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NASA NTRS2019

Improving Accuracy of Structural Dynamic Modification with Augmented Residual Vectors

It is often important to perform sensitivity analysis to determine how a structural model will be impacted by design changes. Often, the structural analysts will manually make changes to the finite element model (FEM) to determine the effects. But when dealing with a large FEM with millions of degrees of freedom these manual changes can be cumbersome and calculation of the effects can computationally expensive. Therefore, it is desirable to determine the effects of model changes through approximation methods. One common technique is to determine the analytical sensitivity of the FEM model with respect to the given change. These analytical sensitivities are valid when small changes are made to the structural model, but invalid if large changes need to be assessed. Another approach is to use Structural Dynamic Modification (SDM) to create a surrogate model to analyze model changes. SDM is a widely-used sensitivity method and is used in applications of model updating, uncertainty quantification, and model design studies. SMD is valid for moderate (10-20 percent) changes in the structural model, but model approximations are often needed for large parameter changes (greater than 20 percent). Structural Dynamic Modification can be improved by using residual vectors to augment the surrogate model formulation from SDM. Adding the residual modes increases the fidelity of the surrogate model while keeping the computational cost low. This paper discusses the application and limitations of the augmented residual modes method to two structures: the Integrated Spacecraft and Payload Element (ISPE) of the Space Launch System (SLS) and the full SLS as it is configured during its Integrated Modal Test (IMT).

Stewart, Eric C.↗

NASA NTRS2005

Wavelengths, f-Values, and Cross Sections in the UV Spectra of Astrophysical, Atoms, Ions, and Molecules

Data analysis for Fe III was completed in 2004. The new spectra give wavelengths and some energy levels for Fe III that are at least an order of magnitude more accurate than values in the literature. However, the data set is missing - because they are outside the wavelength range that we can study at Imperial College or with ancillary FT spectroscopy measurements at NIST - important transitions that would allow all energy levels to be determined with improved accuracy. We are assessing collaborations at other labs. We have made test runs with a number of cathodes (pure metals and alloys) in the Penning discharge source and selected four iron group (3d) elements, Cr, Mn, Co, and Ni, for further measurements. Cathodes of pure Cr and Co and an alloy of Ni were found to be best. Mn has not nm stably yet, and other cathode geometries or alloys may need to be assessed. Optimum Penning discharge (PD) lamp conditions (buffer gas, gas pressure, and current/voltage) were established for Co, and investigations are underway for Cr and Ni. Definitive measurements for Co await purchase of new mirrors and photomultiplier tubes that will improve signal to noise ratio. Our plan for the next year is to continue evaluating cathodes and operating conditions through March 05, and then to begin definitive measurements. The UV wavelength measurements made at Imperial College with the unique UV FT spectrometer will be complemented by visible and near IR range measurements at NIST in June and/or July. Approximately one year from now, we intend to visit Lund University to collaborate on lifetime measurements that will allow our branching ration data to be used to determine f-values.

Raymond, John C.↗

NASA NTRS1994

The Development of Silicon Carbide Based Hydrogen and Hydrocarbon Sensors

Silicon carbide is a high temperature electronic material. Its potential for development of chemical sensors in a high temperature environment has not been explored. The objective of this study is to use silicon carbide as the substrate material for the construction of chemical sensors for high temperature applications. Sensors for the detection of hydrogen and hydrocarbon are developed in this program under the auspices of Lewis Research Center, NASA. Metal-semiconductor or metal-insulator-semiconductor structures are used in this development. Specifically, using palladium-silicon carbide Schottky diodes as gas sensors in the temperature range of 100 to 400 C are designed, fabricated and assessed. The effect of heat treatment on the Pd-SiC Schottky diode is examined. Operation of the sensors at 400 C demonstrate sensitivity of the sensor to hydrogen and hydrocarbons. Substantial progress has been made in this study and we believe that the Pd-SiC Schottky diode has potential as a hydrogen and hydrocarbon sensor over a wide range of temperatures. However, the long term stability and operational life of the sensor need to be assessed. This aspect is an important part of our future continuing investigation.

Liu, Chung-Chiun↗

NASA NTRS2006

In-Space Cryogenic Propellant Depot (ISCPD) Architecture Definitions and Systems Studies

The objectives of the ISCPD Architecture Definitions and Systems Studies were to determine high leverage propellant depot architecture concepts, system configuration trades, and related technologies to enable more ambitious and affordable human and robotic exploration of the Earth Neighborhood and beyond. This activity identified architectures and concepts that preposition and store propellants in space for exploration and commercial space activities, consistent with Exploration Systems Research and Technology (ESR&T) objectives. Commonalities across mission scenarios for these architecture definitions, depot concepts, technologies, and operations were identified that also best satisfy the Vision of Space Exploration. Trade studies were conducted, technology development needs identified and assessments performed to drive out the roadmap for obtaining an in-space cryogenic propellant depot capability. The Boeing Company supported the NASA Marshall Space Flight Center (MSFC) by conducting this Depot System Architecture Development Study. The primary objectives of this depot architecture study were: (1) determine high leverage propellant depot concepts and related technologies; (2) identify commonalities across mission scenarios of depot concepts, technologies, and operations; (3) determine the best depot concepts and key technology requirements and (4) identify technology development needs including definition of ground and space test article requirements.

Fikes, John C.↗

NASA NTRS2005

Learning Science Through Visualization

In the context of an introductory physical science course for non-science majors, I have been trying to understand how scientific visualizations of natural phenomena can constructively impact student learning. I have also necessarily been concerned with the instructional and assessment approaches that need to be considered when focusing on learning science through visually rich information sources. The overall project can be broken down into three distinct segments : (i) comparing students' abilities to demonstrate proportional reasoning competency on visual and verbal tasks (ii) decoding and deconstructing visualizations of an object falling under gravity (iii) the role of directed instruction to elicit alternate, valid scientific visualizations of the structure of the solar system. Evidence of student learning was collected in multiple forms for this project - quantitative analysis of student performance on written, graded assessments (tests and quizzes); qualitative analysis of videos of student 'think aloud' sessions. The results indicate that there are significant barriers for non-science majors to succeed in mastering the content of science courses, but with informed approaches to instruction and assessment, these barriers can be overcome.

Chaudhury, S. Raj↗

NASA NTRS2016

Risk of Performance Decrements and Adverse Health Outcomes Resulting from Sleep Loss, Circadian Desynchronization, and Work Overload

Sleep loss, circadian desynchronization, and work overload occur to some extent for ground and flight crews, prior to and during spaceflight missions. Ground evidence indicates that such risk factors may lead to performance decrements and adverse health outcomes, which could potentially compromise mission objectives. Efforts are needed to identify the environmental and mission conditions that interfere with sleep and circadian alignment, as well as individual differences in vulnerability and resiliency to sleep loss and circadian desynchronization. Specifically, this report highlights a collection of new evidence to better characterize the risk and reveals new gaps in this risk as follows: Sleep loss is apparent during spaceflight. Astronauts consistently average less sleep during spaceflight relative to on the ground. The causes of this sleep loss remain unknown, however ground-based evidence suggests that the sleep duration of astronauts is likely to lead to performance impairment and short and long-term health consequences. Further research is needed in this area in order to develop screening tools to assess individual astronaut sleep need in order to quantify the magnitude of sleep loss during spaceflight; current and planned efforts in BHP's research portfolio address this need. In addition, it is still unclear whether the conditions of spaceflight environment lead to sleep loss or whether other factors, such as work overload lead to the reduced sleep duration. Future data mining efforts and continued data collection on the ISS will help to further characterize factors contributing to sleep loss. Sleep inertia has not been evaluated during spaceflight. Ground-based studies confirm that it takes two to four hours to achieve optimal performance after waking from a sleep episode. Sleep inertia has been associated with increased accidents and reduced performance in operational environments. Sleep inertia poses considerable risk during spaceflight when emergency situations necessitate that crewmembers wake from sleep and make quick decisions. A recently completed BHP investigation assesses the effects of sleep inertia upon abrupt awakening, with and without hypnotics currently used in spaceflight; results from this investigation will help to inform strategies relative to sleep inertia effects on performance. Circadian desynchrony has been observed during spaceflight. Circadian desynchrony during spaceflight develops due to schedule constraints requiring non-24 operations or 'slam-shifts' and due to insufficient or mis-timed light exposure. In addition, circadian misalignment has been associated with reduced sleep duration and increased medication use. In ground-based studies, circadian desynchrony has been associated with significant performance impairment and increased risk of accidents when operations coincide with the circadian nadir. There is a great deal of information available on how to manage circadian misalignment, however, there are currently no easily collected biomarkers that can be used during spaceflight to determine circadian phase. Current research efforts are addressing this gap. Work overload has been documented during current spaceflight operations. NASA has established work hour guidelines that limit shift duration, however, schedule creep, where duty requirements necessitate working beyond scheduled work hours, has been reported. This observation warrants the documentation of actual work hours in order to improve planning and in order to ensure that astronauts receive adequate down time. In addition to concerns about work overload, ground based evidence suggests that work underload may be a concern during deep space missions, where torpor may develop and physically demanding workload will be exchanged for monitoring of autonomous systems. Given that increased automation is anticipated for exploration vehicles, fatigue effects in the context of such systems needs to be further understood. Performance metrics are needed to evaluate fitness-for-duty during spaceflight. Although ground-based evidence supports the notion that sleep loss, circadian desynchronization and work overload lead to performance impairment, inconsistency in the measures used to evaluate performance during spaceflight make it difficult to evaluate the magnitude of performance impairment during spaceflight. Work is underway to standardize measures of performance evaluation during spaceflight. Once established, such performance indicators need to be correlated with operational performance. Individual differences in sleep need and circadian preference, phase shifting ability and period have been documented in ground-based studies. Individual differences in response to sleep loss and circadian misalignment have also been documented and are presumed to be associated with genetic polymorphisms. No studies have systematically reported individual differences in sleep or circadian-related outcomes during spaceflight. More work is needed in this area in order to identify genetic or phenotypic biomarkers that predict resilience or vulnerability to sleep loss in order to personalize countermeasure strategies and mitigate performance impairment during spaceflight. Two laboratory and field investigations specific to this topic are currently ongoing; additional efforts, including an effort to mine existing biological data from spaceflight relative to sleep and circadian outcomes, are planned. Sex differences in sleep need and circadian period and phase have been reported in ground-based studies. The impact of these sex differences on performance is unclear. Sex differences in sleep need and circadian rhythms have not been systematically studied during spaceflight, presumably due to the small number of women that have flown in space. More research is needed in this area to evaluate whether any of the observed sex differences in physiology lead to altered performance in spaceflight and on the ground.

Flynn-Evans, Erin↗

NASA NTRS2023

Implementing the GEOSS Water Strategy: From Observations to Decisions

In 2014, The GEOSS Water Strategy – From Observations to Decisions was published and steps were taken to implement the Strategy’s recommendations. The Strategy highlighted priority areas where the application of Earth observations to water research and water management decisions would have significant scientific and societal benefits. This article reviews the implementation of the Strategy’s recommendations over the past eight years. After a review of the Strategy’s assessment of the needs for water observations and their applications, it then reviews actions taken in response to the Strategy’s recommendations in its four major themes: improved data acquisition for Essential Water Variables, research and product development, interoperability, and capacity development. It highlights significant achievements in the implementation of the Strategy including some motivated by factors beyond this Strategy, reviews actions taken by participating agencies and programs for each of the main themes and summarizes the remaining challenges in achieving the Strategy’s full implementation. The article not only is an update for the Water Community regarding the GEOSS Water Strategy, but it is also an example of how other communities could develop and promulgate a set of strategic recommendations, monitor progress, and carry out assessments of their effectiveness.

Earth observations↗

NASA NTRS1990

An assessment of potential degradation products in the gas-phase reactions of alternative fluorocarbons in the troposphere

Tropospheric chemical transformations of alternative hydrofluorocarbons (HCF's) and hydrochlorofluorocarbons (HCFC's) are governed by hydroxyl radical initiated oxidation processes, which are likely to be analogous to those known for alkanes and chloroalkanes. A schematic diagram is used to illustrate plausible reaction mechanisms for their atmospheric degradation, where R, R', and R'' denote the F- and/or Cl-substituted alkyl groups derived from HCF's and HCFC's subsequent th the initial H atom abstraction by HO radicals. At present, virtually no kinetic data exist for the majority of these reactions, particularly for those involving RO. Potential degradation intermediates and final products include a large variety of fluorine- and/or chlorine-containing carbonyls, acids, peroxy acids, alcohols, hydrogen peroxides, nitrates and peroxy nitrates, as summarized in the attached table. Probably atmospheric lifetimes of these compounds were also estimated. For some carbonyl and nitrate products shown in this table, there seem to be no significant gas-phase removal mechanisms. Further chemical kinetics and photochemical data are needed to quantitatively assess the atmospheric fate of HCF's and HCFC's, and of the degradation products postulated in this report.

Niki, Hiromi↗

NASA NTRS2015

Comparative Analysis of Static and Dynamic Probabilistic Risk Assessment

This study examines three different methodologies for producing loss-of-mission (LOM) and loss-of-crew (LOC) risks estimates for probabilistic risk assessments (PRA) of crewed spacecraft. The three bottom-up, component-based PRA approaches examined are a traditional static fault tree, a dynamic Monte Carlo simulation, and a fault tree hybrid that incorporates some dynamic elements. These approaches were used to model the reaction control system thruster pod of a generic crewed spacecraft and mission, and a comparative analysis of the methods is presented. The methodologies are assessed in terms of the process of modeling a system, the actionable information produced for the design team, and the overall fidelity of the quantitative risk evaluation generated. The system modeling process is compared in terms of the effort required to generate the initial model, update the model in response to design changes, and support mass-versus-risk trade studies. The results are compared by examining the top-level LOM/LOC estimates and the relative risk driver rankings at the failure mode level. The fidelity of each modeling methodology is discussed in terms of its capability to handle real-world system dynamics such as cold-sparing, changes in mission operations due to loss of redundancy, and common cause failure modes. The paper also discusses the applicability of each methodology to different phases of system development and shows that a single methodology may not be suitable for all of the many purposes of a spacecraft PRA. The fault tree hybrid approach is shown to be best suited to the needs of early assessments during conceptual design phases. As the design begins to mature, the level of detail represented in the risk model must go beyond redundancy and nominal mission operations to include dynamic, time- and state-dependent system responses as well as diverse system capabilities. This is best accomplished using the dynamic simulation approach, since these phenomena are not easily captured by static methods. Ultimately, once the design has been finalized and the goal of the PRA is to provide design validation and requirement verification, more traditional, static fault tree approaches may become as appropriate as the simulation method.

Mattenberger, Christopher J.↗

NASA NTRSDate not supplied

Research Needs for Developing Qualification Standards for Flight Simulation Training Devices with Head Mounted Displays

This presentation discusses research needs to support evidence-based qualification standards for Flight Simulation Training Devices (FSTDs) with head mounted displays (HMDs). Currently, the FAA and EASA have no qualification standards specifically for FSTDs using HMDs and extended reality (XR) visuals, and existing qualification standards may not be sufficient. Special Conditions can be prescribed for the evaluation and qualification of individual devices, but these Special Conditions need to be assessed and adjusted on a case-by-case basis resulting in an elaborate process. Furthermore, test tolerances used in Special Conditions are often based on conventional visual systems and may not be adequate. This presentation first identifies gaps in the current knowledge of using HMDs in pilot training, and, more specifically, using HMDs in the training of manual aircraft control with motion cues. Next, research is proposed to help close these gaps, inform the development of qualification criteria and tolerances, and guide efforts to update regulations. The Vertical Motion Simulator (VMS) at NASA Ames Research Center, with its large motion capability, is currently undergoing significant upgrades including a state-of-the-art out-the-window visual system. In addition, an HMD capability will be introduced to use in conjunction with the conventional visual system. With its long history of setting standards in the simulation industry, the VMS is the ultimate tool to conduct research that could help accelerate the development of standards for the use of HMDs in FSTDs. The goal of the talk is ultimately to spark a discussion about the research needs and priorities to best serve the development of new qualification standards.

XR↗

NASA NTRSDate not supplied

Mars Surface Habitat Concept Design

An initial Mars Surface Habitat (MSH) concept design study was conducted as part of the National Aeronautics and Space Administration (NASA) Habitation Systems Development Office’s effort to inform NASA crewed Mars architecture decisions. The study assessed the unique challenges, risks, and benefits of a surface habitation element within the Mars architecture trade space. The goal of the study was to identify unique functional capabilities necessary to support a crewed mission on the Martian surface, the unique challenges and risks associated with such an architecture, and the areas of further analysis required to make such a mission possible. Continuing NASA’s development and execution of the Moon to Mars lunar surface missions, attention will continue progressing toward the initial crewed Mars mission. To prepare for this, NASA’s Exploration Systems Development Mission Directorate (ESDMD) has established a strategic analysis cycle (SAC) where an architectural trade space is identified and evaluated. Given that the Mars architecture and mission profile are still in this trade space, the architecture and mission considered for this study is SAC21. In addition, reference conceptual designs are being refined for the Mars Transit Habitat (TH) and MSH systems which will enable crew to safely travel to and inhabit the surface of Mars. The NASA Mars architectures trade space includes the use of a Pressurized Rover (PR) to address both crew habitation and mobility needs. This study assesses the use of a dedicated habitat via the MSH and an unpressurized terrain vehicle for crew mobility and exploration in lieu of the PR. Determining the optimum mission architecture will require continued analysis by ESDMD teams and this study is intended to support of such a study. The MSH concept design team aims to explore this area of the Mars habitation trade space, and in doing so, inform and highlight the considerations associated with a MSH in the surface architecture. It is not the intention of this study to make specific habitation or architecture decisions, but instead to provide a habitation element concept compatible with the Mars architecture trade space.

Mars Surface Habitat↗

NASA NTRSDate not supplied

Mars Surface Habitat (MSH) Concept Design

Ryan Hughes↗

NASA NTRS1997

Renal stone risk assessment during Space Shuttle flights

PURPOSE: The metabolic and environmental factors influencing renal stone formation before, during, and after Space Shuttle flights were assessed. We established the contributing roles of dietary factors in relationship to the urinary risk factors associated with renal stone formation. MATERIALS AND METHODS: 24-hr. urine samples were collected prior to, during space flight, and following landing. Urinary and dietary factors associated with renal stone formation were analyzed and the relative urinary supersaturation of calcium oxalate, calcium phosphate (brushite), sodium urate, struvite and uric acid were calculated. RESULTS: Urinary composition changed during flight to favor the crystallization of calcium-forming salts. Factors that contributed to increased potential for stone formation during space flight were significant reductions in urinary pH and increases in urinary calcium. Urinary output and citrate, a potent inhibitor of calcium-containing stones, were slightly reduced during space flight. Dietary intakes were significantly reduced for a number of variables, including fluid, energy, protein, potassium, phosphorus and magnesium. CONCLUSIONS: This is the first in-flight characterization of the renal stone forming potential in astronauts. With the examination of urinary components and nutritional factors, it was possible to determine the factors that contributed to increased risk or protected from risk. In spite of the protective components, the negative contributions to renal stone risk predominated and resulted in a urinary environment that favored the supersaturation of stone-forming salts. Dietary and pharmacologic therapies need to be assessed to minimize the potential for renal stone formation in astronauts during/after space flight.

STS Shuttle Project↗

NASA NTRSDate not supplied

Thermal Protection System to Enable Ice Giant Aerocapture Mission for Delivering Both an Orbiter and an In Situ Probe

The Ice Giants have been identified as high priority science destinations in the last Decadal Survey [1] and could benefit from aerocapture as the primary method for orbit insertion [2]. A mass-efficient aerocapture system will enable the delivery of an orbiter along with an atmospheric probe (for in situ measurements to anchor global data collected by the orbiter) and possibly a lander at Triton [3]. Aerocapture could be executed either using low L/D rigid aeroshell with lift modulation (LMA) [4] or using deployable aeroshell using drag modulation (DMA) [3]. Nearly two decades ago, a NASA-funded team performed Neptune-Triton aerocapture studies with a mid-L/D lifting configuration [5] for achieving orbit using LMA. This study showed aerocapture challenges. Due to very high peak entry conditions combined with very high heat-load, a suite of TPS materials was required and this suite was deemed problematic from a qualification perspective, due test facility limitations. In the past 20 years, progress made in GN&C for lift-guided entry missions such as MSL, Orion EFT1, Mars 2020 and the upcoming Artemis missions, and the expertise in blunt body aerodynamics at large scale (~ 5m) has led the EDL community to conclude that aerocapture is a “go do” engineering activity and most technologies are in hand to propose missions with aerocapture [6] [7]. Aerocapture using DMA, currently in development, is an option for Ice Giant Missions. While DMA is simpler in some sense, due to ballistic entry and no need for lift-guided maneuvering, it has challenges and it’s maturity is lower. LMA and DMA both require one or more ablative Thermal Protection System (TPS) materials for the rigid aeroshell element. The ablative TPS needs to be robust and mass efficient due to the high heat loads and size of the rigid aeroshell. Currently, there are capable ablative thermal protection materials, e.g., Heatshield for Extreme Entry Environments Technology (HEEET), 3-D woven Mid-Density Carbon- Phenolic (3MDCP), and PICA (Phenolic-Impregnated Carbon Ablator) that are mature, i.e., at TRL 6 or higher. NASA also invested in Conformal PICA that was matured to TRL 5. Our goal is to evaluate the applicability of high TRL TPS and consider other design options. We first establish bounding aerocapture trajectories for a wide range of arrival conditions and the associated aerothermal environment. Based on the environments, we then determine the predicted TPS mass for the aeroshell [4]. In this presentation, we will outline the process by which we establish bounding aerocapture trajectories for hyperbolic excess velocities ranging from 27 km/s to 35 km/s, which are shown to be a range of velocities that can reduce the trip time from ~14 years to 8 years. The above velocity range translates to ~12 km/s to ~24 km/s arrival velocities at the planetary entry interface [2]. The velocity reduction required to achieve orbit ranges between ~2.5 km/s to 9.5 km/s for both Neptune and Triton. Propulsive insertion alone, due to the amount of fuel required to achieve the required velocity reduction, limits the science returned [2]. We establish the bounding aerocapture trajectories for a low L/D (~ 0.4) configuration for three different ballistic coefficients. The ballistic coefficient range is determined from three different aeroshell diameters of 3m, 4m and 5m and with an entry system mass of 2200 kg. With the above range of design parameters, we then determine conservative/bounding estimates of aerothermal environments by using a combination of CFD simulations and stagnation point heating estimates [7]. This engineering approach allows us to first assess the TPS need vs. TPS capability and determine the applicability of existing TPS. Once an applicable suite of TPS is determined, the TPS thickness and mass are computed. We show that the TPS mass fraction can be as low as 5% to as high as 20%, depending on total trip time reduction and other design parameters for a range of TPS. This is a large range for TPS mass fraction. We show PICA and HEEET can indeed enable aerocapture missions, but the missions incur a mass penalty. TPS mass savings, can be further reduced with the use of conformal PICA. Advancing the development of Conformal PICA to make it robust across the entire aerothermal environment (peak heat-flux, pressure and shear) range will result in TPS mass fractions of < 10% for Ice Giant aerocapture missions such as the Neptune-Triton mission. Aerocapture allows for not only shortening the trip time but enables larger mass to be placed in orbit. Furthermore, probes deployed from orbit will benefit in reduced entry environments allowing for a lower risk TPS implementation as compared to mission designs where the probe is released prior to orbit insertion. One of the challenges for the Ice Giant community is to ensure mission designs that maximize science and allow flexibility in the placement of the entry probe. The traditional approach to release the probe ahead of the orbiter may not optimize returned science. In this presentation, we will make the case for mature TPS such as HEEET and PICA. While these materials can enable aerocapture missions, completing the development of conformal PICA and extending Conformal PICA to be more robust, will have significant impact to TPS mass efficiency and significantly enhance science return for future Gas- and Ice-Giant missions.

E Venkatapathy↗

NASA NTRSDate not supplied

Next Generation Thermal Protection System for Outer Planet Probes and Orbiter

Saturn Probe and Ice Giant Orbiter along with in-situ Probe Missions continue to be very high priority mis-sions. A result of the advocacy by OPAG and other Analysis Groups, the 3D Woven, Dual-Layer HEEET thermal protection system, mature at TRL 6, has closed the TPS gap for extreme environment missions. A mid density follow on to DL HEEET, developed to meet earth entry requirements, is a Single Layer vari-ant of the 3D woven TPS, which provides a mass effi-cient single layer 3D Mid-Density TPS (3MDCP) that has been baselined as the heatshield for MSR EEV. Continued development of 3MDCP will elevate it to TRL 6 by 2025. Conformal-PICA (C-PICA) devel-opment was pursued to establish a more efficient and robust alternate to PICA, and it is at TRL 4+. Our rationale for the next generation of TPS de-velopment is based on the on the missions needs of the next decade Outer Planet missions that are unique and more demanding than any other destinations. Taking advantage of the recent planned development of sev-eral materials, the next generation of TPS offers a much more mass efficient option for small, medium, and large class Outer Planet missions. Saturn Probes: While mission designers are gen-erally interested in shallow entry to maintain the g-load during entry around 50g, the heat-load for shallow entry can range between (100 kJ/cm2 – 300 kJ/cm2), two orders of magnitude higher than Venus or Sample Return missions. TPS must not only offer protection but must be mass efficient to perform reasonable sci-ence. TPS mass can quickly become 50% or more of the mass of the entire entry system. Recent analysis performed shows Saturn Probe missions could signifi-cantly benefit from the single layer HEEET (SL-HEEET/3MDCP). A DL-HEEET based heatshield mass could be ~ (40% -50%), SL-HEEET can provide additional (30% - 50%) mass savings. At the same time, C-PICA can provide (30% - 50%) mass savings on the backshell. The combined mass savings can be significant enough to carry an additional probe, if de-sired. Ice Giant Aerocapture Missions: Aerocapture mission architectures can provide significant ad-vantage over traditional propulsive insertion missions in multiple ways. 1) Reduced trip time ~ (4- 6) years (30% -40%), 2) Enables placing the orbiter, probe, and lander, all together and 3) Allows for greater science mass (probes and landers) due to mass efficiency. The delivery of a probe from orbit makes it easier and eliminates mission design constraints by HEEET for direct entry [4] of probes and allows for more targeted in-situ science once the Orbiter is able to collect data. In the past 20 years, progress made in GN&C for lift-guided entry missions (MSL, Orion EFT1, Mars 2020) and the expertise in blunt body aerodynamics at large scale (~ 5m) has led the EDL community to conclude that aerocapture is a “go do” engineering activity. An aerocapture mission that will deplete the excess energy of a fast arrival mission will require a mass efficient TPS that can handle extreme heat-load, ~ (100 kJ/cm2 – 500 kJ/cm2). Hence TPS, feasibility as well as mass efficiency requires assessment. Utilizing the recent developments, a comprehensive, bounding analysis was done to establish the potential for SOA (HEEET) system as well as emerging new TPS such as SL-HEEET and C-PICA. In this proposed poster, we will outline the process by which we establish bounding aerocapture trajecto-ries for hyperbolic excess velocities ranging from 27 km/s to 35 km/s, for low L/D (~ 0.4) configurations and determine conservative/bounding estimate of aer-othermal environment by using a combination of CFD simulations and stagnation point heating estimates [7]. This engineering approach allows us to assess the TPS need vs. TPS capability and determine the applicability of existing TPS. Once an applicable suite of TPS is determined, the TPS thickness and mass are comput-ed. We show that the TPS mass fraction can be as low as 5% to as high as 20%, depending on the use of ad-vanced TPS, while HEEET is sufficient but will require 50% of the entry mass.

E Venkatapathy↗

NASA NTRS1972

Technology assessment in the Executive Office of the President

The involvement of the President with technology, directly and indirectly, and the best way in which his responsibilities can be discharged are discussed. Technology assessment is considered essential at all levels of the Executive agencies, but the capacity of the agencies for assessment is limited and needs to be supplemented within the Executive Branch. Complete centralization of technological assessment is felt to be ineffective. The role of the Executive Office in initiating proposals for Presidential action and sustaining links with Congress are outlined, and the apparatus for technology assessment is described, emphasizing the Office of Science and Technology. A significant area of technology assessment for the Executive Office is the field of environmental quality, and the duties of the Environmental Quality Council are summarized. It is suggested that it may be more effective to set up a separate organization for the restoration and protection of the environment and to define the task in terms of what is to be protected rather than in terms of technology.

Kidd, C. V.↗

NASA NTRS1976

Prediction methods for jet V/STOL propulsion aerodynamics

The current status of prediction methods for propulsive flows and propulsion-induced effects which occur on jet V/STOL aircraft is reviewed. Among the major topics studied are flows in propulsive ducts, propulsion-induced ground and thermal effects, aerodynamic loads induced during V/STOL and transition flight, flow vectoring devices, and thrust augmented ejector and lift-fan studies. The current predictive capability in jet V/STOL propulsion aerodynamics is assessed. Future research needs are identified, with particular reference to activities that can improve the usefulness of prediction methods for jet V/STOL aircraft.

Platzer, M. F.↗

NASA NTRS1979

Effects of noise frequency on performance and annoyance

Using a complex psychomotor task performed for 50 minutes in the presence of low frequency noise, high frequency noise, or ambient noise, annoyance ratings were obtained for noises of various frequencies by the method of magnitude estimation. The results suggest that high frequency noise affects female performance to a greater extent than male performance. Contrasted to these performance effects, the sexes did not differ in their annoyance ratings. A monotonically increasing relationship between annoyance and noise frequency was found (except for a decrease in annoyance at 8,000 Hz). It is concluded that both performance and annoyance responses may need to be assessed in certain situations to adequately describe human reaction to noise.

Key, K. F.↗