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Enabling Interoperability in Earth System Digital Twins (ESDT): Integrating Observations, Models, and AI for Actionable Insights Through NASA'S Intelligent Systems Technology Program

NASA’s Intelligent Systems Technology Program (IST) is driving a paradigm shift in Earth science through the development of Earth System Digital Twins (ESDT). These integrated information systems create a dynamic "digital replica" of the Earth by harmonizing continuous, multi-source observations with high-fidelity models and state-of-the-art artificial intelligence (AI) that enable “What now?”, “What next?”, and “What if?” scenario building. These scenarios are reflected in NASA IST’s series of ESDTs, from the Coastal Zone Digital Twin that integrates complex data on the current state of the Chesapeake Bay to the Terrestrial Environmental Rapid-Replication and Assimilation Hydrometeorological (TerraHydro) AI-based ESDT that forecasts water movement across Earth’s surface, to the Agriculture Land Information System (AgLIS) which can be used to assess optimal planting dates and crop yield estimates. By bridging the gap between vast data archives and actionable insights, these projects enable a system-of-systems approach to understanding complex, interacting Earth processes. This poster will highlight recent innovations and future directions from NASA’s ESDT initiatives: Continuous Data Assimilation & Multi-Source Fusion. A core requirement of the ESDT work is the transition from static models to dynamic "living" replicas. This involves creating frameworks for the continual assimilation of near-real-time data from uncoordinated, heterogeneous sources, including satellite observations and airborne assets, and ground-based Internet of Things (IoT) sensors. These systems link design, operational status, and environmental data, ensuring the digital twin accurately reflects the current state of the physical Earth system. High-Fidelity Hybrid Modeling & Computational Acceleration to enable interactive "what-if" explorations, programs are moving beyond traditional, slow physical solvers by developing fast surrogate machine learning models and Deep Generative Models (DGMs). These hybrid approaches use neural networks to emulate complex physics, such as cloud feedback or ocean dynamics, at a fraction of the original computing cost, often leveraging advanced hardware like Graphics Processing Units (GPUs) to achieve the necessary scale. Federated Ecosystems & Interoperable Frameworks rather than building isolated tools, NASA IST is moving toward federated ESDTs and reusable analytic collaborative frameworks. This theme focuses on interoperability standards and common ontologies that allow specialized digital twins to interact and share data. This system-of-systems architecture supports multi-discipline investigations, such as analyzing how upstream watershed changes impact downstream urban flooding or how wildfire emissions affect regional air quality. By leveraging these advancements, ESDTs empower researchers and decision-makers to conduct real-time analysis and run complex hypothetical scenarios, ultimately improving our understanding of Earth’s evolving systems and informing critical real-world applications.

Earth System

Advances in Design Capabilities for Planetary Missions from the NASA Entry Systems Modeling and Instrumentation Portfolio

The Entry Systems Modeling project (ESM) is supported by both the NASA Space Technology and the Science Mission Directorates and focuses on developing simulation tools and validated models for characterizing the performance of entry systems tailored to planetary destinations across the Solar System. ESM is organized into six technical capability areas that together address all relevant factors related to spacecraft entry, as well as some aspects of descent: Thermal Protection System (TPS) Materials; Aerothermodynamics; Entry & Descent Vehicle Dynamics; Guidance, Navigation, and Control; Vehicle Systems Analysis; and Advanced Tools and Numerical Methods. Development within the capability areas is undertaken explicitly with a focus on transition and infusion to science missions, human exploration missions, and commercial space activities. The present talk details developments that specifically impact science missions, including simulation tool capabilities that aid in mission design and model development to understand entry system performance at a given destination. Examples of the successful infusion and transition of such project outcomes to science missions also are provided. Several simulation tool development efforts within ESM have resulted in new design capabilities for missions. One such outcome is improved toolsets for mission trajectory and concept of operations design. Specifically, an initiative to couple a leading tool for entry, ascent/descent, and orbital trajectory optimization (Program to Optimize Simulated Trajectories II or POST2) to those used within the Agency for interplanetary trajectory optimization (Copernicus and Monte) has made substantial progress, with the outcomes to date promising to allow efficient trajectory optimization across mission phases. Additionally, toolchains for the evaluation of vehicle performance during entry and descent have been developed that allow assessment of multi-dimensional aeroheating on detailed vehicle geometries, characterization of deployment and inflation of parachutes, and assessment of vehicle dynamic stability during descent. These capabilities are achieved by coupling diverse sets of physics together – material response, computational fluid dynamics, radiation, and vehicle dynamics – to suitably describe complex entry and descent phenomena. Several model development and validation efforts for specific destinations and entry regimes also are underway within the ESM project. For instance, new experimental capabilities to validate radiation models at low densities/high altitudes recently have been established with project support, specifically the Low-Density Shock Tube (LDST) at the NASA Ames Research Center Electric Arc Shock Tube (EAST) facility. The LDST is being leveraged to develop improved models of shock layer kinetics and radiation in Titan atmospheres, while future studies will be conducted in the LDST and the existing high velocity shock tube to provide validation data for radiation models of Venus, Ice Giants, and Mars atmospheres. Models describing the aerothermal and thermo-structural performance of Thermal Protection System (TPS) materials has been another focus, with multiscale modeling activities on-going for the two leading TPS materials applicable to a range of entry conditions and science missions: the Phenolic-Impregnated Carbon Ablator (PICA) and woven materials like 3D Mid-Density Carbon Phenolic (3MDCP). A continual effort is made to infuse and transition outcomes from ESM simulation tool and model development activities into relevant science missions. Significant progress has been made on this front, with missions such as Dragonfly, DAVINCI, and Mars Missions benefitting from project outcomes. The groundwork also is being laid to provide insights into forward looking missions to Gas/Ice Giants as well as for potential sample returns.

Justin Haskins

The NERVA Engine Program

The objective of the NERVA engine program is the development of a nuclear rocket engine for use in space missions. The letters N E R V A mean Nuclear Engine for Rocket Vehicle Application. NERVA is a long-range program that had its beginning in about 1955 when the Los Alamos Scientific Laboratory began preliminary studies on the feasibility of thermal reactors for rocket application. At about the same time, the Livermore Laboratory began parallel studies, but this dual effort was discontinued about a year later. In 1961 an industrial contractor team, the Aerojet-General Corporation and the Westinghouse Electric Corporation, was selected to carry out the development of the NERVA engine, and their activity began in mid-1961. Aerojet was made the prime contractor with responsibility for the complete engine development program, and Westinghouse was made a principal subcontractor with responsibility for the development of the reactor. A government field office, the Cleveland Extension of the Space Nuclear Propulsion Office, was set up to manage this development program. This office is located in Cleveland because of the availability of technical backup at the Lewis Research Center.

Lester C Corrington

The dynamical origins of the dark comets and a proposed evolutionary track

So-called ‘dark comets’ are small, morphologically inactive near-Earth objects (NEOs) that exhibit nongravitational accelerations inconsistent with radiative effects. These objects exhibit short rotational periods (minutes to hours), where measured. We find that the strengths required to prevent catastrophic disintegration are consistent with those measured in cometary nuclei and expected in rubble pile objects. We hypothesize that these dark comets are the end result of a rotational fragmentation cascade, which is consistent with their measured physical properties. We calculate the predicted size-frequency distribution for objects evolving under this model. Using dynamical simulations, we further demonstrate that the majority of these bodies originated from the 𝜈6 resonance, implying the existence of volatiles in the current inner main belt. Moreover, one of the dark comets, (523599) 2003 RM, likely originated from the outer main belt, although a JFC origin is also plausible. These results provide strong evidence that volatiles from a reservoir in the inner main belt are present in the near-Earth environment.

Aster G Taylor

Symposium on Thermal Radiation of Solids

The Symposium was intended to provide for presentation and discussion of significant developments in the theory of thermal radiation of solids and in our understanding of the important effects of surfaces and interfaces and of surface imperfections on this radiation, of the effects of the space environment on radiation properties, and of the application of this information to the thermal designer's problems. Presentation of data as such-for example, absorptances and emittances of various types of coatings-was not considered a primary purpose of the Symposium; nevertheless, as the reader will observe, an appreciable amount of significant data of this type is contained in some of the papers. Developments in measurement techniques were also not considered basic to the main theme, especially since it was the theme of the preceding Symposium. However, because the subject remains of continuing concern, one session was devoted to it. These Proceedings contain all the papers presented orally at the Symposium together with the discussions that followed them, and, in addition, nine papers that were accepted for publication only. Each paper was reviewed by the session chairman and by the editor, and any apparent technical discrepancies were called to the attention of the author for clarification. As a further aid to the reader, the editor has tried to achieve some degree of uniformity in organization and format of the papers—at least to the extent permitted by the subject matter, and he has also striven for clarity and readability of the text. In this task he has had not only the cooperation of the authors but also extensive help from the Langley Technical Editing Section, the Langley Library (where most of the cited references were checked), and the NASA Headquarters Technical Publications Branch.

Solids

Astrophysical science with a spaceborne photometric telescope

The FRESIP Project (FRequency of Earth-Sized Inner Planets) is currently under study at NASA Ames Research Center. The goal of FRESIP is the measurement of the frequency of Earth-sized extra-solar planets in inner orbits via the photometric signature of a transit event. This will be accomplished with a spaceborne telescope/photometer capable of photometric precision of two parts in 100,000 at a magnitude of m(sub v) = 12.5. To achieve the maximum scientific value from the FRESIP mission, an astrophysical science workshop was held at the SETI Institute in Mountain View, California, November 11-12, 1993. Workshop participants were invited as experts in their field of astrophysical research and discussed the astrophysical science that can be achieved within the context of the FRESIP mission.

Granados, Arno F.

Spray Forming of NiTi and NiTiPd Shape-Memory Alloys

In the work to be presented, vacuum plasma spray forming has been used as a process to deposit and consolidate prealloyed NiTi and NiTiPd powders into near net shape actuators. Testing showed that excellent shape memory behavior could be developed in the deposited materials and the investigation proved that VPS forming could be a means to directly form a wide range of shape memory alloy components. The results of DSC characterization and actual actuation test results will be presented demonstrating the behavior of a Nitinol 55 alloy and a higher transition temperature NiTiPd alloy in the form of torque tube actuators that could be used in aircraft and aerospace controls.

Aero-Surface Controls

Ground-Based Microwave Measurements of ClO and O3 Over Scott Base, Antarctica

We present measurements from a new microwave instrument that has been deployed at Scott Base, Antarctica, primarily to measure ClO. The new instrument allows for the extension of the time series of lower stratospheric ClO measurements begun in 1996 at this site, while some of the technical improvements offer the possibility of making additional measurements. We show measurements of ClO and O 3 in both the upper and lower stratosphere near both the fall and spring equinox and document the diurnal variations of these measurements throughout the season. The ground-based measurements are compared with Aura Microwave Limb Sounder (MLS) measurements, which are available twice per day, and with a NASA Goddard 2D model (GSFC2D) simulation. We show that, in agreement with the GSFC2D model diurnal variations, upper stratospheric ClO mixing ratios gradually increase throughout the daylight hours, while in the lower stratospheric austral spring, when heterogeneous chemistry associated with polar stratospheric clouds occurs, daily maximum ClO mixing ratios of near 2 ppbv occur near noon. We also show measurements of stratospheric O 3 , primarily in the upper stratosphere, which, while exhibiting a low bias of ∼15%–20% relative to Aura MLS, show temporal variations in good agreement with MLS.

stratospheric ozone

NASA Scatterometer Oceanic Wind Measurement System

Satellite scatterometers are active microwave radars designed to yield measurements of near surface horizontal wind velocity over the ocean. Scatterometers are unique in that they are the only existing microwave remote sensing instruments that allow measurements of both wind speed and wind direction. NASA will fly a scatterometer, NSCAT, aboard the Navy Ocean Remote Sensing System (N-ROSS) mission starting in late 1990. N-ROSS is a spaceborne ocean remote sensing system with a planned mission life of three years. In addition to the NSCAT, N-ROSS will have three other microwave instruments mounted on a single satellite flying in a near polar orbit: an altimeter; a special sensor microwave/imager (SSM/I); and a low frequency microwave radiometer. The NSCAT to be flown on N-ROSS is described.

M Freilich

Fuels and Combustion Technology for Advanced Aircraft Engines [Les Propergols et les Systèmes de Combustion pour les Moteurs d'Aéronefs]

The Conference Proceedings contains the 38 papers presented at the Propulsion and Energetics Panel 81st Symposium on "Fuels and Combustion Technology for Advanced Aircraft Engines" which was held from 10th-14th May 1993, in Fiuggi, Italy. The Technical Evaluation Report and the Keynote Address are included at the beginning, and discussions follow most papers. The Symposium was arranged in the following Sessions: Technology Overview Papers (2); Modelling: Pollutant Formation (4); Modelling: Combustor Design (5); High Temperature Fuels and Fuel Systems (6); Combustion Research: Performance (6); Combustion Research: Emissions (5); Fuel Atomization: Diagnostics and Modelling (5); and Combustion Research: Flowfleld and Mixing (4). The last paper is a contribution from Russia not allocated to a session. New technologies for low NOx combustors and advanced high-pressure/high temperature cycle engines result in unique problems in design and performance. There have been significant advances in modelling and diagnostics to aid the development of these technologies. The purpose of the Symposium was to bring together experts from industry, research establishments and universities to discuss fundamental and applied research in these areas as relevant to the development of advanced gas turbine engines, to exchange practical experience and to discuss the state of the art.

Fuels for aircraft

Nickel-hydrogen battery design for the Transporter Energy Storage Subsystem (TESS)

Information is given in viewgraph form on nickel hydrogen battery design for the transporter energy storage subsystem (TESS). Information is given on use in the Space Station Freedom, the launch configuration, use in the Mobile Servicing Center, battery design requirements, TESS subassembley design, proof of principle testing of a 6-cell battery, possible downsizing of TESS to support the Mobile Rocket Servicer Base System (MBS) redesign, TESS output capacity, and cell testing.

Lapinski, John R.

Thermal Neutral Format Based on the Step Technology

The exchange of models is one of the most serious problems currently encountered in the practice of spacecraft thermal analysis. Essentially, the problem originates in the diversity of computing environments that are used across different sites, and the consequent proliferation of native tool formats. Furthermore, increasing pressure to reduce the development's life cycle time has originated a growing interest in the so-called spacecraft concurrent engineering. In this context, the realization of the interdependencies between different disciplines and the proper communication between them become critical issues. The use of a neutral format represents a step forward in addressing these problems. Such a means of communication is adopted by consensus. A neutral format is not directly tied to any specific tool and it is kept under stringent change control. Currently, most of the groups promoting exchange formats are contributing with their experience to STEP, the Standard for Exchange of Product Model Data, which is being developed under the auspices of the International Standards Organization (ISO 10303). This paper presents the different efforts made in Europe to provide the spacecraft thermal analysis community with a Thermal Neutral Format (TNF) based on STEP. Following an introduction with some background information, the paper presents the characteristics of the STEP standard. Later, the first efforts to produce a STEP Spacecraft Thermal Application Protocol are described. Finally, the paper presents the currently harmonized European activities that follow up and extend earlier work on the area.

P Planas Almazan

The Effect of Gravity on the Combustion of Bulk Metals

In recent years, metal combustion studies at the University of Colorado have focused on the effects of gravity (g) on the ignition and burning behavior of bulk metals. The impetus behind this effort is the understanding of the ignition conditions and flammability properties of structural metals found in oxygen (O,sub>2 ) systems for space applications. Since spacecraft are subjected to higher-than-1g loads during launch and reentry and to a zero-gravity environment while in orbit, the study of ignition and combustion of bulk metals at different gravitational accelerations is of great practical concern. From the scientific standpoint, studies conducted under low gravity conditions provide simplified boundary conditions, since buoyancy is removed, and make possible the identification of fundamental ignition and combustion mechanisms. This investigation is intended to provide experimental verification of the influence of natural convection on the burning behavior of metals. In addition, the study offers the first findings of the influence of gravity on ignition of bulk metals and on the combustion mechanism and structure of metal-oxygen, vapor-phase diffusion flames in a buoyancy-free environment. Titanium (Ti) and magnesium (Mg) metals were chosen because of their importance as elements of structural materials and their simple chemical composition-pure metals instead of multicomponent alloys to simplify chemical and spectroscopic analyses. In addition, these elements present the two different combustion modes observed in metals: heterogeneous or surface burning (for Ti) and homogeneous or gas-phase reaction (for Mg). Finally, Mg, Ti, and their oxides exhibit a wide range of thermophysical and chemical properties. Metal surface temperature profiles, critical and ignition temperatures, propagation rates, burning times, and spectroscopic measurements are obtained under normal and reduced gravity. Visual evidence of all phenomena is provided by high-speed photography.

Melvyn C Branch

Stability Measurements of the Radio Science System at the 34-m High-Efficiency Antennas

From 1991 to 1993 the fractional frequency stability of the operational Radio Science System was measured at DSS's 15, 45, and 65. These stations are designed to have the most stable uplink and downlink equipment in the Deep Space Network (DSN). Some measurements were performed when the antenna was moving and the frequency was ramped. The stability, including contributions of all elements in the station except for the antenna and the hydrogen maser, was measured to be 0.3 to 1.3 x 10 -15 when the frequency was fixed, and 0.6 to 6.0 x 10 -15 when the frequency was ramped (sample interval, 1000 sec). Only one measurement out of fifteen exceeded specification. In all other cases, when previous measurements on the antenna and the hydrogen maser were added, a total system stability requirement of 5.0 x 10 -15 as met. In addition, ambient temperature was found to cause phase variation in the measurements at a rate of 5.5 deg of phase per deg C.

T T Pham

Thermal Design and Analysis of Green Propulsion Dual Method CubeSat

Green Propulsion Dual Method (GPDM) is a collaboration between NASA Marshall Space Flight Center (MSFC) and Georgia Tech to create a 6U CubeSat demonstrating the use of the green propellant Advanced Spacecraft Energetic Non-Toxic (ASCENT) in two propulsion systems: using a traditional chemical thruster and an electrospray thruster system. The driving thermal considerations includes a planned orbit always in Sun view without any time in Earth’s eclipse, and a chemical thruster reaching 1300°C during firing. Thermal design and analysis on CubeSats are not always emphasized, particularly in experimental or academic environments. This paper will describe the thermal design and analysis performed on GPDM and the mitigations implemented for this mission, which will highlight some of the thermal challenges unique to experimental small satellites.

Thermal Analysis

Thermal Design and Analysis of Green Propulsion Dual Mode CubeSat

Green Propulsion Dual Mode (GPDM) is a collaboration between NASA Marshall Space Flight Center (MSFC) and Georgia Tech to create a 6U CubeSat demonstrating the use of the green propellant Advanced Spacecraft Energetic Non-Toxic (ASCENT) in two propulsion systems: using a traditional chemical thruster and an electrospray thruster system. The driving thermal considerations includes a planned orbit always in Sun view without any time in Earth’s eclipse, and a chemical thruster reaching 1300°C during firing. Thermal design and analysis on CubeSats are not always emphasized, particularly in experimental or academic environments. This paper will describe the thermal design and analysis performed on GPDM and the mitigations implemented for this mission, which will highlight some of the thermal challenges unique to experimental small satellites.

Thermal Analysis

Bipolar Ag-Zn battery

The silver-zinc (AgZn) battery system has been unique in its ability to safely satisfy high power demand applications with low mass and volume. However, a new generation of defense, aerospace, and commercial applications will impose even higher power demands. These new power demands can be satisfied by the development of a bipolar battery design. In this configuration the power consuming, interelectrode current conductors are eliminated while the current is then conducted via the large cross-section electrode substrate. Negative and positive active materials are applied to opposite sides of a solid silver foil substrate. In addition to reducing the weight and volume required for a specified power level, the output voltage performance is also improved as follows. Reduced weight through: elimination of the plastic cell container; elimination of plate leads and intercell connector; and elimination of internal plate current collector. Increased voltage through: elimination of resistance of current collector; elimination of resistance of plate lead; and elimination of resistance of intercell connector. EPI worked previously on development of a secondary bipolar silver zinc battery. This development demonstrated the electrical capability of the system and manufacturing techniques. One difficulty with this development was mechanical problems with the seals. However, recent improvements in plastics and adhesives should eliminate the major problem of maintaining a seal around the periphery of the bipolar module. The seal problem is not as significant for a primary battery application or for a requirement for only a few discharge cycles. A second difficulty encountered was with activation (introducing electrolyte into the cell) and with venting gas from the cell without loss of electrolyte. During previous work, the following projections for energy density were made from test data for a high power system which demonstrated in excess of 50 discharge/charge cycles. Projected system power = 100 kilowatts; discharge time = 30 seconds; discharge current density = 1.75 amps/sq in.; system weight = 86 lbs (9.7 WH/lb); and system volume = 1071 cu. in. (.78 WH/cu. in.). EPI is currently working on a development program to produce a bipolar silver-zinc battery design for NASA. The potential application would be to power electromechanical actuators for space launch vehicles.

Giltner, L. John

Lyotropic Liquid Crystalline Phase Behavior of Boron Nitride Nanotube Aqueous Dispersions

Boron nitride nanotubes (BNNTs) are gaining significant interest due to their outstanding mechanical and thermal properties, as well as their potential to serve as a model nanorod system. Processing BNNT liquid crystalline (LC) dispersions enables precise control over BNNT orientation in macroscopic assemblies, while their low absorption in the visible spectrum facilitates studying LCs at exceptionally high concentrations. Here, we investigate the behavior of BNNTs in aqueous solutions stabilized by the surfactant sodium deoxycholate (SDC), examining the effect of BNNT purity and BNNT−SDC concentrations on lyotropic LC formation. We disperse up to 15wt% BNNT in SDC solutions and use polarized light microscopy to detail the transition from an isotropic state to a biphasic regime, where isotropic and nematic domains coexist due to phase separation, to a single fully nematic phase. Cryogenic electron microscopy provides direct evidence of BNNT alignment within nematic domains. Our results show that enhanced depletion-induced attractions, driven by increased surfactant concentration, lower the threshold concentration of BNNT required to form nematic domains. In contrast, low surfactant concentrations relative to BNNT result in insufficiently coated nanotube surfaces, leading to poor dispersions and BNNT aggregation. Additionally, we fabricate well-aligned BNNT films from aqueous LC dispersions. Our findings advance the understanding of BNNT LCs, offering insight into controlling their orientation and highlighting their potential for high-performance materials.

Joe Khoury