History of NASA's Determination of Offgassed Products (Test 7)

NASA's Determination of Offgassed Products (Test 7) from materials and assembled articles for spaceflight has evolved since the Apollo program for over 50 years to meet various habitable spacecraft nonmetallic programmatic requirements. Now mandated by NASA STD-6016A, Standard Materials and Processes Requirements for Spacecraft, all nonmetallic materials used in habitable flight compartments, with the exception of ceramics, metal oxides, inorganic glasses, and materials used in sealed containers, must meet the offgassing requirements in NASA-STD-6001B Test 7. This manuscript presents the history of Test 7, beginning with the Apollo spacecraft nonmetallic materials selection guidelines and test requirements in 1967, in which tests were performed in mostly oxygen atmospheres. It progresses through Skylab, Space Shuttle, International Space Station nonmetals testing, and acceptance requirements with milder test environments. This review of the history of Test 7 presents the reader with a perspective on the development and changes undergone since inception to the present. Related NASA standard tests (some now former, discontinued, combined, or supplemental) including Test 6, Odor Assessment, Test 16, Determination of Offgassed Products from Assembled Articles, and Test 12, Total Spacecraft Cabin Offgassing, are discussed in contex

Selected Parametric Effects on Materials Flammability Limits

NASA-STD-(I)-6001B Test 1 is currently used to evaluate the flammability of materials intended for use in habitable environments of U.S. spacecraft. The method is a pass/fail upward flame propagation test conducted in the worst case configuration, which is defined as a combination of a material s thickness, test pressure, oxygen concentration, and temperature that make the material most flammable. Although simple parametric effects may be intuitive (such as increasing oxygen concentrations resulting in increased flammability), combinations of multi-parameter effects could be more complex. In addition, there are a variety of material configurations used in spacecraft. Such configurations could include, for example, exposed free edges where fire propagation may be different when compared to configurations commonly employed in standard testing. Studies involving combined oxygen concentration, pressure, and temperature on flammability limits have been conducted and are summarized in this paper. Additional effects on flammability limits of a material s thickness, mode of ignition, burn-length criteria, and exposed edges are presented. The information obtained will allow proper selection of ground flammability test conditions, support further studies comparing flammability in 1-g with microgravity and reduced gravity environments, and contribute to persuasive scientific cases for rigorous space system fire risk assessments

Oxygen Partial Pressure and Oxygen Concentration Flammability: Can They Be Correlated?

NASA possesses a large quantity of flammability data performed in ISS airlock (30% Oxygen 526mmHg) and ISS cabin (24.1% Oxygen 760 mmHg) conditions. As new programs develop, other oxygen and pressure conditions emerge. In an effort to apply existing data, the question arises: Do equivalent oxygen partial pressures perform similarly with respect to flammability? This paper evaluates how material flammability performance is impacted from both the Maximum Oxygen Concentration (MOC) and Maximum Total Pressures (MTP) perspectives. From these studies, oxygen partial pressures can be compared for both the MOC and MTP methods to determine the role of partial pressure in material flammability. This evaluation also assesses the influence of other variables on flammability performance. The findings presented in this paper suggest flammability is more dependent on oxygen concentration than equivalent partial pressure

History of NASA's Determination of Offgassed Products (Test 7)

NASA's Determination of Offgassed Products (Test 7) from materials and assembled articles for spaceflight has evolved since the Apollo program for over 50 years to meet various habitable spacecraft non-metallic programmatic requirements. Now mandated by NASA-STD-6016B Standard Materials and Processes Requirements for Spacecraft, all nonmetallic materials used in habitable flight compartments,with the exception of ceramics, metal oxides, inorganic glasses, and materials used in sealed containers must meet the offgassing requirements of in NASA-STD-6001B Test 7. This manuscript presents the history of Test 7 beginning with the Apollo spacecraft nonmetallic materials selection guidelines and test requirements in 196

Elaborated Odor Test for Extended Exposure

Concerns were raised when incidental exposure to a proprietary bonding material revealed the material had an irritating odor. The NASA-STD-6001B document describes a supplemental test method option for programs to evaluate materials with odor concerns (Test 6, Odor Assessment). In addition to the supplemental standard odor assessment with less than 10 seconds of exposure, the NASA White Sands Test Facility (WSTF) Materials Flight Acceptance Testing section was requested to perform an odor test with an extended duration to evaluate effects of an extended exposure and to more closely simulate realistic exposure scenarios. With approval from the NASA Johnson Space Center Industrial Hygienist, WSTF developed a 15-minute odor test method. WSTF performed this extended-duration odor test to evaluate the odor and physical effects of the bonding material configured between two aluminum plates, after the safety of the gas was verified via toxicity analysis per NASA-STD-6001B Test 7, Determination of Offgassed Products. During extended-duration testing, odor panel members were arranged near the test material in a small room with the air handlers and doors closed to minimize dilution. The odor panel members wafted gas toward themselves and recorded their individual assessments of odor and physical effects at various intervals during the 15-minute exposure and posttest. A posttest interview was conducted to obtain further information. Testing was effective in providing data for comparison and selection of an optimal offgassing and odor containment configuration. The developed test method for extended exposure is proposed as a useful tool for further evaluating materials with identified odors of concern if continued use of the material is anticipated

Characterization of Laptop Fires in Spacecraft

An accidental fire involving the Lithium-Ion (Li-ion) battery in a laptop computer is one of the most likely fire scenarios on-board a spacecraft. These fires can occur from a defect in the battery that worsens with time, over-charging the battery and leading to failure or accidental damage caused by thermal runaway. While this is a relatively likely fire scenario, very little is known about the how a laptop computer fire would impact a sealed spacecraft. The heat release would likely cause a pressure rise, possibly exceeding the pressure limit of the vehicle and causing a relief valve to open. The combustion products from the fire could pose a short-term and long-term health hazard to the crew and the fire itself could cause injury to the crew and damage to the spacecraft. Despite the hazard posed by a laptop fire, there is little quantitative data on the fire size, heat release and toxic product formation. This paper presents the results of initial attempts to quantify the fire resulting from a failed laptop fire tested at the NASA White Sands Test Facility (WSTF). The data from the testing is useful to attempt to determine the fire size and characteristics such as maximum heat release rate, total heat release, maximum temperatures and fire duration are determined. Using existing models and correlations for fires, the measured fire characteristics are extrapolated to laptop fires on a vehicle the approximate size of the Orion spacecraft

Cutinase activity in supercritical and organic media: water activity, solvation and acid–base effects

We performed a comparative study on the activity of Fusarium solani pisi cutinase immobilized on zeolites NaA and NaY, in n-hexane, acetonitrile, supercritical ethane (sc-ethane) and sc-CO2, at two different water activity (aW) values set by salt hydrate pairs in situ and at acid–base conditions fixed with solid-state buffers of aqueous pKa between 4.3 and 10.6. The reaction studied was the transesterification of vinyl butyrate by (R,S)-2-phenyl-1-propanol. The transesterification activity of cutinase was highest and similar in sc-ethane and in n-hexane,about one order of magnitude lower in acetonitrile and even lower in sc-CO2. Activity coefficients (γ) generated for the two substrates indicated that they were better solvated in acetonitrile and thus less available for binding at the active site than in the other three solvents. γ data also suggested higher reaction rates in sc-ethane than in n-hexane, as observed, and provided evidence for a direct negative effect of sc-CO2 on enzyme activity. Manipulation of the acid–base conditions of the media did not afford any improvement of the initial rates of transesterification relative to the blanks (no added acid–base buffer, only salt hydrate pair), except in the case of cutinase immobilized on zeolite NaA in sc-ethane at aW = 0.7. The poor performance of the blank in this case and the great improvement observed in the presence of a basic buffer suggest a deleterious acidic effect in the medium which, an experiment without additives confirmed, was not due to the known acidic character of the salt hydrate pair used to set aW = 0.7. In acetonitrile, increasing aW was accompanied by a decrease in initial rates of transesterification, unlike in the other solvents. There was considerable hydrolysis in acetonitrile, where initial rates of hydrolysis increased about 20-fold from aW = 0.2 to 0.7. Hydrolysis was less pronounced in sc-ethane and in n-hexane, and only at aW = 0.7, and in sc-CO2 butyric acid was detected only at very long reaction times, in agreement with a generally low catalytic activity. Cutinase enantio-selectivity towards the alcohol substrate was low and unaffected by any manipulation of medium conditions.This work has been supported by Fundação para a Ciência e Tecnologia (FCT, Portugal) through the contracts PRAXIS/PBIO/14314/1998 and POCTI/35429/QUI/2000 and the grant PRAXIS XXI/BD/21615/99 (S. Garcia), and by FEDER.We thank Ricardo Baptista for help in the production of cutinase

Orion Portable Fire Extinguisher Performance Testing Against a Laptop Lithium-Ion Battery Stored-Energy Fire-Method, Magnesium Fires, and Combustion By-Product Toxicity

As part of the qualification of the International Space Station (ISS) fine water mist portable fire extinguisher (PFE), several test methods were developed to determine firefighting capability against stored-energy sources. The most challenging of these devised stored-energy fire test methods proved to be the Lithium-ion (Li-ion) battery fire test scenario. The Orion crew capsule will utilize a different PFE technology from ISS (water spray rather than water mist), which spurred the need for the same type of evaluation focused on the sources of stored energy slated for use on Orion. Laptops were identified as a realistic source for stored-energy fires, requiring a modified Li-ion battery fire test scenario. In addition to open test cell (ambient oxygen concentration) testing to evaluate new proposed PFE performance, sealed chamber (20.9% and elevated oxygen concentration) testing was also performed. Chamber testing included combustion product sampling at various fire progression points for analysis and application to Orion emergency equipment design and response planning. The PFE stored-energy fire test methodology was modified and testing performed. Initial tests indicated ignition of the laptop magnesium laptop cases was possible. Additional tests were performed to characterize the laptop magnesium case fire behavior in various configurations. The new water spray PFE technology proved effective in extinguishing laptop stored-energy fires, and much was learned in the way these types of fires progressed. Findings indicate potential laptop magnesium case ignition mitigation strategies need to be further investigated

Excess ribosomal protein production unbalances translation in a model of Fragile X Syndrome

Dysregulated protein synthesis is a core pathogenic mechanism in Fragile X Syndrome (FX). The mGluR Theory of FX predicts that pathological synaptic changes arise from the excessive translation of mRNAs downstream of mGlu1/5 activation. Here, we use a combination of CA1 pyramidal neuron-specific TRAP-seq and proteomics to identify the overtranslating mRNAs supporting exaggerated mGlu1/5 -induced long-term synaptic depression (mGluR-LTD) in the FX mouse model (Fmr1−/y). Our results identify a significant increase in the translation of ribosomal proteins (RPs) upon mGlu1/5 stimulation that coincides with a reduced translation of long mRNAs encoding synaptic proteins. These changes are mimicked and occluded in Fmr1−/y neurons. Inhibiting RP translation significantly impairs mGluR-LTD and prevents the length-dependent shift in the translating population. Together, these results suggest that pathological changes in FX result from a length-dependent alteration in the translating population that is supported by excessive RP translation

Solstice PF Spray Cleaner (Aerosol) for Cleaning of LOX/GOX Components

No abstract availabl