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Three New On-orbit Fragmentations - NASA’s ODPO Wins Software of the Year Award - Aerodynamic Demise Model for Carbon Fiber Polymer Fiber - DebriSat: 10 years and Growing - Meeting Reports - Upcoming Meetings - NASA ODPO Abstracts - Space Missions, and Satellite Box Score

The International Space Station (ISS) deploys dozens of small satellites into Low Earth Orbit (LEO) each year. This presentation and associated paper cover the ISS Jettison Policy requirements and review/approval process, as well as best practices for satellite Payload Developers who have satellites manifested for deployment from ISS. Specifically, topics will include ISS Jettison Policy requirements to limit generation of orbital debris, limit risk of collision with ISS, and limit risk of collision with ISS visiting vehicles. The paper will include details on the ISS Program jettison candidate analysis and approval process, timelines for data submittal to ISS Program, resources for small satellite developers, and design & analysis recommendations for small satellite developers to maximize their likelihood of successful deployment from ISS. New Station deploy capabilities and ways the ISS Program addresses and facilitates innovations in small satellite technology, including propulsion systems, deorbit devices, constellation development, and novel tech demos, will also be explored. The 2024 session topic that best fits this abstract is Orbital Debris, SSA & STM. The ISS Jettison Policy intends to quantify and control the risks of deploying and operating small satellites, not only to ensure the safety of the humans flying in space, but also to preserve the orbital environment for world space activities and enable the significant benefits brought by such utilization. The ISS Program is committed to working with smallsat providers to address their challenges and enable safe, accessible, innovative missions. The Policy has grown with the industry, with each deploy yielding hard-earned lessons learned that improve our process – not only for the next deploy campaign, but with applicability and adaptability for future applications in LEO and beyond.

NASA’s Orbital Debris Program Office (ODPO) develops and maintains a number of modeling tools to analyze and simulate the orbital debris environment. One of the most important products produced by the NASA ODPO is the Orbital Debris Engineering Model (ORDEM). This model can be used by satellite designers and operators to design missions for better protection against the debris environment. The ODPO is currently working on the next generation, designated ORDEM 4.0. ORDEM 4.0 will include many known features from previous models, such as the ability to input a spacecraft orbit and time and the ability to compute the flux as a function of debris size, impact speed, impact direction, and debris material densities, as well as uncertainty information on the flux. A new addition will be a parameterized debris shape model based on laboratory hypervelocity impact tests, including DebriSat. ORDEM is primarily based on dedicated debris measurements, such as by the Haystack Ultrawideband Satellite Imaging Radar (HUSIR), NASA’s Goldstone radar, and observations of geosynchronous orbits (GEO) using the Eugene Stansbery-Meter Class Autonomous Telescope (ES-MCAT). In addition to ORDEM, the ODPO also maintains other models, such as the LEO-to-GEO Environment Debris (LEGEND) model for studies of long-term evolution of Earth’s debris environment, with the ability to study various mitigation and remediation strategies. Another model, the Satellite Breakup Risk Assessment Model (SBRAM), is used to analyze how satellite breakups may affect critical space missions (such as the ISS) on short notice. In addition to these models, the ODPO maintains other secondary models used to model satellite explosions and collisions, analyze radar, optical, and in situ data, and to model such things as solar activity and orbit evolution. In this presentation, a survey of these models will be presented, showing how the different models are used together to create a comprehensive picture of Earth’s debris environment.

For many years, the NASA Orbital Debris Program Office (ODPO) has partnered with the U.S. Department of Defense and the Massachusetts Institute of Technology Lincoln Laboratory (MIT/LL) to collect data on the orbital debris environment using the Haystack radar. These measurements are used to characterize the small debris environment in low Earth orbit (LEO), down to a noise-limited size of approximately 5 mm—depending on altitude. The Haystack radar operated by MIT/LL underwent upgrades starting in May 2010, with operations resuming in 2014 as the Haystack Ultra-wideband Satellite Imaging Radar (HUSIR). HUSIR is the primary source of data used by the ODPO to statistically sample orbital debris in the 5-mm to 10-cm size regime in LEO and is a key source of data to build and validate the NASA Orbital Debris Engineering Model. In this presentation, we will present recent HUSIR results and show how NASA uses them to understand the orbital debris environment.

Key elements of NASA’s Moon to Mars Objectives for expanding humanity’s presence beyond low-Earth orbit will require surface-based, partial-gravity extravehicular activities (EVAs). Surface EVA needs affect many aspects of the exploration architecture, including EVA suit subsystems, such as suit or pressure garment mobility, the portable life support system, and the informatics system; and external systems, such as habitation modules and surface mobility platforms.

The Second International Orbital Debris Conference - ISS Maneuvers to Avoid Potential November 2023 Collision - Goldstone Radar Measurements of the Orbital Debris Environment: 2022 - ODPO Lab Updates - Conference and Workshop Reports - Upcoming Meetings - IOC II Conference Abstracts from the NASA HVIT - IOC II Conference Abstracts from the NASA ODPO - Space Missions and Satellite Box Score

An NESC Technical Bulletin captures critical knowledge in the form of new engineering information or best practices in a one-page format that have resulted from NESC independent testing, analysis, and assessments. This document contains all NESC Technical Bulletins from 2007 through 2023.

The NASA Engineering and Safety Center (NESC) was requested to support the development of a governing philosophy to provide a consistent and systematic approach for fracture control certification of additive manufacturing (AM) hardware that cannot be reliably inspected. The overall goal of the NESC assessment was to make progress toward a framework for general certification of un-inspectable fracture critical AM hardware and toward approaches for evaluating risks associated with these components. This report contains the results of the assessment.

In recent years, the United States (U.S.) Government has issued several new National policies that fundamentally change the approach to nuclear flight safety for aerospace applications, including the complete revision of the Federal policy for handling launch of spacecraft containing space nuclear systems. In response, the National Aeronautics and Space Administration (NASA) is updating its nuclear flight safety program while still maintaining consistency with other Federal policies, international conventions, and NASA’s own policies. To achieve this evolution, NASA is factoring in an objectives-driven and assurance case mindset to develop a risk-informed and performance-based program. NASA and others have successfully applied this mindset in other disciplines and contexts and it is being pursued here via broad cooperation within NASA and with external stakeholders. This paper will briefly describe how the NASA nuclear flight safety program is evolving to meet these changing needs.

The NASA Suborbital Crew (SubC) project is focused on enabling flights by NASA civil servants, such as scientists and engineers conducting research, on suborbital vehicles. A broader goal is ensuring that commercial human spaceflight is both viable and safe. Within the Commercial Crew Program (CCP), the SubC project is exploring game-changing methods to perform safety assessments to enable NASA personnel to fly on suborbital missions. Commercial suborbital space flight capabilities are anticipated to be more accessible, affordable, and available than missions to the International Space Station and could provide additional opportunities for testing and qualification of space flight hardware, human-tended microgravity research, and further cutting-edge research enabled by the space environment. Although NASA currently permits human tended suborbital payloads for non-civil servants under auspices of NASA’s Flight Opportunities Program, the SubC effort will enable civil servant scientists, researchers, and even engineers to accompany their experiments and tests into the space microgravity environment. Figure 1 illustrates how the SubC program complements other microgravity experimental platforms. The targeted scope for SubC includes end-to-end suborbital capabilities reaching ~80km with several minutes of sustained microgravity (Table 1). The NASA SubC project office is working with the Federal Aviation Administration’s Office of Commercial Space Transportation (FAA-AST) and the commercial suborbital space transportation industry to develop an efficient and holistic approach to a safety review and eventual government participation in suborbital flight. The current FAA certification process for suborbital launches is congressionally mandated to only consider public safety. NASA is responsible for understanding the risks to its employees should they fly on a commercially available suborbital flight. The SubC project is employing a Safety Case approach, applied to commercial suborbital providers, which is not a traditional certification process as was used for the SpaceX Dragon and Boeing Starliner vehicles. Rather, it is an assessment using elements of NASA’s Risk-Informed Safety Case and the Armstrong Flight Research Center’s Airworthiness Assessment process.

Since 1961, more than 250 satellites have fragmented while in orbit about the Earth, from very low Earth orbit out to the geostationary belt. The problem of orbital debris has been recognized since at least the late 1970s, with the institution of the NASA Orbital Debris Program Office (ODPO) in 1979 at the Johnson Space Center. Efforts to mitigate the growth of the orbital debris environment have mainly focused in two areas: the reduction and elimination of accidental explosions of spacecraft and rocket upper stages and the timely removal of spacecraft and rocket upper stages from orbit after completion of their missions. The ODPO continues to analyze the orbital population in orbit based on object type, mass, and other parameters of interest for characterizing the overall growth of objects in Earth’s orbit. Of the 268 known fragmentation events, 46 have occurred more than ten years after the affected satellites’ launch. These long-delayed breakups increase the population of orbital debris on the date of fragmentation, but we can also consider that the debris generated during that event could be attributed to the launch date of that satellite. We will present here an analysis of the historical growth of the low-Earth orbit debris environment, removing intentional fragmentation events, and examine the effectiveness of mitigation measures (such as passivation and reducing post-mission orbital lifetime).

In this issue: - ISS Maneuvers to Avoid Potential Collisions Twice in August 2023 - Derelict Cosmos Communications Spacecraft Breaks Up in June 2023 - Gene Stansbery, Former NASA Program Manager for Orbital Debris, Passes - HUSIR Radar Measurements of the Orbital Debris Environment: 2022 - Thirty Years Later: A Look Back at the 1993 JSC Perseid Stormwatch Center - IOC II Commences in December 2023 - NASA ODPO and HVIT Abstract - Conference Report - Orbital Debris Environment Plots - Space Missions and Satellite Box Score

The National Aeronautics and Space Administration (NASA) actively works to further the expectations of space exploration and research. NASA has been able to develop innovative technology and methods that has allowed for continued discovery and innovation. NASA is in the midst of work for the Artemis mission, which is to return to the moon in an effort to prepare for future Mars exploration. After the successful launch of Artemis I last November, our sights have shifted to Artemis II, which is set to launch next year and bring humans into the lunar orbit for the first time in over fifty years. Artemis II will be the first crewed mission for the program and will represent another step forward in our mission to advance our knowledge of the universe around us. From there, the Artemis program will move onto building a permanent site on the moon that will allow us to eventually reach Mars. During my time at NASA, I was able to work with the NE-XF Branch, also known as the Environmental and Life Support Systems Branch. I specifically worked with the Environmental Control Systems (ECS) team. During my time here, construction on the system in the Vehicle Assembly Building (VAB) and at Launchpad 39B have been progressing at full force. ECS is used to provide processed and purged air at specific temperatures, pressures, and humidity’s to fulfill requirements necessary to support Orion and the SLS. While the Pad has been undergoing upgrades from the original Artemis I configuration, the VAB has a completely new ECS very similar to it. While both systems have been undergoing upgrades, we have been able to transition into testing the systems as we prepare for stacking in the VAB early next year. My role has allowed me to learn about how the systems work and function through walkdowns and visits out to both the Pad and the VAB. I’ve been able to see firsthand how the system operates and have learned how the system affects the vehicle. I’ve been able to shadow my mentor, my coworkers, and COMET operators to oversee the construction efforts of the system along with the testing of the software and the system itself. I even was able to aid in testing at the console myself at Pad 39B. Additionally, I am also revising and reviewing displays for Artemis IV that will be used to remotely control parts of the system. Eventually these displays will be used to support the future of Artemis.

Many space-faring organizations have requirements to limit the growth of orbital debris by passivating spacecraft that remain in orbit after mission end. These requirements state that a stored energy devices are to be fully depleted at the end of a spacecraft’s useful life. Spacecraft designs not able to comply with those requirements use a so-called “soft passivation” option. This report presents the results of two studies aimed at better understanding spacecraft pressure vessel passivation state-of-the-art. They summarize current practices and principles of pressure vessel passivation and present an approach that can be used to show that spacecraft propulsion system passivation has been achieved.

The NASA Electronic Parts and Packaging Program co-manager, requested the NASA Engineering and Safety Center (NESC) to compile a body of publicly available knowledge on copper (Cu) wire bonds and perform reliability testing and analysis on these bonds, including environment tests, sample destructive physical analysis, and bond pull/shear tests during environment test intervals. The goal was to understand the risks of using Cu wire bonds for space applications and develop guidelines on Cu bond pull/shear limits for NASA applications. This document contains the results of the NESC assessment.

A highly reflective spray-on coating and tile material has been under development at Kennedy Space Center (KSC) that scatters away most of the Sun’s energy, thereby allowing coated objects to remain cool in space. The best performing tile material has achieved 1% solar absorptivity while the best performing spray-on coating has achieved around 4%. Both versions passively maintain cryogenic temperatures below 120 K at 1 astronomical unit (AU) from the Sun, but the tile material consistently sustains temperatures below 90 K, which is low enough to preserve oxygen and methane in a liquid state. Besides keeping propellants cold, this “solar white” material has the potential to passively maintain high-temperature superconductors (HTS) in a superconducting state without the support of liquid nitrogen cooling. If superconductors can be operated without the added infrastructure of liquid nitrogen cooling, it may enable them to be used in space for applications like magnetic radiation shielding and efficient energy management. Long duration exposure to both galactic cosmic radiation and coronal mass ejections can pose health risks for the astronauts and increase the potential for damage to electronics. This makes shielding essential to accomplish long duration missions, particularly when astronauts are onboard. The objective of this project was to determine the extent we could keep a high-temperature superconducting (HTS) material passively chilled to maintain its superconducting state. Both the tile and spray-on versions of solar white were investigated. We focused on finding a version that could support passive cooling at 1 AU from the Sun and determined the closest operating distances for samples that were unable to perform at 1 AU. Early in the project, we selected bismuth strontium calcium copper oxide (BSCCO) as the HTS to test based on its reputable usage in superconducting wires. The version we selected was Bi-2223, which has a critical temperature of about 108 K. Sample bars with contacts for a four-point probe were obtained from Quantum Levitation: https://quantumlevitation.com/product/superconductor-bar-for-4-point-tc-experiment/.

Mission or safety-critical spaceflight systems should be developed to both reduce the likelihood of software faults pre-flight and to detect/mitigate the effects of software errors should they occur in-flight. New data is available that categorizes software errors from significant historic spaceflight software incidents with implications and considerations to better develop and design software to both minimize and tolerate these most likely software failures.

NASA’s Orbital Debris Program Office (ODPO) and Hypervelocity Impact Technology (HVIT) team have coordinated to better understand the risks to upper stages and spacecraft from non-spherical orbital debris. It is well understood that fragmentation (collision or explosion) events in orbit produce fragments of various materials, sizes, and shapes. To further characterize these parameters, the ODPO is developing the next-generation Orbital Debris Engineering Model (ORDEM) version 4.0 to include orbital debris shape distributions. Ground-based assets, such as radar and optical sensors, can provide size estimates and some insight into material based on radar return or optical filter photometry/spectroscopy, respectively. Characterizing an object’s shape requires more laboratory analyses to infer how shape affects these measurements. More importantly, in addition to size and material/density, the shape of fragments in orbit will alter the ballistic limit equations used in orbital debris risk assessments with NASA’s Bumper Code. The ODPO plans to release ORDEM 4.0 in the coming years. Performing ground-based laboratory impact tests on high-fidelity spacecraft mockups provides the means to directly measure size, mass, material/density, and shape of fragments, all key parameters needed to characterize real-world break up events. The DebriSat test, the results of which are provided, showcases the details of this type of experiment. The goal of this collaborative research between the ODPO and the HVIT team is to include a shape parameter in the environmental and breakup models used to assess risk for various space structures. This paper examines ground-based laboratory impact tests and the associated fragment shape categories. Provided these defined shapes, the approach is simplified by assuming a right circular cylinder (RCC) approximation with varying length-to-diameter ratios. Highlights of impact tests conducted by the HVIT team using non-spherical projectiles based on the RCC approximation are presented. Hydrocode simulations have also been performed to expand on the complexity of variations with non-spherical projectiles. Lastly, ray-tracing simulations of various RCCs of known material are provided to support the ongoing research on optical reflectance distributions with known shapes and to highlight how this may modify the current optical size estimation model. The status and plan forward are outlined for NASA's orbital debris shape effect investigation using a multidisciplinary approach by the ODPO and the HVIT team.

The scope of the NASA Engineering and Safety Center (NESC) Unconservatism of Linear-Elastic Fracture Mechanics (LEFM) Analysis Post Autofrettage assessment was to evaluate the influence of the elastic-plastic autofrettage cycle on elastic cycles post autofrettage and generate data to support damage tolerance life analysis verification approach. The decision to include an elastic-plastic autofrettage cycle is informed by other factors beyond damage tolerance, including manufacturing and fatigue crack initiation. The results of the NESC assessment are contained in this report.

The NASA Engineering and Safety Center (NESC) was requested to provide space plasma instrumentation data analysis expertise in support of Floating Potential Measurement Unit (FPMU) data analysis and data processing algorithm development. Subject matter expertise was requested to support modification of FPMU data processing algorithms to account for aging of the FPMU instrument suite, improve the science quality of the FPMU data sets that are made available to the science community, and provide analysis of FPMU data for complex spacecraft orientation and geophysical situations. This document contains the results of the NESC assessment.

The BLiSS: Cargo Management and Retrieval project is a submission to the NASA X-Hab challenge for an autonomous system of cargo storage and retrieval for use on the Lunar Gateway system. The system is designed to stow 5 tonnes of cargo within a capsule that has an internal diameter of 3.2 meters and height of 6 meters for cargo that will be up to 0.8 meters in any one dimension. The system will inventory all cargo items placed in each cargo container and then track the containers using RFID chips for autonomous stowage and retrieval upon request by on-station crew.

This assessment was requested by the NASA Engineering and Safety Center (NESC), which, based on findings from the NESC study “Safe Human Expeditions Beyond Low Earth Orbit (LEO)” (Valinia et al., 2022), determined its topic to be an underrecognized critical and urgent Agency need, due to impending Artemis vehicle procurements. The principal objective of this assessment was to review and update current Agency-level maintainability requirements for space systems to support crew on expeditions beyond LEO in both preventive and corrective maintenance. This report contains the results of the NESC assessment.

The purpose of this handbook is to facilitate a repeatable and robust process that promotes clear and effective interfaces between activities and stakeholders focused on meeting nuclear flight safety requirements for missions utilizing space nuclear systems (SNS), within the context of NASA’s broader nuclear-related activities and interfaces. NPR 8715.26, Nuclear Flight Safety, requires that the NASA project manager “incorporate nuclear flight safety considerations starting with program or project formulation through the point at which the SNS or other radioactive material no longer has the potential to affect Earth’s biosphere.” NASA’s use of SNS inherently involves partnering with other stakeholders to conduct a range of related activities that interface with nuclear flight safety. From a categorical perspective these include: (i) meeting the authorities and licensing requirements for possession and use of nuclear material, as governed by other Federal authorities; (ii) conducting National Environmental Policy Act (NEPA) activities for nuclear-enabled missions; (iii) meeting Federal nuclear launch authorization requirements; (iv) conducting radiological contingency planning activities, including those associated with international commitments; (v) performing risk communication and public outreach activities; and (vi) ensuring decommissioning and disposal strategies reflect National policies and interests. It is the intent of this handbook to promote an effective interface between nuclear flight safety and these interrelated categorical activities. In addition to activities undertaken with partnering agencies, there are individual nuclear-related activities and programs that have a nexus to nuclear flight safety, and these include: (i) applicable NASA Standing Review Boards; (ii) the US Department of Energy nuclear safety activities conducted in partnership with NASA under Memoranda of Understanding; (iii) the Department of Defense’s Range Safety activities; (iv) NASA’s general involvement in interagency and international dialogues regarding nuclear safety; (v) the NASA-administered Interagency Nuclear Safety Review Board; (vi) NASA’s program and project governance activities and nuclear-specific Technical Discipline Team activities under the Office of the Chief Engineer; and others. It is the intent of this handbook to promote effective leveraging of these additional interrelated organizational activities, as appropriate.

We assessed the integrated safety, health, and performance risk to crews on long-duration missions, specifically to Mars. Using a systems approach rather than one focused on individual countermeasures, we examined the trade space around several such risks to identify high-potential risk mitigation strategies and characterize aspects of Mars mission architectures that could lower aggregated risk. Current Mars Design Reference missions would require durations well over two years and would increase crew exposure to radiation and microgravity well beyond ISS levels, likely resulting in significantly reduced performance beyond our current capability to mitigate that could jeopardize mission success. A “fast Mars transit” round-trip mission concept was studied using an innovative flight dynamics approach to quantify the minimum total mission energy required for a Mars transit with total mission duration less than 400 days. This approach holds promise for sending humans to Mars and returning them safely with acceptable, potentially mitigatable, exposure to microgravity and radiation using current or near-term technologies. The fast transit concept would also result in fewer time-driven vehicle failures and enable sustainable deployment of humans and infrastructure to Mars on a regular cadence, allowing steady exploration and colonization of Mars. Finally, we conclude that reliance on the Low Earth Orbit (LEO) mission operations paradigm – i.e., one of near-complete real-time dependence on experts at Mission Control to manage the combined state of the mission, vehicle, and crew – is high risk given the communication delays and limited resupply of any Mars mission, and this risk is not eliminated by the shorter missions durations of fast transit scenarios. Based on historical trends, it is highly likely that the crew will face a high-consequence problem of uncertain origin during Mars transit when ground support will be greatly reduced. While it may be possible to reduce anomaly rates through improved reliability analysis and testing, and to reduce anomaly impacts through added robustness, such mitigations address only known failure modes and known uncertainties. Therefore, a radical shift in the Human-Systems Integration Architecture (HSIA) that defines the operational paradigm, systems design, and human-systems interactions is required to improve the risk posture to an acceptable level regardless of mission duration.

As a foundational element of the National Aeronautics and Space Administration (NASA) Artemis Campaign, the Gateway is an incrementally built cislunar spacecraft that will serve as a platform for deep space human exploration, science, and technology demonstration. The Gateway will be a unifying catalyst for partners around the world to establish sustained deep space scientific investigations, lunar surface access, and missions to Mars. As human exploration moves farther from Earth, spacecraft designs must optimize mass and volume while minimizing human and spacecraft risk. To accomplish this, the Gateway Program Safety and Mission Assurance (S&MA) office develops, implements, and ensures compliance with requirements, in concert with the accurate characterization and transparent communication of residual hazard risks, for integrated safety, reliability and maintainability, and quality assurance. This paper will detail the evolution of the Gateway Program S&MA integration functions, and provide its current status and lessons learned for future human spaceflight programs.

This document summarizes and updates the NESC Guidance, Navigation, and Control (GN&C) Technical Discipline Team’s (TDT) work to synthesize and document the current best practices for the design & development of robust and reliable GN&C systems for robotic and crewed (human-rated) spacecraft. These GN&C best practices for future science and exploration missions were derived from the lessons learned, both positive and negative, on earlier spaceflight projects, both robotic and crewed. An attempt has been made to capture preferred practices that reflect the key considerations, trades, and processes directly attributed to past mission success.

Several NASA centers have developed independent flight mechanics tools to meet the science needs of missions. This NASA Engineering and Safety Center (NESC) assessment sought to explore the ways to increase the interoperability of three specific tools: Copernicus from Johnson Space Center (JSC), the General Mission Analysis Tool (GMAT) from Goddard Spaceflight Flight Center (GSFC), and the Mission-Analysis Operations Navigation Toolkit Environment (MONTE) from the Jet Propulsion Laboratory (JPL). Before this assessment, these tools were not integrated and could not easily share data, models, or components. This report contains the outcome of the NESC assessment.

This is the first revision by the Office of the Chief Engineer of the 2020 Handbook updated to reflect the release of NPR 8079.1, NASA Spacecraft Conjunction Analysis and Collision Avoidance for Space Environment Protection.

Dual Docked Operations (DDO) is the docking or undocking of a Russian Vehicle (RV) during Space Shuttle Orbiter/International Space Station (ISS) mated operations. - This paper and presentation summarizes the concept definition, studies, and analysis results generated by the Space Shuttle Program (SSP), ISS Program (ISSP), and Mission Operations Directorate for implementing DDO during mated Orbiter/ISS missions. [1] - Due to the ever-increasing visiting vehicle traffic to and from the ISS, it became apparent to both the ISSP and the SSP that there would arise occasions where conflicts between a visiting vehicle docking and/or undocking could overlap with a planned Space Shuttle launch and/or during mated Orbiter/ISS operations. - This potential conflict provided the genesis for evaluating risk mitigations to gain maximum flexibility for managing potential visiting vehicle traffic to and from the ISS and to maximize launch and landing opportunities for all visiting vehicles. - Reviews were conducted to assess the viability and readiness of the SSP to protect for DDO on any given mission and it was found to be t echnically feasible

All spacecraft are subject to the possibility of high-speed particle impacts during their mission life. In low earth orbit, those impacts could be the result of collisions with pieces of orbital debris or with meteorites. Beyond LEO, and especially beyond GEO, those impacts will likely be caused by meteorites. Such high-speed impacts on spacecraft surfaces create debris clouds that travel towards and eventually impact other downstream spacecraft components. In addition to the impulsive load that such debris clouds would impart to the spacecraft elements with which they subsequently collide, the largest fragment in these debris clouds poses a significant threat on its own to those spacecraft elements. In order to be able to assess the severity of the threat posed by such a fragment, it is important to be able to predict the extent of damage sustained by the impacted spacecraft element. In this paper, we present a new process for determining the penetration depth in a shielded TPS tile system. The requirements for the process were that it be applicable across a full spectrum of impact low velocities (i.e. from ~ 7 km/s to above 50 km/s), that it be applicable over a wide range of projectile materials densities (i.e. ranging from water to steel, for example), and that it be applicable over a wide range of trajectory obliquities (i.e. not just normal impacts). Furthermore, the process developed should be sufficiently flexible so that it can be used for shield design parameter and / or system configuration trade studies (i.e. be written in terms of as many shield and TPS tile system parameters as possible). Following the initial impact of the projectile on the outer wall of the dual-wall shield, a debris cloud (i.e. the primary debris cloud) is created that travels towards and impacts the inner wall of the shield. Within this debris cloud is a combination of solid, liquid, and vaporized material, depending on the impact velocity and the impedance mismatch of the projectile and outer wall materials. The impact of this debris cloud on the inner wall creates another debris cloud (i.e. the secondary debris cloud) that then travels towards and impacts the TPS tile. Within the particulate distribution of the material in each of these debris clouds is a so-called largest fragment. The process used to calculate the penetration depth in a shielded TPS tile system developed herein consists of the following three steps: 1. Does the initial projectile perforate the outer wall of the shield? If NO, the TPS tile remains undamaged. If YES, calculate the size and speed of the largest fragment exiting the outer wall of the shield and traveling towards the shield’s inner wall. 2. Does the largest fragment in the debris cloud exiting the outer wall of the shield perforate the inner wall of the shield? If NO, the TPS tile again remains undamaged. If YES, calculate the size and speed of the largest fragment exiting the rear of the shield inner wall. 3. Calculate the penetration depth of the largest fragment in the debris cloud exiting the inner wall into the TPS. Perforation of the inner and outer shield walls is predicted using the Cour-Palais penetration depth equation and an associated failure criterion [1]. The largest debris cloud fragment diameters and associated velocities are calculated using regression equations developed from a mix of hydrocode and experimental diameter and velocity information [2]. Finally, TPS penetration depths are calculated using an empirical penetration depth predictor equation based on high-speed impact test data and are calibrated using a limited number of hydrocode penetration depth predictions for water, nylon, aluminum, Dunite, and steel projectiles The predictions of the penetration depth calculation process are compared against the predictions of more than 60 SPHC hydrocode runs. These comparisons show that the process used to calculate TPS tile penetration depths usually yields values that are within 1 mm of the predictions of hydrocode simulations. If a maximum allowable TPS penetration depth is known, the process developed herein can now be used to develop a failure limit equation that would predict whether or not an impacting particle would penetrate deeply enough into the TPS to result in a “failed” or “not failed” end state. References [1] E.L. Christiansen, “Design and performance equations for advanced meteoroid and debris shields”, International Journal of Impact Engineering, Vol. 14, 1993, pp. 145-156. [2] W.P. Schonberg, “Predicting the size of the largest particle fragment in a debris cloud created by an orbital debris impact and its associated velocity”, 2021 Applied Space Environments Conference, NASA Jet Propulsion Laboratory, Pasadena, California, November, 2021.

The existing VMEbus (VersaModular Eurocard bus) International Trade Association (VITA)-78 industry standard, also known as SpaceVPX, is an avionics board- and chassis-level standard derived from the OpenVPX standard as defined in VITA-65. While VITA-65 defines backplane and board-level profiles from COTS vendors to ensure interoperability of products used in developing systems and subsystems, the VITA-78 standard defines SpaceVPX to incorporate fault tolerance features that are required by many spaceflight systems. However, VITA-78 allows so much flexibility that interoperability between modules cannot be assured. This assessment provides guidelines on the use of, and extensions to, the VITA-78 standard to enable avionics interoperability for future NASA missions. The assessment team was comprised of subject matter experts (SMEs) from Goddard Space Flight Center (GSFC), the Jet Propulsion Laboratory (JPL), Johnson Space Center (JSC), and Langley Research Center (LaRC). The team included valuable external consulting support from a SME who was a key participant in the development of the VITA-78 standard. The team had extensive collaboration with the NASA Space Technology Mission Directorate (STMD) High Performance Spaceflight Computing (HPSC) project, specifically in the development of SpaceVPX interconnect findings, observations, and NESC recommendations. To provide an understanding of the breadth of implementations that SpaceVPX must accommodate, multiple NASA use cases were analyzed to assess the requirements for SpaceVPX implementations across a wide range of NASA missions (Appendix C). Applications included crewed missions, science missions, and orbital and surface robotic systems. Product surveys were conducted to assess the level of industry support for SpaceVPX, applications, and the variations in their implementations (Appendix D). In-depth analysis was conducted in the areas of: (a) power management and distribution, (b) form factors and daughtercards, (c) interconnect, and (d) fault tolerance. Leveraging the use cases, product surveys, and SMEs from multiple NASA Centers, these areas were analyzed to determine the range of implementations permitted by the VITA-78 standard and potential interoperability issues. Applicable findings and NESC recommendations were provided for each area. During this assessment, there were multiple opportunities to engage with other agencies to learn about their interest in SpaceVPX, their strategies for implementing SpaceVPX-based systems, and their internal development efforts. These engagements also generated findings and NESC recommendations. Based on this assessment analysis, NESC recommendations were made regarding the feature set and module profiles to support NASA SpaceVPX implementations. This feature set includes restrictions on features in VITA-78, and extensions to the standard. Key recommendations in this area include the use of 10 Gigabit Ethernet and Peripheral Component Interconnect Express (PCIe) as high bandwidth interconnect on the backplane, the retention of SpaceWire interconnect for control functions, and support for 3U (unit) and 6U, form factors for NASA systems. Restrictions were proposed on the usage of user-defined signals to promote interoperability, and specific power managements and distribution schemes for 3U systems. Beyond the technical implementation of SpaceVPX, recommendations were made on areas that warrant further investigation. Primary among these is the recommendation for NASA to collaborate with other space-going agencies and industry to incorporate recommendations into a future ‘dot spec’ of VITA-78. This would ensure wide adoption and availability of the modules that comply with the specification. The assessment includes appendices with candidate module profiles that can be considered as a starting point for this activity, and example systems based on the recommendations. Follow-on studies are recommended for architectures beyond SpaceVPX to address potential enhancements including condensed set of interconnect, software required to implement protocol layers on the interconnect (and other features), alternative power architectures, and system-level testability.

The James Webb Space Telescope (JWST) is a multi-national program with instruments and hardware supplied by companies all over the world and numerous states in the United States. In order to transport larger assemblies, like the Optical Telescope Element / Integrated Science Instrument Module (OTIS), and ultimately JWST, the Space Telescope Transporter for Air, Road and Sea (STTARS) was designed and constructed. STTARS is a massive mobile cleanroom (longer than 2 semi-trailers) that provides an ISO class 7 payload environment while being transported by road, airborne and marine vehicles. Temperature, humidity, and particle counts are controlled and continuously tracked, with fallout and NVR witness samples placed in strategic locations for confirmation. Instruments or sensitive hardware were purged continuously during transport. STTARS has 5 main components: the upper tent frame, lower tent frame, pallet, strong back and lid. After transporting OTIS to Northrup Grumman (NG), STTARS was modified to increase its height to house the JWST Observatory on its voyage to French Guiana. This new configuration was designated Observatory STTARS (OSTTARS). OSTTARS was too tall to travel by C5 aircraft, so the trip to the launch site was made by ship. Through JWST’s land, air, and sea transports, STTARS and OSTTARS kept JWST hardware exceptionally clean and safe.

During the ISS4Mars workshops in 2020–2021, personnel from the International Space Station (ISS) partner agencies convened to reflect on scenarios for how the ISS could be used and its operations possibly modified to simulate aspects of a human mission to Mars. Scientific leaders, operations experts, crewmembers, managers, and flight surgeons discussed the five hazards of human spaceflight—gravity transitions, radiation, isolation and confinement, distance from Earth, and hostile closed environments—and considered how an ISS-based analog of Mars transit could benefit assessments and mitigations of these hazards. A focused writing team then discussed the advantages and disadvantages of each approach identified by the workshop participants before developing a set of eight use cases to consider the feasibility of implementing on the ISS. The writing team also identified the prerequisites needed, including ground analog studies simulating a mission to Mars required to verify measurements and procedures, before testing could begin on the ISS. Five of the use cases were considered feasible to assess in simulations using an ISS-based analog of Mars transit if some ground rules and assumptions were met. These five use cases were Earth-independent medical operations, Earth-independent integrated operations, life support and food for a one year duration, lower-body negative pressure as a countermeasure against the effects of exposure to microgravity, and fitness levels after landing. In addition, three more extensive interventions—extended Mars surface operations, a small-volume transit analog, and artificial gravity—were deemed unfeasible for testing on the ISS. Experience gained from the five use cases executed on the ISS may help answer some of the questions in the deferred scenarios, or it may be possible to complete them on another platform (e.g. commercial space station, lunar habitat). Simulating conditions during a Mars mission on the ISS will afford higher fidelity for assessing multiple integrated hazards of human spaceflight, however, ground analogs of Mars missions can be used to ensure effective measures and experimental design before testing begins on the ISS. The strategic concepts refined as part of these workshops were brought to a multilateral forum, Mulitlateral Human Research Planel for Exploration (MHRPE), where ISS partner agencies are now discussing implementation plans to provide new opportunities to use the ISS to prepare for deep space exploration over the coming decade. In this publication we present a summary of the international strategic plans for future research that will enable operations, software, and countermeasures to be developed that will reduce the risk to humans during future crewed missions to Mars.

This document describes work to determine a proposed set of concise design requirements for manned spacecraft to yield satisfactory handling qualities when the pilot is performing manual control. This is done primary via the analysis of various historic spacecraft. Partial requirements verification is performed via the creation of a simulated pilot used to determine limits of satisfactory vehicle performance. Partial requirements validation is per-formed via example conceptual design of a spacecraft that is compliant with all relevant proposed requirements.

There is some level of uncertainty in every finite element model (FEM), which flows to a level of uncertainty in predicted results. The purpose of uncertainty quantification (UQ) is to provide statistical bounds on prediction accuracy based on model uncertainty. This is distinct from model updating, which attempts to modify models to improve their accuracy. UQ does not improve the accuracy of models, but accepts that the models are inherently inaccurate and attempts to quantify the impact of that inaccuracy on predicted results. Previously, an alternate method for UQ, called the Hybrid Parametric Variation (HPV) method, was applied to Space Launch System (SLS) Hurty/Craig-Bampton (HCB) components to predict system-level statistics for launch vehicle attitude control transfer functions and core stage section loads due to buffet. The HPV method combines a parametric variation of the HCB fixed-interface (FI) modal frequencies with a nonparametric variation (NPV) method that randomly varies the HCB mass and stiffness matrices as Wishart random matrix distributions using random matrix theory (RMT). Alternatively, the most common method for modeling uncertainty in the structural dynamics community is a parametric approach, which varies physical parameters in the model. However, there are several disadvantages associated with the parametric method. Determining a reduced set of parameters that have a significant impact on the system response can be time consuming, and the selected parameter probability distributions are rarely reliably known. Therefore, in practice, the parameters are surrogates for the actual errors, and the link to parameter uncertainty is unknown. Another major drawback is that the uncertainty that can be represented is limited to the form of the nominal FEM. It is the experience of the authors that based on numerous aerospace programs, almost all FEM errors are in form rather than parameter values. This hypothesis is supported by the observation of the authors that it is almost never possible to ‘tune’ a FEM to match modal test results by only modifying model parameters. Model-form uncertainty cannot be directly represented by FEM input parameters nor included in a parametric approach. However, model-form uncertainty can be modeled using RMT, where a probability distribution is developed for the matrix ensemble of interest. The major advantage of the NPV method is that it covers errors in model form. The HPV method anchors uncertainty at the HCB component level to component modal test results by matching the HCB and test modes based on mode descriptions or other methods, and then applying differing levels of frequency variation. The specific variations depend on the confidence to which a component FEM has been validated through modal testing. The NPV method is layered on the frequency variation to match modal test self-orthogonality and cross-orthogonality (XO) results. Once the component uncertainty models are identified, they are assembled, and the uncertainty is propagated to the system level using a Monte Carlo (MC) analysis approach that generates statistics for system-level predictions This provides a UQ method that can be traced to test data, which can be updated as additional data and improved correlated models become available. The purpose of this paper is to collect and present all of the theory for HPV that has been previously published in reports and papers and to present examples of its application. Specifically, component uncertainty models based on the dispersion of corresponding mass and stiffness matrices using proposed test/analysis correlation metrics are investigated. The first example is purely academic so that the true answers are known, and the validity of the HPV method and the corresponding uncertainty models can be determined. The purpose of this paper is to collect and present all of the theory for HPV that has been previously published in reports and papers and to present examples of its application. Specifically, component uncertainty models based on the dispersion of corresponding mass and stiffness matrices using proposed test/analysis correlation metrics are investigated. The first example is purely academic so that the true answers are known, and the validity of the HPV method and the corresponding uncertainty models can be determined. The second example is an application to a component that is design specific to the SLS. Based on this work and other assessments, the HPV method provides another tool to the toolset used for complex system UQ analysis. From experience gathered to date using the HPV method, additional design specific applications must be investigated to provide further confidence in the validity of the HPV method of UQ analysis.

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

The onset of the COVID-19 pandemic brought a dramatic and rapid transformation to almost every aspect of humanity. The world’s space agencies and their missions were not immune to the wide-sweeping changes. One discipline principally affected was mission operations and the various groups supporting that function. Mission support teams, especially for complex and crewed missions like the International Space Station (ISS) were forced to rethink how and where control center staff performed their vital work. Operations training – an essential element to mission ops, had unique hurdles to overcome. Operations training is responsible for preparing astronaut crews for their missions, training and certifying flight controllers, as well as ensuring that new team members are ready to join their colleagues. Every element of training was impacted during the pandemic. From orientation and introductory classes for new controllers, simulations, and advanced lessons, On the Job Training (OJT) and final evaluations; all aspects faced challenges. Trainers at NASA’s Marshall Space Flight Center in Huntsville, Alabama were forced to become more efficient with trainees and resources to continue supporting ISS payload operations. The pandemic arrived in the USA in March 2020. Immediately, NASA mandated that the support for ISS real-time operations was critical. As a result, physical access to key facilities was restricted. Trainers and trainees had to quickly shift to 100% remote learning. In the short term, this was not a problem. However, instructors discovered lessons they were accustomed to delivering in a classroom environment often did not translate to remote teaching. Another hurdle to operations training was the mandate that all simulations could only be held remotely. The logistics of even small simulations proved to be challenging due to Information Technology (IT) restrictions and public internet limitations. With simulations essentially halted, as well as the restrictions on most OJT, trainees were essentially stopped in their advancement towards certification. Once limitations were identified, trainers prioritized new options. Transitioning to all electronic learning materials was a relatively easy fix. Teaching to large groups took additional shifts in the training paradigm. Methods for preparing astronauts for their missions were revised. Simulation supervisors found efficient techniques to provide realistic training experiences. Communication and coordination with management was essential. In every case, the payload operations instructors found novel solutions to all functions listed. This paper discusses the factors and solutions payloads operations trainers found to keep scientific research on the ISS flying forward to mission success.

NASA Crew Transportation System (CTS) Certification is the authorization granted by the Agency that allows the use of a Commercial Provider’s CTS to transport NASA Crew to and from the ISS. The CTS Certification decision is made by the NASA Associate Administrator based on the comprehensive assessment of the Certification Review Board and recommendations from the CCP and ISS Program Managers and the NASA Associate Administrator of Space Operations Mission Directorate. The Commercial Provider is responsible for developing and executing its plan for certifying the CTS. The Commercial Crew Program (CCP) with the International Space Station (ISS) Program must substantiate the Commercial Provider’s certification assertion of compliance with NASA requirements and NASA Crew safety.

NASA Commercial Crew Program (CCP) Crew Transportation System (CTS) Certification of Flight Readiness (CoFR) is the authorization granted by the Agency that certifies the flight readiness of a Commercial Provider’s CTS to conduct a flight test or mission to transport NASA Crew to and from the ISS. The Commercial Provider is responsible for developing and executing its plan for certifying the flight readiness of its CTS. The CCP with the International Space Station (ISS) Program must substantiate the Commercial Provider’s CoFR assertion to ensure compliance with NASA requirements and NASA Crew safety. NASA CCP CTS CoFR is the approval of the Commercial Provider’s evidence that: • The physical as-built CTS was produced, assembled, integrated, and tested within the approved production and operational constraints. • The mission specific requirements are enveloped within the certified CTS capabilities. • The CTS personnel are trained and certified to support the mission. • All aspects of the CTS are ready for the mission.

NASA’s first asteroid sample return mission, OSIRIS-REx, collected a sample from the surface of near-Earth asteroid Bennu in October 2020 and will deliver it to Earth in September 2023. Selecting a sample collection site on Bennu’s surface was challenging due to the surprising lack of large ponded deposits of regolith particles exclusively fine enough (≤ 2 cm diameter) to be ingested by the spacecraft’s Touch-and-Go Sample Acquisition Mechanism (TAGSAM). Here we describe the Sampleability Map of Bennu, which was constructed to aid in the selection of candidate sampling sites and to estimate the probability of collecting sufficient sample. “Sampleability” is a numeric score that expresses the compatibility of a given area’s surface properties with the sampling mechanism. The algorithm that determines sampleability is a best fit functional form to an extensive suite of laboratory testing outcomes tracking the TAGSAM performance as a function of four observable properties of the target asteroid. The algorithm and testing were designed to measure and subsequently predict TAGSAM collection amounts as a function of the minimum particle size, maximum particle size, particle size frequency distribution, and the tilt of the TAGSAM head off the surface. The sampleability algorithm operated at two general scales, consistent with the resolution and coverage of data collected during the mission. The first scale was global and evaluated nearly the full surface. Due to Bennu’s unexpected boulder coverage and lack of ponded regolith deposits, the global sampleability efforts relied heavily on additional strategies to find and characterize regions of interest based on quantifying and avoiding areas heavily covered by material too large to be collected. The second scale was site-specific and used higher-resolution data to predict collected mass at a given contact location. The rigorous sampleability assessments gave the mission confidence to select the best possible sample collection site and directly enabled successful collection of hundreds of grams of material.

This report details a sub-task (regarding Uncertainty Propagation for Model Validation) from a NASA Engineering and Safety Center assessment that is a multi-year activity spanning the complete development of the Space Launch System integrated vehicle structural dynamic models, and the development of the certification of flight readiness for the Artemis 1 and Artemis 2 vehicles and their variants.