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NASA NTRS2018

A Systems Architecting Methodology Using Bloom’s Taxonomy to Promote Creative Engineering Synthesis

Architecting complex systems requires high-level cognitive processing and extensive knowledge of the system elements, functions, relationships, and constraints. This paper describes a systems architecting methodology implemented through cognitive psychological creative processes using Bloom’s taxonomy as a framework to generate the expert knowledge required to effectively and systematically synthesize new systems. Systems architecting activities were carried out to identify, develop, and capture factual and conceptual knowledge relevant to the system subject matter and functional elements, as well as to facilitate active processing of the knowledge through remembering, understanding, applying, analyzing, evaluating, and creating. Dual channel and limited capacity principles of learning were incorporated into the format of the systems engineering tools developed to assist with information processing and retention. Meta-cognitive strategies associated with memory and creative idea generation were implemented into the methodology to effectively and efficiently develop system alternatives using the full collection of knowledge. Synthesis of an orbiting sample capture and orientation system architecture to enable spacecraft-based on orbit capture of a Mars sample container for a potential Mars Sample Return campaign was used as a case study.

Adajian, Rama↗

NASA NTRS2019

Hybrid propulsion technology development for a potential near-term Mars Ascent Vehicle

A technology development program for a potential hybrid Mars Ascent Vehicle (MAV) is currently underway to enable its infusion into a potential Mars Sample Return (MSR) campaign as early as 2026. A NASA team from the Jet Propulsion Laboratory (JPL), Marshall Space Flight Center (MSFC) and Ames Research Center (ARC) is leading and coordinating this program. A new propellant combination: the wax-based fuel, SP7, and MON-30 were proposed for a hybrid option for the MAV propulsion system several years ago. Since that time, hotfire testing with a similar propellant combination (SP7/MON-3) has been completed and a pathway to achieving high performance with the flight propellant combination is currently being pursued. Highlights of the progress to date and plans for risk reduction and the next steps in hybrid technology will be presented.

Zilliac, Greg↗

NASA NTRS2019

Flux pinning concepts for on-orbit capture and orientation of an MSR orbiting sample container

Concepts for on-orbit capture and orientation of a Mars orbiting sample container (OS) using flux pinning were developed as candidate technologies for potential Mars Sample Return (MSR). The systems consist of a set of type-II superconductors field cooled below their critical temperature using a cryocooler, and operate on an orbiting sample container with a series of permanent magnets spaced around the exterior, along with an integrated layer of shielding to preserve the magnetic properties of the returned samples. Benefits of the approaches include passive, non-contact capture and orientation, as well as a reduction in the number of actuators relative to various mechanical methods.

Chiu, Chi Yeung↗

NASA NTRSDate not supplied

Hold Down and Release Mechanism Hardware Simulator for Ground Deployment Testing

Hold Down and Release Mechanisms (HDRMs) are a common piece of spacecraft hardware which restrain components during launch, transit, and later allow them to be extended, jettisoned, separated, etc. at the spacecraft’s destination. Due to prohibitively high cost, long lead times, and limited reset capability, testing of mechanisms that require HDRMs is often difficult. This project explored the possibility of designing HDRM-analogue devices that would replicate the function of flight HDRMs during ground-based testing for a fraction of the cost of a flight HDRM. These devices were designed with the requirements of the Spin Eject Mechanism to be used on the Mars Sample Return (MSR) Capture, Containment, and Return System (CCRS) in mind. A trade study was conducted to determine the optimal internal mechanism design of the device, comparing several mechanisms from existing HDRMs to several simpler, more novel mechanisms. CAD software was used to create a preliminary design of the device utilizing a mix of commercial off-the-shelf parts and custom-manufactured parts. Several straightforward analyses were conducted to determine the most effective models for the off-the-shelf parts. A prototype largely composed of 3D-printed components was also created to proof the design concept. Although this HDRM simulator was designed for a particular mechanism for the CCRS mission, its general design is useful for ground testing of a variety of mechanisms requiring similar HDRM simulators.

Kian Vilhauer↗

NASA NTRSDate not supplied

Interpretation of Vehicle Tumbling Predictions from 6-DOF Entry and Descent Simulation

Blunt body entry vehicles are subject to dynamic instability during terminal descent. This often manifests as limit cycle oscillations in total angle of attack, but can diverge into tumbling behavior under certain conditions. For the Mars Sample Return Earth Entry Vehicle (MSR EEV), there is a constraint on the orientation of the sample tubes so backward impact is impermissible. Past missions have chosen to deploy parachutes to preclude tumbling, but active events after release of MSR EEV have been ground-ruled out with the intent to maximize system reliability. Prevention of tumbling during subsonic descent is a design driver for MSR EEV. During preliminary design of the MSR EEV, six degree-of-freedom numerical simulations indicated an unacceptably high probability of tumbling for a 60degree sphere-cone forebody geometry, which necessitated a design change. Decreasing the forebody angle was expected to improve dynamic stability, but would also adversely impact mass, aeroheating, and manufacturing risk. Hence there was strong motivation to understand the physical drivers for the onset of tumbling, and to determine: (a) whether the causes of tumbling are representative of physically realizable vehicle entry configurations and (b) what changes can be made to existing design and analysis practices to ensure a stable vehicle.

Entry Vehicle↗

NASA NTRSDate not supplied

Lessons for Future In-Space Telerobotic Servicing from Robotic Refueling Mission

The Robotic Refueling Mission (RRM) was a multi-phased technology development effort by the National Aeronautics & Space Administration (NASA) and the Canadian Space Agency (CSA). The program leveraged the existing robotic systems and expertise of the International Space Station (ISS) program and the tool design and satellite servicing expertise of NASA’s Exploration & In-space Services (NExIS) Projects Division at Goddard Space Flight Center (GSFC) to evaluate new hardware and techniques for on-orbit telerobotic servicing. Between 2011 and 2021, two external ISS payloads housed over a dozen robotic tools and adapters designed to service a variety of existing and novel satellite interfaces. Robot operators at NASA’s Johnson Space Center (JSC) and CSA used the Special Purpose Dexterous Manipulator (SPDM) to retrieve and operate these tools for tasks such as cutting wires or multi-layer insulation blanketing, removing valve caps, mating electrical connectors, transferring fluids, and performing visual inspections inside a vehicle. Each phase of RRM involved years of preparation. Tool and interface designs were prototyped and evaluated using both NASA and Canadian ground robotic systems. Procedures were developed by GSFC engineers and vetted in partnership with JSC and CSA robot operators. GSFC engineers were trained to provide real-time support during on-orbit operations. These preparatory efforts and the successful on-orbit evaluations yielded an array of lessons for future in-space telerobotic missions. Designing robotic tools for the space environment requires special consideration of materials, indicators, and differences between ground and flight use cases and environments. When there is a limited window for on-orbit operations, devoting time and high-fidelity hardware to ground testing can be critical. Needs during potential troubleshooting are more essential to camera view quality, frame rate, and position requirements more than nominal operations. Detailed hardware manuals, nominal and contingency procedures, along with clearly defined operations team roles and protocols are vital for efficiency. RRM also demonstrated how the ISS can be utilized to increase the technology readiness levels required for future missions and led to additional technology partnerships between NExIS and the ISS program. The lessons from RRM are currently being applied to designs, operations concepts, and ground test methodology for missions such as On-orbit Servicing, Assembly, and Manufacturing1(OSAM-1)and Mars Sample Return.

Zakiya Tomlinson↗

NASA NTRSDate not supplied

Hydrogen Peroxide as a Method for Bioburden Reduction in Facilities with Strict Materials Requirements.

The cleanrooms used to curate NASA’s Astromaterials samples are carefully monitored for particulate and inorganic contamination. The clean labs also have a very limited set of acceptable materials and cleaning agents to further minimize the potential for contamination. Labs are cleaned primarily with isopropyl alcohol. Astromaterials samples are handled with tools made of stainless steel (304 or 316), Teflon, or aluminum alloy (6061). Although our current collections are not particularly susceptible to biological alteration or organic contamination, this will not be the case for new collections from the OSIRIS-REx mission, Hayabusa2, and from Mars Sample Return. Therefore, it is necessary to develop and test methods to reduce the bioburden in astromaterials cleanrooms without introducing unwanted contaminants. We will report on the results of three case studies where 7.5 wt% hydrogen peroxide was prepared from a stock solution of ultrapure 30 wt% hydrogen peroxide (JT Baker) using curation-grade ultrapure water. We followed CDC (Center for Disease Control) guidelines for using hydrogen peroxide as a high level disinfectant. This solution was used to clean a glovebox prior to processing Apollo samples, as well as surfaces in the Antarctic meteorite processing lab and Stardust lab after facilities monitoring indicated an unwanted increase in bioburden. In all three instances, the culturable bioburden was significantly reduced after a 30 min. exposure to the 7.5% hydrogen peroxide solution without a corresponding increase in inorganic or organic contamination. We observed 77 to 100% reductions in the bioburden recovery rate. In one case study, we also performed amplicon DNA sequencing on samples collected from the surfaces before and after cleaning. We observed a significant change in microbial community composition after peroxide cleaning. These results suggest that routine cleaning with hydrogen peroxide could be an effective way to control bioburden in astromaterials cleanrooms and other facilities with strict contamination control requirements.

A B Regberg↗

NASA NTRSDate not supplied

Comparison between Hayabusa 2 Spectral Measurements and Simulations

This paper compares recent Hayabusa 2 spectral measurements with state-of-the-art shock-layer radiation simulations resulting from the LAURA/HARA code suite. These simulations include coupled ablation, which accounts for the injection of ablation products into the flowfield, and coupled radiation, which accounts for radiative energy loss in the flowfield. To enable the coupled ablation simulations, a best-estimate model is developed for Hayabusa’s carbon-phenolic ablator, based on the limited available published information. The comparison between the simulations and measurements focuses on two atomic nitrogen lines and two atomic oxygen lines, as well as the CN Violet band system. For the atomic lines, the measurements and simulations agree within 25% over most of the trajectory. This excellent agreement is unprecedented for observed radiation measurements of atomic lines, where previous Stardust and Hayabusa 1 comparisons were significantly worse. The improved agreement for these Hayabusa 2 comparisons is both the result of improved measurement quality and enhanced flowfield/radiation modeling. To provide a link between these observed radiation measurements and the radiative heating to a vehicle surface, the recently developed flowfield property binning approach is used to identify flowfield properties that provide the dominant emission contribution to the measured spectrum. These identified flowfield properties are then shown to match those for the surface radiative heating to the currently developed Mars Sample Return (MSR) Earth Entry System (EES) at a specific trajectory point and surface location. This matching of flowfield properties indicates that this EES radiative heating and Hayabusa 2 observed radiation simulations are equivalent radiation problems. Therefore, the excellent agreement between Hayabusa 2 measurements and simulations may be leveraged to inform the radiation heating margin for the MSR EES.

Christopher O Johnston↗

NASA NTRSDate not supplied

Hydrogen Peroxide as a Method for Bioburden Reduction in Facilities with Strict Materials Requirements

A B Regberg↗

NASA NTRS2021

Perseverance’s Scanning Habitable Environments with Raman and Luminescence for Organics and Chemicals (SHERLOC) Investigation

The Scanning Habitable Environments with Raman and Luminescence for Organics and Chemicals (SHERLOC) is a robotic arm-mounted instrument on NASA’s Perseverance rover. SHERLOC has two primary boresights. The Spectroscopy boresight generates spatially resolved chemical maps using fluorescence and Raman spectroscopy coupled to microscopic images (10.1 μm/pixel). The second boresight is a Wide Angle Topographic Sensor for Operations and eNgineering (WATSON); a copy of the Mars Science Laboratory (MSL) Mars Hand Lens Imager (MAHLI) that obtains color images from microscopic scales (∼13 μm/pixel) to infinity. SHERLOC Spectroscopy focuses a 40 μs pulsed deep UV neon-copper laser (248.6 nm), to a ∼100 μm spot on a target at a working distance of ∼48 mm. Fluorescence emissions from organics, and Raman scattered photons from organics and minerals, are spectrally resolved with a single diffractive grating spectrograph with a spectral range of 250 to ∼370 nm. Because the fluorescence and Raman regions are naturally separated with deep UV excitation (<250 nm), the Raman region ∼ 800 – 4000 cm−1 (250 to 273 nm) and the fluorescence region (274 to ∼370 nm) are acquired simultaneously without time gating or additional mechanisms. SHERLOC science begins by using an Autofocus Context Imager (ACI) to obtain target focus and acquire 10.1 μm/pixel greyscale images. Chemical maps of organic and mineral signatures are acquired by the orchestration of an internal scanning mirror that moves the focused laser spot across discrete points on the target surface where spectra are captured on the spectrometer detector. ACI images and chemical maps (< 100 μm/mapping pixel) will enable the first Mars in situ view of the spatial distribution and interaction between organics, minerals, and chemicals important to the assessment of potential biogenicity (containing CHNOPS). Single robotic arm placement chemical maps can cover areas up to 7x7 mm in area and, with the < 10 min acquisition time per map, larger mosaics are possible with arm movements. This microscopic view of the organic geochemistry of a target at the Perseverance field site, when combined with the other instruments, such as Mastcam-Z, PIXL, and SuperCam, will enable unprecedented analysis of geological materials for both scientific research and determination of which samples to collect and cache for Mars sample return.

Rohit Bhartia↗

NASA NTRSDate not supplied

Response of Ablative Thermal Protection Materials to Degradation in Low Earth Orbit –Characterization of Specimens from MISSE-13

The environment of low Earth orbit presents unique material interactions due to the presence of atomic oxygen and solar spectrum UV. A variety of degradation mechanisms can occur depending, inlarge part, on the specific material system involved. This talk will review the characterization of two ablative materials, PICA-D and HEEET, as well as relevant adhesive joints and coatings. PICA-D is a variant of the phenolic impregnated carbon ablator (PICA) and is the baseline thermal protection system (TPS) on Dragonfly and the lander for Mars Sample Return (MSR). HEEET is a 3D woven system from which MSR’s Earth entry TPS is derived. The samples for these materials were flown in orbit during the Materials International Space Station Experiment-13 (MISSE-13) which launched on March 6, 2020 and returned to Earth on January 13, 2021. Changes to surface microstructure and reflectivity will be presented along with tomographic analysis. The effect of differential erosion rates on the composites and the impacts of the orbit environment on coating performances will be discussed in the context of TPS performance and mission design aspects.

MISSE↗

NASA NTRS2022

Sample Materials Considerations for Curating and Processing Pristine MSR Samples

The perseverance rover is collecting and caching samples of Mars as part of the Mars 2020 mission, which represents the first leg of a multi-mission Mars Sample Return Campaign. The MSR Campaign is an international partnership that will result in delivery of the first martian samples to Earth that were not delivered through meteoritic infall. All meteorites, regardless of how they were handled from recovery to curation, have experienced uncontrolled entry and exposure to the terrestrial environment. Whilst meteorite deliveries are serendipitous, they are also unplanned events that require reactionary responses for recovery and curation. However, with the direct return of pristine astromaterials from another body, we are afforded the ability to design a facility in advance of sample delivery to keep those samples in a pristine (i.e., as returned) state for an indefinite period of time. Given that the curation and processing infrastructure needs to be made out of something, it is important to choose materials for the pristine curation environment that will optimize between the need to effectively process samples and the need to minimize contamination of the samples. The Johnson Space Center (JSC) has an optimized list of materials that have been used in previous sample return missions that includes 304/316 Stainless Steel, Teflon, and T6061 Aluminum (1). This set of materials are compatible with inorganic, organic, and biological cleanliness requirements and protocols. Furthermore, only these materials are permitted to come in contact with pristine samples. We note that JSC uses Neoprene and Hypalon for the gloves on their gloveboxes, but the glove material never comes in direct contact with the samples, only the approved materials. The MSR sample tubes will be made of Ti, so Ti may be an acceptable material for making tools, but the minor and trace element abundances of 304 and 316 stainless steel are well known and do not inhibit scientific investigations of metals, including HSE (2). More work is needed to determine whether the same is true for Ti alloys. In addition to defining the materials in the pristine environment, one must also choose whether the pristine environment will be under vacuum or under a specific atmospheric composition and pressure. Although JAXA has successfully implemented pristine curation vacuum chambers for their Hayabusa and Hayabusa2 samples (3), a vacuum environment is not appropriate for martian samples because it may drive deliquescence of mineral phases in the samples that are sensitive to pressure and relative humidity (4). Consequently, the pristine environment for the martian samples should be under an inert gas. It will be crucial to minimize the number of gases that come into direct contact with samples and these gases will need to be high purity and consistent throughout the pristine isolators. Samples at JSC are stored under high purity gaseous nitrogen (1). Dry N2 gas has not been a problem for N isotope studies for high-T release phases, but an additional inert atmosphere like Ar may be needed for samples where there is a particular concern about low-T release of N from bulk sample analysis. References: (1) McCubbin FM, et al. (2019) Space Science Reviews, 215, 1-81. (2) Day JMD, et al. (2018) Meteorit. Planet. Sci. 53:1283-1291. (3) Yada, T., et al., (2014). Meteorit. Planet. Sci. 49, 135-153. (4) Tosca NJ, et al. (2021). Astrobiology, in press, doi:10.1089/ast.2021.0115.

F M McCubbin↗

NASA NTRSDate not supplied

SHERLOC: Results of the first 350 sols of operations

On February 18th 2021, the Perseverance rover landed in Jezero crater, Mars. This site was chosen because orbiter data analysis provides evidence that the crater hosted a stream-fed lake during the Martian Noachian period. The Octavia Butler landing site is located ~1.9 km east of the remnants of a river delta. Deltaic and lacustrine sediments can preserve biosignatures, making Jezero crater a prime target for Mars sample return science. One of the seven instruments on Perseverance’s science payload is SHERLOC –Scanning Habitable Environments with Raman and Luminescence for Organics and Chemicals. SHERLOC combines fluorescence and Raman spectroscopy with microscopic imaging to analyze surface material to better understand the history of the aqueous environments recorded in the rocks of Jezero crater and to search for potential biosignatures. SHERLOC imaging obtains high spatial resolution images of geological targets to identify grain-scale structure and texture. SHERLOC spectroscopy enables high-sensitivity detection, characterization, and spatially resolved correlation of trace organic materials. Native fluorescence emissions from aromatic organic species allow for detection and classification of aromatic organic molecules, whereas Raman scattered photons from molecules allow identification of functional groups of organics, chemicals, and minerals. In the first 300 sols, SHERLOC has analyzed 3 natural surfaces, and 5 abraded rock patches created during the Crater Floor Campaign within Jezero crater. SHERLOC has been able to identify phosphates, amorphous/microcrystalline silicate (AMS), olivine, sulfates, and carbonates in abraded patches in the green zone campaign within Jezero Crater Máaz and Séítah formations. Within these detections we have begun to tell the story of what this crater was like when it was full of liquid water over 3 billion years ago. In each of these samples we have identified fluorescence features that are likely aromatic organics native to the rock interiors. We have identified multiple unique fluorescence signatures, within each of the abraded patches. The organic signatures have either been widely distributed over an extended area, which is probably due to planetary wide dust, or have spatially resolved locations that are collocated with different mineral signatures. Note: Additional information available on attachment.

L. W. Beegle↗

NASA NTRS2021

Dynamics associated with the Corer on M2020 Perseverance Rover

This paper will report on the development of the Dynamics specifications for the Corer on Mars 2020. The corer is a critical piece of the M2020 mission, leading into the Mars Sample Return campaign. However, the configuration of the rover places it on the turret of the Robotic Arm assembly, and near to several science sensors (PIXL, SHERLOC) which are also mounted to the Turret. This paper will provide some similarities and differences to the MSL drill. Details in the development, evolution, and verification of the Dynamics specifications will be described in detail, including the hardware which had to meet these challenging specifications. In addition, the special testing venues used throughout the development & verification of M2020 (EDU corer, EM actuators, HALT testing [simulation of coring dynamics], and QMDT) will be described.

Chrystal, Kyle↗

NASA NTRSDate not supplied

NASA’s Planetary Protection Program to Assure Mission Safety and Success

NASA’s planetary protection program seeks to understand and control harmful contamination of solar systems targets of exploration by terrestrial contamination and prevent harmful biological contamination of the Earth-Moon system by extraterrestrial life, should it exist. To accomplish these objective’s NASA has developed a balanced safety and mission assurance strategy that leverages COSPAR Policy guidelines, workshops, scientiﬁc consensus, partnerships and international working groups to develop policy and implementation guidelines. Upcoming crewed missions to the Moon and Mars, as well as robotic missions to small solar system bodies, Europa, Titan and Mars are some of the driving activities of astrobiological interest that continue to emphasize the importance of planetary protection throughout the project life cycle. Development of a responsive and updated agency planetary protection policy has been a focus area in supporting upcoming mission opportunities for exploration to include Mars sample return and crewed mission concepts. An extensive update of this policy is underway which encompasses crewed and robotic procedural polices, a general technical requirements standard, and an implementation handbook. During this timeframe NASA has been working with the international community to develop scientiﬁc consensus, and to identify and ﬁll in knowledge gaps for developing balanced policy guidelines, incorporation of risk informed decision making and quantitative technical standards. NASA has developed a planetary protection roadmap as a technology management strategy to track and monitor the development of each knowledge gaps. The Committee of Space Research (COSPAR) Policy on Planetary Protection and the National Academies of Science, Engineering, and Medicine’s Committee of Planetary Protection are used to inform updates to the planetary protection polices and guidelines. This integrated strategy for planetary protection seeks to provide a transparent, structured approach for enabling missions, providing guidance for NASA and NASA partnered missions, and being responsive to the increased interest and activities in space exploration whilst maintaining an understanding and control of harmful contamination.

James Benardini↗

NASA NTRSDate not supplied

Adopting an Objectives-Driven Assurance Case Approach for Achieving Space Flight Mission Planetary Protection Objectives

Traditionally, NASA has utilized prescriptive technical and process requirements to ensure safety and mission assurance performance objectives for space ﬂight missions are achieved. While prescriptive re-quirements may be easier to communicate and manage throughout the systems engineering process, the highly-constrained nature of prescriptive requirements can limit the ability to take advantage of cost-saving opportunities and oﬀer limited ability to explore other options or alternative designs, processes, and methods. It can also be diﬃcult to develop prescriptive requirements for objectives that are prob-abilistic in nature or that cannot be satisﬁed by direct veriﬁcation. In contrast, the development of an assurance case allows for a compelling, comprehensible, and valid argument to be developed with support-ing evidence that shows safety and mission assurance objectives have been satisﬁed. Analogous to how patent applications are constructed for inventions, an assurance case has a high-level claim of meeting a safety and mission assurance objective, followed by a more speciﬁc set of sub-claims and technical evidence which supports the claims. The objectives-driven assurance case approach allows for a better understand-ing and exploration of the trade space, more ﬂexibility to balance trades, and the ability to realize and implement technical and process innovations for resource, time, and cost savings. The assurance case is a living case that evolves over the entire program life cycle. Recently, NASA’s Oﬃce of Planetary Pro-tection (OPP) has adopted the assurance case approach as an acceptable methodology for demonstrating avoidance of contamination of target solar system bodies explored by NASA space ﬂight missions. This methodology has been incorporated into NASA’s new technical standard for planetary protection and is currently being utilized by the Mars Sample Return campaign for safe sample containment during sample return. This presentation will explore the development and implementation of an assurance case approach in the context of planetary protection, the shift from prescriptive requirements and the ongoing culture change in the technical community, and the support and guidance from NASA’s OPP in adopting the assurance case approach for achieving planetary protection objectives on NASA’s space ﬂight missions.

Elaine Seasly↗

NASA NTRSDate not supplied

Comparison between Hayabusa 2 Spectral Measurements and Simulations

Recent Hayabusa 2 spectral measurements are compared with state-of-the-art shock-layer radiation simulations resulting from the LAURA/HARA code suite. These simulations include coupled ablation, which accounts for the injection of ablation products into the flowfield, and coupled radiation, which accounts for radiative energy loss in the flowfield. To enable the cou- pled ablation simulations, a best-estimate model is developed for Hayabusa’s carbon-phenolic ablator based on available published information. The comparison between the simulations and measurements focuses on three atomic nitrogen lines, two atomic oxygen lines, one atomic hydrogen line, and the CN Violet band system. Parametric uncertainties are evaluated for these features using a recently developed capability in LAURA/HARA. These uncertainties capture the impact of flowfield and radiation modeling uncertainties on the observed radiation simulations, and include the impact of coupled radiation and ablation product emission. The resulting parametric uncertainties range from 50 to over 100% for the atomic lines, and 80% for CN Violet. Uncertainties in flowfield kinetics and non-Boltzmann modeling provide the dominant contribution to these uncertainties. For the atomic nitrogen and oxygen lines, com- parisons between the nominal simulations and measurements show agreement well within these simulation uncertainty bounds, with the measurements within 20% of the nominal simulation over most of the trajectory, and within 10% at peak emission. This excellent agreement is un- precedented for observed radiation measurements of atomic lines, where previous Stardust and Hayabusa 1 comparisons were significantly worse. The improved agreement for these Hayabusa 2 comparisons is both the result of improved measurement quality and enhanced flowfield and radiation modeling. For the ablation product emission from the 656 nm atomic hydrogen line, the agreement between measurements and simulations is within ±20% for all trajectory points except one outlier. This good comparison is surprising considering this species depends on the ablation rate and is shown to have strong wake contribution, which both contribute to the large ≈±70% parametric uncertainty. For the ablation product emission from CN Violet, the simulations over-predict the measurements by over a factor of two early in the trajectory, with the comparison improving later in the trajectory. This disagreement for CN Violet is consistent with the ≈±80% parametric uncertainty bounds evaluated for the simulations. To utilize the excellent agreement between the atomic line simulations and measurements in the assessment of the radiative heating margin for a future flight vehicle, the flowfield property binning (FPB) approach is applied. Using the Mars Sample Return (MSR) Earth Entry System (EES) as an example, the combination of the excellent Hayabusa comparisons and the FPB analysis justify nearly a 10% reduction in the radiative heating margin from an assumed baseline margin of 30%. This direct quantitative link between observed radiation measurements and the radia- tive heating margin of future flight vehicles demonstrates the value of these observed radiation measurements.

Shock-Layer Radiative Heating↗

NASA NTRSDate not supplied

Response of Ablative Thermal Protection Materials to Degradation in Low Earth Orbit – Characterization of Specimens from MISSE-13

The environment of low Earth orbit presents unique material interactions due to the presence of atomic oxygen and solar spectrum UV. A variety of degradation mechanisms can occur depending, in large part, on the specific material system involved. This talk will review the characterization of two ablative materials, PICA-D and HEEET, as well as relevant adhesive joints and coatings. PICA-D is a variant of the phenolic impregnated carbon ablator (PICA) and is the baseline thermal protection system (TPS) on Dragonfly and the lander for Mars Sample Return (MSR). HEEET is a 3D woven system from which MSR’s Earth entry TPS is derived. The samples for these materials were flown in orbit during the Materials International Space Station Experiment-13 (MISSE-13) which launched on March 6, 2020 and returned to Earth on January 13, 2021. Changes to surface microstructure and reflectivity will be presented along with tomographic analysis. The effect of differential erosion rates on the composites and the impacts of the orbit environment on coating performances will be discussed in the context of TPS performance and mission design aspects.

MISSE↗