SEARCH · Search NASA

Results for “REMOVAL”

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.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 37 records · Page 2

All sources NASA NTRS DOE OSTI

NASA NTRS2005

Resistively-Heated Microlith-based Adsorber for Carbon Dioxide and Trace Contaminant Removal

An integrated sorber-based Trace Contaminant Control System (TCCS) and Carbon Dioxide Removal Assembly (CDRA) prototype was designed, fabricated and tested. It corresponds to a 7-person load. Performance over several adsorption/regeneration cycles was examined. Vacuum regenerations at effective time/temperature conditions, and estimated power requirements were experimentally verified for the combined CO2/trace contaminant removal prototype. The current paper details the design and performance of this prototype during initial testing at CO2 and trace contaminant concentrations in the existing CDRA, downstream of the drier. Additional long-term performance characterization is planned at NASA. Potential system design options permitting associated weight, volume savings and logistic benefits, especially as relevant for long-duration space flight, are reviewed. The technology consisted of a sorption bed with sorbent- coated metal meshes, trademarked and patented as Microlith by Precision Combustion, Inc. (PCI). By contrast the current CO2 removal system on the International Space Station employs pellet beds. Preliminary bench scale performance data (without direct resistive heating) for simultaneous CO2 and trace contaminant removal was reviewed in SAE 2004-01-2442. In the prototype, the meshes were directly electrically heated for rapid response and accurate temperature control. This allowed regeneration via resistive heating with the potential for shorter regeneration times, reduced power requirement, and net energy savings vs. conventional systems. A novel flow arrangement, for removing both CO2 and trace contaminants within the same bed, was demonstrated. Thus, the need for a separate trace contaminant unit was eliminated resulting in an opportunity for significant weight savings. Unlike the current disposable charcoal bed, zeolites for trace contaminant removal are amenable to periodic regeneration.

Roychoudhury, S.↗

NASA NTRS2011

Engineering Challenges for Active Debris Removal

Recent modeling studies on the instability of the debris population in the low Earth orbit (LEO) region and the collision between Iridium 33 and Cosmos 2251 have underlined the need for active debris removal. A 2009 analysis by the NASA Orbital Debris Program Office shows that, in order to maintain the LEO debris population at a constant level for the next 200 years, an active debris removal of about five objects per year is needed. The targets identified for removal are those with the highest mass and collision probability products in the environment. Many of these objects are spent upper stages with masses ranging from 1 to more than 8 metric tons, residing in several altitude regions and concentrated in about 10 inclination bands. To remove five of those objects on a yearly basis, in a cost-effective manner, represents many challenges in engineering, technology development, and operations. This paper outlines a conceptual end-to-end debris removal operation, including launch, precision tracking, rendezvous, stabilization (of the tumbling targets), capture, and deorbit of the targets; and highlights major challenges associated with the operations. Pros and cons of several proposed removal techniques are also evaluated.

Liou, Jer-Chyi↗

NASA NTRSDate not supplied

Quantitation of Trace Water in ISS Atmosphere Samples Recovered from CO2-Removal Systems

As crewed spaceflight continues to push the limits of exploration, instruments and hardware used to maintain and monitor crew and vehicle health must become more integrated, reliable, and efficient. By combining a carbon dioxide (CO2) removal system with a resource recovery system like a Sabatier or Bosch reactor, the waste gas from the removal system can be converted into valuable resources that help reduce reliance on ground resupply. Due to the high-pressure nature of the Sabatier and Bosch reactions, the vent gas from most CO2 removal systems will need to be compressed before it can be processed. In order to prevent condensation in the compressor of the recovery system, it is critical to ensure that the vent stream from the CO2 removal system does not contain an excess of water. There are currently three different CO2 removal systems that are being developed as candidates for exploration missions. Each of these systems will be evaluated as a technology demonstration on ISS, and vent gas samples will be collected in Summa sampling canisters fitted with Entech valves. Due to the need to measure low levels of water in these samples, it was not possible to use the current ISS miniature grab sample containers (GSCs) to collect these samples. The Summa containers, which were used to collect archive samples during Shuttle missions, have a different surface treatment that makes it possible to measure the low levels of water in samples collected in these containers. This paper will provide some background on the CO2 removal systems being evaluated for exploration missions as well as results from ground-based testing of the current miniature GSCs and Summa canisters. Details on the development of the analytical method and the plan for preparing the canisters that will be used for in-flight sampling are also discussed.

Steven W Beck↗

NASA NTRSDate not supplied

Quantitation of Trace Water in ISS Atmosphere Samples Recovered from CO2-Removal Systems

As crewed spaceflight continues to push the limits of exploration, instruments and hardware used to maintain and monitor crew and vehicle health, must become more integrated, reliable, and efficient. By combining a carbon dioxide (CO2) removal system with a resource recovery system like a Sabatier or Bosch reactor, the waste gas from the removal system can be converted into valuable resources that help reduce reliance on ground resupply. Due to the high-pressure nature of the Sabatier and Bosch reactions, the vent gas from most CO2 removal systems will need to be compressed before it can be processed. In order to prevent condensation in the compressor of the recovery system, it is critical to ensure that the vent stream from the CO2 removal system does not contain an excess of water. There are currently two different CO2 removal systems that are being developed as candidates for exploration missions. Each of these systems will be evaluated as a technology demonstration on ISS, and vent gas samples will be collected in Summa sampling canisters fitted with Entech valves for ground analysis. Due to the need to measure low levels of water in these samples, it was not possible to use the current ISS mini-grab sample containers (m-GSC) to collect these samples. The Summa containers, which were used to collect archive samples during Shuttle missions, have a different surface treatment that makes it possible to measure the low levels of water in samples collected in these containers. This paper will provide some background on the CO2 removal systems being evaluated for exploration missions as well as results from ground-based testing of the Summa canisters. Details on the development of the analytical method and the plan for preparing the canisters that will be used for in-flight sampling are also discussed.

William M. King↗

NASA NTRS1975

Water hyacinths and alligator weeds for removal of lead and mercury from polluted waters

Removal of lead and mercury by water hyacinths (Eichhornia crassipes) (Mart.) Solms and alligator weeds (Alternanthera philoxeroides) (Mart.) Griesb. was investigated. Water hyacinths demonstrated the ability to remove 0.176 mg of lead and 0.150 mg of mercury per gram of dry plant material from distilled water and river water in a 24-hour period. One acre of water hyacinths is potentially capable of removing 105.6 grams of lead and 90.0 grams of mercury per day. Alligator weeds removed 0.101 mg of lead per gram of dry plant material in a 24-hour period. This same plant also demonstrated the ability to remove a minimum of 0.153 mg of mercury per gram of dry plant material in a six hour period.

Wolverton, B. C.↗

NASA NTRS1989

Selection of optimum median-filter-based ambiguity removal algorithm parameters for NSCAT

The NASA Scatterometer, NSCAT, is an active spaceborne radar designed to measure the normalized radar backscatter coefficient (sigma0) of the ocean surface. These measurements can, in turn, be used to infer the surface vector wind over the ocean using a geophysical model function. Several ambiguous wind vectors result because of the nature of the model function. A median-filter-based ambiguity removal algorithm will be used by the NSCAT ground data processor to select the best wind vector from the set of ambiguous wind vectors. This process is commonly known as dealiasing or ambiguity removal. The baseline NSCAT ambiguity removal algorithm and the method used to select the set of optimum parameter values are described. An extensive simulation of the NSCAT instrument and ground data processor provides a means of testing the resulting tuned algorithm. This simulation generates the ambiguous wind-field vectors expected from the instrument as it orbits over a set of realistic meoscale wind fields. The ambiguous wind field is then dealiased using the median-based ambiguity removal algorithm. Performance is measured by comparison of the unambiguous wind fields with the true wind fields. Results have shown that the median-filter-based ambiguity removal algorithm satisfies NSCAT mission requirements.

Shaffer, Scott↗

NASA NTRS1991

Design of equipment for lunar dust removal

NASA has a long range goal of constructing a fully equipped, manned lunar base on the near side of the moon by the year 2015. During the Apollo Missions, lunar dust coated and fouled equipment surfaces and mechanisms exposed to the lunar environment. In addition, the atmosphere and internal surfaces of the lunar excursion module were contaminated by lunar dust which was brought in on articles passed through the airlock. Consequently, the need exists for device or appliance to remove lunar dust from surfaces of material objects used outside of the proposed lunar habitat. Additionally, several concepts were investigated for preventing the accumulation of lunar dust on mechanisms and finished surfaces. The character of the dust and the lunar environment present unique challenges for the removal of contamination from exposed surfaces. In addition to a study of lunar dust adhesion properties, the project examines the use of various energy domains for removing the dust from exposed surfaces. Also, prevention alternatives are examined for systems exposed to lunar dust. A concept utilizing a pressurized gas is presented for dust removal outside of an atmospherically controlled environment. The concept consists of a small astronaut/robotic compatible device which removes dust from contaminated surfaces by a small burst of gas.

Belden, Lacy↗

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 NTRS1993

A feasibility study of using Langley 0.3-m transonic cryogenic tunnel sidewall boundary-layer removal system for heavy gas testing

This report presents the results of a preliminary study for using the 0.3-m Transonic Cryogenic Tunnel sidewall boundary-layer removal system with heavy gas sulfur hexafluoride as the test medium. It is shown that the drive motor speed/power of the existing system and the additional heat load on the tunnel heat exchanger are the major problems limiting the boundary-layer removal system performance. Overcoming these problems can provide the capability to remove about 1.5 percent of the test section mass flow at Mach number M = 0.8 and about 5 percent at M = 0.25. Previous studies have shown that these boundary-layer mass flow removal rates can reduce the boundary-layer thickness by a factor of two at the model station. Also the effect of upstream boundary-layer removal on the airfoil test data is not likely to be significant under high lifting conditions. Near design conditions, corrections to the test Mach number may be necessary to account for sidewall boundary-layer effects.

Murthy, A. V.↗

NASA NTRS2000

Enhancement of Directional Ambiguity Removal Skill in Scatterometer Data Processing Using Planetary Boundary Layer Models

Planetary boundary layer (PBL) models are utilized to enhance directional ambiguity removal skill in scatterometer data processing. The ambiguity in wind direction retrieved from scatterometer measurements is removed with the aid of physical directional information obtained from PBL models. This technique is based on the observation that sea level pressure is scalar and its field is more coherent than the corresponding wind. An initial wind field obtained from the scatterometer measurements is used to derive a pressure field with a PBL model. After filtering small-scale noise in the derived pressure field, a wind field is generated with an inverted PBL model. This derived wind information is then used to remove wind vector ambiguities in the scatterometer data. It is found that the ambiguity removal skill can be improved when the new technique is used properly in conjunction with the median filter being used for scatterometer wind dealiasing at JPL. The new technique is applied to regions of cyclone systems which are important for accurate weather prediction but where the errors of ambiguity removal are often large.

Kim, Young-Joon↗

NASA NTRS1994

Electrochemical Technology for Oxygen Removal and Measurement in the CELSS Test Facility, Engineering Development Unit

The Life Support Flight Program is evaluating regenerative technologies, including those that utilize higher plants, as a means to reduce resupply over long duration space missions. Constructed to assist in the evaluation process is the CELSS Test Facility Engineering Development Unit (CTF-EDU) an environmentally closed (less than 1% mass and thermal leakage) technology test bed. This ground based fully functional prototype is currently configured to support crop growth, utilizing the power, volume and mass resources allocated for two space station racks. Sub-system technologies were selected considering their impact on available resources, their ability to minimize integration issues, and their degree of modularity. Gas specific mass handling is a key sub-system technology for both biological and physical/chemical life support technologies. The CTF-EDU requires such a system to accommodate non-linear oxygen production from crops, by enabling the control system to change and sustain partial pressure set points in the growth volume. Electrochemical cells are one of the technologies that were examined for oxygen handling in the CTF-EDU. They have been additionally considered to meet other regenerative life support functions, such as oxygen generation, the production of potable water from composite waste streams, and for having the potential to integrate life support functions with those of propulsion and energy storage. An oxygen removal system based on an electrochemical cell was chosen for the EDU due to it's low power, volume and mass requirements (10W, 0.000027 cu m, 4.5 kg) and because of the minimal number of integration considerations. Unlike it's competitors, the system doesn't require post treatments of its byproducts, or heat and power intensive regenerations, that also mandate system redundancy or cycling. The EDUs oxygen removal system only requires two resources, which are already essential to controlled plant growth: electricity and water. Additionally, the amount of oxygen that is removed from the EDU is directly proportional to the cell input current via Faraday's constant, potentially allowing for a mol/electron measurement of photosynthetic rate. The currently operative oxygen removal system has maintained reduced oxygen set points within the EDU, and preparation is underway to verify of the accuracy of electrochemical measurement of oxygen production and hence, photosynthesis. This paper examines the working principles of the electrochemical cell, outlines the overall design of the oxygen removal system and its integration with other EDU subsystems, and summarizes test results obtained over crop growth cycles in the CTF-EDU.

Drews, Michael E.↗

NASA NTRS2005

International Space Station Carbon Dioxide Removal Assembly (ISS CDRA) Concepts and Advancements

An important aspect of air revitalization for life support in spacecraft is the removal of carbon dioxide from cabin air. Several types of carbon dioxide removal systems are in use in spacecraft life support. These systems rely on various removal techniques that employ different architectures and media for scrubbing CO2, such as permeable membranes, liquid amine, adsorbents, and absorbents. Sorbent systems have been used since the first manned missions. The current state of key technology is the existing International Space Station (ISS) Carbon Dioxide Removal Assembly (CDRA), a system that selectively removes carbon dioxide from the cabin atmosphere. The CDRA system was launched aboard UF-2 in February 2001 and resides in the U.S. Destiny Laboratory module. During the past four years, the CDRA system has operated with varying degrees of success. There have been several approaches to troubleshooting the CDRA system aimed at developing work-around solutions that would minimize the impact on astronaut time required to implement interim solutions. The paper discusses some of the short-term fixes applied to promote hardware life and restore functionality, as well as long-term plans and solutions for improving operability and reliability. The CDRA is a critical piece of life support equipment in the air revitalization system of the ISS, and is demonstrated technology that may ultimately prove well-suited for use in lunar or Mars base, and Mars transit life support applications.

ElSherif, Dina↗

NASA NTRS2007

A Sensitivity Study on the Effectiveness of Active Debris Removal in LEO

The near-Earth orbital debris population will continue to increase in the future due to ongoing space activities, on-orbit explosions, and accidental collisions among resident space objects. Commonly adopted mitigation measures, such as limiting postmission orbital lifetimes of satellites to less than 25 years, will slow down the population growth, but may be insufficient to stabilize the environment. The nature of the growth, in the low Earth orbit (LEO) region, is further demonstrated by a recent study where no future space launches were conducted in the environment projection simulations. The results indicate that, even with no new launches, the LEO debris population would remain relatively constant for only the next 50 years. Beyond that, the debris population would begin to increase noticeably, due to the production of collisional debris. Therefore, to better limit the growth of future debris population to protect the environment, remediation option, i.e., removing existing large and massive objects from orbit, needs to be considered. This paper does not intend to address the technical or economical issues for active debris removal. Rather, the objective is to provide a sensitivity study to quantify the effectiveness of various remediation options. A removal criterion based upon mass and collision probability is developed to rank objects at the beginning of each projection year. This study includes simulations with removal rates ranging from 2 to 20 objects per year, starting in the year 2020. The outcome of each simulation is analyzed, and compared with others. The summary of the study serves as a general guideline for future debris removal consideration.

Liou, J. C.↗

NASA NTRS2009

Carbon Dioxide Removal Troubleshooting aboard the International Space Station (ISS) during Space Shuttle (STS) Docked Operations

The International Space Station (ISS) represents a largely closed-system habitable volume which requires active control of atmospheric constituents, including removal of exhaled Carbon Dioxide (CO2). The ISS provides a unique opportunity to observe system requirements for (CO2) removal. CO2 removal is managed by the Carbon Dioxide Removal Assembly (CDRA) aboard the US segment of ISS and by Lithium Hydroxide (LiOH) aboard the Space Shuttle (STS). While the ISS and STS are docked, various methods are used to balance the CO2 levels between the two vehicles, including mechanical air handling and management of general crew locations. Over the course of ISS operation, several unexpected anomalies have occurred which have required troubleshooting, including possible compromised performance of the CDRA and LiOH systems, and possible imbalance in CO2 levels between the ISS and STS while docked. This paper will cover efforts to troubleshoot the CO2 removal systems aboard the ISS and docked STS.

Matty, Christopher M.↗

NASA NTRS2011

Dust Removal on Mars Using Laser-Induced Breakdown Spectroscopy

Dust coatings on the surface of Mars complicate and, if sufficiently thick, mask the spectral characteristics and compositional determination of underlying material from in situ and remote sensing instrumentation. The Laser-Induced Breakdown Spectroscopy (LIBS) portion of the Chemistry & Camera (ChemCam) instrument, aboard the Mars Science Laboratory (MSL) rover, will be the first active remote sensing technique deployed on Mars able to remove dust. ChemCam utilizes a 5 ns pulsed 1067 nm high-powered laser focused to less than 400 m diameter on targets at distances up to 7 m [1,2]. With multiple laser pulses, dust and weathering coatings can be remotely analyzed and potentially removed using this technique [2,3]. A typical LIBS measurement during MSL surface operations is planned to consist of 50 laser pulses at ~14 mJ, with the first 5 to 10 pulses used to analyze as well as remove any surface coating. Additionally, ChemCam's Remote Micro-Imager (RMI) is capable of resolving 200 m details at a distance of 2 m, or 1 mm at 10 m [1,4]. In this study, we report on initial laboratory experiments conducted to characterize the removal of dust coatings using similar LIBS parameters as ChemCam under Mars-like conditions. These experiments serve to better understand the removal of surface dust using LIBS and to facilitate the analysis of ChemCam LIBS spectral data and RMI images.

Graff, T. G.↗

NASA NTRS2010

CO2 Removal and Atmosphere Revitalization Systems for Next Generation Space Flight

Removal of metabolic CO2 from breathing air is a vital process for life support in all crewed space missions. A CO2 removal processor called the Low Power CO2 Removal (LPCOR) system is being developed in the Bioengineering Branch at NASA Ames Research Center. LPCOR utilizes advanced adsorption and membrane gas separation processes to achieve substantial power and mass reduction when compared to the state-of-the-art carbon dioxide removal assembly (CORA) of the US segment of the International Space Station (ISS). LPCOR is an attractive alternative for use in commercial spacecraft for short-duration missions and can easily be adapted for closed-loop life support applications. NASA envisions a next-generation closed-loop atmosphere revitalization system that integrates advanced CO2 removal, O2 recovery, and trace contaminant control processes to improve overall system efficiency. LPCOR will serve as the front end to such a system. LPCOR is a reliable air revitalization technology that can serve both the near-term and long-term human space flight needs of NASA and its commercial partners.

Luna, Bernadette↗

NASA NTRS2012

Active Debris Removal

Orbital debris in Low Earth Orbit (LEO) is an international problem that threatens the success of future space ventures. An analysis of a wide variety of alternative solutions for active debris removal (ADR) has been performed. The solution selected is an efficient, effective, and executable solution to remove large debris in LEO, primarily spent rocket bodies. Removing large debris objects is a critical step in reducing the hazard from orbital debris, because of the large amount of medium and small debris created through large body collisions. Based on the analysis of alternatives, the concept and design for a vehicle which could efficiently address the debris hazard by disposing of several large objects per mission has been developed. This concept establishes a comprehensive, detailed technical approach for an actual end-to-end, on-orbit ADR solution to remove large debris. This robust solution enables the start of solving the problem of debris removal before it reaches a critical and potentially irreversible state by "getting there as soon as possible, as economically as possible, with the most capability".

Burns, Susan H.↗

NASA NTRS2013

Low Temperature Catalyst for NH3 Removal

Air revitalization technologies maintain a safe atmosphere inside spacecraft by the removal of C02, ammonia (NH3), and trace contaminants. NH3 onboard the International Space Station (ISS) is produced by crew metabolism, payloads, or during an accidental release of thermal control refrigerant. Currently, the ISS relies on removing NH3 via humidity condensate and the crew wears hooded respirators during emergencies. A different approach to cabin NH3 removal is to use selective catalytic oxidation (SCO), which builds on thermal catalytic oxidation concepts that could be incorporated into the existing TCCS process equipment architecture on ISS. A low temperature platinum-based catalyst (LTP-Catalyst) developed at KSC was used for converting NH3 to H20 and N2 gas by SCO. The challenge of implementing SCO is to reduce formation of undesirable byproducts like NOx (N20 and NO). Gas mixture analysis was conducted using FTIR spectrometry in the Regenerable VOC Control System (RVCS) Testbed. The RVCS was modified by adding a 66 L semi-sealed chamber, and a custom NH3 generator. The effect of temperature on NH3 removal using the LTP-Catalyst was examined. A suitable temperature was found where NH3 removal did not produce toxic NO, (NO, N02) and N20 formation was reduced.

Monje, Oscar↗