loading conditions are identified and resultant loads mapped onto the structure in order to review the effects of the mission loading conditions. The HL-20 structural concept is sized for the mission loads and the resulting structural weights are calculated.
Bush, Lance B.↗
Suitport Feasibility - Development and Test of a Suitport and Space Suit for Human Pressurized Space Suit Donning Tests
The suitport concept has been recently implemented as part of the small pressurized lunar rover (Currently the Space Exploration vehicle, or SEV) and the Multi-Mission Space Exploration Vehicle (MMSEV) concept demonstrator vehicle. Suitport replaces or augments the traditional airlock function of a spacecraft by providing a bulkhead opening, capture mechanism, and sealing system to allow ingress and egress of a spacesuit while the spacesuit remains outside of the pressurized volume of the spacecraft. This presents significant new opportunities to EVA exploration in both microgravity and surface environments. The suitport concept will enable three main improvements in EVA by providing reductions in: pre-EVA time from hours to less than thirty minutes; airlock consumables; contamination returned to the cabin with the EVA crewmember. To date, the first generation suitport has been tested with mockup suits on the rover cabins and pressurized on a bench top engineering unit. The work on the rover cabin has helped define the operational concepts and timelines, and has demonstrated the potential of suitport to save significant amounts of crew time before and after EVAs. The work with the engineering unit has successfully demonstrated the pressurizable seal concept including the ability to seal after the introduction and removal of contamination to the sealing surfaces. Using this experience, a second generation suitport was designed. This second generation suitport has been tested with a spacesuit prototype using the pressure differentials of the spacecraft. This test will be performed using the JSC B32 Chamber B, a human rated vacuum chamber. This test will include human rated suitports, the suitport compatible prototype suit, and chamber modifications. This test will bring these three elements together in the first ever pressurized donning of a rear entry suit through a suitport. This paper presents design of a human rated second generation suitport, modifications to the JSC human rated chamber B to accept a suitport, and a compatible space suit to support pressurized human donning of the pressurized suit through a suitport. Design challenges and solutions and compromises required to develop the system are presented. Initial human testing results are presented.
Boyle, Robert M.↗