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NASA NTRS2019

Plans for Upcoming DGEN Aeropropulsion Research Turbofan (DART) Testing

This presentation serves as an overview of test plans for an upcoming DGEN Aeropropulsion Research Turbofan (DART) test entry at the NASA GRC AeroAcoustic Propulsion Laboratory (AAPL). The test entry includes: (1)a fan intra-stage velocity field survey, which will be compared to a Computational Fluid Dynamics (CFD) survey of DART, (2) an exploratory noise study of DART with several objectives focused on measurement projection to the far-field, source identification improvements and development of a barrier wall for isolation of various sources, (3) advancement of core/combustor noise research on DART using more extensive engine-mounted instrumentation, and (4) high-temperature pressure sensor technology-readiness-level (TRL) advancement.

Boyle, Devin K.↗
NASA NTRS2016

Closing the Contrast Gap Between Testbed and Model Prediction with WFIRST-CGI Shaped Pupil Coronagraph

JPL has recently passed an important milestone in its technology development for a proposed NASA WFIRST mission: demonstration of a better than 1x10-8 contrast over broad bandwidth (10%) on both shaped pupil coronagraph (SPC) and hybrid Lyot coronagraph (HLC) testbeds with WFIRST telescope optics. Challenges remain, however, in the technology readiness for the proposed mission. One such is the discrepancy between the achieved contrast on testbeds and their corresponding model predictions. A series of testbed diagnosis and modeling activity were planned and (some) carried out on SPC testbed in order to close the gap. A very useful tool we developed was to analyze the measured testbed Jacobian and compare with its model version that was used to control image plane speckle pattern. The difference between these two is the error in the control Jacobian. When the error, which includes both amplitude and phase, was inserted into a separate prediction model with nominal Jacobian, the model prediction became closely matching the SPC testbed behavior in both contrast floor and contrast convergence speed. This offers a new perspective and is a step closer toward model validation for high contrast coronagraph. Further Jacobian analysis and modeling provided clues to the possible sources for the mismatch: the DM misregistration and the underrepresented testbed optics wavefront error (WFE) and the deformable mirror (DM) setting for correcting this WFE. These analyses suggested that high contrast coronagraph has a tight tolerance in the accuracy of its control Jacobian. Modifications to both testbed control model as well as prediction model are being implemented and future works discussed.

diffraction modeling↗
NASA NTRS2019

Design and Acoustic Efficacy of a Broadband Liner for the Inlet of the DGEN Aero-Propulsion Research Turbofan

Advanced fan designs (including higher bypass ratios) and shorter engine nacelles have highlighted a need for increased fan noise reduction over a broader frequency range. With these observations in mind, an acoustic liner optimization process has been developed to achieve improved broadband liner designs. A series of advanced liner design studies at increasing technology readiness levels have been conducted as the overall optimization methodology has been enhanced. As part of the analysis, the overall design and evaluation capability was extended such that external observer locations may be included in the optimization process. This enhancement will provide a much wider design space in designing advanced broadband liners. In this work, further validation was pursued through the fabrication and testing of two liner designs for the NASA Glenn DGEN Aero-propulsion Research Turbofan (DART). The DART was used to document the efficacy of acoustic liners installed in the inlet of the DGEN380. An advanced Multi-Degree of Freedom Liner was designed, fabricated, and tested, along with a traditional Single-Degree-of-Freedom Liner, and those results compared to a hardwall baseline inlet. Farfield acoustic data were acquired from and external array, evaluated and reported herein terms of overall, broadband, and tonal components of the insertion loss. The predicted attenuation results generally matched expected trends of the measured data for the conditions considered.

Liners↗
NASA NTRS2017

R2U2: Tool Overview

R2U2 (Realizable, Responsive, Unobtrusive Unit) is an extensible framework for runtime System HealthManagement (SHM) of cyber-physical systems. R2U2 can be run in hardware (e.g., FPGAs), or software; can monitorhardware, software, or a combination of the two; and can analyze a range of different types of system requirementsduring runtime. An R2U2 requirement is specified utilizing a hierarchical combination of building blocks: temporal formula runtime observers (in LTL or MTL), Bayesian networks, sensor filters, and Boolean testers. Importantly, the framework is extensible; it is designed to enable definitions of new building blocks in combination with the core structure. Originally deployed on Unmanned Aerial Systems (UAS), R2U2 is designed to run on a wide range of embedded platforms, from autonomous systems like rovers, satellites, and robots, to human-assistive ground systems and cockpits. R2U2 is named after the requirements it satisfies; while the exact requirements vary by platform and mission, the ability to formally reason about realizability, responsiveness, and unobtrusiveness is necessary for flight certifiability, safety-critical system assurance, and achievement of technology readiness levels for target systems. Realizability ensures that R2U2 is suficiently expressive to encapsulate meaningful runtime requirements while maintaining adaptability to run on different platforms, transition between different mission stages, and update quickly between missions. Responsiveness entails continuously monitoring the system under test, real-time reasoning, reporting intermediate status, and as-early-as-possible requirements evaluations. Unobtrusiveness ensures compliance with the crucial properties of the target architecture: functionality, certifiability, timing, tolerances, cost, or other constraints.

Rozier, Kristin Y.↗
NASA NTRS2018

Advances in Above- and In-Water Radiometry, Volume 2: Autonomous Atmospheric and Oceanic Observing Systems

This publication documents the scientific advances associated with new instrument systems and accessories built to improve above- and in-water observations of the apparent optical properties (AOPs) of optically complex waters. The principal objective is to be prepared for the launch of next-generation ocean color satellites with the most capable commercial off-the-shelf (COTS) instrumentation in the shortest time possible. The Hybridspectral Alternative for Remote Profiling of Optical Observations for NASA Satellites (HARPOONS) is presented as a case example of technologies conceived, developed, and deployed operationally in support of next-generation mission requirements. The field trials, field commissioning, and operational demonstration resulted in a technology readiness level (TRL) value of 9 for a diversity of laboratory and field instrument systems. Separate detailed presentations of the individual instruments provide the hardware designs, accompanying software for data acquisition and processing, and examples of the results achieved. For the laboratory components, calibration and characterization procedures are described along with an estimation of the sources of uncertainty, which culminates in a full uncertainty budget for the radiometers deployed to the field.

Hooker, Stanford B.↗
NASA NTRS2018

Broadband Inlet Liner Design for the DGEN Aero-Propulsion Research Turbofan

The utilization of advanced fan designs (including higher bypass ratios) and shorter engine nacelles has highlighted a need for increased fan noise reduction over a broad frequency range. With these observations in mind, an acoustic liner optimization process has been developed to achieve improved broadband liner designs. A series of advanced liner design studies at increasing technology readiness levels has been conducted as the overall optimization methodology has been enhanced. In this work, further validation was pursued through the fabrication and testing of two liner designs for the NASA Glenn DGEN Aero-propulsion Research Turbofan. Specifically, single and three layer liners were designed, fabricated, and tested. Analysis of the predicted attenuation results showed them to generally match expected trends for the conditions considered. The effects of source distribution on predicted directivity were also illustrated through the flexibility of a statistical source model. As part of the analysis, the overall design and evaluation capability was extended such that external observer locations may be included in the optimization process. This enhancement will provide a much wider design space for the development of advanced broadband liners. These preliminary results provide further confidence in the design tools and enhancements made to the overall liner design process.

Nark, Douglas M.↗
NASA NTRS2019

Omni-gravity Hydroponics for Space Exploration

As part of the NASA Plant Water Management technology demonstration experiments, a capillary fluidics hydroponic system that can function in a variety of gravity environments has been developed and tested for crop production in space. A passive liquid delivery method is employed that drastically reduces the number of contaminable moving parts providing a high reliability solution requiring minimal resources for operation. The terrestrial, lunar, and Martian environments are managed in a ‘gravity-dominated mode,’ while the low-gravity transit and orbit environments are managed in a ‘capillary fluidics mode,’ where the role of gravity is replaced by the equally passive effects of surface tension, conduit shape, and wettability. The unique considerations for priming, germination, aeration, nutrient supply, root accommodation, layout, crew interaction, etc. are highlighted. Design guides for system function are provided along with high Technology Readiness Level demonstrations of the system during terrestrial and drop tower tests. Long duration tests are planned on short schedule aboard the International Space Station in 2019.

gravity↗
NASA NTRS2019

Characterization of Low-Temperature, Co-Fired Ceramic-Manufactured Electrostatic Thruster-Closeout Report

The goal of the project was to evaluate prototypes of an experimental thruster developed by the University of Arkansas (UA), Fayetteville, AR. The design under evaluation is a radio frequency (RF) electrostatic thruster that was fabricated using the low-temperature, co-fired ceramic (LTCC) materials and fabrication process. This materials system is analogous to printed circuit board (PCB) technology with the most significant difference being that the laminate is replaced by a ceramic material and the copper layer is replaced by printed sinterable silver paste. LTCC designs are baked after fabrication and assembled to realize an entirely monolithic structure with internal conductors, vias, and cavities. In this process, the LTCC electrostatic thruster (LTCC-ET) that is the subject of the present work becomes a monolithic ceramic thruster capable of withstanding temperatures in excess of 500 ºC. The UA and NASA Marshall Space Flight Center (MSFC) jointly performed prototype testing on the LTCC-ET under a NASA Cooperative Agreement Notice (CAN) award. The LTCC-ET was tested at MSFC in May 2018 over a 1-week period. There were two goals for the test program: (1) Testing to determine the operating parameters required to create plasma ignition in the test articles. This was explored by setting a propellant flowrate and increasing RF power until plasma ignition was observed. Testing was conducted with both argon and krypton. (2) Investigate the thrust and specific impulse (Isp) performance of the thruster as a function of propellant flowrate and grid voltage. This goal was not met during the project as technical challenges in maintaining stable plasma ignition arose due to stress and heating of the RF power feed. In summary, a prototype thruster design (consisting of three packaged units) was fabricated by UA and tested for the first time under vacuum conditions at MSFC to experimentally determine basic performance metrics and functionality. It was found that the design was not sufficiently optimized or robust enough in its initial iteration to support a significant test campaign or characterization program. It was concluded that the propellant outlet channels must be reduced in size with the flowpaths adjusted to increase propellant residence time in the thruster, and that the RF connector must be replaced with a version capable of handling higher power throughput and heating. However, even in its unoptimized form, a plasma could be produced in the LTCCET, demonstrating the efficacy of the design approach. The design is especially compelling due to its low cost to manufacture and, more importantly, its scalability of size and power throughput. Low cost and scalability are also important in that additional functionalities, such as thrust vectoring and plume charge neutralization, can be integrated into future designs with minimal additional cost. This project has matured the LTCC-ET development Technology Readiness Level (TRL) from 1 to 2. The low-cost RF plasma source portion of the LTCC device was matured from TRL 2 to 4 through the demonstration of RF plasma ignition under vacuum conditions.

Huang, P.-H. A.↗
NASA NTRS2019

Testbed Requirements to Enable New Observing Strategies

Emerging capabilities to integrate instruments on smallsats, airborne platforms and in situ devices into an intelligent, distributed observing strategy show great promise for measuring Earth science natural phenomena and physical processes that have not previously been characterized. To reduce the threshold for success in deploying such an intelligent, integrated observing strategy, a ground-based testbed system is proposed. Virtually all of the technologies needed for using such a tool have matured to the point of being used, individually. Virtually none of the technologies have been deployed, working together. The technologies to be deployed should be integrated into a working "breadboard" where the components can be debugged and performance and behavior characterized and tuned-up. A system of this complexity should not be expected to work without full integration and experimental characterization. Further, and perhaps more importantly, in order to successfully propose a space-based element to this strategy, teams must convince the relevant science community that the risk is low enough to warrant the investment. The main benefit of the testbed is to retire the risk of integrating these new technologies and increase the Technology Readiness Level (TRL) of each component as well as the System Readiness Level (SRL) of the integrated system.

Little, Mike↗
NASA NTRS2019

Lunar Infrastructure and Surface Operations

The STMD Lunar Surface Innovation Initiative (LSII) aims to spur the creation of novel technologies needed for lunar surface exploration and accelerate the technology readiness of key systems and components. The LSII activities will be implemented through a combination of unique in-house activities, competitive programs, and public-private partnerships.

Vickers, John↗
NASA NTRS2019

Planetary Water Recycling Systems Trade Study

Long-term planetary space missions present new and unique challenges in life-support systems. Water constitutes the majority of the mass required to sustain human life in space and it follows that efficient water recycling has the potential to lower mission costs. The effect of partial gravity in planetary missions mean that terrestrial systems could be applicable. This trade study evaluates terrestrial and NASA developed water recycling technologies on the basis of applicability as a planetary base water recycling systems. Various bioreactors, membrane reactors, filtration, and district water reclamation systems are investigated and rated based on several standardized parameters. A customer-oriented Quality Function Deployment (QFD) is utilized to analyze the ratings of the technologies for the tasks required. The trade study aims to rank the various systems based on their Equivalent System Mass (ESM), Technology Readiness Level (TRL), scalability, crew time, and overall logistics requirements, among others. The results of the study can serve as a basis for future inquiries and studies by NASA and other interested parties. The results of this study provide a down selection from 24 systems to 5 systems that trade very close to each other. The results provide a context and justification for a future comparative hardware test program to determine which of these systems offer the best solution.

Flynn, Michael↗
NASA NTRS2019

The Value Proposition of Multi-Megawatt Electric Power/Propulsion for the Human Exploration of Mars

NASA and other space agencies have been offering stakeholders an architecture for the human exploration of Mars that has remained essentially unchanged since the 1960's. The mission duration and launch mass are the two first order figures of merit that drive the total cost of such an architecture. The options studied to date center on the "conjunction class" or "Long Stay" mission, in which surface infrastructure elements are sent ahead on uncrewed, slow trajectories requiring a minimum amount of propellant, and the crewed elements are sent at the synotic cycle's shortest trajectory, stay on Mars until the next close alignment, and then return to Earth. Total crewed mission durations for these architectures range from 900 to 1100 days, with variations driven primarily by trades between the amount of propellant launched and the effective specific mass of the propulsion technology assumed (e.g., chemical, nuclear thermal, solar electric, nuclear electric). Mars transit propulsion systems assumed in mission architectures studied to date have all resulted in architectural figures of merit that drive the cost to a level of "too much." However, nuclear electric propulsion (NEP) technology offers a "knob" that might be turned to enable a radically different Mars architecture, whose launch mass and mission duration may enable a value proposition more palatable to mission stakeholders. Mars architectures studied to date have assumed an NEP system providing 2.5 MWe at a specific mass of no less than 20 kg/kWe. This has often been seen as obtainable with a moderately high temperature fission reactor. An NEP system providing 15 MWe at specific mass of ~1 kg/kWe, though, could enable a short stay (30 days on surface) Mars mission, requiring only two or three SLS-class launch vehicles and a total mission duration of under one calendar year. However, turning this NEP "knob" would require a high risk development program driving innovation on the order of that delivered by the Manhattan Project, but for a fraction of the cost. Any technology option that might offer such a capability at such a development cost now stands at a low Technology Readiness Level (TRL) 3, would be based on a nuclear energy source (likely fusion), and would require an extremely high risk (and rapid) development effort. The aggressive, parallel path project management paradigm exemplified by the original Manhattan Project might have the best chance of success. An energy source developed in this manner may also have a major impact on the terrestrial power industry.

power↗
NASA NTRS2019

Setting Sail for the Sun: The NEA Scout & Solar Cruiser Missions

Join HAL5 as we welcome back Les Johnson, who will talk about his work on developing solar sails at Marshall Space Flight Center and its role in propulsion and exploration of the Sun. With the successful flights of NASA's NanoSail-D and the Planetary Society's LightSail, solar sails are making the transition from an interesting idea to be demonstrated to technology ready for use on space missions. Scientists and engineers here in Huntsville are doing just that with the development of the Near Earth Asteroid Scout's 925 square foot solar sail that will fly in 2020. And that's not all, in August, a team led by NASA MSFC was selected as a finalist to develop an 18,000 square foot solar sail for a project called, Solar Cruiser, that may fly as early as 2024. If you would like to learn the fundamentals of solar sailing and get the scoop on these two innovative and exciting missions, then hang on as we "Set Sail for the Sun!"

Heliophysics↗
NASA NTRS2019

Advancing the Standards for Unmanned Air System Communications, Navigation and Surveillance

Under NASA program NNA16BD84C, new architectures were identified and developed for supporting reliable and secure Communications, Navigation and Surveillance (CNS) needs for Unmanned Air Systems (UAS) operating in both controlled and uncontrolled airspace. An analysis of architectures for the two categories of airspace and an implementation technology readiness analysis were performed. These studies produced NASA reports that have been made available in the public domain and have been briefed in previous conferences. We now consider how the products of the study are influencing emerging directions in the aviation standards communities. The International Civil Aviation Organization (ICAO) Communications Panel (CP), Working Group I (WG-I) is currently developing a communications network architecture known as the Aeronautical Telecommunications Network with Internet Protocol Services (ATN/IPS). The target use case for this service is secure and reliable Air Traffic Management (ATM) for manned aircraft operating in controlled airspace. However, the work is more and more also considering the emerging class of airspace users known as Remotely Piloted Aircraft Systems (RPAS), which refers to certain UAS classes. In addition, two Special Committees (SCs) in the Radio Technical Commission for Aeronautics (RTCA) are developing Minimum Aviation System Performance Standards (MASPS) and Minimum Operational Performance Standards (MOPS) for UAS. RTCA SC-223 is investigating an Internet Protocol Suite (IPS) and AeroMACS aviation data link for interoperable (INTEROP) UAS communications. Meanwhile, RTCA SC-228 is working to develop Detect And Avoid (DAA) equipment and a Command and Control (C2) Data Link MOPS establishing LBand and C-Band solutions. These RTCA Special Committees along with ICAO CP WG/I are therefore overlapping in terms of the Communication, Navigation and Surveillance (CNS) alternatives they are seeking to provide for an integrated manned- and unmanned air traffic management service as well as remote pilot command and control. This paper presents UAS CNS architecture concepts developed under the NASA program that apply to all three of the aforementioned committees. It discusses the similarities and differences in the problem spaces under consideration in each committee, and considers the application of a common set of CNS alternatives that can be widely applied. As the works of these committees progress, it is clear that the overlap will need to be addressed to ensure a consistent and safe framework for worldwide aviation. In this study, we discuss similarities and differences in the various operational models and show how the CNS architectures developed under the NASA program apply.

Ponchak, Denise S.↗
NASA NTRS2019

Microwave SQUID Multiplexing for the Lynx X-Ray Microcalorimeter

The Lynx x-ray microcalorimeter (LXM) is an imaging spectrometer for the Lynx satellite mission, an x-ray telescope being considered by NASA to be a new flagship mission. Lynx will enable unique astrophysical observations into the x-ray universe due to its high angular resolution and large field of view. The LXM consists of an array of over 100,000 pixels and poses a significant technological challenge to achieve the high degree of multiplexing required to read out these sensors. We discuss the details of microwave superconducting quantum interference device (SQUID) multiplexing and describe why it is ideally suited to the needs of the LXM. This case is made by summarizing the current and predicted performance of microwave SQUID multiplexing and describing the steps needed to optimize designs for all the LXM arrays. Finally, we describe our plan to advance the technology readiness level (TRL) of microwave SQUID multiplexing of the LXM microcalorimeters to TRL-5 by 2024.

Bennett, Douglas A.↗
NASA NTRS2020

Prospects for Interstellar Propulsion

In recognition of the increasing prospects for Earth-like exoplanet discoveries and its significance for spurring future interstellar voyages of discovery, the United States Congress recently directed NASA to undertake an interstellar mission technology assessment report. In response to this legislative charge to action, NASA has undertaken a series of extramural interstellar workshops aimed at identifying and evaluating technology concepts for enabling an interstellar scientific probe mission, associated technical challenges, technology readiness level assessments, risks, potential near-term milestones, and funding requirements. This paper summarizes these activities and discusses the scientific and technical rationale for a long-term program consisting of incremental, staged technical developments that are extensible for interstellar travel to a nearby star system over many decades.

Litchford, Ronald J.↗
NASA NTRS2019

Lynx X-Ray Microcalorimeter Cryogenic System

The Lynx x-ray microcalorimeter instrument on the Lynx X-ray Observatory requires a state-of-the-art cryogenic system to enable high-precision and high-resolution x-ray spectroscopy. The cryogenic system and components described provide the required environment using cooling technologies that are already at relatively high technology readiness levels and are progressing toward flight-compatible subsystems. These subsystems comprise a cryostat, a 4.5-K mechanical cryocooler, and an adiabatic demagnetization refrigerator that provides substantial cooling power at 50 mK.

DiPirro, Michael↗
NASA NTRS2020

Mars Ascent Vehicle Hybrid Propulsion Configuration

As part of a Mars Sample Return (MSR) campaign, two Mars Ascent Vehicle (MAV) configurations have been designed in parallel. Each ascent vehicle configuration has a different propulsion system which ultimately leads to two unique vehicle designs. As part of a Preliminary Architecture Assessment (PAA), these vehicle designs were developed to the same level of maturity in order to inform the selection of one of the vehicles as the point of departure design for the campaign. The selection will be made in November 2019. The initial MSR architecture called for a hybrid-based propulsion MAV. This type of propulsion system calls for a solid wax motor that would utilize liquid MON-25 as an oxidizer. Hybrid rocket propulsion allows for more flexibility than traditional solid or liquid propulsion options, and typically benefits from the advantages of both. A hybrid motor can be throttled and shut down easily, and avoids significant risk in manufacturing and handling. On a theoretical level, hybrid motors perform at a higher specific impulse (Isp) than solid motors. The primary disadvantage of hybrid motors comes from additional complexity and significantly less flight heritage and low Technology Readiness Level (TRL). This paper describes the design of the hybrid propulsion configuration. An additional paper will be published describing the design of the solid propulsion configuration1. The hybrid propulsion configuration MAV was developed in 2019 by NASA Marshall Space Flight Center (MSFC) in association with NASA Jet Propulsion Laboratory (JPL). It features a Single Stage to Orbit (SSTO) design with an SP7A solid wax fuel and MON-25 liquid oxidizer. The liquid portion of the vehicle allows for a Liquid Injection Thrust Vector Controller (LITVC) as well as hypergolic propellant additives for ignition. The vehicle was designed to deliver approximately 0.31kg of Martian geological samples to a circular orbit at Mars of 343km at a 25o inclination. Although hybrid propulsion in general has been used on launch vehicles in the past, the integrated vehicle subsystems that operate in conjunction with these propulsion elements do not typically operate in a Martian environment, which in this application can get as cold as -40oC. The PAA advanced the maturity of these subsystems by performing detailed design and analysis on the vehicle with respect to structures and mechanisms, Guidance/Navigation/Control (GNC) systems, avionics, Reaction Control System (RCS), LITVC, thermal environments, and advanced Computational Fluid Dynamics (CFD). This paper will summarize the results of these studies.

Yaghoubi, Darius↗