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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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At least 379 records · Page 21
All sourcesNASA NTRSDOE OSTI
NASA NTRS1978

Flight investigation of insect contamination and its alleviation

An investigation of leading edge contamination by insects was conducted with a JetStar airplane instrumented to detect transition on the outboard leading edge flap and equipped with a system to spray the leading edge in flight. The results of airline type flights with the JetStar indicated that insects can contaminate the leading edge during takeoff and climbout. The results also showed that the insects collected on the leading edges at 180 knots did not erode at cruise conditions for a laminar flow control airplane and caused premature transition of the laminar boundary layer. None of the superslick and hydrophobic surfaces tested showed any significant advantages in alleviating the insect contamination problem. While there may be other solutions to the insect contamination problem, the results of these tests with a spray system showed that a continouous water spray while encountering the insects is effective in preventing insect contamination of the leading edges.

Peterson, J. B., Jr.↗
NASA NTRS1978

Trace contaminant studies of HSC adsorbent

The adsorption and desorption of fifteen trace contaminants on HSC (polyethylenimine coated acrylic ester) adsorbent were experimentally investigated with the following two objectives: to test the removal potential and the adsorption reversibility of the selected trace contaminants, and to test the effect a preadsorbed trace contaminant has on the CO2 adsorption capacity. The experimental method for acquiring the adsorption equilibrium data used is based on the volumetric (or displacement) concept of vacuum adsorption. From the experimental results, it was found that the HSC adsorbent has good adsorption potential for contaminants of alcohol compounds, esters, and benzene compounds; whereas, adsorption of ketone compounds, oxidizing and reducing agents are detrimental to the adsorbent. In addition, all liquid contaminants reduce the CO2 capacity of HSC adsorbent.

Yieh, D. T. N.↗
NASA NTRS1979

Ultraviolet absorption of common spacecraft contaminants

Organic contamination of ultraviolet optical systems is discussed. Degradation of signal by reflection, scattering, interference, and absorption is shown. The first three processes depend on the physical state of the contaminant while absorption depends on its chemical structure. The latter phenomenon is isolated from the others by dissolving contaminants in cyclohexane and determining absorption spectra from 2100A to 3600A. A variety of materials representing the types of contaminants responsible for most spaceflight hardware problems is scanned and the spectra is presented. The effect of thickness is demonstrated for the most common contaminant, di(2 ethyl hexyl)phthalate, by scanning successive dilutions.

Colony, J. A.↗
NASA NTRS1978

Space Shuttle contamination overview

Consideration is given to particle and gaseous contamination associated with Shuttle payload orbital delivery. An approach to control contamination is discussed which consists of analytical environment assessment, vehicle design optimization, and flight environment measurement. The analytical assessment of orbital contamination source characteristics and their effects on the Shuttle orbital environment has resulted in vehicle design changes and a detailed understanding of system operational flexibility. Verification of resulting Shuttle contamination performance will be made by the Induced Environment Contamination Monitor.

Leger, L.↗
NASA NTRS1982

Optical degradation due to contamination on the SAGE/SAGE II spacecraft instruments

An optical model for contamination effects has been developed for the SAGE II/ERBS instrument. This model describes instrument throughput efficiency and response characteristics as a function of molecular contamination thickness for indexes of refraction representative of Shuttle/ERBS/SAGE II contaminants at seven spectral wavelengths between 0.385 and 1.02 micrometers. Contamination effects are treated as thin film coatings on selected optical elements which cause changes in those elements' reflection/transmission/absorption characteristics. SAGE/AEM in-orbit performance data were used to estimate the optical constants for the contaminants. SAGE and SAGE II are radiometers that spatially scan the sun through the earth's atmosphere with a narrow field-of-view in spectral intervals from visible to the near infrared.

Mauldin, L. E., III↗
NASA NTRS1983

Space Shuttle contamination measurements from flights STS-1 through STS-4

Results of contamination measurements performed on the initial four flights of the Space Shuttle Orbiter are summarized and compared with requirements contained in the Space Shuttle Flight and Ground System Specifications and those formulated by the Contamination Requirements Definition Group. In general, the results of measurements carried out with the induced environment contamination monitor indicate that molecular fluxes, deposition rates, and average counts of particulates are within the requirements and close to predicted values. Among the exceptions, were such special circumstances as water dumps, payload bay door closures, and RCS engine, APU, and flash evaporator operations which led to molecular and particulate contamination levels exceeding the limits. In cases where these circumstances would interfere with sensitive payload operations, careful mission planning to preclude a contamination source by operational limitation should be done to avoid losses.

Ehlers, H. K. F.↗
NASA NTRS1983

Contamination sensitivity of typical mirror coatings - A parametric study

Contamination budgeting for space optical systems basically starts at understanding the sensitivity of component performance, e.g. mirror reflectance, window transmittance, etc., to surface deposits. To evaluate contamination sensitivity for mirror coatings, eight types representative of those used in the vacuum ultraviolet, visible, and infrared were modeled assuming that the contaminant is uniformly deposited on the mirror surface. Parametric studies over a range of complex refractive indices combined with an examination of optical data available for several organic materials suggested division of the contaminant layer index into three categories, N = 1.5 + 0.1i, N = 1.5 + 0.5i, and N = 1.5 + 2.0i. Contaminant thickness sensitivity curves were then calculated for each of the selected mirror coatings. For comparative purposes, critical thicknesses for each type were extracted, assuming a reflectance loss of 10 percent was allowable. Critical thicknesses ranged from about 10 A to 1000 A depending on the specifics of coating design and spectral region.

Osantowski, J. F.↗
NASA NTRS1984

Development of a new class of chemical and biological ultrasensors: Ribonuclease contamination and control

In order to define ribonuclease contamination, an assay for ribonuclease having picogram level sensitivity was established. In this assay, polycytidylic acid is digested by ribonuclease leading to smaller fragments of poly C that remain soluble after treatment of the sample with perchloric acid and lanthanum acetate. An absorbance measurement at 260 nm of the supernatant from the centrifuged sample measures the ribonuclease. A standard curve is shown. Using this assay procedure, ribonuclease contamination was found to be significant in routine laboratory proteins, in particular, bovine serum albumin, lysozyme, catalase, and cytochrome C. This was confirmed by demonstrating a considerable reduction in this activity in the presence of phosphate buffer since phosphate inhibits ribonuclease. Ribonuclease contamination was not significantly encountered in routine laboratory glassware, plasticware, column surfaces, chromatographic particles, and buffer reagents, including airborne contamination. Some contamination could be introduced by fingerprints, however.

Source record↗
NASA NTRS1985

Statement of contamination problem

Space station contamination information is given. There are five major areas in which there are task requirements: (1) potential contaminants need to be identified, i.e., both the sources and types of contaminants, (2) the scope and magnitude of contaminant effects need to be determined, i.e., toxicological effects, microbacteriological effects and impurities, (3) mathematical models for predictive methods need to be developed. (4) state-of-the-art and advanced technologies for monitoring contaminants and for methods of decontamination need to be identified, and (5) automated monitoring and control systems need to be designed.

Hoffler, W.↗
NASA NTRS1985

Flight evaluation of an insect contamination protection system for laminar flow wings

The maintenance of minimum wing leading edge contamination is critical to the preservation of drag-reducing laminar flow; previous methods for the prevention of leading edge contamination by insects have, however, been rendered impractical by their excessive weight, cost, or inconvenience. Attention is presently given to the results of a NASA flight experiment which evaluated the performance of a porous leading edge fluid-discharge ice protection system in the novel role of insect contamination removal; high insect contamination conditions were also noted in the experiment. Very small amounts of the fluid are found to be sufficient for insect contamination protection.

Croom, C. C.↗
NASA NTRS1986

Reducing Sodium Contamination in MOS Devices

Method of removing positive ions from oxides in metal-oxide-semiconductor (MOS) transistors and intergrated circuits ensure freedom from contamination by sodium and other mobile positive ions. Electric field applied during oxide growth to push mobile Na + ions to surface. After cooling from growth temperature, field turned off and Na + contaminated surface layer etched away. New method intended to suplement established methods of minimizing ion contamination, such as scrupulous cleanliness in processing, purging with hydrogen chloride to react with and remove contaminants, and growing extra-thick gate oxide, then etching it to remove large portion of contaminants concentrated near surface.

Dehaye, R. F.↗
NASA NTRS1986

Shuttle/spacelab contamination environment and effects handbook

This handbook is intended to assist users of the Spacelab/Space Transportation System by providing contamination environments and effects information that may be of value in planning, designing, manufacturing, and operating a space flight experiment. A summary of available molecular and particulate contamination data on the Space Transportation System and its facilities is presented. Contamination models, contamination effects, and protection methods information are also presented. In addition to contamination, the effects of the space environments at STS altitudes on spacecraft materials are included. Extensive references, bibliographies, and contacts are provided.

Bareiss, L. E.↗
NASA NTRS1987

Development of contamination requirements for spaceborne optical instrumentation

High performance satellites and critical surfaces aboard advanced long-life spacecraft require effective contamination control measures to maintain performance stability and to ensure data accuracy. Contamination is said to exist and be of concern if a spacecraft or launch vehicle produced material interferes with the intended performance of a surface or sensor. This paper will discuss the development of contamination requirements for spaceborne optical instrumentation. In addition, a comparison of instrument contamination requirements to measured instrument degradation levels for mission activities will be presented. If maintained, these requirements ensure against undesirable instrument degradation due to the contamination environment created by fabrication, launch, mission activities, ambient atmosphere and the instruments themselves.

Hansen, Patricia A.↗
NASA NTRS1987

Earth Observing System (EOS)/NOAA candidate propulsion system assessment and instrument contamination requirements

The instrumentation payloads of the Space Station polar platforms consist primarily of Earth Observing System (EOS) instruments and National Oceanic and Atmospheric Administration (NOAA) instruments. The accuracy, lifetime, and mission effectiveness of the instrumentation is adversely affected by the degradation of contamination sensitive surfaces. This paper describes the analysis and results of a study undertaken to select a propellant system for the polar platforms from a contamination standpoint, by evaluation of the potential contamination to three platforms, from three candidate propellant systems. In addition, this paper reports the results of a study which determined both the molecular and particulate contamination requirements for 37 EOS/NOAA instruments. These requirements provide an upper bound for acceptable levels of contamination.

Millard, Jerry M.↗
NASA NTRS1987

Space Station users contamination requirements

An account is given of the contamination sensitivities and requirements of various planned NASA Space Station users in all science categories, as well as the methods by which the Space Station will accomodate these requirements in the cases of attached payloads, core station-attached payloads, and platform payloads. Attention is given to the Space Station's external contamination environment, the degree of protection from contamination that the Space Station user must provide, the amount of warning users will receive prior to the initiation of potentially contamination-generating activities in the Space Station, and different contamination probabilities for the various parts of the Space Station.

Carosso, Nancy J. P.↗
NASA NTRS1989

Spacecraft contamination experience

Effective contamination control must encompass all aspects of ground and flight from design of the system through the end of mission life. Design systems are needed to minimize sensitivity to contamination, ease of cleaning, and contaminant production. Facilities and procedures are critical to maintaining cleanliness during ground operations. Flight operations should be planned so as to minimize contamination. More data from flights are required to assess the adequacy of designs and operations. Standards and specifications should include contamination control requirements.

Borson, E. N.↗
NASA NTRS1989

Contamination concerns in the modular containerless processing facility

This paper describes the problems of the control and management of contamination in the Modular Containerless Processing Facility (MCPF), that is being currently developed at the JPL for the Space Station, and in the MCPF's precursor version, called the Drop Physics Module (DPM), which will be carried aboard one or more Space Shuttle missions. Attention is given to the identification of contamination sources, their mode of transport to the sample positioned within the chamber, and the protection of the sample, as well as to the mathematical simulatiom of the contaminant transport. It is emphasized that, in order to choose and implement the most appropriate contamination control strategy for each investigator, a number of simplified mathematical simulations will have to be developed, and ground-based contamination experiments will have to be carried out with identical materials.

Seshan, P. K.↗
NASA NTRS1989

Contamination removal using various solvents and methodologies

Critical and non-critical bonding surfaces must be kept free of contamination that may cause potential unbonds. For example, an aft-dome section of a redesigned solid rocket motor that had been contaminated with hydraulic oil did not appear to be sufficiently cleaned when inspected by the optically stimulated electron emission process (Con Scan) after it had been cleaned using a hand double wipe cleaning method. As a result, current and new cleaning methodologies as well as solvent capability in removing various contaminant materials were reviewed and testing was performed. Bonding studies were also done to verify that the cleaning methods used in removing contaminants provide an acceptable bonding surface. The removal of contaminants from a metal surface and the strength of subsequent bonds were tested using the Martin Marietta and double-wipe cleaning methods. Results are reported.

Jeppsen, J. C.↗