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At least 433 records · Page 24

All sources NASA NTRS DOE OSTI

NASA NTRS2011

Small Scale Trace Contaminant Testing of SA9T at Ambient and Reduced Pressure Conditions

A principle concern for air revitalization technology in a closed loop system is the capability to control carbon dioxide (CO2) and humidity (H2O). An amine based sorbent technology, SA9T, has long been evaluated for use in this application and several programs are evaluating it for use in both a cabin as well as space suit applications. While the CO2 and H2O performance of the sorbent has been tested extensively, the question of how trace contaminants impact performance requires further evaluation. This paper presents experimental results of small scale SA9T testing that was performed over a variety of test conditions and with a variety of trace contaminants. Testing evaluated the ability of SA9T media to sufficiently remove CO2 and H2O after exposure to a fully saturated trace contaminant at ambient conditions. Testing also evaluated the impact of CO2 and H2O removal performance at suit loop pressures during cyclic operation with a constant inlet contaminant load. In addition, testing evaluated the performance of SA9T at ambient conditions in a continuous 30-day test with a mixed trace contaminant stream.

Broerman, Craig↗

NASA NTRS2011

Bench-Scale Trace Contaminant Testing of SA9T at Ambient and Reduced Pressure Conditions

A principal concern for air revitalization technology in a closed loop system is the capability to control carbon dioxide (CO2) and humidity (H2O). An amine based sorbent technology, SA9T, has been evaluated for use in this application and several programs are evaluating it for use in both cabin and space suit applications. While the CO2 and H2O performance of the sorbent has been tested extensively, the question of how trace contaminants impact performance requires further evaluation. This paper presents experimental results of bench-scale SA9T testing that was performed under a variety of test conditions and with several different trace contaminants. Tests were conducted to determine if the capacity of the SA9T media to sufficiently remove CO2 and H2O is compromised after exposure to a fully saturated trace contaminant at ambient conditions. Tests also were conducted to evaluate the performance of SA9T at ambient conditions in a continuous 30-day test with a mixed trace contaminant stream. In addition, testing also evaluated the impact of CO2 and H2O removal performance at suit loop pressures (29.6 KPa/4.3 psia) during cyclic operation with a constant inlet contaminant load.

Broerman, Craig↗

NASA NTRS2014

International Space Station External Contamination Environment for Space Science Utilization

The International Space Station (ISS) is the largest and most complex on‐orbit platform for space science utilization in low Earth orbit. Multiple sites for external payloads, with exposure to the associated natural and induced environments, are available to support a variety of space science utilization objectives. Contamination is one of the induced environments that can impact performance, mission success and science utilization on the vehicle. The ISS has been designed, built and integrated with strict contamination requirements to provide low levels of induced contamination on external payload assets. This paper addresses the ISS induced contamination environment at attached payload sites, both at the requirements level as well as measurements made on returned hardware, and contamination forecasting maps being generated to support external payload topology studies and science utilization.

Soares, Carlos E.↗

NASA NTRS2015

Modular Open System Architecture for Reducing Contamination Risk in the Space and Missile Defense Supply Chain

To combat contamination of physical assets and provide reliable data to decision makers in the space and missile defense community, a modular open system architecture for creation of contamination models and standards is proposed. Predictive tools for quantifying the effects of contamination can be calibrated from NASA data of long-term orbiting assets. This data can then be extrapolated to missile defense predictive models. By utilizing a modular open system architecture, sensitive data can be de-coupled and protected while benefitting from open source data of calibrated models. This system architecture will include modules that will allow the designer to trade the effects of baseline performance against the lifecycle degradation due to contamination while modeling the lifecycle costs of alternative designs. In this way, each member of the supply chain becomes an informed and active participant in managing contamination risk early in the system lifecycle.

Seasly, Elaine↗

NASA NTRS2016

Exploring Surface Analysis Techniques for the Detection of Molecular Contaminants on Spacecraft

Molecular contamination is a known area of concern for spacecraft. To mitigate this risk, projects involving space flight hardware set requirements in a contamination control plan that establishes an allocation budget for the exposure of non-volatile residues (NVR) onto critical surfaces. The purpose of this work will focus on non-contact surface analysis and in situ monitoring to mitigate molecular contamination on space flight hardware. By using Scanning Electron Microscopy and Energy Dispersive Spectroscopy (SEM-EDS) with Raman Spectroscopy, an unlikely contaminant was identified on space flight hardware. Using traditional and surface analysis methods provided the broader view of the contamination sources allowing for best fit solutions to prevent any future exposure.

Rutherford, Gugu N.↗

NASA NTRS2017

Evaluating Crustal Contamination Effects on the Lithophile Trace Element Budget of Shergottites

The origin of the incompatible trace element (ITE) enriched compositions of shergottites has been a point of contention for decades [1-2]. Two scenarios have been proposed, the first is that enriched shergottite compositions reflect an ITE-enriched mantle source, whereas in the second, the ITE enrichment reflects crustal contamination of mantle-derived parent magmas. Evidence supporting the first scenario is that the ITE-enriched shergottite compositions are consistent with the outcomes of magma ocean crystallization [3], and that Os-Nd isotope relationships for shergottites cannot be explained by realistic crustal contamination models [4]. In contrast, Cl and S isotopes are consistent with shergottite magmas interacting with Mars crust [5,6], and ITE-enriched olivine-hosted melt inclusions and interstitial glass are found in depleted shergottite Yamato 980459 [7]. These findings indicate that some level of crustal interaction occurred but the question of whether ITE-enrichments in some bulk shergottites reflect crustal contamination remains open. Recently, a Mars crustal breccia meteorite has been found, NWA 7034 and its paired stones, that is our best analogue to an average of Mars ancient crust [8-10]. This allows for better constraints on crustal contamination of shergottite magmas. We modeled magma-crust mixing and assimilation-fractional crystallization (AFC) using ITE-depleted shergottite compositions and bulk NWA 7034 and its clasts as end-members. The results of these models indicate that crustal contamination can only explain the ITE-enriched compositions of some bulk shergottites under unusual circumstances. It is thus likely that the shergottite range of compositions reflects primarily mantle sources.

Brandon, A. D.↗

NASA NTRS2018

A Prototype Tool for Assessing Forward Contamination from Space Suits

Crewed exploration missions dramatically increase the capability for large-scale sample collection and return activities, but they also increase the possibility and likelihood of forward contamination. Systematic research on forward contamination from uncrewed spacecraft has steadily progressed since the Viking missions, but parallel research on contamination from space suits has not. Current space suits have leakage rates as high as 100 cc gas/min., but it is unclear how many or what types of microbes are exiting the suits along with this gas. The Human Forward Contamination Assessment team at NASA's Johnson Space Center (JSC) has developed a prototype swab tool that is capable of maintaining sterility during pressure changes associated with entering and exiting vacuum. The primary objective of recent Extravehicular Activity (EVA) Swab Kit testing is to characterize the type of microorganisms typically found on spacesuit external surfaces under suit differential pressure conditions. Most human-associated microorganisms can fit through a 0.5 to 1.0 μm gap. Understanding potential leak paths will inform future hardware design decisions. Knowing which types of microorganisms may leak from EVA suits provides a basis for subsequent studies to characterize the viability of those organisms under destination conditions, as well as how far they might spread through natural or human-influenced processes. The results of EVA suit molecular microbial community analyses will inform NASA exploration mission operations and hardware design, and help close Strategic Knowledge Gap B5, Forward Contamination to Mars.

Rucker, M.↗

NASA NTRS2018

Polymer-Filled Metal Foams for Contamination Resistant Aircraft Leading Edges

Adhesion of contaminants has been identified as a ubiquitous issue for aeronautic exterior surfaces. Organic coatings have been demonstrated to enable reduction in insect residue adhesion as well as a reduction in ice adhesion strength. These approaches however, have yet to demonstrate sufficient durability to enable application to commercial aircraft wing leading edges. High durability materials have been developed in parallel to these efforts; contaminant adhesion issues are not addressed. This work describes a first attempt to identify a solution to the seemingly competing issues of contaminant adhesion and durability. A co-continuous network of organic and metallic domains may provide greater durability, while still enabling the changes in surface-contaminant interactions that have been realized. To that end, unique properties have been achieved through fabrication of composite metal foam materials. Likewise, extensive research has been dedicated toward development of polymeric coatings for mitigation of insect residue adhesion.This work describes initial results from infusion of a low surface free energy epoxy resin into a composite metal foam substrate for the purpose of generating a durable contaminant adhesion-resistant material.

Robbins, Samuel J.↗

NASA NTRSDate not supplied

Overview of the Lunar Gateway External Contamination Environment

As a part of the Artemis mission, Gateway will be a long duration space station in a near rectilinear halo orbit around the Moon. Gateway will be exposed to a variety of external contamination sources, which can degrade external hardware / surfaces and impact science utilization objectives. Requirements and methodologies addressing material outgassing, chemical and electric thruster plumes, vacuum venting, and visiting vehicle interactions have been developed by the Gateway Induced Environments team to ensure vehicle performance and mission success. The external contamination requirements and integration process are described along with required data deliverables. Integrated external contamination analyses are conducted by the Gateway Environments Team to assess compliance with external contamination requirements. This paper provides a current status of integration activities and analysis results, as well as future plans to improve external contamination characterization.

Crystal A. Quiroz↗

NASA NTRSDate not supplied

Trace Contaminant Control Test Bed for Evaluation of TCC Prototypes with Vacuum Regenerable and Non-Regenerable Sorbents

A new Space Suit Exploration Portable Life Support System (xPLSS) is being designed, built, integrated, and tested into the Extra-Vehicular Mobility Unit (xEMU). The Trace Contaminant Control (TCC) system is a component in the oxygen ventilation loop of xPLSS that removes contaminants generated by the crewmembers’ metabolic processes. The primary trace contaminants that must be removed include ammonia (NH3), carbon monoxide (CO), formaldehyde (CH2O), and methyl mercaptan (CH3SH). The current state-of-the-art TCC sorbent is non-regenerable activated carbon. As a non-regenerable sorbent, its use negatively impacts the logistics for future missions. Thus, an ideal solution can be a vacuum-regenerable sorbent integrated with the xPLSS CO2/H2O removal system. To test new designs and sorbents, XploSafe has constructed a recirculating test bed that mimics the environment within the xPLSS by providing concentrations of the trace contaminant analytes generated at the operating temperature, humidity, pressure, and flow rates of the xPLSS. This system can perform regeneration or desorption by exposing the sorbent to a pressure swing from 4.3 psia to <1 torr over approximately 2 minutes. Using this test system, XploSafe evaluated various TCC prototypes constructed using rapid prototyping techniques and identified a process that allows vacuum regenerative TCC designs to be quickly examined for flow, pressure drop, and performance. By using toluene as a segregate for volatile organics, this test system was evaluated using both vacuum regenerable and non-regenerable sorbents to demonstrate the operational effectiveness of these sorbents in maintaining the concentrations of the trace contaminant analytes below the 7-day Spacecraft Maximum Allowable Concentrations.

Nicholas Materer↗

NASA NTRS2024

Overview of the Lunar Gateway External Contamination Environment

Crystal A Quiroz↗

NASA NTRS2026

The Contaminant Footprint of Landed Spacecraft: Toward an Inventory and Modelling Framework

All spacecraft generate and carry contaminants, i.e., unwanted and potentially harmful material. When a spacecraft lands and operates in vacuum, as onto Earth’s Moon, it introduces contaminants into its environment that may compromise mission science objectives and engineering performance. Contamination may degrade sites of unique value to planetary science or in situ resource utilization. This presentation will identify and compare source terms and transport vectors for contaminants – in particular, organic material – generated by landed spacecraft. An integrated modeling framework for the organic contamination footprint of spacecraft missions will be described and presented.

Gas Dynamics↗

DOE OSTI2016

Harvesting contaminants from liquid

Disclosed are examples of apparatuses for evaporative purification of a contaminated liquid. In each example, there is a vessel for storing the contaminated fluid. The vessel includes a surface coated with a layer of superhydrophobic material and the surface is at least partially in contact with the contaminated liquid. The contaminants do not adhere to the surface as the purified liquid evaporates, thus allowing the contaminants to be harvested.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2016

Methods for removing contaminants from algal oil

Methods for removing contaminants from algal oil are provided. In an embodiment, a method comprises the steps of combining a sulfuric acid-aqueous solution that has a pH of about 1 or less with a contaminant-containing algal oil at treatment conditions effective to form an effluent. The effluent comprises a treated algal oil phase and contaminants in an acidic aqueous phase. The contaminants comprise metals, phosphorus, or combinations thereof. The acidic aqueous phase is removed from the effluent to form a contaminant-depleted algal oil.

09 BIOMASS FUELS↗

DOE OSTI2017

Characterization, Identification and Seasonal Evaluation of Microbes in Mercury Contaminated Soils

Mercury (Hg) contamination within the Oak Ridge Reservation has been an ongoing research. A comprehensive understanding of the potentials of predominant microorganisms in selected cleanup strategy is highly paramount. The use of sorbents has been proposed as a cleanup strategy; however, biological factors need to be evaluated as regards to the strategy. The goal of this study was to use microbes isolated from various contaminated sites and determine their effectiveness on sorbents to reduce total Hg (HgT). We isolated DNA from contaminated soils (SB 5-8, SB 14-8) and control soil (Hinds Creek) with littleor no Hg contamination. Pure cultures were obtained from soil samples using broad-spectrum nutrient broth, and natural medium formulated using extracts from the different soil samples. Selected colonies and total DNA from the soils were used for 16S rDNA sequencing. Some Hg reducers (Acinetobacter rhizosphaerae and Serratia marcescens) were isolated. S. marcescens was chosen due to its role in bioremediating and transforming Hg. Study of hg leachability in the contaminated soils showed that the amount of leachable Hg varied in magnitude among the three soils possibly due to seasonal changes. Sorbent was added to determine control in leachability after the soils have been incubated for 14 days in diH2O. S. marcescens was inoculated into the soils along with sorbents and incubated for 48 hrs at 25°C. Total Hg (HgT) concentrations were determined using cold vapor atomic fluorescence in accordance with EPA method 1631. A variable amount of methylators was found in each soil type. Organisms that grew on the nutrient agar grew poorly on the natural medium with variable colonies. However, S. marcescens grew on both media. S. marcescens showed high reduction of Hg2+ compared to the sorbent; however, when inoculated in the soil, the sorbent was found to absorb more HgT in solution.

Egbo, Timothy↗

DOE OSTI2023

Finding a contaminant source in a volume of flowing fluid

A method includes: mapping a boundary of a volume of flowing fluid; partitioning the volume by a computational mesh; finding a contaminant location at a first sensor that is disposed within the volume; obtaining a measured velocity of the flowing fluid within the volume; generating a reversed velocity vector field within the mesh, in response to the measured velocity; time stepping the contaminant location from the first sensor along the reversed velocity vector field until the contaminant location intersects the boundary of the volume; and finding a contaminant source at the intersection of the time stepped contaminant location with the boundary of the volume.

Lopez-Marrero, Vanessa↗

DOE OSTI2016

Corrective Action Decision Document/Corrective Action Plan for Corrective Action Unit 573: Alpha Contaminated Sites Nevada National Security Site, Nevada, Revision 0

CAU 573 comprises the following corrective action sites (CASs): • 05-23-02, GMX Alpha Contaminated Area • 05-45-01, Atmospheric Test Site - Hamilton These two CASs include the release at the Hamilton weapons-related tower test and a series of 29 atmospheric experiments conducted at GMX. The two CASs are located in two distinctly separate areas within Area 5. To facilitate site investigation and data quality objective (DQO) decisions, all identified releases (i.e., CAS components) were organized into study groups. The reporting of investigation results and the evaluation of DQO decisions are at the release level. The corrective action alternatives (CAAs) were evaluated at the FFACO CAS level. The purpose of this CADD/CAP is to evaluate potential CAAs, provide the rationale for the selection of recommended CAAs, and provide the plan for implementation of the recommended CAA for CAU 573. Corrective action investigation (CAI) activities were performed from January 2015 through November 2015, as set forth in the CAU 573 Corrective Action Investigation Plan (CAIP). Analytes detected during the CAI were evaluated against appropriate final action levels (FALs) to identify the contaminants of concern. Assessment of the data generated from investigation activities conducted at CAU 573 revealed the following: • Radiological contamination within CAU 573 does not exceed the FALs (based on the Occasional Use Area exposure scenario). • Chemical contamination within CAU 573 does not exceed the FALs. • Potential source material—including lead plates, lead bricks, and lead-shielded cables—was removed during the investigation and requires no additional corrective action.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

NASA NTRSDate not supplied

Design of an Adsorption Bed for Exploration Trace Contaminant Control

The state-of-the-art in long mission duration spacecraft trace contaminant control processes relies on physical and chemical adsorption for contaminant removal. Target species for adsorption include low and semivolatile organic compounds while chemisorption is utilized for metabolic ammonia control. When adsorption is employed in conjunction with a high temperature oxidation process, a complementary impact on cabin air quality may be realized. The adsorption bed also serves to guard the downstream oxidation catalyst from foulants and potential poisons which may decrease its lifetime and activity. To this end, a packed adsorption guard-bed was sized to control a statistical contaminant load model over a simulated Mars transit mission duration. The updated load model incorporates flight air-quality data and contemporary metabolic source emission literature. The guard-bed was operated in tandem with an exploration prototype thermal catalytic oxidizer. The exploration guard-bed prototype included design considerations from recent flight technology demonstrations and changes intended to improve compatibility with enriched oxygen exploration cabin environments as compared to the prior-art of contaminant control system design.

Trace Contaminant Control↗