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SECAF Kendall offers his vision for the security challenges the Air Force and Space Force could face in 2050 and what is needed to properly respond.
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By NASA
6 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater)
In-person participants L-R standing: Dave Francisco, Joanne Kaouk, Dr. Richard Moon, Dr. Tony Alleman, Dr. Sean Hardy, Sarah Childress, Kristin Coffey, Dr. Ed Powers, Dr. Doug Ebersole, Dr. Steven Laurie, Dr. Doug Ebert; L-R seated: Dr. Alejandro Garbino, Dr. Robert Sanders, Dr. Kristi Ray, Dr. Mike Gernhardt, Dr. Joseph Dervay, Dr. Matt Makowski). Not pictured: Dr. Caroline Fife In June 2024, the NASA Office of the Chief Health and Medical Officer (OCHMO) Standards Team hosted an independent assessment working group to review the status and progress of research and clinical activities intended to mitigate the risk of decompression sickness (DCS) related to patent foramen ovale (PFO) during spaceflight and associated ground testing and human subject studies.
Decompression sickness (DCS) is a condition which results from dissolved gases (primarily nitrogen) forming bubbles in the bloodstream and tissues. It is usually experienced in conditions where there are rapid decreases in ambient pressure, such as in scuba divers, high-altitude aviation, or other pressurized environments. The evolved gas bubbles have various physiological effects and can obstruct the blood vessels, trigger inflammation, and damage tissue, resulting in symptoms of DCS. NASA presently classifies DCS into two categories: Type I DCS, which is less severe, typically leads to musculoskeletal symptoms including pain in the joints or muscles, or skin rash. Type II DCS is more severe and commonly results in neurological, inner ear, and cardiopulmonary symptoms. The risk of DCS in spaceflight presents during extravehicular activities (EVAs) in which astronauts perform mission tasks outside the spaceflight vehicle while wearing a pressurized suit at a lower pressure than the cabin pressure. DCS mitigation protocols based on strategies to reduce systemic nitrogen load are implemented through the combination of habitat environmental parameters, EVA suit pressure, and breathing gas procedures (prebreathe protocols) to achieve safe and effective mission operations. The pathophysiology of DCS has still not been fully elucidated since cases occur despite the absence of detected gas bubbles but includes right to left shunting of venous gas emboli (VGE) via several potential mechanisms, one of which is a Patent Foramen Ovale (PFO).
From: Dr. Schochet & Dr. Lie, Pediatric Pulmonologists
Reference OCHMO-TB-037 Decompression Sickness (DCS) Risk Mitigation technical brief for additional information.
A PFO is a shunt between the right atrium and the left atrium of the heart, which is a persisting remnant of a physiological communication present in the fetal heart. Post-natal increases in left atrial pressure usually force the inter-septal valve against the septum secundum and within the first 2 years of life, the septae permanently fuse due to the development of fibrous adhesions. Thus, all humans are born with a PFO and approximately 75% of PFOs fuse following childbirth. For the 25% of the population’s whose PFOs do not fuse, ~6% have what is considered by some to be a large PFO (> 2 mm). PFO diameter can increase with age. The concern with PFOs is that with a right to left shunt between the atria, venous emboli gas may pass from the right atrium (venous) to the left atrium (arterial) (“shunt”), thus by-passing the normal lung filtration of venous emboli which prevent passage to the arterial system. Without filtration, bubbles in the arterial system may lead to a neurological event such as a stroke. Any activity that increases the right atrium/venous pressure over the left atrium/arterial pressure (such as a Valsalva maneuver, abdominal compression) may further enable blood and/or emboli across a PFO/shunt.
From: Nuffield Department of Clinical Neurosciences
The purpose of this working group was to review and provide analysis on the status and progress of research and clinical activities intended to mitigate the risk of PFO and DCS issues during spaceflight. Identified cases of DCS during NASA exploration atmosphere ground testing conducted in pressurized chambers led to the prioritization of the given topic for external review. The main goals of the working group included:
Quantification of any increased risk associated with the presence of a PFO during decompression protocols utilized in ground testing and spaceflight EVAs, as well as unplanned decompressions (e.g., cabin depressurization, EVA suit leak). Describe risks and benefits of PFO screening in astronaut candidates, current crewmembers, and chamber test subjects. What are potential risk reduction measures that could be considered if a person was believed to be at increased risk of DCS due to a PFO? What research and/or technology development is recommended that could help inform and/or mitigate PFO-related DCS risk? The working group took place over two days at NASA’s Johnson Space Center and included NASA subject matter experts and stakeholders, as well as invited external reviewers from areas including cardiology, hypobaric medicine, spaceflight medicine, and military occupational health. During the working group, participants were asked to review past reports and evidence related to PFOs and risk of DCS, materials and information regarding NASA’s current experience and practices, and case studies and subsequent decision-making processes. The working group culminated in an open-forum discussion where recommendations for current and future practices were conferred and subsequently summarized in a final summary report, available on the public NASA OCHMO Standards Team website.
The following key findings are the main take-aways from the OCHMO independent assessment:
In an extreme exposure/high-risk scenario, excluding individuals with a PFO and treating PFOs does not necessarily decrease the risk of DCS or create a ‘safe’ environment. It may create incremental differences and slightly reduce overall risk but does not make the risk zero. There are other physiological factors that also contribute to the risk of DCS that may have a larger impact (see 7.0 Other Physiological Factors in the findings section). Based on the available evidence and the risk of current decompression exposures (based on current NASA protocols and NASA-STD-3001 requirements to limit the risk of DCS), it is not recommended to screen for PFOs in any spaceflight or ground testing participants. The best strategy to reduce the risk of DCS is to create as safe an environment as possible in every scenario, through effective prebreathe protocols, safety, and the capability to rapidly treat DCS should symptoms occur. Based on opinion, no specific research is required at this time to further characterize PFOs with DCS and altitude exposure, due to the low risk and preference to institute adequate safe protocols and ensuring treatment availability both on the ground and in spaceflight. For engineering protocols conducted on the ground, it should be ensured that the same level of treatment capability (treatment chamber in the immediate vicinity of the testing) is provided as during research protocols. The ability to immediately treat a DCS case is critical in ensuring the safety of the test subjects. The full summary report includes detailed background information, discussion points from the working group, and conclusions and recommendations. The findings from the working group and resulting summary report will help to inform key stakeholders in decision-making processes for future ground testing and spaceflight operations with the main goal of protecting crew health and safety to ensure overall mission success.
Summary Report About the Author
Sarah D. Childress
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Last Updated Dec 31, 2024 Related Terms
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By NASA
An artist’s concept of the Earth, Moon, and Mars.Credit: NASA As NASA develops a blueprint for space exploration throughout the solar system for the benefit of humanity, the agency released several new documents Friday updating its Moon to Mars architecture. The roadmap sets NASA on course for long-term lunar exploration under the Artemis campaign in preparation for future crewed missions to Mars.
Following an Architecture Concept Review, the 2024 updates include a revision of NASA’s Architecture Definition Document which details technical approaches and processes of the agency’s exploration plans, an executive overview, and 12 new white papers on key Moon to Mars topics.
“NASA’s Architecture Concept Review process is critical to getting us on a path to mount a human mission to Mars,” said NASA Associate Administrator Jim Free. “We’re taking a methodical approach to mapping out the decisions we need to make, understanding resource and technological trades, and ensuring we are listening to feedback from stakeholders.”
One newly released white paper highlights NASA’s decision to use fission power as the primary source of power on the Martian surface to sustain crews — the first of seven key decisions necessary for human Mars exploration. Fission power is a form of nuclear power unaffected by day and night cycles or potential dust storms on Mars.
New additions this year also include a broader, prioritized list of key architecture decisions that need to be made early in NASA’s plans to send humans to the Red Planet. Two new elements are now part of the agency’s Moon to Mars architecture — a lunar surface cargo lander and an initial lunar surface habitat. The lunar surface cargo lander will deliver logistics items, science and technology payloads, communications systems, and more. The initial surface habitat will house astronauts on the lunar surface to extend the crew size, range, and duration of exploration missions and enable crewed and uncrewed science opportunities.
The newest revision of the Architecture Definition Document adds more information about NASA’s decision road mapping process — how the agency decides which decisions must be made early in the planning process based on impacts to subsequent decisions — and a list of architecture-driven opportunities that help technology development organizations prioritize research into new technologies that will enable the Moon to Mars architecture.
“Identifying and analyzing high-level architecture decisions are the first steps to realizing a crewed Mars exploration campaign,” said Catherine Koerner, associate administrator, Exploration Systems Development Mission Directorate, NASA Headquarters in Washington. “Each yearly assessment cycle as part of our architecture process is moving us closer to ensuring we have a well thought out plan to accomplish our exploration objectives.”
NASA’s Moon to Mars architecture approach incorporates feedback from U.S. industry, academia, international partners, and the NASA workforce. The agency typically releases a series of technical documents at the end of its annual analysis cycle, including an update of the Architecture Definition Document and white papers that elaborate on frequently raised topics.
Under NASA’s Artemis campaign, the agency will establish the foundation for long-term scientific exploration at the Moon, land the next Americans and first international partner astronaut on the lunar surface, and prepare for human expeditions to Mars for the benefit of all.
For NASA’s Moon to Mars architecture documents, visit:
https://www.nasa.gov/moontomarsarchitecture
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Rachel Kraft / Kathryn Hambleton
Headquarters, Washington
202-358-1600
rachel.h.kraft@nasa.gov / kathryn.a.hambleton@nasa.gov
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Last Updated Dec 13, 2024 EditorJessica TaveauLocationNASA Headquarters Related Terms
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