Lunar Safe Haven: Site Characterization and Preparation
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The fundamental differences regarding the Moon vs. Mars for humans include far longer missions and greater resources required for Mars. In humans-Mars planning, thus far the extant technologies and approaches have not enabled missions which are both fully safe/healthy for humans and affordable. Cost reductions are required to afford health and safety and to reduce their costs. This report suggests and examines a wide spectrum of approaches to improve the affordability of humans-Mars approaches to ensure human safety and health during long distance space exploration and pioneering-on-the-way to colonization with humans-Mars as the exemplar
NASA’s most recent Decadal Survey posed a mission to one of the Ice Giants as the top priorityfor flagship missionsin the organization’s future. However, current technologieslimit the amount of scientific payload available for future Uranian and Neptunian missions due to the need for fuel for orbit insertion maneuvers. Thus, to maximize the scientific potential of futuremissions, atmospheric aerocapture has been heavily researched. While atmospheric aerocapture simulations have proven enabling for capturing around Neptune, its deep atmospheric pass requiresan aeroshell with thermal protection systems(TPS).Magnetohydrodynamically-controlled aerocapture serves as a potential solution to both fully-propulsive orbit insertion and atmospheric aerocapture. Through NASA Langley’s high-fidelity flight dynamics simulation, the Program to Optimize Simulated Trajectories II, both the atmospheric and magnetohydrodynamic aerocapture methods were simulated and compared for identical missions to Neptune. After applying a guidance algorithm for both methods, the results showed that magnetohydrodynamics has not only the control authority to successfully capture around Neptune, but also the unique advantage of a shallower atmospheric pass which decreases the maximum heat load and the required TPS mass.
NASA’s most recent Decadal Survey posed a mission to one of the Ice Giants as the top priority for flagship missions in the organization’s future. However, current technologies limit the amount of scientific payload available for future Uranian and Neptunian missions due to the need for fuel for orbit insertion maneuvers. Thus, to maximize the scientific potential of future missions, atmospheric aerocapture has been heavily researched. While atmospheric aerocapture simulations have proven enabling for capturing around Neptune, its deep atmospheric pass requires an aeroshell with thermal protection systems(TPS). Magnetohydrodynamically-controlled aerocapture serves as a potential solution to both fully-propulsive orbit insertion and atmospheric aerocapture. Through NASA Langley’s high-fidelity flight dynamics simulation, the Program to Optimize Simulated Trajectories II, both the atmospheric and magnetohydrodynamic aerocapture methods were simulated and compared for identical missions to Neptune. After applying a guidance algorithm for both methods, the results showed that magnetohydrodynamics has not only the control authority to successfully capture around Neptune, but also the unique advantage of a shallower atmospheric pass which decreases the maximum heat load and the required TPS mass.
Throughout the past few decades, the demand for farther and more massive missions have increased significantly, especially with the recent push for manned missions to Mars as well as the growing sci- entific interest in the outer giant planets and their re- spective moons. While spacecraft have successfully made it to the surface of Mars and into a flyby of the outer planets, the technologies from these missions are reaching the threshold of their capabilities. These tradi- tional methods are inadequate for higher mass and outer planetary missions due to the inherent propellant mass constraints of using fully-propulsive orbital insertion. Thus, there has been an ongoing effort to introduce new methods of deceleration and flight control during plan- etary EDL to reduce the required orbital insertion pro- pellant mass and enable new missions. One of the most prominently proposed solutions is aerocapture.
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Following the reports of water accumulation in the Extravehicular Mobility Unit (EMU) helmet during the ISS US EVA-80, various efforts for mitigation and further understanding of this phenomenon have been undertaken with the goal of prevention and to ensure crew safety in future EVAs. In support of this goal, a combination of Thermal Desktop thermal modeling and Computational Fluid Dynamics (CFD) has been performed in order to characterize the performance of the EMU components, specifically those within the ventilation/cooling water loops. This modeling effort evaluates the dry/wet gas pressure drop and flow distribution through gas and liquid flow paths using CFD, as well as a two-phase flow assessment of condensation production and water separation/removal performance using an integrated Thermal Desktop model of important EMU ventilation loop components. The models assess this overall thermal-fluid performance in comparison with previous existing models, design points, and historical EVA data using their inputs.
After water was reported in the EMU helmet during ISS US EVA-80, mitigation strategies were created to attempt to arrest the motion of any droplets that enter the helmet for future Extravehicular Activities (EVAs). This included adding absorbent materials into the interior of the helmet. But before a mitigation strategy can be implemented, it must first be proven to be safe. Towards this aim, a computational fluid dynamics (CFD) model was developed to assess the effect that the absorbent material has on the concentration of carbon dioxide in the EMU helmet. Within a small, closed volume such as a helmet, some amount of the carbon dioxide produced by the suit-wearer will be re-inhaled before being cleared from the oral-nasal region. The ability of the suit to remove carbon dioxide is referred to as CO2 washout. Pathological levels of inhaled CO2 (hypercapnia) are associated with dizziness, fatigue, and headaches. The CFD model was built in ANSYS Fluent and adapted to assess CO2 washout in a variety of scenarios grouped into three categories: purge cases, varying metabolic rates, and varying sorbent material configurations. The presence of the sorbent material did not prove detrimental to CO2 washout in the helmet.
Open-source science goes beyond making data from scientific projects (e.g., on-orbit/satellite missions, airborne and field investigations, and other data producing activities) openly available after they are generated, but involves and open sharing of information throughout the project lifecycle. Preservation of the data and associated information required for understanding and reusing the data well after the scientific projects is a contributor to open-source science as well. Considering the high investment in the on-orbit/satellite missions, we had developed a document titled “NASA Earth Science Data Preservation Content Specification (PCS)” in 2011. This document has been used as a requirement for recent on-orbit/satellite missions by NASA. Recently it became clear that the specifications should be applied to other scientific projects as well. Therefore, the document was revised to cover other types of projects, and a Preservation Content Implementation Guidance (PCIG) document was also developed. The revised PCS, and the PCIG, were published in 2022. The purpose of this presentation is to highlight the contents of these documents as they apply to suborbital/airborne investigations. The PCS calls for content preservation in eight general categories - Measuring Instrument/Platform Description, Instrument and Science Data Products and Metadata, Science Raw Data, Product and Algorithm Documentation, Instrument Calibration, Science Algorithm Software, Science Data Product Algorithm Inputs, Science Data Product Validation, and Science Data Access and Analysis Tools. While all these categories apply to various types of projects, a few clarifying sentences have been added to the descriptions of contents in each of the categories to show which categories are especially important to airborne and field investigations and where some contents are not applicable (or difficult to obtain). The PCIG document provides some general guidance applicable to all types of projects and specific guidance in a separate section for airborne and field investigations. This section calls out typical artifacts produced during such investigations that can meet the spirit of the various PCS categories.
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Switchbacks are sudden, large radial deflections of the solar wind magnetic field, widely revealed in interplanetary space by the Parker Solar Probe. The switchbacks’ formation mechanism and sources are still unresolved, although candidate mechanisms include Alfvénic turbulence, shear-driven Kelvin–Helmholtz instabilities, interchange reconnection, and geometrical effects related to the Parker spiral. This Letter presents observations from the Metis coronagraph on board a Solar Orbiter of a single large propagating S-shaped vortex, interpreted as the first evidence of a switchback in the solar corona. It originated above an active region with the related loop system bounded by open-field regions to the east and west. Observations, modeling, and theory provide strong arguments in favor of the interchange reconnection origin of switchbacks. Metis measurements suggest that the initiation of the switchback may also be an indicator of the origin of slow solar wind.
After water was reported in the Extravehicular Mobility Unit (EMU) helmet during ISS US EVA 80, mitigation strategies were created to attempt to arrest the motion of any droplets that enter the helmet for future Extravehicular Activities (EVAs). This included adding absorbent materials into the interior of the helmet. But before a mitigation strategy can be implemented, it must first be proven to be safe. Towards this aim, a computational fluid dynamics (CFD) model was developed to assess the effect that the absorbent material has on the concentration of carbon dioxide in the EMU helmet. Within a small, closed volume such as a helmet, some amount of the carbon dioxide produced by the suit-wearer will be re-inhaled before being cleared from the oral-nasal region. The ability of the suit to remove carbon dioxide is referred to as CO2 washout. Pathological levels of inhaled CO2 (hypercapnia) are associated with dizziness, fatigue, and headaches. The CFD model was built in ANSYS Fluent and adapted to assess CO2 washout in a variety of scenarios grouped into three categories: ventilation cases, varying metabolic rates, and varying sorbent material configurations. The presence of the sorbent material did not prove detrimental to CO2 washout in the helmet.
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After water was reported in the Extravehicular Mobility Unit (EMU) helmet during ISS US EVA 80, mitigation strategies were created to attempt to arrest the motion of any droplets that enter the helmet for future Extravehicular Activities (EVAs). This included adding absorbent materials into the interior of the helmet. But before a mitigation strategy can be implemented, it must first be proven to be safe. Towards this aim, a computational fluid dynamics (CFD) model was developed to assess the effect that the absorbent material has on the concentration of carbon dioxide in the EMU helmet. Within a small, closed volume such as a helmet, some amount of the carbon dioxide produced by the suit-wearer will be re-inhaled before being cleared from the oral-nasal region. The ability of the suit to remove carbon dioxide is referred to as CO2 washout. Pathological levels of inhaled CO2 (hypercapnia) are associated with dizziness, fatigue, and headaches. The CFD model was built in ANSYS Fluent and adapted to assess CO2 washout in a variety of scenarios grouped into three categories: ventilation cases, varying metabolic rates, and varying sorbent material configurations. The presence of the sorbent material did not prove detrimental to CO2 washout in the helmet.
The development of algorithms for remote sensing of water quality (RSWQ) requires a large amount of in situ data to account for the bio-geo-optical diversity of inland and coastal waters. The GLObal Reflectance community dataset for Imaging and optical sensing of Aquatic environments (GLORIA) includes 7,572 curated hyperspectral remote sensing reflectance measurements at 1 nm intervals within the 350 to 900 nm wavelength range. In addition, at least one co-located water quality measurement of chlorophyll a , total suspended solids, absorption by dissolved substances, and Secchi depth, is provided. The data were contributed by researchers affiliated with 59 institutions worldwide and come from 450 different water bodies, making GLORIA the de-facto state of knowledge of in situ coastal and inland aquatic optical diversity. Each measurement is documented with comprehensive methodological details, allowing users to evaluate fitness-for-purpose, and providing a reference for practitioners planning similar measurements. We provide open and free access to this dataset with the goal of enabling scientific and technological advancement towards operational regional and global RSWQ monitoring.
As NASA prepares for the follow on to EOS through the deployment of many new space and airborne-based assets envisioned under the ESO initiative, the need for ensuring user access to the very large and diverse archive of past missions remains a critical endeavor for current and future research. The ESDIS team has been working for many years on developing strategies and implementations that will make the linkage between the data held in our archives and the emerging missions possible. The focus on how best to preserve these past data has proven to be a collaborative effort, and one that may well benefit from the adoption of innovative technical tools that enable organizational efficiencies. This poster reveals both aspects of NASA’s EOS data repository strategy by discussing the collaborative community efforts of development of ISO 19165-2 – an international standard supported by a team from many countries around the world, the use by EOSDIS DAACs of a Preservation Content Specification, and ongoing work with mission teams to ensure mission data and all associated information are preserved and available for current and future use.
Since our completing the NIAC Phase I NIAC on this Advanced Aerocapture System, NASA Langley Research Center has funded or supported a number of studies and code enhancements through its Center Innovation Fund (CIF) and NASA’s NSTGRO and Internship Programs to mature the analysis capabilities and quantify the merits of the MHD Aerocapture System technology. These efforts have resulted in a plug and play analysis capability for assessing MHD aerocapture system performance for arrival at many planetary bodies of interest. Our efforts have especially focused on the potential mass savings for improving the capacity for science observations at Neptune and Triton. A re-cent Forbes article published “‘Orbital mechanics is probably going to decide for us whether we go to Uranus or Neptune because we need to flyby Jupiter,’ said Kunio Sayanagi at Hampton University, Virginia, who also worked on the Neptune Odyssey proposal…. Exactly when a mission can be sent to Uranus, or Neptune, depends on the relative position of Jupiter, which can help give a spacecraft a gravitational slingshot. That drastically shortens the cruise phase.” [1] Since shortening the cruise phase is important for these science missions, any mass savings enabled by the MHD Aerocapture System could be reallocated to increasing Thermal Protection System mass to allow faster arrival speeds and/or for onboarding additional payloads such as science instruments, batteries, or propellant for conducting more science for longer durations in the desired orbits. The analysis steps and codes for conducting trades and sizing vehicles for aerocapture are as follows: Step 1 is to conduct aeroheating analysis using LAURA of the selected entry vehicle shape to identify locations on the forebody where ionization and flow velocity are sufficient for producing Lo-rentz forces. LAURA is a multiblock structured grid finite-volume CFD solver developed at the NASA Langley Research Center. [2] LAURA has been used for aerothermal analysis support of the entry, de-scent and landing (EDL) phase of interplanetary missions over the last three decades [3-7]. Step 2 is to port the LAURA results into CFDWARP to calcu-late electrical and thermal conductivities of ionized flow for sizing MHD patch system and calculating Lorentz forces needed for controls analysis. CFDWARP is a CFD code that uses advanced nu-merical methods that enable the simulation of the full coupling between the aerodynamics, the magne-tohydrodynamics, and the non-neutral plasma sheaths. CFDWARP has the unique capability to simulate efficiently the non-neutral sheaths (near the electrodes) in coupled form with the quasi-neutral bulk MHD flow [8-11]. Step 3 is to link re-sults from LAURA and CFDWARP into POST2 for calculating entry trajectories and comparing MHD control results with other aerodynamic control strategies. The Program to Optimize Simulated Tra-jectories II (POST2) is a generalized point mass, discrete parameter targeting and optimization pro-gram. POST2 provides the capability to target and optimize point mass trajectories for multiple pow-ered or un-powered vehicles near an arbitrary rotat-ing, oblate planet [12]. Step 4: TPS sizing was per-formed using the Fully Implicit Ablation and Ther-mal-response code (FIAT) tool which computes the transient one-dimensional thermal response and surface thermochemistry of a multilayer stackup of thermal protection, bonding, and structural materi-als subject to aeroheating on one surface [13]. The sizing and margining methodology used was based on the approach documented by Mahzari and Milos [14] for the dual-layered heatshield for extreme entry environment technology (DL-HEEET) TPS concept. TPS analysis utilizes trajectory information from POST2. Using this step-wise plug and play MHD Aerocapture performance assessment process, our analysis targets a Neptune aerocapture trajectory that will place the spacecraft in an observation orbit for Triton. [15]. Magnetohydrodynamic (MHD) control of a 4.5-meter diameter MSL-style capsule resulted in TPS mass savings of nearly 2000 kg when using an MHD system mass of under 200 kg. The flight path for a vehicle using the MHD control strategy has a much lower heat rate and heat load compared to the conventional aerodynamic aerocapture strategies known as bank angle con-trolled (BAC) and direct force controlled (DFC). Both BAC and DFC have heat rates significantly greater than 1500 W/cm2 typically used as an upper limit for PICA. Thus, DL-HEEET TPS concept was required for the BAC and DFC control strategies. However, considering the more benign environ-ments for the MHD case, additional TPS concepts with improved mass efficiency were also assessed. PICA was considered for the MHD controlled strat-egy since the maximum heat rate was well within the limits (<1500 W/cm2) of PICA. TPS sizing re-sulted in a significant mass reduction. The PICA layer for this sizing case was about 7.8 cm. As a point of reference, the Mars 2020 mission, which used this same PICA concept, had a PICA thickness of 3.18 cm [16]. The trajectories used for the TPS sizing originat-ed from the POST2 simulations. The current, I, to an electromagnet configuration can be manipulated to allow for active control of the vehicle. Manipula-tion of the current, I, changes the magnetic field, B, which affects the Lorentz force and therefore the MHD drag force on the vehicle. Our analysis in-cluded both open-loop and close-loop control. Closed-loop control will enable improved overall performance when taking into account mission level uncertainties, such as interplanetary delivery errors and atmospheric modeling uncertainties. The open-loop and closed-loop MHD control cases do not dip as deep into the atmosphere as the aerodynamic cases. Three types of aerodynamic-only approach-es are investigated: bank angle modulation (BAM), director force control (DFC), and Drag Modulated. BAM and DFC make use of vehicle aerodynamic angles to steer the vehicle. Thus, changing the aer-odynamic forces acting on the vehicle for control, aerodynamic drag modulated case requires a vary-ing drag area to modulate the drag force. The MHD drag modulated case modulates MHD generated drag force that adds to the aerodynamic drag. This higher atmospheric activation of drag forces by the MHD patch results in significantly less heat flux on the vehicle. The MHD technology will enable shorter cruise times and deceleration of larger payloads for increasing the capacity for science at the Ice Giants or for returning astronauts to Earth from cislunar space or from Mars. The purpose of this presentation is to provide more details about this work and to highlight plans for further research and development including a flight demonstration.