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NASA NTRS2024

Extreme Temperature Additively Manufactured GRX-810 Alloy Development and Hot-fire Testing for Liquid Rocket Engines

Additive manufacturing (AM) has revolutionized component design for liquid rocket engines by offering rapid manufacturing capabilities. This has led to significant opportunities for development and flight programs in the propulsion industry, resulting in cost and schedule savings, as well as performance improvements through new designs and alloy development. A noteworthy example is the GRX-810 oxide dispersion strengthened (ODS) alloy, which was specifically developed for extreme temperatures. This Ni-Co-Cr based alloy was created using integrated computational materials engineering (ICME) techniques to focus on a new class of materials with exceptional temperature and oxidation-resistant properties. The GRX-810 alloy utilizes AM processes to incorporate nano-scale yttria particles throughout its microstructure, resulting in remarkable enhancements. Compared to traditional Nickel-based superalloys, the GRX-810 alloy offers a two-fold increase in tensile strength, 1,000-fold better creep properties, and two-fold improvement in oxidation resistance. NASA successfully demonstrated the development and manufacturing of components using the GRX-810 alloy through laser powder bed fusion (L-PBF) and laser powder directed energy deposition (LP-DED) processes. Extensive efforts were made to model, evaluate metallurgical properties, develop heat treatment processes, characterize the microstructure, and determine mechanical properties. The GRX-810 alloy was specifically designed for aerospace applications, including liquid rocket engine injectors, preburners, turbines, and hot-section components, capable of withstanding temperatures up to 1,100 °C. The objective of this alloy development is to bridge the temperature gap between traditional Nickel-based superalloys and refractory alloys. This paper provides a comprehensive comparison of the GRX-810 alloy with other aerospace alloys, discussing its microstructure, mechanical properties, processing advancements, component development, and hot-fire testing results. The ultimate goal of this development was to elevate the Technology Readiness Level (TRL) of the GRX-810 alloy, enabling its integration into NASA and commercial aerospace applications.

GRX-810↗
NASA NTRSDate not supplied

Accelerating the Deployment of Space-Based Quantum Sensors

Quantum sensors rely on quantum mechanical properties, such as wave-particle duality, atomic energy levels, or entanglement, to measure physical, optical, or electromagnetic information from a target. Examples include Rydberg sensors, nitrogen-vacancy magnetometers, HOM (Hong-Ou-Mandel) interferometers, and SQUIDs (Superconducting Quantum Interference Devices). In general, as quantum sensors rely on interrogation at the atomic and photonic level rather than on classical mechanical measurements, these technologies promise advantages over their traditional counterparts in sensitivity, accuracy, and SWaP (Size, Weight, and Power). Conceptually, the use of quantum sensors unlocks the new phenomenology of sensor entanglement. While an ultra-low TRL (Technology Readiness Level) prospect for most sensor types, multi-sensor entanglement is a high risk, high reward strategy with a potential for exquisite sensitivity and SWaP improvements entirely inaccessible to classical sensors.

Grace Caroline Wusk↗
NASA NTRS2024

Testing of Advanced Capabilities to Enable In-time Safety Management and Assurance for Future Flight Operations

In order to refine an initial Concept of Operations, explore Concepts of Use, and expose/validate requirements for future In-Time Aviation Safety Management Systems (IASMS), testing architectures were created, along with a set of capabilities and underlying information exchange protocols. These systems were conceived and developed based on hazards associated with two envisioned urban area flight domains: (1) highly autonomous small uncrewed aerial systems (sUAS) operating at low altitudes, and (2) highly autonomous air taxis. The initial scope of this development is described in [1]; this report provides an update, focusing on the subsequent developments and test activities. As stated in [1], it is important to note that there are many capabilities already in use by the industry (or soon to be in use) that will play critical roles in future IASMS designs. Those reported here were developed to address a gap in the current state-of-the-art regarding specific hazards/risks, and/or to allow for investigation of the interplay between and across hazard types — particularly regarding how overall safety risk can be reduced or managed effectively. Results of testing and development activities are organized by the operational phase wherein a particular capability would be employed (i.e., preflight, in-flight, and post-flight/off-line). Pre-flight: A set of capabilities were developed to help mitigate safety risk prior to flight (e.g., during flight and mission planning). Results of testing summarize (1) validation activities to raise the Technology Readiness Level (TRL) and (2) evaluation activities where the capabilities were applied to flight/mission planning procedures and used by operators/pilots. For the latter, flight plans were automatically assessed, and operators/pilots were notified of hazardous flight segments so as to enable adjustment of the flight plan and re-evaluation, and/or to better inform go/no-go decisions. Capabilities addressed hazards associated with power consumption, third-party risk, wind, navigation system performance, radiofrequency interference, and proximity to geo-spatial threats (e.g., buildings, trees, and no-fly zones). In-flight: Flight experiments tested capabilities that detect and respond to hazards encountered during flight. In the first series, safety hazards were monitored and assessed onboard, and system-generated mitigation maneuvers were recorded (but not acted upon by the vehicle). In the second series, mitigation maneuver commands directed the aircraft in response to safety hazards (i.e., auto-mitigation). The sUAS used for testing is described in full, as is the test architecture, which included commercial avionics, research avionics, and onboard software designed to detect, assess, and respond to hazards. The onboard system was designed as a run-time assurance framework, consistent with [2] and supportive of both supervisory and automated modes. The primary functions included: real-time risk assessment (RTRA), auto-pilot monitoring, constraint monitoring, and contingency select/triggering. RTRA performs integrated risk assessment considering data from several hazard-related monitors (e.g., battery, motors, navigation, communications, population density, and loss-of-control). Post-flight/off-line: Data monitored and recorded during flights can enable IASMS capabilities that execute after flights have completed (or “off-line”). These include: (1) the ability to identify anomalies and trends that may only be observable when comparing data spanning a number of similar flights; (2) the ability to update and validate pre-flight and in-flight capabilities and any underlying models to improve their performance; (3) the ability to report anomalies/off-nominals that may indicate design changes or maintenance actions are needed; and (4) the ability for humans involved in operations to report safety-relevant observations to help in understanding the flight data and/or the operational context of a flight. Progress on three such capabilities is summarized; the first investigates anomaly detection given a limited set of flight logs and applies an approach previously used for space operations. The second explores what could be identified using a larger set of flight logs, including from web-based forums where flight logs are posted by sUAS autopilot users. The third creates a new means of collecting information on UAS incidents and accidents via the Aviation Safety Reporting System (ASRS).

sUAS↗
NASA NTRSDate not supplied

Development of a Thermal Vacuum Chamber for Lunar Surface Simulation

Simulating the lunar surface environment is a critical component in advancing the Technology Readiness Level (TRL) of newly developed lunar surface exploration systems and understanding regolith dynamics. Developing systems with the ability to simulate the lunar surface environment presents unique challenges associated with both the hardware requirements of the system and the uniqueness of the lunar environment. Additionally, many thermal vacuum testing systems are large and expensive to maintain and operate, increasing the cost for the end users. Many low TRL prototypes are small-scale and low-cost, making it unfeasible and unnecessary to utilize larger scale testing facilities. A small-scale, modular, and easily reconfigurable chamber with a quick testing turnaround time could allow rapid TRL advancement with minimal costs and time commitments relative to many of the current testing facilities. Here, we introduce a thermal vacuum chamber system that will support experimentation and rapid testing and maturation of small-scale hardware systems and subsystems for lunar surface exploration.

Thermal Vacuum Chamber↗
NASA NTRS2024

Extreme Temperature Additively Manufactured GRX-810 Alloy Development and Hot-fire Testing for Liquid Rocket Engines

Additive manufacturing (AM) has revolutionized component design for liquid rocket engines by offering rapid manufacturing capabilities. This has led to significant opportunities for development and flight programs in the propulsion industry, resulting in cost and schedule savings, as well as performance improvements through new designs and alloy development. A noteworthy example is the GRX-810 oxide dispersion strengthened (ODS) alloy, which was specifically developed for extreme temperatures. This Ni-Co-Cr based alloy was created using integrated computational materials engineering (ICME) techniques to focus on a new class of materials with exceptional temperature and oxidation-resistant properties. The GRX-810 alloy utilizes AM processes to incorporate nano-scale yttria particles throughout its microstructure, resulting in remarkable enhancements. Compared to traditional Nickel-based superalloys, the GRX-810 alloy offers a two-fold increase in tensile strength, 1,000-fold better creep properties, and two-fold improvement in oxidation resistance. NASA successfully demonstrated the development and manufacturing of components using the GRX-810 alloy through laser powder bed fusion (L-PBF) and laser powder directed energy deposition (LP-DED) processes. Extensive efforts were made to model, evaluate metallurgical properties, develop heat treatment processes, characterize the microstructure, and determine mechanical properties. The GRX-810 alloy was specifically designed for aerospace applications, including liquid rocket engine injectors, preburners, turbines, and hot-section components, capable of withstanding temperatures up to 1,100 °C. The objective of this alloy development is to bridge the temperature gap between traditional Nickel-based superalloys and refractory alloys. This paper provides a comprehensive comparison of the GRX-810 alloy with other aerospace alloys, discussing its microstructure, mechanical properties, processing advancements, component development, and hot-fire testing results. The ultimate goal of this development was to elevate the Technology Readiness Level (TRL) of the GRX-810 alloy, enabling its integration into NASA and commercial aerospace applications.

GRX-810↗
NASA NTRSDate not supplied

String Potentiometers for Supersonic Split-Line Thrust Vector Amplification Factor Verification

The static fire of NASA’s Mars Ascent Vehicle (MAV) first stage Solid Rocket Motor (SRM1) Demonstration Motor-1 (DM-1) occurred at Edwards Air Force Base (AFB) on April 7, 2023. Among other objectives, this test successfully demonstrated the Thrust Vector Control (TVC) system, including the Technology Readiness Level (TRL) of the Supersonic Split-Line (SSSL) nozzle. An essential characteristic of the SSSL is the thrust vector amplification factor (TVAF) it exhibits; however, empirically quantifying this behavior is difficult due to the limitations of measuring the internal nozzle gas dynamics of a Solid Rocket Motor (SRM) during burn. Using four string potentiometers mounted inside the test chamber connected to the nozzle and motor case and a thrust measurement system (TMS), the TVAF can be derived from the known nozzle and motor geometry. Increasing the accuracy of the TVAF is essential for certain groups working on the MAV including the Guidance, Navigation, and Control (GN&C) group, who prior to DM-1, solely relied on Computational Fluid Dynamics (CFD) data in their Monte Carlo simulations for TVAF. The methodology shown in this paper can be generally applied to any test article implementing a SSSL nozzle, presuming string potentiometers are a viable option and the facility is conducive of their implementation.

Supersonic Split-Line↗
NASA NTRSDate not supplied

Bypass Duct Acoustic Liner Design With and Without Bifurcation Effects

The growth in air traffic and the commitment to sustainable aviation continue to provide new challenges to reducing aircraft noise levels. Acoustic liner design methodologies must therefore provide the capability to efficiently predict the acoustic benefits of novel liner configurations within complex aircraft nacelle geometries. With these observations in mind, a broadband acoustic liner optimization process has been developed and assessed through a series of design and experimental studies at increasing technology readiness levels. This work applies the design process to the aft-fan noise component and explores the effects of bypass duct bifurcations (e.g., the pylon and lower bifurcation). In addition to this new application, the design study is expanded to include the use of a commercially available duct propagation code. Despite the different general workflow for the two propagation codes, consistent optimized impedance spectra and in-duct attenuation predictions were obtained for several acoustic treatment options. The preliminary results are promising, and this work increases confidence in the enhanced broadband liner design methodology and lays the groundwork for complimentary use of the codes in future studies. The potential benefits of acoustic treatment on the upper and lower bifurcations are also demonstrated. The knowledge gained through this preliminary stage of the liner design process will be used to guide the identification of candidate liner designs for a proposed static engine test within the next year.

Acoustic Liner Design↗
NASA NTRSDate not supplied

Bypass Duct Acoustic Liner Design with and without Bifurcation Effects

The growth in air traffic and the commitment to sustainable aviation continue to provide new challenges to reducing aircraft noise levels. Acoustic liner design methodologies must therefore provide the capability to efficiently predict the acoustic benefits of novel liner configurations within complex aircraft nacelle geometries. With these observations in mind, a broadband acoustic liner optimization process has been developed and assessed through a series of design and experimental studies at increasing technology readiness levels. This work applies the design process to the aft-fan noise component and explores the effects of bypass duct bifurcations (e.g., the pylon and lower bifurcation). In addition to this new application, the design study is expanded to include the use of a commercially available duct propagation code. Despite the different general workflow for the two propagation codes, consistent optimized impedance spectra and in-duct attenuation predictions were obtained for several acoustic treatment options. The preliminary results are promising, and this work increases confidence in the enhanced broadband liner design methodology and lays the groundwork for complimentary use of the codes in future studies. The potential benefits of acoustic treatment on the upper and lower bifurcations are also demonstrated. The knowledge gained through this preliminary stage of the liner design process will be used to guide the identification of candidate liner designs for a proposed static engine test within the next year.

Acoustic Liner Design↗
NASA NTRSDate not supplied

X-57 Systems Engineering Lessons Learned

The X-57 Maxwell is an electric aircraft based on a 4-passenger, twin engine Tecnam P2006T General Aviation aircraft. The X-57 project originally envisioned a straightforward integration of commercial-off-the-shelf hardware components and software into a novel configuration to demonstrate the aerodynamic and performance benefits of Distributed Electric Propulsion (DEP). The project was initially started with a high-risk venture capitalist approach under NASA’s Convergent Aeronautics Solutions (CAS) project, which led to an initial philosophy of Project Management “light” (which was then interpreted as Systems Engineering (SE) “light”). As the project matured, it was forced to transition to one with increasing SE-rigor as the project scope changed, hardware and software deficiencies were found, and the team realized the magnitude of the technical and integration challenges. In hindsight, these technical challenges came in part from an overly optimistic technology readiness assessment (TRA) at the beginning of the project, which resulted in the project assuming that little to no subsystem development would be required. The project’s approach to systems engineering evolved throughout three separate informal phases of the project as it underwent two key transitions as a result of the team wrestling with the technical challenges and resultant changing project scope. This paper discusses the assumptions, approaches, and challenges encountered from a Systems Engineering standpoint in each of the three informal phases of the X-57 project. This paper also provides recommendations on how future projects can apply Systems Engineering best practices upfront along with a realistic TRA to aid projects that find themselves with similar challenges.

Systems Engineering↗
NASA NTRSDate not supplied

Deep Space Habitat Primary Structure - A Comparison between Metallic, Inflatable, and Composite Materials

This paper presents a comprehensive trade study comparing metallic, inflatable, and composite primary structure materials for a Mars Transit Habitat module. The study evaluates the impact of these materials on the overall mass, outfitting, and mission complexity of the habitat. The results show that the composite module outperforms the other options in terms of minimum mass, being 33% lighter than the metallic configurations and 41% lighter than the inflatable option. The study highlights the potential of composite habitats for future space missions and emphasizes the need for further development and testing to increase the Technology Readiness Level.

Matthew T. Ziglar↗
NASA NTRSDate not supplied

Overview of the National Airspace System (NAS) Digital Twin Simulation Environment

The National Airspace System (NAS) Digital Twin is an environment for building and running diverse, realistic simulations of current or future airspace operations. The environment allows for many different types of simulations including both fast-time and real-time operating modes. Playback of historical or live NAS traffic can be combined with simulated aircraft to create a detailed, live, virtual, and constructive environment. These capabilities go together to create an environment that allows for development of concepts through the entire Technology Readiness Levels scale from initial concept to field evaluations. This extended abstract will discuss details of the software-foundations of the NAS Digital Twin environment. Then, several example simulations and analyses will be presented to illustrate the breadth and power of the tool.

airspace simulation, digital twin↗
NASA NTRSDate not supplied

Performance Testing of TRL4-6 LISA Laser System

The Laser Interferometer Space Antenna (LISA) is an ESA-led future mission to measure gravitational waves from astronomical sources in space. LISA has been adopted as a formal mission by ESA in January 2024, and is expected to become a formal project at NASA within 2024. The laser system (LS), which includes four laser heads (LH) each containing a laser optical module (LOM) and laser electronics module (LEM), a frequency reference system (FRS, optical frequency reference) and four power monitor detectors (PMON), is one of the three U.S. contributions to LISA from NASA. The Lasers and Electro-Optics Branch at NASA GSFC has been developing and managing the design of the LISA LS. Currently, the TRL (technology readiness level) of the NASA LISA laser system is transitioning from 4 to 6. TRL 4/5 LISA LOM was sent to ESA in early 2023 and has undergone optical performance testing. [1] By late summer of 2024, NASA plans to deliver the TRL 6 LOM to ESA for performance evaluation. Since the delivery of the TRL4/5 LOM to ESA, we have taken steps to advance the TRL of the overall LS and have also started end-to-end system level testing involving other subsystems. They include 1) optical performance test of TRL6 LOM and TRL 5 LEM under thermal cycling, 2) end-to-end test of the laser head (LH) and the GSE (ground support equipment) FRS, driven by TRL 4 FRS electronics (FRS-E) provided by Ball Aerospace, 3) end-to-end test of the laser head (LH) with the GSE phase meter system (PMS) provided by Albert Einstein Institute, and 4) optical performance test of the LH with the PMON subsystem developed by NASA. The FRS, PMS, and PMON provide necessary frequency stability, relative phase stability between lasers, and output power stability, respectively. Since they are all vital for the sensitive laser interferometry performed in LISA, it is necessary to perform these system level testing by combining the LH and other subsystems, and to prove the optical performance at an early stage during the LS development. Our recent work has successfully demonstrated the intra-connectivity of the LS, as well as critical external interface with the PMS to meet the LISA’s performance requirements. In this talk, we will report on the latest status of the LH testing and system level test. We will also discuss the paths to bring each subsystem to TRL6+ and plans for future system level testing.

LISA↗
NASA NTRSDate not supplied

Overview of the National Airspace System (NAS) Digital Twin Simulation Environment

The National Airspace System (NAS) Digital Twin is an environment for building and running diverse, realistic simulations of current or future airspace operations. The environment allows for many different types of simulations including both fast-time and real-time operating modes. Playback of historical or live NAS traffic can be combined with simulated aircraft to create a detailed, live, virtual, and constructive environment. These capabilities go together to create an environment that allows for development of concepts through the entire Technology Readiness Levels scale from initial concept to field evaluations. This extended abstract will discuss details of the software-foundations of the NAS Digital Twin environment. Then, several example simulations and analyses will be presented to illustrate the breadth and power of the tool.

airspace simulation↗
NASA NTRSDate not supplied

Seeing the Future of Spaceflight: Applications of Extended Reality (XR) Technologies

INTRODUCTION Advances in Earth Independent Medical Operations (EIMO) focused capabilities will be crucial for completing successful beyond low-earth-orbit (LEO) missions, where traditional Earth-based medical support and near real-time communication are limited, intermittent, or absent. In such restricted or limited communication environments, emerging extended reality (ER or XR) technologies may play a vital role in ensuring crew health and safety. Virtual Reality (VR), Augmented Reality (AR), and Mixed Reality (MR) are common terms used to describe technologies that "generate or modify" while “extended reality” (ER or XR) is often used as an umbrella term for these technologies. This review explores how such cutting-edge “extended reality” information delivery systems are currently applied across various disciplines within NASA. The review focuses on their capabilities, limitations, and prospective future applications as they pertain to Earth-Independent Medical Operations and its components of pre-mission planning, medical decision making, resource management, and task load management. METHODS/DESIGN The review began with a literature search to identify relevant disciplines (e.g., medical education, austere environments) where XR technologies have been studied to highlight areas where evidence is lacking. Previous and current NASA XR projects and applications, as well as commercial partnerships, such as those with Small Business Innovation Research (SBIR), were identified. Discussions with technical experts involved in the design, development, and application of these technologies allowed for classification based on their respective spaceflight applications. RESULTS AND CONCLUSION This review highlights current and emerging XR technologies that have been developed, tested, and implemented both terrestrially and in spaceflight by NASA, its international partners, the U.S. Armed Forces, and various relevant commercial entities. While these novel information delivery systems vary in their respective technology readiness levels (TRL), they have the potential to be implemented on Earth, in LEO, and during deep space exploration. These systems have the potential for impacting and optimizing many aspects of EIMO.

Yevgeniy Zhivotovskiy↗
NASA NTRSDate not supplied

Overview of the NASA LISA Laser System Development

NASA Goddard Space Flight Center (GSFC) is developing the Laser System (LS) for the Laser Interferometer Space Antenna (LISA) mission, led by the European Space Agency (ESA) with a launch date of 2035. The LS under development at NASA GSFC consists of the Laser Head (LH), the Frequency Reference System (FRS), and the Power Monitor (PMON) Detector Assemblies. Since late 2017, we have been developing various models to advance the technology readiness level (TRL) for the LH from prototype (TRL4) to a system model demonstration in a relevant environment (TRL6). For the LH and FRS, the models further breakdown into the optical and electronics modules where the LH is made up of the Laser Optical Module (LOM) and the Laser Electronics Module (LEM) and the FRS consists of the FRS Optical Reference Cavity (FRS-O) and the FRS Electronics (FRS-E). The LS development follows the established NASA process in demonstrating the performance requirements [1] through the TRL4 effort and then advancing the form factor and package design to meet relevant environment requirements and qualifying the TRL6 design through rigorous testing and performance verification for space applications. The LOM for the LH is a main oscillator power amplifier (MOPA) with wavelength of 1064 nm and nominal output power of 2 Watt throughout the mission. The low-power, low-noise main oscillator (MO) is a custom micro non-planar ring oscillator (µNPRO) [2] that is phase modulated then amplified by the forward pumped ytterbium-dope fiber power amplifier (PA) stage to meet the output power requirement. The FRS is baselined on the GRACE Follow-On (GFO) [3] approach with updated FRS-E design to work with the LH-LEM. The PMON is located on the Optical Bench Assembly (OBA) [4] that samples a small portion of the LH output signal and provides the feedback signal to the LH-LEM for relative intensity noise (RIN) control. In this paper, we will report on the latest status of the LH testing and system level tests, explain the other subsystems involved in the test campaigns, and discuss the path to bring each LS subsystem to TRL6. We will also present the NASA GSFC roadmap in advancing the LISA LS to TRL6+ and plans for future system level testing as well as the preparation for space flight development to meet the LISA launch date of 2035.

amplifier↗
NASA NTRS2024

Lunar Vehicle Active Charge Control System (LVACCS)+

The Lunar Vehicle Active Charge Control System (LVACCS) is an instrument in development that will measure the electrical potential of a spacecraft or rover under both positive and negative charge conditions, actively discharge negative charge, and charge the vehicle to a safe positive potential. All surfaces immersed in a plasma charge to non-zero potentials. In very low-density plasma (< 100 cm^-3), space vehicle charging can interfere with plasma probe measurements, degrade avionics performance, or cause a total system failure. LVACCS provides real-time in-situ space situational awareness that overcome these challenges in a small package. LVACCS has been awarded a NASA PICASSO grant to bring the instrument to technology readiness level 5. LVACCS consists of two main components: a collimated photoelectron gun (CPEG) and a Spacecraft Charge Detector (SCD).Monitoring charge build up on the lunar surface isa critical first step to understand hazards for crew, rovers, and instrumentation operating there.The LVACCS instrument will be able to fill in this gap providing robust lunar surface potential measurements and active charge dissipation.

Moon↗
NASA NTRS2025

Transit Habitat Government-Reference Conceptual Design Reaction Control System Propulsion Concept Design Data Book

The function of Transit Habitat (TH) Reaction Control System (RCS) propulsion is to provide free-flying spacecraft capabilities and to augment Gateway stack control when docked on Gateway. The requirements of multiple propellant replenishments and extensive life operation have significant impacts on selection of the propulsion system concept and components for the RCS. The intent of this document is to provide insight into the government-reference conceptual design of a propulsion system for TH element. A pressure-fed hypergolic bi-propellant system is the assumed propulsion approach for the RCS. Its architectural concept is being traded within the NASA Moon to Mars architecture. A pressure-regulated system is examined. The propellants under consideration are Monomethyl Hydrazine (MMH) and Mixed Oxides of Nitrogen with 3% Nitric Oxide (MON3). A peer review was conducted to assess the flow schematic design and propulsion component selection, compliant with a set of assumed requirements. Redundant components to satisfy one-fault tolerance for function and two-fault tolerance against catastrophic events are incorporated in the propulsion concept design. Instrumentation laid out on the schematic would be used to gather data to monitor the health of the propulsion system and to support quantity gauging of the propulsion system fluids. Venting propellant ullage gas overboard during the refilling operations poses a significant concern to the external surfaces of the TH. A liquid/gas separator would be required to eliminate, or at least reduce, the amount of liquid propellant expelled in the vent gas mixture. The technology readiness level of the phase separator for the TH must be advanced. Metal diaphragm and non-positive-expulsion PMD propellant tank systems were traded against each other, with the PMD architecture being selected. A blowdown concept is also considered for the TH RCS propulsion. Its fluid schematic is derived from the pressure-regulated schematic with removal of assemblies involving the helium pressurization and ullage venting. Its system wet mass is 10% heavier than the pressure-regulated due to thruster performance loss and larger propellant tanks. There is no firm constraint on the propulsion system mass at this phase of the design. The blowdown concept can offer reduction in component count and operation, that would lead to a more reliable propulsion system. The blowdown concept would also benefit avionics, thermal, power, and structures on the TH. Assessing these benefits will be carried as a future work. Drawbacks of thrust and minimum impulse bit (MIB) variations due to the blowdown operation would be acceptable to Guidance, Navigation, and Control (GNC). Although the blowdown concept has been selected as a current baseline, further evaluation of the concept will be the subject of future work to ensure that the blowdown propulsion operation is appropriate for the HT RCS propulsion. This document also highlights key trade studies and design decisions, including pros and cons of the selected concept. Other appropriate options for components are pointed out for future assessments. Additional background information and documents for further review are referenced in this report.

spacecraft propulsion↗
NASA NTRSDate not supplied

Design, Development, and Test of the Advanced Apollo Orbital Assembly System

As spaceflight moves toward commercial solutions for Crew Vehicles and Space Stations, opportunity exists to lower costs with novel designs. Probe and cone docking systems provide a lightweight, low cost, and high-performance docking solution. This work revisits the Apollo probe and cone design and modifies it for the requirements of today’s computer-controlled spacecraft. This new system is called the Advanced Apollo Orbital Assembly (APOA) system, and is intended to support satellite, cargo, and space station assembly missions. A simulation of the APOA was programmed, components were sized, and a design was created by scaling the probe to the size of an EELV Secondary Payload Adapter (ESPA) tunnel. Prototype test hardware was 3D printed using Fused Deposition Modeling (FDM) methods with Polylactic Acid (PLA) material. Testing of the APOA-ESPA was conducted at Marshall Space Flight Center’s (MSFC) Flat Floor, and a test-correlated simulation is used to evaluate a Monte-Carlo of Initial Contact Conditions (ICC’s) to establish baseline performance. The successful development, test, and correlation of the APOA-ESPA proves the design validity and increases Technology Readiness Level (TRL) from 2 to 4. This work opens the door to construction of an APOA-ESPA from flight like materials, and to develop a larger scale prototype APOA. When the full scale APOA is incorporated with the Common Berthing Mechanism (CBM), becomes the Hybrid Berthing System (HBS), which allows for berthing without a robotic arm.

Berthing↗