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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 1,171 records · Page 65
All sourcesNASA NTRSDOE OSTI
NASA NTRS2022

Direct Imaging and Spectroscopy of Exoplanetary Systems with the JWST Early Release Science Program

The direct characterization of exoplanetary systems with high contrast imaging is among the highest priorities for the broader exoplanet community. As large space missions will be necessary for detecting and characterizing exo-Earth twins, developing the techniques and technology for direct imaging of exoplanets is a driving focus for the community. For the first time, JWST will directly observe extrasolar planets at mid-infrared wavelengths beyond 5 μm, deliver detailed spectroscopy revealing much more precise chemical abundances and atmospheric conditions, and provide sensitivity to analogs of our solar system ice-giant planets at wide orbital separations, an entirely new class of exoplanet. However, in order to maximise the scientific output over the lifetime of the mission, an exquisite understanding of the instrumental performance of JWST is needed as early in the mission as possible. In this paper, we describe our 55-hour Early Release Science Program that will utilize all four JWST instruments to extend the characterisation of planetary mass companions to ∼15-20 μm as well as image a circumstellar disk in the mid-infrared with unprecedented sensitivity. Our program will also assess the performance of the observatory in the key modes expected to be commonly used for exoplanet direct imaging and spectroscopy, optimize data calibration and processing, and generate representative datasets that will enable a broad user base to effectively plan for general observing programs in future cycles.

Michael W McElwain↗
NASA NTRS1999

Evaluation of Space Power Materials Flown on the Passive Optical Sample Assembly

Evaluating the performance of materials on the exterior of spacecraft is of continuing interest, particularly in anticipation of those applications that will require a long duration in low Earth orbit. The Passive Optical Sample Assembly (POSA) experiment flown on the exterior of Mir as a risk mitigation experiment for the International Space Station was designed to better understand the interaction of materials with the low Earth orbit environment and to better understand the potential contamination threats that may be present in the vicinity of spacecraft. Deterioration in the optical performance of candidate space power materials due to the low Earth orbit environment, the contamination environment, or both, must be evaluated in order to propose measures to mitigate such deterioration. The thirty two samples of space power materials studied here include solar array blanket materials such as polyimide Kapton H and SiO(x) coated polyimide Kapton H, front surface aluminized sapphire, solar dynamic concentrator materials such as silver on spin coated polyimide and aluminum on spin coated polyimide, CV 1144 silicone, and the thermal control paint Z-93-P. The physical and optical properties that were evaluated prior to and after the POSA flight include mass, total, diffuse, and specular reflectance, solar absorptance, and infrared emittance. Additional post flight evaluation included scanning electron microscopy to observe surface features caused by the low Earth orbit environment and the contamination environment, and variable angle spectroscopic ellipsometry to identify contaminant type and thickness. This paper summarizes the results of pre- and post-flight measurements, identifies the mechanisms responsible for optical properties deterioration, and suggests improvements for the durability of materials in future missions.

Jaworske, Donald A.↗
DOE OSTI2023

A high‐order discontinuous Galerkin approach for physics‐based thermospheric modeling

Abstract The accurate prediction of aerodynamic drag on satellites orbiting in the upper atmosphere is critical to the operational success of modern space technologies, such as satellite‐based communication or navigation systems, which have become increasingly popular in the last few years due to the deployment of constellations of satellites in low‐Earth orbit. As a result, physics‐based models of the ionosphere and thermosphere have emerged as a necessary tool for the prediction of atmospheric outputs under highly variable space weather conditions. This paper proposes a high‐fidelity approach for physics‐based space weather modeling based on the solution of the Navier–Stokes equations using a high‐order discontinuous Galerkin method, combined with a matrix‐free strategy suitable for high‐performance computing on GPU architectures. The approach consists of a thermospheric model that describes a chemically frozen neutral atmosphere in nonhydrostatic equilibrium driven by the external excitation of the Sun. A novel set of variables is considered to treat the low densities present in the upper atmosphere and to accommodate the wide range of scales present in the problem. At the same time, and unlike most existing approaches, radial and angular directions are treated in a nonsegregated approach. The study presents a set of numerical examples that demonstrate the accuracy of the approximation and validate the current approach against observational data along a satellite orbit, including estimates of established empirical and physics‐based models of the ionosphere‐thermosphere system. Finally, a one‐dimensional radial derivation of the physics‐based model is presented and utilized for conducting a parametric study of the main thermal quantities under various solar conditions.

Engineering↗
DOE OSTI2025

An effective field theory for muon conversion and muon decay-in-orbit

Muon conversion is one of the best probes of charged lepton flavor violation. The experimental limit is soon expected to improve by four orders of magnitude, thus calling for precise predictions of the shape of the signal spectrum. Equally important are precise predictions for muon decay-in-orbit, the main background for muon conversion. While the calculation of electromagnetic corrections to the two processes above the nuclear scale does not involve significant challenges, it becomes substantially more complex below that scale due to multiple scales, bound-state effects and experimental setup. Here, we present a systematic framework that addresses these challenges by resorting to a series of effective field theories. Combining Heavy Quark Effective Theory (HQET), Non-Relativistic QED (NRQED), potential NRQED, Soft-Collinear Effective Theory I and II, and boosted HQET, we derive a factorization theorem and present the renormalization group equations. Our framework allows for the proper calculation of precise predictions for the rates of the two processes, with crucial implications for the upcoming muon conversion searches. We also provide the most accurate prediction of the signal shape for those searches.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
NASA NTRS1988

Gateway: An earth orbiting transportation node

University of Texas Mission Design (UTMD) has outlined the components that a space based transportation facility must include in order to support the first decade of Lunar base buildup. After studying anticipated traffic flow to and from the hub, and taking into account crew manhour considerations, propellant storage, orbital transfer vehicle maintenance requirements, and orbital mechanics, UTMD arrived at a design for the facility. The amount of activity directly related to supporting Lunar base traffic is too high to allow the transportation hub to be part of the NASA Space Station. Instead, a separate structure should be constructed and dedicated to handling all transportation-related duties. UTMD found that the structure (named Gateway) would need a permanent crew of four to perform maintenance tasks on the orbital transfer and orbital maneuvering vehicles and to transfer payload from launch vehicles to the orbital transfer vehicles. In addition, quarters for 4 more persons should be allocated for temporary accommodation of Lunar base crew passing through Gateway. UTMD was careful to recommend an expendable structure that can adapt to meet the growing needs of the American space program.

Source record↗
NASA NTRS2019

An Analytic Model for Estimating the First Contact Resistance Needed to Avoid Damaging ESD During Spacecraft Docking in GEO

NASA’s Gateway program will involve spacecraft (s/c) docking in the outer radiation belt in order to transfer Gateway elements between s/c for transport to lunar orbit. The charging of these s/c to different potentials prior to docking raises the possibility of a damaging electrostatic discharge (ESD) at the time of first contact between the s/c. A proposed mitigation strategy is for first contact to occur prior to docking through a resistor with resistance R that would lower the potential difference at an optimal rate to a sufficiently low value to prevent ESD damage. The coupling of s/c by a resistor can be modeled by SPIS, but for realistic two s/c models SPIS can take hours to simulate the evolution of the s/c surface charges and potentials to an equilibrium state. Our objective is to develop a simpler model of s/c resistive coupling that runs orders of magnitude faster while providing useful first design estimates of the time variation of the s/c potentials, current through the resistor, and how these vary with R and s/c configuration This configuration is defined by the relative separation and orientation of the s/c, and their solar illumination. The configuration and geometry of the s/c determine their capacitive coupling. The s/c capacitances are computed using Nascap-2K. This poster presents the first version of such a model, and initial tests.

Goodman, Michael L.↗
NASA NTRS2017

Human Cargo Resupply Logistics at Mars Using 150kW SEP Tug Cyclers

The ultimate goal of the Evolvable Mars Campaign is to build up a sustainable outpost at Mars that would be continually staffed with rotating crews. During this stage of human Mars exploration, it would be necessary to provision the crews with equipment and supplies both before and during their missions. In this paper, we study the use of 150 kW reusable SEP tugs as a means to deliver elements both to orbit and to the surface. The SEP tugs would make use of technology currently being developed for the proposed Asteroid Robotic Redirect Mission (ARRM). They would also be used to deliver food and supplies to sustain the crews similar to resupply missions for the International Space Station. The SEP tugs envisioned would be staged at a quasi-stable Lunar Near Rectilinear Orbit (NRO). The tugs would then mate with cargo vessels and xenon propellant being delivered by an SLS launch vehicle and continue on to Mars orbit where the cargo is delivered and the SEP tug returns to NRO to repeat the process. It was found that it is more efficient to deliver surface cargo via direct launch and entry versus using the tug cycler. Thousands of optimized low-thrust trajectories were simulated in order to create “Bacon plots” (like porkchop plots, but for low thrust transfers) in order to map out potential trajectories for dates from 2039 to 2052. This study maps out the buildup of a surface outpost as well as the necessary orbital and surface resupply launches in order to maintain it. In the steady state, a cadence of 9 cargo launches is required every 4 years to sustain the human outpost.

Post, Kevin↗
DOE OSTI2021

Eject, crash, or survive: Using machine learning to predict orbital instability of exoplanetary systems

Astronomers throughout history, including titans like Kepler and Newton, have tackled planetary dynamics and orbital instability. Despite strides taken in research, understanding the evolution of planetary orbits remains an intricate, computationally expensive, and analytically unsolved problem. I apply machine learning classification methods to numerical simulations of planetary systems in order to predict the long-term fate of the planet - whether the planet remains in a stable orbit or not. My method uses the first 41.1 years (≤ 500 orbits) of data from a planet’s simulation to calculate 17 dynamically-motivated metrics; I trained my classifier on these features to predict a planet’s stability after 107 years. At 84.33%, my classifier was comparable in accuracy to pre-existing literature, despite using significantly less computational power than most other methods. In my research, I found that the standard deviation of eccentricity, mass ratios for neighboring planets, and semi-major axis ratio with the outer planet neighbor to be the most predictive features of instability. I propose reasons for the importance of these features, their role in planetary dynamics, as well as possible explanations for why some planets were misclassified. By understanding the important metrics of instability and reasons for misclassification, we can begin to understand more about system architectures, orbital motion and dynamics, and the formation and evolution of the exoplanetary systems. This is applicable in our own Solar System, and with exoplanet discovery missions such as TESS, this research becomes especially relevant in understanding the new exoplanetary systems we discover.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2021

Eject, crash, or survive: Using machine learning to predict orbital instability of exoplanetary systems

Astronomers throughout history, including titans like Kepler and Newton, have tackled planetary dynamics and orbital instability. Despite strides taken in research, understanding the evolution of planetary orbits remains an intricate, computationally expensive, and analytically unsolved problem. I apply machine learning classification methods to numerical simulations of planetary systems in order to predict the long-term fate of the planet - whether the planet remains in a stable orbit or not. My method uses the first 41.1 years (≤ 500 orbits) of data from a planet’s simulation to calculate 17 dynamically-motivated metrics; I trained my classifier on these features to predict a planet’s stability after 107 years. At 84.33%, my classifier was comparable in accuracy to pre-existing literature, despite using significantly less computational power than most other methods. In my research, I found that the standard deviation of eccentricity, mass ratios for neighboring planets, and semi-major axis ratio with the outer planet neighbor to be the most predictive features of instability. I propose reasons for the importance of these features, their role in planetary dynamics, as well as possible explanations for why some planets were misclassified. By understanding the important metrics of instability and reasons for misclassification, we can begin to understand more about system architectures, orbital motion and dynamics, and the formation and evolution of the exoplanetary systems. This is applicable in our own Solar System, and with exoplanet discovery missions such as TESS, this research becomes especially relevant in understanding the new exoplanetary systems we discover.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS1978

Five years in the life of an inertial system operating in orbit

The paper describes the in-orbit performance of the gyroscopes and strapdown attitude reference system for the OAO-C (Copernicus) satellite, launched on Aug. 21, 1972. In order to fulfill NASA requirements, the inertial system had to: (1) operate for at least one year in orbit without failure, (2) maintain an inertial reference with an uncertainty of 50 microradians or less for at least one hour, and (3) control attitude changes with an accuracy of at least 30 parts per million. During the orbit period, the inertial system has demonstrated a capability for maintaining an inertial reference that is significantly better than these performance goals.

Harris, R. A.↗
NASA NTRS2010

Roles of Engineering Correlations in Hypersonic Entry Boundary Layer Transition Prediction

Efforts to design and operate hypersonic entry vehicles are constrained by many considerations that involve all aspects of an entry vehicle system. One of the more significant physical phenomenon that affect entry trajectory and thermal protection system design is the occurrence of boundary layer transition from a laminar to turbulent state. During the Space Shuttle Return To Flight activity following the loss of Columbia and her crew of seven, NASA's entry aerothermodynamics community implemented an engineering correlation based framework for the prediction of boundary layer transition on the Orbiter. The methodology for this implementation relies upon similar correlation techniques that have been is use for several decades. What makes the Orbiter boundary layer transition correlation implementation unique is that a statistically significant data set was acquired in multiple ground test facilities, flight data exists to assist in establishing a better correlation and the framework was founded upon state of the art chemical nonequilibrium Navier Stokes flow field simulations. Recent entry flight testing performed with the Orbiter Discovery now provides a means to validate this engineering correlation approach to higher confidence. These results only serve to reinforce the essential role that engineering correlations currently exercise in the design and operation of entry vehicles. The framework of information related to the Orbiter empirical boundary layer transition prediction capability will be utilized to establish a fresh perspective on this role, and to discuss the characteristics which are desirable in a next generation advancement. The details of the paper will review the experimental facilities and techniques that were utilized to perform the implementation of the Orbiter RTF BLT Vsn 2 prediction capability. Statistically significant results for multiple engineering correlations from a ground testing campaign will be reviewed in order to describe why only certain correlations were selected for complete implementation to support the Shuttle Program. Historical Orbiter flight data on early boundary layer transition due to protruding gap fillers will be described in relation to the selected empirical correlations. In addition, Orbiter entry flight testing results from the BLT Flight Experiment will be discussed in relation to these correlations. Applicability of such correlations to the entry design problem will be reviewed, and finally a perspective on the desirable characteristics for a next generation capability based on high fidelity physical models will be provided.

Campbell, Charles H.↗
NASA NTRS2019

An Analytic Model for Estimating the First Contact Resistance Needed to Avoid Damaging ESD During Spacecraft Docking in GEO

NASA’s Gateway program is to involve spacecraft (s/c) docking in the outer radiation belt in order to transfer Gateway elements between s/c for transport to lunar orbit. The charging of these s/c to different potentials prior to docking raises the possibility of a damaging electrostatic discharge (ESD) at the time of first contact between the s/c. A proposed mitigation strategy is for first contact to occur prior to docking through a resistor with resistance R that would lower the potential difference at an optimal rate to a sufficiently low value to prevent a damaging ESD. The coupling of s/c by a resistor can be modeled by SPIS (Spacecraft Plasma Interaction System), but for realistic two s/c models SPIS can take hours to simulate the evolution of the s/c surface charges and potentials to an equilibrium state. Our objective is to develop a simpler model of s/c resistive coupling that runs orders of magnitude faster while providing useful first design estimates of the time variation of the s/c potentials, current through the resistor, and how these vary with R and s/c configuration. This configuration is defined by the relative separation and orientation of the s/c, and their solar illumination. The configuration and geometry of the s/c determine their capacitive coupling. The s/c capacitances are computed using Nascap-2K. This abstract and the associated poster describe the first version of such a model, and initial tests.

Goodman, Michael L.↗
NASA NTRS1983

Flow field description for the reaction control system of the Space Shuttle Orbiter

The flow field for the Reaction Control System (RCS) jets of the Space Shuttle Orbiter has been calculated from the nozzle throat to the far-field flow region. The calculations involved the use of recently improved rocket engine nozzle/plume codes and the source flow analytic model. The flow solution is discussed and used to produce impingement forces and moments for surfaces immersed in the flow. The impingement results are compared to calculations involving previous flow solutions in order to evaluate the impingement effects due to the RCS jets during orbital operations.

Alred, J. W.↗
NASA NTRSDate not supplied

Modeling Methods for 3D Lightning Mapping from Space

Global lightning detection has advanced greatly over the past few decades both on ground and from orbit. Ground-based systems like the Lightning Mapping Array (LMA) excel at high-precision 3D reconstruction of local flashes, while spaceborne lightning sensors have much larger potential coverage but are limited by coarser resolution and often rely on data from other instruments to determine 3D flash locations. CubeSpark is a new mission concept focused on combining these two methods in the form of six small satellites in low-Earth orbit. CubeSpark will combine RF and bispectral optical measurements of lightning in order to map the 3D structure of both individual flashes and their parent thunderstorms at 1-2 km spatial resolution on a global scale, enabling a host of new atmospheric, climate, and space electricity studies. The goal of this study is to assess the feasibility and expected resolution of lightning mapping via indivudal VHF sources using different methods and detector combinations. Flashes were simulated beneath orbital configurations consisting of 1-6 satellites, taking into account the complicated interactions with Earth's ionosphere. In the multi-satellite (>5) approach, RF detectors on each satellite measure the arrival times of impulsive VHF sources to collectively pinpoint their locations in 3D and reconstruct flashes with higher resolution than has been achieved from space. The same can process can be performed with 3-4 satellites by constraining sources' horizontal locations with onboard optical imagers. A 1-2 station approach follows the established method of determining the height of an RF source using the arrival time difference between direct RF waves and their reflections off the Earth's surface. Here we present preliminary results of the expected accuracy of these methods to inform potential satellite missions like CubeSpark.

Lightning↗
NASA NTRS2018

MMS Extended Mission Design: Evaluation of a Lunar Gravity Assist Option

This paper will describe a study that was carried out on the design of a set of maneuvers that were considered for the later stages of an extended mission of the Magnetospheric Multiscale (MMS) mission. The goal of these maneuvers was to put MMS into a significantly different orbit from those flown heretofore, so allowing science collection in a different region of the magnetosphere. This study was made feasible by the fact that the rate at which fuel is being consumed to maintain small formations on the MMS high-apogee orbit is less than expected pre-flight: the current consumption rate is only about 2 kg/yr/spacecraft. In addition, the spacecraft finished the prime mission with a significant amount of fuel remaining: this was about 1-sigma above the mean when compared with pre-launch Monte Carlo simulations. The resulting situation is similar to that of a libration orbit mission, where station-keeping requires so little fuel that any margin at all will lead to an extensive mission lifetime. In the case of MMS, the spacecraft could, if desired, perform formation flying in the current orbit for several decades. Alternatively, the spacecraft could use a significant fraction of the remaining fuel to perform major orbit modifications, while still leaving enough to conduct formation flying for on the order of a decade. The extended mission maneuvers studied here are further apogee-raises, with the goal of setting up one or more lunar gravity assists. Geometry dictates that a lunar encounter is only achievable when the MMS apogee vector lies approximately in the lunar orbit plane: this limits the possible dates to mid-2021 or early 2027.

Design↗
DOE OSTI2020

The Biomechanics of Indirect Traumatic Optic Neuropathy Using a Computational Head Model With a Biofidelic Orbit

Indirect traumatic optic neuropathy (ITON) is an injury to the optic nerve due to head trauma and usually results in partial or complete loss of vision. In order to advance a mechanistic understanding of the injury to the optic nerve, we developed a head model with a biofidelic orbit. Head impacts were simulated under controlled conditions of impactor velocity. The locations of impact were varied to include frontal, lateral, and posterior parts of the head. Impact studies were conducted using two types of impactors that differed in their rigidity relative to the skull. The simulated results from both the impactors suggest that forehead impacts are those to which the optic nerve is most vulnerable. The mode and location of optic nerve injury is significantly different between the impacting conditions. Simulated results using a relatively rigid impactor (metal cylinder) suggest optic nerve injury initiates at the location of the intracranial end of the optic canal and spreads to the regions of the optic nerve in the vicinity of the optic canal. In this case, the deformation of the skull at the optic canal, resulting in deformation of the optic nerve, was the primary mode of injury. On the other hand, simulated results using a relatively compliant impactor (soccer ball) suggest that primary mode of injury comes from the brain tugging upon the optic nerve (from where it is affixed to the intracranial end of the optic canal) during coup countercoup motion of the brain. This study represents the first published effort to employ a biofidelic simulation of the full length of the optic nerve in which the orbit is integrated within the whole head.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2020

Benchmarking an Embedded Adaptive Sampling Configuration Interaction Method for Surface Reactions: H 2 Desorption from and CH 4 Dissociation on Cu(111)

Embedded (emb-) correlated wavefunction (CW) theory enables accurate assessments of both ground- and excited-state reaction mechanisms involved in heterogeneous catalysis. Embedded multireference second-order perturbation theory (emb-MRPT2) based on reference wavefunctions generated via embedded complete active space self-consistent field (emb-CASSCF) theory is currently state-of-the-art. However, the factorial scaling of CASSCF limits the size of active space and the complexity of systems that can be studied. In this work, we assess the efficacy of an alternative CW method, adaptive sampling configuration interaction (ASCI)–which enables large active spaces to be used–for studying surface reactions. We couple ASCI with density functional embedding theory (DFET) and benchmark its performance for two reactions: H 2 desorption from and CH 4 dissociation on the Cu(111) surface. Unlike embedded complete active space second-order perturbation theory (emb-CASPT2) that accurately reproduces a measured H 2 desorption barrier, embedded ASCI, using a very large active space (though one that still comprises a small portion of the full set of orbitals) fails to do so. Adding an extra correlation term from embedded Møller–Plesset second-order perturbation theory (emb-MP2) improves the desorption barrier and endothermicity predictions. Thus, the inaccuracy of embedded ASCI comes from the missing dynamic correlation from the many other electrons and orbitals not included in the active space. For CH 4 dissociation, again embedded ASCI overestimates the dissociation barrier compared to emb-CASPT2 predictions. Adding dynamic correlation from emb-MP2 helps correct the barrier. However, this composite approach suffers from double counting of correlation within embedded ASCI followed by emb-MP2 calculations. We therefore conclude that the state-of-the-art emb-MRPT2 based on reference wavefunctions generated via emb-CASSCF remains the method of choice for studying surface reactions. emb-ASCI is useful when large active spaces beyond the limit of emb-CASSCF are essential, such as to study complex surface reactions with significant multiconfigurational character (static correlation) but weak dynamic correlation.

08 HYDROGEN↗
NASA NTRS1980

Technologies Involved in Configuring an Advanced Earth-to-Orbit Transport for Low Structural Mass

The current space shuttle is expected to adequately meet Government and industry needs for the transport of cargo to and from orbit well into the 1990's. However, continual study of potential follow-on shuttle systems is necessary and desirable in order to complement ongoing research in materials, structures, propulsion, aerodynamics, and other related areas. By studying alternate systems well in advance, it will be possible to explore the various technologies and develop those for which there is the greatest apparent payoff. In this paper a single-stage Earth-to-orbit transport designed for delivery of approximately 29,500 kg (65,000 lb) payload will be described. The vehicle, which takes off vertically and lands horizontally, is 60 m (197 feet) long and weighs approximately 1.8 Gg (4 M lb) at liftoff. In the interest of weight reduction, a simple body of revolution is utilized for the main body shell. In this design the main propulsion tanks serve as a primary load-carrying structure. Further, in order to minimize structural mass, the cargo bay is located between two of the main propellant tanks. The cargo volume, at 396 cu m (14,000 cu feet), exceeds that provided by the shuttle; but the bay itself is nonconforming in shape - being approximately 10 m (32 feet) in diameter by 5 m (17 feet) long. Dual-fuel propulsion is employed, since a number of studies have shown that (though lowering performance) the operation of hydrocarbon (RP) engines in parallel with LOX/LH2 engines results in a net reduction in the vehicle's physical size and structural mass. Other weight-saving features entail the extensive use of honeycomb sandwiches, advanced materials, and advanced fabrication techniques. The vehicle presented is utilized only as a means to study and identify various technologies needed in order to develop a low mass Earth-to-orbit transportation system for the future. The conclusion of this study is that vehicle geometry and structural/materials technology are critical to the development of efficient single-stage Earth-to-orbit transports.

MacConochie, Ian O.↗