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NASA NTRS1990

Spacecraft thermal blanket cleaning: Vacuum bake of gaseous flow purging

The mass losses and the outgassing rates per unit area of three thermal blankets consisting of various combinations of Mylar and Kapton, with interposed Dacron nets, were measured with a microbalance using two methods. The blankets at 25 deg C were either outgassed in vacuum for 20 hours, or were purged with a dry nitrogen flow of 3 cu. ft. per hour at 25 deg C for 20 hours. The two methods were compared for their effectiveness in cleaning the blankets for their use in space applications. The measurements were carried out using blanket strips and rolled-up blanket samples fitting the microbalance cylindrical plenum. Also, temperature scanning tests were carried out to indicate the optimum temperature for purging and vacuum cleaning. The data indicate that the purging for 20 hours with the above N2 flow can accomplish the same level of cleaning provided by the vacuum with the blankets at 25 deg C for 20 hours, In both cases, the rate of outgassing after 20 hours is reduced by 3 orders of magnitude, and the weight losses are in the range of 10E-4 gr/sq cm. Equivalent mass loss time constants, regained mass in air as a function of time, and other parameters were obtained for those blankets.

Scialdone, John J.↗

NASA NTRS1992

Spacecraft thermal blanket cleaning - Vacuum baking or gaseous flow purging

The mass losses and the outgassing rates per unit area of three thermal blankets consisting of various combinations of Mylar and Kapton, with interposed Dacron nets, were measured with a microbalance using two methods. The blankets at 25 deg C were either outgassed in vacuum for 20 hours, or were purged with a dry nitrogen flow of 3 cu. ft. per hour at 25 deg C for 20 hours. The two methods were compared for their effectiveness in cleaning the blankets for their use in space applications. The measurements were carried out using blanket strips and rolled-up blanket samples fitting the microbalance cylindrical plenum. Also, temperature scanning tests were carried out to indicate the optimum temperature for purging and vacuum cleaning. The data indicate that the purging for 20 hours with the above N2 flow can accomplish the same level of cleaning provided by the vacuum with the blankets at 25 deg C for 20 hours. In both cases, the rate of outgassing after 20 hours is reduced by 3 orders of magnitude, and the weight losses are in the range of 10E-4 gr/sq cm. Equivalent mass loss time constants, regained mass in air as a function of time, and other parameters were obtained for those blankets.

Scialdone, John J.↗

NASA NTRS1953

Measurements obtained during the glide-flight program of the Bell X-2 research airplane

Results obtained during the glide-flight program of the Bell X-2 research airplane are presented. Landing characteristics and limited data evaluating static longitudinal stability at low speeds are included. The data indicated positive static longitudinal stability in unaccelerated flight from indicated airspeeds of 152 to 178 miles per hour for the clean configuration, between 142 and 171 miles per hour with the flaps up and gear extended, and between 142 and 204 miles per hour with flaps and gear extended. A region of neutral stability, both stick fixed and stick free, was apparent between 178 and 192 miles per hour for the clean configuration. Data obtained during a turn made at an indicated airspeed of approximately 235 miles per hour with steadily increasing acceleration indicated positive stick-free and stick-fixed longitudinal stability. Stick force per unit normal acceleration was approximately 15 pounds. Pilots' notes indicated that dynamic stability in each plane of reference was apparently positive with satisfactory damping for the speed range covered. The main landing-skid surface area was enlarged 300 percent for flights 2 and 3 with a resulting improvement in landing characteristics. Average longitudinal deceleration during the ground run was decreased from 0.7 unit of acceleration for flight 1 to a value of 0.3 unit of acceleration for flights 2 and 3. Normal acceleration at the nose wheel was correspondingly reduced from 4 to 2.8 units of acceleration. The addition of inboard wing skids prevented rolling onto a wing tip during ground run.

Richard E Day↗

NASA NTRS2007

Triaxial Probe Magnetic Data Analysis

The Triaxial Magnetic Moment Analysis software uses measured magnetic field test data to compute dipole and quadrupole moment information from a hardware element. It is used to support JPL projects needing magnetic control and an understanding of the spacecraft-generated magnetic fields. Evaluation of the magnetic moment of an object consists of three steps: acquisition, conditioning, and analysis. This version of existing software was extensively rewritten for easier data acquisition, data analysis, and report presentation, including immediate feedback to the test operator during data acquisition. While prior JPL computer codes provided the same data content, this program has a better graphic display including original data overlaid with reconstructed results to show goodness of fit accuracy and better appearance of the report graphic page. Data are acquired using three magnetometers and two rotations of the device under test. A clean acquisition user interface presents required numeric data and graphic summaries, and the analysis module yields the best fit (least squares) for the magnetic dipole and/or quadrupole moment of a device. The acquisition module allows the user to record multiple data sets, selecting the best data to analyze, and is repeated three times for each of the z-axial and y-axial rotations. In this update, the y-axial rotation starting position has been changed to an option, allowing either the x- or z-axis to point towards the magnetometer. The code has been rewritten to use three simultaneous axes of magnetic data (three probes), now using two "rotations" of the device under test rather than the previous three rotations, thus reducing handling activities on the device under test. The present version of the software gathers data in one-degree increments, which permits much better accuracy of the fit ted data than the coarser data acquisition of the prior software. The data-conditioning module provides a clean data set for the analysis module. For multiple measurements at a given degree, the first measurement is used. For omitted measurements, the missing field is estimated by linear interpolation between the two nearest measurements. The analysis module was rewritten for the dual rotation, triaxial probe measurement process and now has better moment estimation accuracy, based on the finer one degree of data acquisition resolution. The magnetic moments thus computed are used as an input to summarize the total spacecraft field.

Shultz, Kimberly↗

NASA NTRS2004

JDD, Inc. Database

JDD Inc, is a maintenance and custodial contracting company whose mission is to provide their clients in the private and government sectors "quality construction, construction management and cleaning services in the most efficient and cost effective manners, (JDD, Inc. Mission Statement)." This company provides facilities support for Fort Riley in Fo,rt Riley, Kansas and the NASA John H. Glenn Research Center at Lewis Field here in Cleveland, Ohio. JDD, Inc. is owned and operated by James Vaughn, who started as painter at NASA Glenn and has been working here for the past seventeen years. This summer I worked under Devan Anderson, who is the safety manager for JDD Inc. in the Logistics and Technical Information Division at Glenn Research Center The LTID provides all transportation, secretarial, security needs and contract management of these various services for the center. As a safety manager, my mentor provides Occupational Health and Safety Occupation (OSHA) compliance to all JDD, Inc. employees and handles all other issues (Environmental Protection Agency issues, workers compensation, safety and health training) involving to job safety. My summer assignment was not as considered "groundbreaking research" like many other summer interns have done in the past, but it is just as important and beneficial to JDD, Inc. I initially created a database using a Microsoft Excel program to classify and categorize data pertaining to numerous safety training certification courses instructed by our safety manager during the course of the fiscal year. This early portion of the database consisted of only data (training field index, employees who were present at these training courses and who was absent) from the training certification courses. Once I completed this phase of the database, I decided to expand the database and add as many dimensions to it as possible. Throughout the last seven weeks, I have been compiling more data from day to day operations and been adding the information to the database. It now consists of seven different categories of data (carpet cleaning, forms, NASA Event Schedules, training certifications, wall and vent cleaning, work schedules, and miscellaneous) . I also did some field inspecting with the supervisors around the site and was present at all of the training certification courses that have been scheduled since June 2004. My future outlook for the JDD, Inc. database is to have all of company s information from future contract proposals, weekly inventory, to employee timesheets all in this same database.

Miller, David A., Jr.↗

NASA NTRS1972

Criticality experiments and analysis of molybdenum reflected cylindrical uranyl fluoride water solution reactors

Clean criticality data were obtained from molybdenum-reflected cylindrical uranyl-fluoride-water solution reactors. Using ENDF/B molybdenum cross sections, a nine energy group two-dimensional transport calculation of a reflected reactor configuration predicted criticality to within 7 cents of the experimental value. For these reactors, it was necessary to compute the reflector resonance integral by a detailed transport calculation at the core-reflector interface volume in the energy region of the two dominant resonances of natural molybdenum.

Fieno, D.↗

NASA NTRS1978

Round-Robin approach to data flow optimization

A large data base, circular in structure, was required (for the Voyager Mission to Jupiter/Saturn) with the capability to completely update the data every four hours during high activity periods. The data is stored in key ordered format for retrieval but is not input in key order. Existing access methods for large data bases with rapid data replacement by keys become inefficient as the volume of data being replaced grows. The Round-Robin method was developed to alleviate this problem. The Round-Robin access method allows rapid updating of the data with continuous self cleaning where the oldest data (by key) is deleted and the newest data (by key) is kept regardless of the order of input.

Witt, J.↗

NASA NTRS1992

Effects of long term space environment exposure on optical substrates and coatings (S0050-2)

The experiment consisted of Fused Silica and Ultra Low Expansion (ULE(tm)) glass samples which were either uncoated or had high reflectance silver, antireflectance, or solar rejection coatings. A set of duplicate control samples was manufactured and stored in a controlled environment for comparison purposes. We will present spectral curves for the glass and coatings which define preflight, postflight, and post-cleaning performance. Data on the analysis of the contaminate deposited on the samples and stress measurements in the glass will also be presented. Some results of particular interest are that the contaminate composition varied between different types of samples, and no darkening of the ULE(tm) glass occurred due to the radiation exposure.

Vallimont, John↗

NASA NTRS2000

United States Air Force Wipe Solvent Testing

The Wright-Patterson Air Force Base (WPAFB), as part of the Air Force Material Command, requested that NASA Johnson Space Center (JSC) White Sands Test Facility (WSTF) conduct testing and analyses in support of the United States Air Force Wipe Solvent Development Project. The purpose of the wipe solvent project is to develop an alternative to be used by Air Force flight line and maintenance personnel for the wipe cleaning of oxygen equipment. This report provides material compatibility, liquid oxygen (LOX) mechanical impact, autogenous ignition temperature (AIT), and gauge cleaning test data for some of the currently available solvents that may be used to replace CFC-113 and methyl chloroform. It provides data from previous WSTF test programs sponsored by the Naval Sea Systems Command, the Kennedy Space Center, and other NASA programs for the purpose of assisting WP AFB in identifying the best alternative solvents for validation testing.

Hornung, Steven D.↗

NASA NTRS2016

A Parametric Model of Shoulder Articulation for Virtual Assessment of Space Suit Fit

Shoulder injury is one of the most severe risks that have the potential to impair crewmembers' performance and health in long duration space flight. Overall, 64% of crewmembers experience shoulder pain after extra-vehicular training in a space suit, and 14% of symptomatic crewmembers require surgical repair (Williams & Johnson, 2003). Suboptimal suit fit, in particular at the shoulder region, has been identified as one of the predominant risk factors. However, traditional suit fit assessments and laser scans represent only a single person's data, and thus may not be generalized across wide variations of body shapes and poses. The aim of this work is to develop a software tool based on a statistical analysis of a large dataset of crewmember body shapes. This tool can accurately predict the skin deformation and shape variations for any body size and shoulder pose for a target population, from which the geometry can be exported and evaluated against suit models in commercial CAD software. A preliminary software tool was developed by statistically analyzing 150 body shapes matched with body dimension ranges specified in the Human-Systems Integration Requirements of NASA ("baseline model"). Further, the baseline model was incorporated with shoulder joint articulation ("articulation model"), using additional subjects scanned in a variety of shoulder poses across a pre-specified range of motion. Scan data was cleaned and aligned using body landmarks. The skin deformation patterns were dimensionally reduced and the co-variation with shoulder angles was analyzed. A software tool is currently in development and will be presented in the final proceeding. This tool would allow suit engineers to parametrically generate body shapes in strategically targeted anthropometry dimensions and shoulder poses. This would also enable virtual fit assessments, with which the contact volume and clearance between the suit and body surface can be predictively quantified at reduced time and cost.

Kim, K. Han↗

NASA NTRS2000

Evaluation of Non-Ozone-Depleting-Chemical Cleaning Methods for Space Mechanisms Using a Vacuum Spiral Orbit Rolling Contact Tribometer

Because CFC 113, an ozone depleting chemical (ODC), can no longer be produced, alternative bearing cleaning methods must be studied. The objective of this work was to study the effect of the new cleaning methods on lubricant lifetime using a vacuum bearing simulator (spiral orbit rolling contact tribometer). Four alternative cleaning methods were studied: ultra-violet (UV) ozone, aqueous levigated alumina slurry (ALAS), super critical fluid (SCF) CO2 and aqueous Brulin 815GD. Baseline tests were done using CFC 113. Test conditions were the following: a vacuum of at least 1.3 x 10(exp -6) Pa, 440C steel components, a rotational speed of 10 RPM, a lubricant charge of between 60-75 micrograms, a perfluoropolyalkylether lubricant (Z-25), and a load of 200N (44.6 lbs., a mean Hertzian stress of 1.5 GPa). Normalized lubricant lifetime was determined by dividing the total number of ball orbits by the amount of lubricant. The failure condition was a friction coefficient of 0.38. Post-test XPS analysis was also performed, showing slight variations in post-cleaning surface chemistry. Statistical analysis of the resultant data was conducted and it was determined that the data sets were most directly comparable when subjected to a natural log transformation. The natural log life (NL-Life) data for each cleaning method were reasonably normally (statistically) distributed and yielded standard deviations that were not significantly different among the five cleaning methods investigated. This made comparison of their NL-Life means very straightforward using a Bonferroni multiple comparison of means procedure. This procedure showed that the ALAS, UV-ozone and CFC 113 methods were not statistically significantly different from one another with respect to mean NL-Life. It also found that the SCF CO2 method yielded a significantly higher mean NL-Life than the mean NL-Lives of the ALAS, UV-ozone and CFC 113 methods. It also determined that the aqueous Brulin 815GD method yielded a mean NL-Life that was statistically significantly higher than the mean NL-Lives of each of the other four methods. Baseline tests using CFC 113 cleaned parts yielded a mean NL-Life 3.62 orbits/micro-g. ALAS and UV-ozone yielded similar mean NL-Life (3.31 orbits/mg and 3.33 orbits/micro-g, respectively). SCF CO2, gave a mean NL-Life of 4.08 orbits/mg and aqueous Brulin 8l5GD data yielded the longest mean NL-Life (4.66 orbits/micro-g).

Jansen, Mark J.↗

NASA NTRS2012

Time Manager Software for a Flight Processor

Data analysis is a process of inspecting, cleaning, transforming, and modeling data to highlight useful information and suggest conclusions. Accurate timestamps and a timeline of vehicle events are needed to analyze flight data. By moving the timekeeping to the flight processor, there is no longer a need for a redundant time source. If each flight processor is initially synchronized to GPS, they can freewheel and maintain a fairly accurate time throughout the flight with no additional GPS time messages received. How ever, additional GPS time messages will ensure an even greater accuracy. When a timestamp is required, a gettime function is called that immediately reads the time-base register.

Zoerne, Roger↗

NASA NTRS1993

ROSAT investigation of flaring and activity on Prox Cen

The objective of this program was to investigate with high sensitivity the low-level flare activity which may underlie coronal heating. This was done. The ROSAT observations of Prox Cen were scheduled for 50 ks spread out from 26 Feb. - 10 Mar. 1992. Unfortunately because of spacecraft problems many of these pointings turned out to contain no useful data or extremely truncated valid data sets. Considerable time was spent trying to determine which of the data would be scientifically useful and which would not. Fortunately, several developments took place to augment the original data in such a way that the scientific goal of advancing the study of flaring and variability was able to be achieved after all. These are as follows: (1) a second round of ROSAT observations was carried out in Feb. 1993 which only came to the attention of the PI in Apr. 1993 when a new data tape arrived; (2) simultaneous IUE observations were requested and obtained; (3) data from the UK WFC are available via the collaboration with Dr. G. Bromage; and (4) the 'cleaned-up' original data set was found to include one major flare and 2 moderate flares. Because of the problems with the original data set, the unexpected acquisition of new data only two months ago, and the availability of IUE and WFC data, an article on Prox Cen for publication is not ready at this time. Such an article is being developed and can be completed as part of ongoing ROSAT research efforts on stellar coronae and flaring.

Haisch, Bernhard↗

NASA NTRS1985

The effects of surface pretreatment and nitrogen tetroxide purification on the corrosion rate of Type 304L stainless steel

Corrosion rates of 304L stainless steel coupons in MON-1 oxidizer have been measured as a function of cleaning procedures employed, surface layer positions, propellant impurity levels, and short-term exposure durations (14 to 90 days). Of special interest was propellant contamination by buildup of soluble iron, which may cause flow decay. Surface treatments employed were combinations of cleaning, pickling, and passivation procedures. Propellants used were MIL-SPEC MON-1 and several types of purified NTO (i.e., low water, low chloride) which may, at a later time, be specified as spacecraft grade. Pretest coupon surface analysis by X-ray photoelectron spectroscopy (XPS-ESCA) has revealed important differences, for the different cleaning procedures, in the make-up of the surface layer, both in composition and state of chemical combination of the elements involved. Comparisons will be made of XPS/ESCA data, for different cleaning procedures, for specimens before and after propellant exposure.

Blue, G. D.↗

NASA NTRS1973

Application of ERTS data to the detection of thin cirrus and clean air turbulence

The author has identified the following significant results. The feasibility of detecting a thin cirrus and clear air turbulence from ERTS-1 MSS data is explored. The result of analyses indicates that a thin cirrus not shown in a conventional meteorological satellite picture can be revealed in ERTS-1 MSS pictures. Is also found that the core of jet stream can be located with high accuracy from ERTS-1 pictures and the possible area of clear air turbulence can be predicted if the data of the quality of ERTS-1 data are available in real time.

Tsuchiya, K.↗

NASA NTRS2024

Automated Detection of Spurious Signals in VLBI Phase Calibration Data

In this memorandum, a set of processing strategies for automatic masking of phase calibration tones is outlined as implemented in the software package PIMA in the task Generate Phase Calibration Mask, or GEPM. The task relies on a robust procedure of cleaning phase calibration data before employing several mathematical strategies designed to selectively identify spurious signals from phase calibration tones. These strategies were derived as more rigorous implementations of heuristics traditionally used by analysts in manually identifying problematic phase calibration data. The task is intended to automate the process of generating a phase calibration mask and in so doing increase the speed and regularity of VLBI analysis. At the outset of the project, a series of goals were identified to evaluate the success of this mask generation. This included the development of an algorithm to identify and mask short-term (defined as less than 10 seconds in length) spurious signals affecting phase calibration data, the development of an algorithm to identify and mask phase calibration tones affected by constant radio-frequency interference, the implementation of a detection scheme for identifying large jumps in phase calibration phase caused by clock breaks, and finally a method of reporting phase calibration health metrics to the user. Processing of over 10 experiments has demonstrated that the final form of the task GEPM as detailed in this technical memorandum satisfies each of these conditions and satisfactorily performs the task of automatic phase calibration data masking, although the wide variety in quality and characteristics of phase calibration data makes a single solution to the problem quite difficult. A series of user inputs have therefore been defined to assist analysts in tailoring automatic masking to specific stations and phase calibration generators. The vast majority of applicable code was written in FORTRAN to increase execution speed and ease of interfacing with the existing code base in PIMA, but a wrapper function in Python was also written to allow for a simpler method of interacting with GEPM and inputting relevant parameters. In addition to this report, thorough documentation was added to the already existing repositories associated with PIMA as a whole.

Geodesy↗

NASA NTRS1971

Experiment M405: Tri-axis flux gate magnetometer

A tri-axis flux-gate magnetometer was used on four Gemini spacecraft for determination of the magnitude and direction of the local geomagnetic field with respect to the spacecraft. Conclusions derived from the data are not only important to the proton-electron spectrometer experiment, but also are of significance to any directional charged particle experiments that may be conducted. Even though the Gemini spacecraft was not clean magnetically, the data could be reduced to a form that supplied directional information on the magnetic field in relation to the spacecraft. Stray fields were the result of spacecraft structure, not the result of current flows that were produced within the spacecraft electrical systems. Efforts were made to reduce spacecraft stray fields and to facilitate the acquisition of more accurate data.

Womack, W. D.↗

NASA NTRS2016

Erasing the Milky Way: New Cleaning Technique Applied to GBT Intensity Mapping Data

We present the first application of a new foreground removal pipeline to the current leading HI intensity mapping dataset, obtained by the Green Bank Telescope (GBT). We study the 15- and 1-h field data of the GBT observations previously presented in Masui et al. (2013) and Switzer et al. (2013), covering about 41 square degrees at 0.6 less than z is less than 1.0, for which cross-correlations may be measured with the galaxy distribution of the WiggleZ Dark Energy Survey. In the presented pipeline, we subtract the Galactic foreground continuum and the point source contamination using an independent component analysis technique (fastica), and develop a Fourier-based optimal estimator to compute the temperature power spectrum of the intensity maps and cross-correlation with the galaxy survey data. We show that fastica is a reliable tool to subtract diffuse and point-source emission through the non-Gaussian nature of their probability distributions. The temperature power spectra of the intensity maps is dominated by instrumental noise on small scales which fastica, as a conservative sub-traction technique of non-Gaussian signals, can not mitigate. However, we determine similar GBT-WiggleZ cross-correlation measurements to those obtained by the Singular Value Decomposition (SVD) method, and confirm that foreground subtraction with fastica is robust against 21cm signal loss, as seen by the converged amplitude of these cross-correlation measurements. We conclude that SVD and fastica are complementary methods to investigate the foregrounds and noise systematics present in intensity mapping datasets.

Wolz, L.↗