Jump to content

Understanding Risk, Artificial Intelligence, and Improving Software Quality


Recommended Posts

  • Publishers
Posted

The software discipline has broad involvement across each of the NASA Mission Directorates. Some recent discipline focus and development areas are highlighted below, along with a look at the Software Technical Discipline Team’s (TDT) approach to evolving discipline best practices toward the future.

Understanding Automation Risk

Software creates automation. Reliance on that automation is increasing the amount of software in NASA programs. This year, the software team examined historical software incidents in aerospace to characterize how, why, and where software or automation is mostly likely to fail. The goal is to better engineer software to minimize the risk of errors, improve software processes, and better architect software for resilience to errors (or improve fault-tolerance should errors occur).

techup2023-pg50-51-art1.png

Some key findings shown in the above charts, indicate that software more often does the wrong thing rather than just crash. Rebooting was found to be ineffective when software behaves erroneously. Unexpected behavior was mostly attributed to the code or logic itself, and about half of those instances were the result of missing software—software not present due to unanticipated situations or missing requirements. This may indicate that even fully tested software is exposed to this significant class of error. Data misconfiguration was a sizeable factor that continues to grow with the advent of more modern data-driven systems. A final subjective category assessed was “unknown unknowns”—things that could not have been reasonably anticipated. These accounted for 19% of software incidents studied.

The software team is using and sharing these findings to improve best practices. More emphasis is being placed on the importance of complete requirements, off-nominal test campaigns, and “test as you fly” using real hardware in the loop. When designing systems for fault tolerance, more consideration should be given to detecting and correcting for erroneous behavior versus just checking for a crash. Less confidence should be placed on rebooting as an effective recovery strategy. Backup strategies for automations should be employed for critical applications—considering the historic prevalence of absent software and unknown unknowns. More information can be found in NASA/TP-20230012154, Software Error Incident Categorizations in Aerospace.

Employing AI and Machine Learning Techniques

The rise of artificial intelligence (AI) and machine learning (ML) techniques has allowed NASA to examine data in new ways that were not previously possible. While NASA has been employing autonomy since its inception, AI/ML techniques provide teams the ability to expand the use of autonomy outside of previous bounds. The Agency has been working on AI ethics frameworks and examining standards, procedures, and practices, taking security implications into account. While AI/ML generally uses nondeterministic statistical algorithms that currently limit its use in safety-critical flight applications, it is used by NASA in more than 400 AI/ML projects aiding research and science. The Agency also uses AI/ML Communities of Practice for sharing knowledge across the centers. The TDT surveyed AI/ML work across the Agency and summarized it for trends and lessons.

Common usages of AI/ML include image recognition and identification. NASA Earth science missions use AI/ML to identify marine debris, measure cloud thickness, and identify wildfire smoke (examples are shown in the satellite images below). This reduces the workload on personnel. There are many applications of AI/ML being used to predict atmospheric physics. One example is hurricane track and intensity prediction. Another example is predicting planetary boundary layer thickness and comparing it against measurements, and those predictions are being fused with live data to improve the performance over previous boundary layer models.

techup2023-pg50-51-art2.png?w=1815
Examples of how NASA uses AI/ML. Satellite images of clouds with estimation of cloud thickness (left) and wildfire detection (right).
techup2023-pg50-51-art3.png?w=2048
NASA-HDBK-2203, NASA Software Engineering and Assurance Handbook (https://swehb.nasa.gov)

The Code Analysis Pipeline: Static Analysis Tool for IV&V and Software Quality Improvement

The Code Analysis Pipeline (CAP) is an open-source tool architecture that supports software development and assurance activities, improving overall software quality. The Independent Verification and Validation (IV&V) Program is using CAP to support software assurance on the Human Landing System, Gateway, Exploration Ground Systems, Orion, and Roman. CAP supports the configuration and automated execution of multiple static code analysis tools to identify potential code defects, generate code metrics that indicate potential areas of quality concern (e.g., cyclomatic complexity), and execute any other tool that analyzes or processes source code. The TDT is focused on integrating Modified Condition/Decision Coverage analysis support for coverage testing. Results from tools are consolidated into a central database and presented in context through a user interface that supports review, query, reporting, and analysis of results as the code matures.

The tool architecture is based on an industry standard DevOps approach for continuous building of source code and running of tools. CAP integrates with GitHub for source code control, uses Jenkins to support automation of analysis builds, and leverages Docker to create standard and custom build environments that support unique mission needs and use cases.

Improving Software Process & Sharing Best Practices

The TDT has captured the best practice knowledge from across the centers in NPR 7150.2, NASA Software Engineering Requirements, and NASA-HDBK-2203, NASA Software Engineering and Assurance Handbook (https://swehb.nasa.gov.) Two APPEL training classes have been developed and shared with several organizations to give them the foundations in the NPR and software engineering management. The TDT established several subteams to help programs/projects as they tackle software architecture, project management, requirements, cybersecurity, testing and verification, and programmable logic controllers. Many of these teams have developed guidance and best practices, which are documented in NASA-HDBK-2203 and on the NASA Engineering Network.

NPR 7150.2 and the handbook outline best practices over the full lifecycle for all NASA software. This includes requirements development, architecture, design, implementation, and verification. Also covered, and equally important, are the supporting activities/functions that improve quality, including software assurance, safety configuration management, reuse, and software acquisition. Rationale and guidance for the requirements are addressed in the handbook that is internally and externally accessible and regularly updated as new information, tools, and techniques are found and used.

The Software TDT deputies train software engineers, systems engineers, chief engineers, and project managers on the NPR requirements and their role in ensuring these requirements are implemented across NASA centers. Additionally, the TDT deputies train software technical leads on many of the advanced management aspects of a software engineering effort, including planning, cost estimating, negotiating, and handling change management.

View the full article

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Similar Topics

    • By NASA
      From left to right, NASA Marshall engineers Carlos Diaz and John Luke Bili, U.S. Naval Research Laboratory mechanical engineer contractor Eloise Stump, and Marshall engineers Tomasz Liz, David Banks, and Elise Doan observe StarBurst in the cleanroom environment before it’s unboxed from its shipping container. The cleanroom environment at Marshall is designed to minimize contamination and protect the observatory’s sensitive instruments. Image Credit: NASA /Daniel Kocevski   StarBurst, a wide-field gamma ray observatory, arrived at NASA’s Marshall Space Flight Center in Huntsville, Alabama, March 4 for environmental testing and final instrument integration. The instrument is designed to detect the initial emission of short gamma-ray bursts, a key electromagnetic indicator of neutron star mergers.
      “Gamma-ray bursts are among the most powerful explosions in the universe, and they serve as cosmic beacons that help us understand extreme physics, including black hole formation and the behavior of matter under extreme conditions,” said Dr. Daniel Kocevski, principal investigator of the StarBurst mission at NASA Marshall.
      According to Kocevski, neutron star mergers are particularly exciting because they produce gamma-ray bursts and gravitational waves, meaning scientists can study these events using two different signals – light and ripples in space time.
      Starburst Principal Investigator Dr. Daniel Kocevski, left, and Integration and Test Engineer Elise Doan, right, pose with the StarBurst instrument after it was unboxed in the cleanroom environment at NASA Marshall. The Naval Research Lab transferred the instrument to NASA in early March.Image Credit: NASA/Davy Haynes The merging of neutron stars forges heavy elements such as gold and platinum, revealing the origins of some of Earth’s building blocks.
      “By studying these gamma-ray bursts and the neutron star mergers that produce them, we gain insights into fundamental physics, the origins of elements, and even the expansion of the universe,” Kocevski said. “Neutron star mergers and gamma-ray bursts are nature’s laboratories for testing our understanding of the cosmos.”
      StarBurst will undergo flight vibration and thermal vacuum testing at Marshall in the Sunspot Thermal Vacuum Testing Facility. These tests ensure it can survive the rigors of launch and harsh environment of space.
      Final instrument integration will happen in the Stray Light Facility, which is a specialized environment to help identify and reduce unwanted light in certain areas of the optical systems.
      The StarBurst Multimessenger Pioneer is a wide-field gamma-ray observatory designed to detect the initial emission of short gamma-ray bursts, important electromagnetic indicators of neutron star mergers. With an effective area over five times that of the Fermi Gamma-ray Burst Monitor and complete visibility of the unobscured sky, StarBurst will conduct sensitive observations. NASA/Daniel Kocevski StarBurst is a collaborative effort led by NASA’s Marshall Space Flight Center, with partnerships with the U.S. Naval Research Laboratory, the University of Alabama Huntsville, the Universities Space Research Association, and the UTIAS Space Flight Laboratory. StarBurst was selected for development as part of the NASA Astrophysics Pioneers program, which supports lower-cost, smaller hardware missions to conduct compelling astrophysics science.
      To learn more about StarBurst visit:
      https://science.nasa.gov/mission/starburst/
      Media Contact:
      Lane Figueroa
      Marshall Space Flight Center
      Huntsville, Alabama
      256.544.0034
      lane.e.figueroa@nasa.gov
      View the full article
    • By NASA
      2 min read
      Preparations for Next Moonwalk Simulations Underway (and Underwater)
      The Double Asteroid Redirection Test required extreme precision in mission planning to achieve its mission of impacting an asteroid. The founders of Continuum Space worked on astrodynamics relating to this mission, which they used to inform their product.NASA Planning space missions is a very involved process, ensuring orbits are lined up and spacecraft have enough fuel is imperative to the long-term survival of orbital assets. Continuum Space Systems Inc. of Pasadena, California, produces a cloud-based platform that gives mission planners everything they need to certify that their space resources can accomplish their goals. 

      Continuum’s story begins at NASA’s Jet Propulsion Laboratory in Southern California. Loic Chappaz, the company’s co-founder, started at JPL as an intern working on astrodynamics related to NASA’s Double Asteroid Redirection Test. There he met Leon Alkalai, a JPL technical fellow who spent his 30-year career at the center planning deep space missions. After Alkalai retired from NASA, he founded Mandala Space Ventures, a startup that explored several avenues of commercial space development. Chappaz soon became Mandala’s first employee, but to plan their future, Mandala’s leadership began thinking about the act of planning itself. 

      Because the staff had decades of combined experience at JPL, they knew the center had the building blocks for the software they needed. After licensing several pieces of software from JPL, the company began building planning systems that were highly adaptable to any space mission they could come up with. Mandala eventually evolved into a venture firm that incubated space-related startups. However, because Mandala had invested considerably in developing mission-planning tools, further development could be performed by a new company, and Continuum was fully spun off from Mandala in 2021. 

      Continuum’s platform includes several features for mission planners, such as plotting orbital maneuvers and risk management evaluations. Some of these are built upon software licensed from the Jet Propulsion Laboratory.Continuum Space Systems Inc. Continuum’s tools are designed to take a space mission from concept to completion. There are three different components to their “mission in a box” — design, build and test, and mission operations. The base of these tools are several pieces of software developed at NASA. As of 2024, several space startups have begun planning missions with Continuum’s NASA-inspired software, as well as established operators of satellite constellations. From Continuum to several startups, NASA technologies continue to prove a valuable foundation for the nation’s space economy.  
      Read More Share
      Details
      Last Updated Mar 25, 2025 Related Terms
      Technology Transfer & Spinoffs Spinoffs Technology Transfer Explore More
      2 min read NASA Expertise Helps Record all the Buzz
      Article 2 weeks ago 2 min read What is a NASA Spinoff? We Asked a NASA Expert: Episode 53
      Article 3 weeks ago 3 min read NASA Partners with US Patent and Trademark Office to Advance Technology Transfer
      Article 3 months ago Keep Exploring Discover Related Topics
      Planetary Defense – DART
      NASA’s Double Asteroid Redirection Test (DART), built and managed by the Johns Hopkins Applied Physics Laboratory (APL) for NASA’s Planetary…
      Jet Propulsion Laboratory – News
      Science Missions
      Solar System
      View the full article
    • By NASA
      5 min read
      Preparations for Next Moonwalk Simulations Underway (and Underwater)
      In-person participants (L-R) – Back row: Jason Lytle, Stuart Lee, Eric Bershad, Ashot Sargsyan, Aaron Everson, Philip Wells, Sergi Vaquer Araujo, Steven Grover, John A. Heit, Mehdi Shishehbor, Laura Bostick; Middle row: Sarah Childress Taoufik, Stephan Moll, Brandon Macias, Kristin Coffey, Ann-Kathrin Vlacil, Dave Francisco; Front row: James Pavela, Doug Ebert, Kathleen McMonigal, Esther Kim, Emma Hwang; Not pictured: Tyson Brunstetter, J. D. Polk
      Online participants: Stephen Alamo, Mark Crowther, Steven Nissen, Mark Rosenberg, Jeffrey Weitz, R. Eugene Zierler, Serena Aunon, Tina Bayuse, Laura Beachy, Becky Brocato, Daniel Buckland, Jackie Charvat, Diana Cruz Topete, Quinn Dufurrena, Robert Haddon, Joanne Kaouk, Kim Lowe, Steve Laurie, Karina Marshall-Goebel, Sara Mason, Shannan Moynihan, James Pattarini, Devan Petersen, Ruth Reitzel, Donna Roberts, Lucia Roccaro, Mike Stenger, Terry Taddeo, Gavin Travers, Mary Van Baalen, Liz WarrenNASA In October 2024, NASA’s Office of the Chief Health and Medical Officer (OCHMO) initiated a working group to review the status and progress of research and clinical activities intended to mitigate the risk of venous thromboembolism (VTE) during spaceflight. The working group took place over two days at NASA’s Johnson Space Center; a second meeting on the topic was held in December 2024 at the European Space Agency (ESA) facility in Cologne, Germany.
      Read More about the Risk of VTE The working group was assembled from internal NASA subject matter experts (SMEs), the NASA OCHMO Standards Team, NASA and ESA stakeholders, and external SMEs, including physicians and medical professionals from leading universities and medical centers in the United States and Canada.

      Background
      Spaceflight Venous Thrombosis (SVT)
      Spaceflight Venous Thrombosis (SVT) refers to a phenomenon experienced during spaceflight in which a thrombus (blood clot) forms in the internal jugular vein (and/or associated vasculature) that may be symptomatic (thrombus accompanied by, but not limited to, visible internal jugular vein swelling, facial edema beyond “nominal” spaceflight adaptation, eyelid edema, and/or headache) or asymptomatic. Obstructive thrombi have been identified in a very small number of crewmembers, as shown in the figure below.

      Note that the figure below is for illustrative purposes only; locations are approximate, and size is not to scale.

      Approximate location of identified thrombi in crewmembers.Source: Modified from Cerebral Sinus Venous Thrombosis – University of Colorado Denver With treatment, crewmembers were able to complete their mission, and anticoagulants were discontinued several days prior to landing to minimize the risk of bleeding in the event of a traumatic injury. Some thromboses completely resolved post landing, and some required additional treatment.
      Pathophysiology of Venous Thromboembolism (VTE)
      The proposed pathogenesis of VTE is referred to as Virchow’s triad and suggests that VTE occurs as the result of:
      Alterations in blood flow (i.e., stasis), Vascular endothelial injury/changes, and/or, Alterations in the constituents of the blood leading to hypercoagulability (i.e., hereditary predisposition or acquired hypercoagulability). Note: pathophysiology are the changes that occur during a disease process; hypercoagulability is the increased tendency to develop blood to clots.
      The Virchow’s triad of risk factors for venous thrombosis.Bouchnita, 2017 Blood stasis, or venous stasis, refers to a condition in which the blood flow in the veins slows down which leads to pooling in the veins. This slowing of the blood may be due to vein valves becoming damaged or weak, immobility, and/or the absence of muscular contractions. Associated symptoms include swelling, skin changes, varicose veins, and slow-healing sores or ulcers. In terrestrial medicine, venous thrombosis is typically caused by damaged or weakened vein valves, which can be due to many factors, including aging, blood clots, varicose veins, obesity, pregnancy, sedentary lifestyle, estrogen use, and hereditary predisposition.

      Spaceflight Considerations
      Altered Venous Blood Flow and Spaceflight Associated Neuro-ocular Syndrome

      In addition to the terrestrial risk factors of VTE, there are physiological changes associated with spaceflight that are hypothesized to potentially play a role in the development of VTE in weightlessness. Specifically, researchers have explored the effects of the microgravity environment and subsequent observed headward fluid shifts that occur, and the potential impact on blood flow. Crewmembers onboard the International Space Station (ISS) experience weightlessness due to the microgravity environment and thus experience a sustained redistribution of bodily fluids from the legs toward the head. The prolonged headward fluid shifts during weightlessness results in facial puffiness, decreased leg volume, increased cardiac stroke volume, and decreased plasma volume.
      Crewmembers have also experienced altered blood flow during spaceflight, including retrograde venous blood flow (RVBF) (the backflow of venous blood towards the brain) or stasis (a stoppage or slowdown in the flow of blood). While the causes of the observed stasis and retrograde blood flow in spaceflight participants is not well understood, the potential clinical significance of the role it may have in the development of thrombus formation warrants further investigation.
      Doppler imaging of a retrograde flow in the left internal jugular vein.Yan & Seow, 2009 Other physiological concerns affected by fluid shifts are being studied to consider if any relation to VTE exists. Chronic weightlessness can cause bodily fluids such as blood and cerebrospinal fluid to move toward the head, which can lead to optic nerve swelling, folds in the retina, flattening of the back of the eye, and swelling in the brain. This collection of eye and brain changes is called “spaceflight associated neuro-ocular syndrome,” or SANS. Some astronauts only experience mild changes in space, while others have clinically significant outcomes. The long-term health outcome from these changes is unknown but actively being investigated. The risk of developing SANS is higher during longer-duration missions and remains a top research priority for scientists ahead of a Mars mission.
      Conclusions and Further Work
      Based on expert opinion and the assessment of the risk factors for thrombosis, an algorithm was developed to provide guidance for in-mission assessment and treatment of thrombus formation in weightlessness. The algorithm is based on early in-flight ultrasound testing to determine the flow characteristic of the left internal jugular vein and associated vasculature.
      NASA Working Group Recommendations
      The working group recommended several areas for further investigation to assess feasibility and potential to mitigate the risk of thrombosis in spaceflight:
      Improved detection capabilities to identify when a thrombus has formed in-flight, Pathophysiology/factors leading to thrombi formation during spaceflight, Countermeasures and treatment
      For more information on the working group meeting and a complete list of references, please see the Risk of Venous Thromboembolism (VTE) During Spaceflight Summary Report.
      Risk of Venous Thromboembolism (VTE) During Spaceflight Summary Report Share
      Details
      Last Updated Mar 14, 2025 EditorKim Lowe Related Terms
      Office of the Chief Health and Medical Officer (OCHMO) Astronauts General Human Health and Performance Humans in Space The Human Body in Space Keep Exploring Discover Related Topics
      OCHMO Independent Assessments
      Independent assessment plays a crucial role in NASA’s long-term success by addressing essential questions requiring rapid response to support further…
      Aerospace Medical Certification Standard
      This NASA Technical Standard provides medical requirements and clinical procedures designed to ensure crew health and safety and occupational longevity…
      Human Spaceflight Standards
      The Human Spaceflight & Aviation Standards Team continually works with programs to provide the best standards and implementation documentation to…
      Human Spaceflight and Aviation Standards
      The Human Spaceflight and Aviation Standards Team continuously works with subject matter experts and with each space flight program to…
      View the full article
    • By NASA
      6 min read
      Preparations for Next Moonwalk Simulations Underway (and Underwater)
      Risks Concept Risk is inherent in human spaceflight. However, specific risks can and should be understood, managed, and mitigated to reduce threats posed to astronauts. Risk management in the context of human spaceflight can be viewed as a trade-based system. The relevant evidence in life sciences, medicine, and engineering is tracked and evaluated to identify ways to minimize overall risk to the astronauts and to ensure mission success. The Human System Risk Board (HSRB) manages the process by which scientific evidence is utilized to establish and reassess the postures of the various risks to the Human System during all of the various types of existing or anticipated crewed missions. The HSRB operates as part of the Health and Medical Technical Authority of the Office of the Chief Health and Medical Officer of NASA via the JSC Chief Medical Officer.
      The HSRB approaches to human system risks is analogous to the approach the engineering profession takes with its Failure Mode and Effects Analysis in that a process is utilized to identify and address potential problems, or failures to reduce their likelihood and severity. In the context of risks to the human system, the HSRB considers eight missions which different in their destinations and durations (known as Design Reference Missions [DRM]) to further refine the context of the risks. With each DRM a likelihood and consequence are assigned to each risk which is adjusted scientific evidence is accumulated and understanding of the risk is enhanced, and mitigations become available or are advanced.
      Human System Risks This framework enables the principles of Continuous Risk Management and Risk Informed Decision Making (RIDM) to be applied in an ongoing fashion to the challenges posed by Human System Risks. Using this framework consistently across the 29 risks allows management to see where risks need additional research or technology development to be mitigated or monitored and for the identification of new risks and concerns. Further information on the implementation of the risk management process can be found in the following documents:
      Human System Risk Management Plan – JSC-66705 NASA Health and Medical Technical Authority (HMTA) Implementation – NPR 7120.11A NASA Space Flight Program and Project Management Requirements – NPR 7120.5 Human System Risk Board Management Office
      The HSRB Risk Management Office governs the execution of the Human System Risk management process in support of the HSRB. It is led by the HSRB Chair, who is also referred to as the Risk Manager.
      Risk Custodian Teams
      Along with the Human System Risk Manager, a team of risk custodians (a researcher, an operational researcher or physician, and an epidemiologist, who each have specific expertise) works together to understand and synthesize scientific and operational evidence in the context of spaceflight, identify and evaluate metrics for each risk in order to communicate the risk posture to the agency.
      Directed Acyclic Graphs 
      Summary
      The HSRB uses Directed Acyclic Graphs (DAG), a type of causal diagramming, as visual tools to create a shared understanding of the risks, improve communication among those stakeholders, and enable the creation of a composite risk network that is vetted by members of the NASA community and configuration managed (Antonsen et al., NASA/TM– 20220006812). The knowledge captured is the Human Health and Performance community’s knowledge about the causal flow of a human system risk, and the relationships that exist between the contributing factors to that risk.
      DAGs are:
      Intended to improve communication between: Managers and subject matter experts who need to discuss human system risks Subject matter experts in different disciplines where human system risks interact with one another in a potentially cumulative fashion Visual representations of known or suspected relationships Directed – the relationship flows in one direction between any two nodes Acyclic – cycles in the graph are not allowed Example of a Directed Acyclic Graph. This is a simplified illustration of how and the individual, the crew, and the system contribute to the likelihood of successful task performance in a mission. Individual readiness is affected by many of the health and performance-oriented risks followed by the HSRB, but the readiness of any individual crew is complemented by the team and the system that the crew works within. Failures of task performance may lead to loss of mission objectives if severe.NASA View Larger (Example of a Directed Acyclic Graph) Image
      Details
      At NASA, the Human System Risks have historically been conceptualized as deriving from five Hazards present in the spaceflight environment. These are: altered gravity, isolation and confinement, radiation, a hostile closed environment, and distance from Earth. These Hazards are aspects of the spaceflight environment that are encountered when someone is launched into space and therefore are the starting point for causal diagramming of spaceflight-related risk issues for the HSRB.
      These Hazards are often interpreted in relation to physiologic changes that occur in humans as a result of the exposure; however, interaction between human crew (behavioral health and performance), which may be degraded due to the spaceflight environment – and the vehicle and mission systems that the crew must operate – can also be influenced by these Hazards.
      Each Human System Risk DAG is intended to show the causal flow of risk from Hazards to Mission Level Outcomes. As such, the structure of each DAG starts with at least one Hazard and ends with at least one of the pre-defined Mission Level Outcomes. In between are the nodes and edges of the causal flow diagrams that are relevant to the Risk under consideration. These are called ‘contributing factors’ in the HSRB terminology, and include countermeasures, medical conditions, and other Human System Risks. A graph data structure is composed of a set of vertices (nodes), and a set of edges (links). Each edge represents a relationship between two nodes. There can be two types of relationships between nodes: directed and undirected. For example, if an edge exists between two nodes A and B and the edge is undirected, it is represented as A–B, (no arrow). If the edge were directed, for example from A to B, then this is represented with an arrow (A->B). Each directed arrow connecting one node to another on a DAG indicates a claim of causality. A directed graph can potentially contain a cycle, meaning that, from a specific node, there exists a path that would eventually return to that node. A directed graph that has no cycles is known as acyclic. Thus, a graph with directed links and no cycles is a DAG.  DAGs are a type of network diagram that represent causality in a visual format.
      DAGs are updated with the regular Human System Risk updates generally every 1-2 years. Approved DAGs can be found in the NASA/TP 20220015709 below or broken down under each Human System Risk.
      Documents
      Directed Acyclic Graph Guidance Documentation – NASA/TM 20220006812 Directed Acyclic Graphs: A Tool for Understanding the NASA Human Spaceflight System Risks – NASA/TP 20220015709 Publications
      npj Microgravity – Causal diagramming for assessing human
      system risk in spaceflight
      Apr 22, 2024
      PDF (3.09 MB)
      npj Microgravity –
      Levels of evidence for human system risk
      evaluation
      Apr 22, 2024
      PDF (2.47 MB)
      npj Microgravity –
      Updates to the NASA human system risk management process
      for space exploration
      Apr 22, 2024
      PDF (2.24 MB)
      Points of Contact
      Mary Van Baalen
      Dan Buckland
      Bob Scully
      Kim Lowe
      Human System Risks Share
      Details
      Last Updated Mar 11, 2025 EditorRobert E. LewisLocationJohnson Space Center Related Terms
      Human Health and Performance Human System Risks Explore More
      1 min read Concern of Venous Thromboembolism
      Article 31 mins ago 1 min read Risk of Acute and Chronic Carbon Dioxide Exposure
      Article 30 mins ago 1 min read Risk of Adverse Cognitive or Behavioral Conditions and Psychiatric Disorders
      Article 30 mins ago Keep Exploring Discover More Topics From NASA
      Humans In Space
      Missions
      International Space Station
      Solar System
      View the full article
    • By NASA
      1 min read
      Preparations for Next Moonwalk Simulations Underway (and Underwater)
      The space shuttle Endeavour is seen on launch pad 39a as a storm passes by prior to the rollback of the Rotating Service Structure (RSS), Thursday, April 28, 2011, at Kennedy Space Center in Cape Canaveral, Fla. During the 14-day mission, Endeavour and the STS-134 crew will deliver the Alpha Magnetic Spectrometer (AMS) and spare parts including two S-band communications antennas, a high-pressure gas tank and additional spare parts for Dextre. Launch is targeted for Friday, April 29 at 3:47 p.m. EDT.NASA It is important to protect humans from unintended electrical current flow during spaceflight. The thresholds for contact electrical shock are well established, and standards and requirements exist that minimize the probability of contact electrical shock. Current thresholds were chosen (vs. voltage thresholds) because body impedance varies depending on conditions such as wet/dry, AC/DC, voltage level, large/small contact area, but current thresholds and physiological effects do not change. By addressing electrical thresholds, engineering teams are able to provide the appropriate hazard controls, usually through additional isolation (beyond the body’s impedance), current limiters, and/or modifying the voltage levels. Risk assessment determined that the probability of an event was extremely low, and the most serious consequence is expected to be involuntary muscle contraction.
      Lightning strikes the Launch Pad 39B protection system as preparations for launch of NASA’s Space Launch System (SLS) rocket with the Orion spacecraft aboard continue, Saturday, Aug. 27, 2022, at NASA’s Kennedy Space Center in Florida. NASA’s Artemis I flight test is the first integrated test of the agency’s deep space exploration systems: the Orion spacecraft, SLS rocket, and supporting ground systems. Launch of the uncrewed flight test is targeted for no earlier than Aug. 29 at 8:33 a.m. ET. Photo Credit: (NASA/Bill Ingalls) Directed Acyclic Graph Files
      + DAG File Information (HSRB Home Page)
      + Electrical Shock Risk DAG and Narrative (PDF)
      + Electrical Shock Risk DAG Code (TXT)
      Human System Risks Share
      Details
      Last Updated Mar 11, 2025 EditorRobert E. LewisLocationJohnson Space Center Related Terms
      Human Health and Performance Human System Risks Explore More
      1 min read Risk of Toxic Substance Exposure
      Article 15 mins ago 1 min read Risk of Urinary Retention
      Article 15 mins ago 1 min read Risk to Vehicle Crew Egress Capability and Task Performance as Applied to Earth and Extraterrestrial Landings
      Article 14 mins ago Keep Exploring Discover More Topics From NASA
      Humans In Space
      Missions
      International Space Station
      Solar System
      View the full article
  • Check out these Videos

×
×
  • Create New...