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NASA NTRS2011

Overview and Assessment of Antarctic Ice-Sheet Mass Balance Estimates: 1992-2009

Mass balance estimates for the Antarctic Ice Sheet (AIS) in the 2007 report by the Intergovernmental Panel on Climate Change and in more recent reports lie between approximately ?50 to -250 Gt/year for 1992 to 2009. The 300 Gt/year range is approximately 15% of the annual mass input and 0.8 mm/year Sea Level Equivalent (SLE). Two estimates from radar altimeter measurements of elevation change by European Remote-sensing Satellites (ERS) (?28 and -31 Gt/year) lie in the upper part, whereas estimates from the Input-minus-Output Method (IOM) and the Gravity Recovery and Climate Experiment (GRACE) lie in the lower part (-40 to -246 Gt/year). We compare the various estimates, discuss the methodology used, and critically assess the results. We also modify the IOM estimate using (1) an alternate extrapolation to estimate the discharge from the non-observed 15% of the periphery, and (2) substitution of input from a field data compilation for input from an atmospheric model in 6% of area. The modified IOM estimate reduces the loss from 136 Gt/year to 13 Gt/year. Two ERS-based estimates, the modified IOM, and a GRACE-based estimate for observations within 1992 2005 lie in a narrowed range of ?27 to -40 Gt/year, which is about 3% of the annual mass input and only 0.2 mm/year SLE. Our preferred estimate for 1992 2001 is -47 Gt/year for West Antarctica, ?16 Gt/year for East Antarctica, and -31 Gt/year overall (?0.1 mm/year SLE), not including part of the Antarctic Peninsula (1.07% of the AIS area). Although recent reports of large and increasing rates of mass loss with time from GRACE-based studies cite agreement with IOM results, our evaluation does not support that conclusion

Zwally, H. Jay↗

NASA NTRS2012

Potassium Stable Isotopic Compositions Measured by High-Resolution MC-ICP-MS

Potassium isotopic (K-41/K-39) compositions are notoriously difficult to measure. TIMS measurements are hindered by variable fractionation patterns throughout individual runs and too few isotopes to apply an internal spike method for instrumental mass fractionation corrections. Internal fractionation corrections via the K-40/K-39 ratio can provide precise values but assume identical K-40/K-39 ratios (e.g. 0.05% (1sigma) in [1]); this is appropriate in some cases (e.g. identifying excess K-41) but not others (e.g., determining mass fractionation effects and metrologically traceable isotopic abundances). SIMS analyses have yielded measurements with 0.25% precisions (1sigma) [2]. ICP-MS analyses are significantly affected by interferences from molecular species such as Ar-38H(+) and Ar-40H(+) and instrument mass bias. Single collector ICP-MS instruments in "cold plasma" mode have yielded uncertainties as low as 2% (1sigma, e.g. [3]). Although these precisions may be acceptable for some concentration determinations, they do not resolve isotopic variation in terrestrial materials. Here we present data from a series of measurements made on the Thermo Scientific NEPTUNE Plus multi-collector ICP-MS that demonstrate the ability to make K-41/K-39 ratio measurements with 0.07% precisions (1sigma). These data, collected on NIST K standards, indicate the potential for MC-ICP-MS measurements to look for K isotopic variations at the sub-permil level. The NEPTUNE Plus can sufficiently resolve 39K and 41K from the interfering 38ArH+ and 40ArH+ peaks in wet cold plasma and high-resolution mode. Measurements were made on small but flat, interference-free, plateaus (ca. 50 ppm by mass width for K-41). Although ICP-MS does not yield accurate K-41/K-39 values due to significant instrumental mass fractionation (ca. 6%), this bias can be sufficiently stable over the time required for several measurements so that relative K-41/K-39 values can be precisely determined via sample-standard bracketing. As cold plasma conditions can amplify matrix effects, experiments were conducted to test the matrix tolerance of measurements; the use of clean, matrix-matched samples and standards is critical. Limitations of the cold-plasma high-resolution MC-ICP-MS methodology with respect to matrix tolerance are discussed and compared with the limitations of TIMS methodologies.

Morgan, Leah E.↗

NASA NTRS2012

Burning Questions in Gravity-Dependent Combustion Science

Building upon a long history of spaceflight and ground based research, NASA's Combustion Science program has accumulated a significant body of accomplishments on the ISS. Historically, NASAs low-gravity combustion research program has sought: to provide a more complete understanding of the fundamental controlling processes in combustion by identifying simpler one-dimensional systems to eliminate the complex interactions between the buoyant flow and the energy feedback to the reaction zone to provide realistic simulation of the fire risk in manned spacecraft and to enable practical simulation of the gravitational environment experienced by reacting systems in future spacecraft. Over the past two decades, low-gravity combustion research has focused primarily on increasing our understanding of fundamental combustion processes (e.g. droplet combustion, soot, flame spread, smoldering, and gas-jet flames). This research program was highly successful and was aided by synergistic programs in Europe and in Japan. Overall improvements were made in our ability to model droplet combustion in spray combustors (e.g. jet engines), predict flame spread, predict soot production, and detect and prevent spacecraft fires. These results provided a unique dataset that supports both an active research discipline and also spacecraft fire safety for current and future spacecraft. These experiments have been conducted using the Combustion Integrated Rack (CIR), the Microgravity Science Glovebox and the Express Rack. In this paper, we provide an overview of the earlier space shuttle experiments, the recent ISS combustion experiments in addition to the studies planned for the future. Experiments in combustion include topics such as droplet combustion, gaseous diffusion flames, solid fuels, premixed flame studies, fire safety, and super critical oxidation processes.

Urban, David↗

NASA NTRS2016

Cleaning Genesis Sample Return Canister for Flight: Lessons for Planetary Sample Return

Sample return missions require chemical contamination to be minimized and potential sources of contamination to be documented and preserved for future use. Genesis focused on and successfully accomplished the following: - Early involvement provided input to mission design: a) cleanable materials and cleanable design; b) mission operation parameters to minimize contamination during flight. - Established contamination control authority at a high level and developed knowledge and respect for contamination control across all institutions at the working level. - Provided state-of-the-art spacecraft assembly cleanroom facilities for science canister assembly and function testing. Both particulate and airborne molecular contamination was minimized. - Using ultrapure water, cleaned spacecraft components to a very high level. Stainless steel components were cleaned to carbon monolayer levels (10 (sup 15) carbon atoms per square centimeter). - Established long-term curation facility Lessons learned and areas for improvement, include: - Bare aluminum is not a cleanable surface and should not be used for components requiring extreme levels of cleanliness. The problem is formation of oxides during rigorous cleaning. - Representative coupons of relevant spacecraft components (cut from the same block at the same time with identical surface finish and cleaning history) should be acquired, documented and preserved. Genesis experience suggests that creation of these coupons would be facilitated by specification on the engineering component drawings. - Component handling history is critical for interpretation of analytical results on returned samples. This set of relevant documents is not the same as typical documentation for one-way missions and does include data from several institutions, which need to be unified. Dedicated resources need to be provided for acquiring and archiving appropriate documents in one location with easy access for decades. - Dedicated, knowledgeable contamination control oversight should be provided at sites of fabrication and integration. Numerous excellent Genesis chemists and analytical facilities participated in the contamination oversight; however, additional oversight at fabrication sites would have been helpful.

Allton, J. H.↗

NASA NTRS2015

A New Technique for the Retrieval of Near Surface Water Vapor Using DIAL Measurements

Water vapor is one of the most important atmospheric trace gas species and influences radiation, climate, cloud formation, surface evaporation, precipitation, storm development, transport, dynamics, and chemistry. For improvements in NWP (numerical weather prediction) and climate studies, global water vapor measurements with higher accuracy and vertical resolution are needed than are currently available. Current satellite sensors are challenged to characterize the content and distribution of water vapor in the Boundary Layer (BL) and particularly near the first few hundred meters above the surface within the BL. These measurements are critically needed to infer surface evaporation rates in cloud formation and climate studies. The NASA Langley Research Center Lidar Atmospheric Sensing Experiment (LASE) system, which uses the Differential Absorption Lidar (DIAL) technique, has demonstrated the capability to provide high quality water vapor measurements in the BL and across the troposphere. A new retrieval technique is investigated to extend these DIAL water vapor measurements to the surface. This method uses signals from both atmospheric backscattering and the strong surface returns (even over low reflectivity oceanic surfaces) using multiple gain channels to cover the large signal dynamic range. Measurements can be made between broken clouds and in presence of optically thin cirrus. Examples of LASE measurements from a variety of conditions encountered during NASA hurricane field experiments over the Atlantic Ocean are presented. Comparisons of retrieved water vapor profiles from LASE near the surface with dropsonde measurements show very good agreement. This presentation also includes a discussion of the feasibility of developing space-based DIAL capability for high resolution water vapor measurements in the BL and above and an assessment of the technology needed for developing this capability.

Ismail, Syed↗

NASA NTRS2016

GeneLab: Multi-Omics Investigation of Rodent Research-1 Bio-Banked Tissues

NASAs Rodent Research (RR) project is playing a critical role in advancing biomedical research on the physiological effects of space environments. Due to the limited resources for conducting biological experiments aboard the International Space Station (ISS), it is imperative to use crew time efficiently while maximizing high-quality science return. NASAs GeneLab project has as its primary objectives to 1) further increase the value of these experiments using a multi-omics, systems biology-based approach, and 2) disseminate these data without restrictions to the scientific community. The current investigation assessed viability of RNA, DNA, and protein extracted from archived RR-1 tissue samples for epigenomic, transcriptomic, and proteomic assays. During the first RR spaceflight experiment, a variety of tissue types were harvested from subjects, snap-frozen or RNAlater-preserved, and then stored at least a year at -80OC after return to Earth. They were then prioritized for this investigation based on likelihood of significant scientific value for spaceflight research. All tissues were made available to GeneLab through the bio-specimen sharing program managed by the Ames Life Science Data Archive and included mouse adrenal glands, quadriceps, gastrocnemius, tibialis anterior, extensor digitorum longus, soleus, eye, and kidney. We report here protocols for and results of these tissue extractions, and thus, the feasibility and value of these kinds of omics analyses. In addition to providing additional opportunities for investigation of spaceflight effects on the mouse transcriptome and proteome in new kinds of tissues, our results may also be of value to program managers for the prioritization of ISS crew time for rodent research activities. Support from the NASA Space Life and Physical Sciences Division and the International Space Station Program is gratefully acknowledged.

GeneLab↗

NASA NTRS2018

Improving Scientific Payload Communication Over Multiple, Low-Capacity Links

Communication is an important part of every airborne science mission. It provides a means for a large group of ground-based scientists to monitor and adjust experiments aboard aircraft that often cannot support a large number of passengers. In some cases, such as unmanned aircraft, communication becomes critical to a successful mission. Existing communication systems require the use of multiple, low-capacity channels, or links, to handle the capacity requirements of the scientists. Current communication solutions attempt to balance performance and reliability, but ultimately suffer from some critical design flaws that limit the ability of the system to handle additional links. We show how adding resources to the current system results in decreased performance and reliability. We explore the use of a new communication protocol, MultiPath Transmission Control Protocol, to make better use of multiple communication links and propose a total system capable of scaling to any number of channels efficiently and dynamically. The tools developed to support and measure this solution are also detailed.

MPTCP↗

NASA NTRS2019

NASA Wallops Overview of Rideshare Mission Integration Capability

Highlighting Wallops capabilities to support the Agency's new rideshare initiative. The presentation covers Wallops' capabilities experience with previous programs of similar nature and highlights examples of recent projects that have ideally positioned Wallops to play a critical role in implementation of the NASA rideshare initiative.

Wilcox, David A.↗

NASA NTRSDate not supplied

Developing Soft Skill in the Geosciences: NASA DEVELOP’s Approach to Strengthening Soft Skills in the Future Geospatial Workforce

Part of NASA’s Applied Sciences, the DEVELOP Program bridges the gap between NASA Earth Science and potential users through rapid feasibility studies that apply Earth observations to environmental decision making needs. The program conducts 50-60 studies a year that engage participants – students, recent graduates, early career individuals, and transitioning career professionals – in autonomous teamwork with an emphasis on professional development and communication. The experience offers participants a robust opportunity to build their teaming skills (facilitated through programmatic personality assessments and discussions), interpersonal communication, and critical thinking skills which are central to project work in the DEVELOP model. The program also offers leadership opportunities where participants lead their peers within a supportive environment. This presentation will introduce the DEVELOP model for soft skill development, lessons learned, and highlight testimonials of past participants.

Amanda Clayton↗

NASA NTRSDate not supplied

Four Problematic Methods in Reliability Analysis

Some basic methods used in reliability analysis are problematic because they produce incorrect and overoptimistic predictions. Initially gratifying forecasts are often invalidated by testing and operational experience. The problematic methods in reliability analysis include estimating the system failure rate as the sum of component failure rates, assuming that reliability growth continues indefinitely during testing, overestimating the benefits of redundancy, and using the fault tolerance count instead of a detailed reliability analysis. Reliability analysis can produce more optimism than accuracy. This bug may now be a feature. The optimistic bias inevitable in project planning should be corrected by realistic reliability analysis that reflects relevant experience. That the repeated poor performance of reliability analysis is found to be surprising suggests willful blindness. Rigorous methods and impartial critical review are necessary to improve reliability analysis.

Reliability analysis↗

NASA NTRSDate not supplied

Four Problematic Methods in Reliability Analysis

Reliability analysis↗

NASA NTRS2026

Thermal Considerations for 2039 Opposition Class Nuclear Electric Propulsion/Chemical Propulsion Crewed Mars Mission

The high specific impulse (Isp) of Nuclear Electric Propulsion (NEP) technology offers the potential for advanced space mission capabilities. However, the five critical technology elements of NEP vehicles have yet to prove technical maturity levels for consideration into mission design. In response to the critical reviews by the NASA Engineering and Safety Center (NESC) and the National Academies of Sciences, Engineering, and Medicine (NASEM), NASA’s Space Nuclear Propulsion (SNP) project created an NEP Technology Maturation Plan (TMP) for focused development of NEP technology. The TMP called for a coordinated set of technology development efforts to meet this objective. The Modular Assembled Radiators for NEP VehicLes (MARVL) Early Career Initiative (ECI) project was initiated to develop a portion of the fifth Critical Technology Element (CTE) of the NEP vehicle: the Primary Heat Rejection Subsystem (PHRS). A target application of a 2039 human-rated Mars mission was outlined in the TMP. For the outlined mission, a NEP vehicle will experience several thermal environments which will impact the design and operation of the PHRS. To maintain radiator temperatures within the required effective temperature range, the effect of natural, induced, and NEP internally generated heat loads on the radiator panel must be well understood. Furthermore, this analysis is critical for analyzing the influence of various orientations and positions of the NEP vehicle relative to nearby celestial bodies throughout the mission. This study conducted a complete enveloping analysis of the thermal environments influencing the NEP vehicle throughout the mission. Thermal analysis was conducted for the radiator panels based on the defined mission environments. This thermal analysis concludes with the selection of ideal radiator orientations for the NEP vehicle, and the identification of worst case hot and cold environmental sink temperatures throughout the mission. For the target application, the environmental sink temperature while the reactor is powered OFF or powered ON ranges from 30 K to 353 K and 2.7 K to 243 K respectively. When considering interplanetary space, the minimum environmental sink temperature when the reactor is powered OFF and the radiators are oriented “edge to Sun” is 2.7 K. The environmental thermal models generated in this study will be used for future studies with the full vehicle system model. The environmental sink temperature curves generated will be used for future radiator and component analysis to predict transient performance in the space environment. The environmental sink temperature and heat rejection capability curves will inform the trade between commissioning orbits that are in consideration. The model may also serve as a useful tool as reference for future crewed space missions, missions involving radiators or temperature sensitive equipment, or other missions requiring analysis of natural orbital thermal environments.

Nuclear Electric Propulsion↗

NASA NTRS2012

A Posteriori Study of a DNS Database Describing Super critical Binary-Species Mixing

Currently, the modeling of supercritical-pressure flows through Large Eddy Simulation (LES) uses models derived for atmospheric-pressure flows. Those atmospheric-pressure flows do not exhibit the particularities of high densitygradient magnitude features observed both in experiments and simulations of supercritical-pressure flows in the case of two species mixing. To assess whether the current LES modeling is appropriate and if found not appropriate to propose higher-fidelity models, a LES a posteriori study has been conducted for a mixing layer that initially contains different species in the lower and upper streams, and where the initial pressure is larger than the critical pressure of either species. An initially-imposed vorticity perturbation promotes roll-up and a double pairing of four initial span-wise vortices into an ultimate vortex that reaches a transitional state. The LES equations consist of the differential conservation equations coupled with a real-gas equation of state, and the equation set uses transport properties depending on the thermodynamic variables. Unlike all LES models to date, the differential equations contain, additional to the subgrid scale (SGS) fluxes, a new SGS term that is a pressure correction in the momentum equation. This additional term results from filtering of Direct Numerical Simulation (DNS) equations, and represents the gradient of the difference between the filtered pressure and the pressure computed from the filtered flow field. A previous a priori analysis, using a DNS database for the same configuration, found this term to be of leading order in the momentum equation, a fact traced to the existence of high-densitygradient magnitude regions that populated the entire flow; in the study, models were proposed for the SGS fluxes as well as this new term. In the present study, the previously proposed constantcoefficient SGS-flux models of the a priori investigation are tested a posteriori in LES, devoid of or including, the SGS pressure correction term. The present pressure-correction model is different from, and more accurate as well as less computationally intensive than that of the a priori study. The constant-coefficient SGS-flux models encompass the Smagorinsky (SMC), in conjunction with the Yoshizawa (YO) model for the trace, the Gradient (GRC) and the Scale Similarity (SSC) models, all exercised with the a priori study constant coefficients calibrated at the transitional state. The LES comparison is performed with the filtered- and-coarsened (FC) DNS, which represents an ideal LES solution. Expectably, an LES model devoid of SGS terms is shown to be considerably inferior to models containing SGS effects. Among models containing SGS effects, those including the pressure-correction term are substantially superior to those devoid of it. The sensitivity of the predictions to the initial conditions and grid size are also investigated. Thus, it has been discovered that, additional to the atmospheric-pressure models currently used, a new model is necessary to simulate supercritical-pressure flows. This model depends on the thermodynamic characteristics of the chemical species involved.

Bellan, Josette↗

NASA NTRS1995

The subscale orbital fluid transfer experiment

The work during the present year consisted of examining concepts for visual observation of the fluid transfer process, examination of methods for accurately metering the amount of liquid transferred between the two tanks, examination of possible test fluids, and consideration of the materials to use for the elastomeric diaphragm. The objective of the visual observation is to locate the fluid-vapor interfaces and, if possible, quantify the amount of vapor and the area of the interface. It is proposed to use video cameras to view the overall process in each tank and to place borescopes or other devices through the tank walls to obtain detailed, undistorted views inside the tanks of critical portions of the transfer process. Further work will continue to find an economical means for providing this detailed view, which clearly would increase the data obtained from the experiment.

Meserole, J. S.↗

NASA NTRS1988

An experiment in software reliability: Additional analyses using data from automated replications

A study undertaken to collect software error data of laboratory quality for use in the development of credible methods for predicting the reliability of software used in life-critical applications is summarized. The software error data reported were acquired through automated repetitive run testing of three independent implementations of a launch interceptor condition module of a radar tracking problem. The results are based on 100 test applications to accumulate a sufficient sample size for error rate estimation. The data collected is used to confirm the results of two Boeing studies reported in NASA-CR-165836 Software Reliability: Repetitive Run Experimentation and Modeling, and NASA-CR-172378 Software Reliability: Additional Investigations into Modeling With Replicated Experiments, respectively. That is, the results confirm the log-linear pattern of software error rates and reject the hypothesis of equal error rates per individual fault. This rejection casts doubt on the assumption that the program's failure rate is a constant multiple of the number of residual bugs; an assumption which underlies some of the current models of software reliability. data raises new questions concerning the phenomenon of interacting faults.

Dunham, Janet R.↗

NASA NTRS1997

Analyses of Technology for Solid State Coherent Lidar

Over past few years, considerable advances have been made in the areas of the diode-pumped, eye-safe, solid state lasers and room temperature, wide bandwidth, semiconductor detectors operating in the near-infrared region. These advances have created new possibilities for the development of reliable and compact coherent lidar systems for a wide range of applications. This research effort is aimed at further developing solid state coherent lidar technology for remote sensing of atmospheric processes such as wind, turbulence and aerosol concentration. The work performed by the UAH personnel under this Delivery Order concentrated on design and analyses of laboratory experiments and measurements, and development of advanced lidar optical subsystems in support of solid state laser radar remote sensing systems which are to be designed, deployed, and used to measure atmospheric processes and constituents. Under this delivery order, a lidar breadboard system was designed and analyzed by considering the major aircraft and space operational requirements. The lidar optical system was analyzed in detail using SYNOPSIS and Code V optical design packages. The lidar optical system include a wedge scanner and the compact telescope designed by the UAH personnel. The other major optical components included in the design and analyses were: polarizing beam splitter, routing mirrors, wave plates, signal beam derotator, and lag angle compensator. This lidar system is to be used for demonstrating all the critical technologies for the development of a reliable and low-cost space-based instrument capable of measuring global wind fields. A number of laboratory experiments and measurements were performed at the NASA/MSFC Detector Characterization Facility, previously developed by the UAH personnel. These laboratory measurements include the characterization of a 2-micron InGaAs detectors suitable for use in coherent lidars and characterization of Holographic Optical Element Scanners. UAH personnel actively participated in the development of performance and operational requirements for the development of the high pulse energy transmitter laser and frequency-agile local oscillator laser, that are in-progress at NASA Langley Research Center and Jet Propulsion Laboratory.

Amzajerdian, Farzin↗

NASA NTRS1991

The CONE program - An overview

The Cryogenic Orbital Nitrogen Experiment (CONE) is a liquid nitrogen cryogenic storage and supply system demonstration placed in orbit by the National Space Transportation System (NSTS) Orbiter and operated as an in-bay payload whose objective is to demonstrate needed critical components and technologies. A conceptual approach has been developed and an overview of the CONE program is described which includes the following: (1) a definition of the background and scope of the technology objectives being investigated, (2) a description of the payload design and operation, major features and rationale for the experiments being conducted, and (3) the justification for CONE relating to potential near-term benefits and risk mitigation for future systems.

Bailey, William J.↗

NASA NTRS1972

Preparative electrophoresis experiment design

A multifaceted study supporting the NASA programs to develop a space electrophoresis capability has been conducted. The study involved principally the technique of continuous free electrophoresis. It comprised a critical review of the art, study of new techniques for enhancing resolution and stability, and construction and initial testing of a high resolution cell. The effort resulted in a significant advance in free electrophoresis technique. It has provided also a much improved base for developments exploiting the added advantages of a zero-gravity environment.

Thiehler, A.↗