Review of NASA's Evidence Reports on Human Health Risks 2015 Letter Report (2016) / Chapter Skim
Currently Skimming:
2015 Letter Report
2015 Letter Report
Pages 1-54
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 1... ...
, has es stablished the Committee to e Review NASA's Evidence Reports on Hum Health Ri w E man isks. This lettter report is the third in a series of five repor (IOM, 2014, 2015)
|
From page 2... ...
This report also builds on the 2008 IOM report Review of NASA's Human Research Program Evidence Books: A Letter Report, which assessed the process for developing NASA's evidence reports and provided an initial and brief review of NASA's original evidence report.1 The committee approached its task by analyzing each evidence report's overall quality, which included readability; internal consistency; the source and breadth of cited evidence; identification of existing knowledge and research gaps; authorship expertise; and, if applicable, response to recommendations from the IOM letter report previously described. It is difficult to characterize and compare the quality of evidence cited in individual evidence reports.
|
From page 3... ...
to provide an independent review of more than 30 evidence reports on human health risks for long duration and exploration spaceflight. The evidence reports, which are publicly available, are categorized into five broad cate gories: (1)
|
From page 4... ...
Although no formal recommendations are included in this report, the committee's observations are intended to inform and improve NASA's ongoing efforts to update the content of individual evidence reports. THE NASA HUMAN RESEARCH ROADMAP The evidence reports reviewed in this IOM report are part of a larger roadmap process developed and under implementation by NASA's Human Research Program (HRP)
|
From page 5... ...
nce isk red Perforrmance Due to Reduced Muscle Mass Strength, a Enduran M s, and nce (Ploutzz-Snyder et al., 2015) provides a su p ubstantive ov verview of t the breadth of evidence regarding th risks relate to skeletal muscle heal e he ed l lth
|
From page 6... ...
Does the Evidence Report Provide Sufficient Evidence, as Well as Sufficient Risk Context, That the Risk Is of Concern for Long-Term Space Missions? The evidence report provides an excellent summary of manned spaceflight from the early missions to current 6-month stays on the ISS.
|
From page 7... ...
highlights the large individual variability in muscle strength changes with long-duration stays on the ISS and stands out as an example of the challenges with skeletal muscle health with spaceflight. Interestingly, the variability presented is well outside the range observed in numerous human ground-based analog studies (i.e., bed rest)
|
From page 8... ...
• Further research is needed to identify the proper balance of aero bic and resistance exercise best suited to protect skeletal muscle health during spaceflight, especially in light of Figure 11 of the evidence report that shows the extensive differences in individu al variability. To date, the exercise prescription remains incom plete, and more scientific data at the whole body and cell level are needed to further elucidate the best exercise paradigm.
|
From page 9... ...
and their influence on hormonal balance and muscle physiology and performance should be further explored. As a re sult, this area has the potential to impact health beyond skeletal muscle and would be crosscutting for other biological systems (i.e., systems biology)
|
From page 10... ...
should be explored and discussions of potential interactions should be added to the relevant evidence reports. The committee also noted the potential impact of exercise devices on various physiological systems (i.e., integrative biology)
|
From page 11... ...
There are several emerging areas resulting in additional knowledge gaps involving skeletal muscle health that intersect with other disciplines (i.e., nutrition, microcirculation, hormone biology, drug interactions) that will most likely require additional input from experts in these areas for future iterations of the evidence report.
|
From page 12... ...
The committee's responses to the key review questions are summarized below. Does the Evidence Report Provide Sufficient Evidence, as Well as Sufficient Risk Context, That the Risk Is of Concern for Long-Term Space Missions?
|
From page 13... ...
Furthermore, scientifically based evidence was presented to further highlight the potential health risks associated with spaceflight. Several of the gaps focused on the need to better understand the peak aerobic physiological stresses (intensity and duration)
|
From page 14... ...
• The need to integrate the aerobic exercise countermeasure stand ards with: o Skeletal muscle standards. o Nutrition planning relevant to voluntary exercise and food needs.
|
From page 15... ...
Does the Evidence Report Address Relevant Interactions Among Risks? The report does an excellent job discussing the interactions among the risks listed in the evidence report, in particular the interactions between aerobic deconditioning and orthostatic intolerance.
|
From page 16... ...
As noted above, the aerobic exercise standards, performance demands, and training interventions need ongoing integration with the skeletal muscle and nutrition evidence base. All of these need to be integrated with the physiological demands of anticipated and emergency tasks.
|
From page 17... ...
. The evidence report Risk of Orthostatic Intolerance During Re-Exposure to Gravity (Stenger et al., 2015)
|
From page 18... ...
The evidence report also makes the case that orthostatic intolerance recovers rapidly following return to 1G, but there is a fundamental lack of evidence regarding landing in or return from fractional G environments. The evidence report provides an extensive discussion of the multifactorial etiology of orthostatic intolerance, including fluid redistribution, hypovolemia, cardiac/vascular atrophy, and autonomic dysregulation.
|
From page 19... ...
The evidence report provides no reports of orthostatic events during ascent or re-entry phases of spaceflight. • There is a well-established interaction between thermal stress and orthostatic intolerance, associated with a displacement of a portion of circulating blood volume to the compliant cutaneous vascular bed.
|
From page 20... ...
• Paradoxically, acute, high-intensity exercise appears to improve orthostatic intolerance, while prolonged exercise decreases it. Understanding the interaction with exercise could be modeled theoretically and tested experimentally.
|
From page 21... ...
These interventions need ongoing integration with the skeletal muscle and nutrition evidence base. All of these need to be integrated with the quantification of physiological demands of nominal and emergency tasks.
|
From page 22... ...
The report discusses the issues associated with suit design and presents data from the ISS and Apollo-era experiences; the report also includes results of studies conducted to identify characteristics of future suits to support EVA requirements during expedition-class missions. This evidence report provides a comprehensive review of both the external hazards faced in EVA operations, particularly excessive radiation exposure and unviable breathing environments, as well as the hazards and challenges posed within the microclimate of the space suit such as hypoxia, humidity, suit pressure, and the biological challenges including thermal dysregulation, nutrition and hydration, and waste removal needs.
|
From page 23... ...
BOX 2 Research Gaps Identified in the Evidence Report • EVA 6: What crew physiological and performance capabilities are required for EVA operations in exploration environments? • EVA 7: How do EVA suit system design parameters affect crew health and performance in exploration environments?
|
From page 24... ...
• EVA 1: What models and techniques are re quired to evaluate various suit designs and op erational concepts to optimize crew health and performance? • EVA 2: What are the physiological and bio mechanical stimuli associated with various suit designs and EVA tasks?
|
From page 25... ...
All garments, from running shorts to elaborate protective ensembles are designed with an understanding of the tasks that will be performed while wearing them. The primary research gap missing from many of the NASA evidence reports, including this one, is the need for a systematic analysis of tasks likely to be performed by crew personnel during long-duration space missions.
|
From page 26... ...
Th evidence report is base on the assu his r ed umption that g gas-pressurizzed suit arrchitecture is the only opttion available and all gap addressed b e, ps by the aut thors derive from this assu f umption. Muc of the gap analysis wou ch uld be diffferent if EVA gap 1 had not been retir and altern A n red native architeectures to convention gas-pressu t nal urized design had been e ns evaluated in t the eviden report.
|
From page 27... ...
highlight some of the limitations of the conventional gaspressurized suit design. According to the Apollo lunar crews, the most fatiguing part of surface EVA tasks was repetitive gripping.
|
From page 28... ...
The evidence report identifies links to the evidence reports on inadequate human–computer interaction, training deficiencies, personnel selection issues, and mostly the risk of decompression sickness. Additional interactions that require attention include • Risk of Inadequate Nutrition (Smith et al., 2015)
|
From page 29... ...
Additional input is needed from experts who can evaluate alternative approaches to conventional pressure suits for expedition-class space missions. At the very least, the authors should explain why other approaches to suit design were not mentioned in the report.
|
From page 30... ...
The design of tasks that necessitate EVA must necessarily consider the physical and other limitations created by the suit." The committee notes that the current evidence report reflects and addresses this recommendation, but would also add that the tasks anticipated during planetary surface exploration are in some ways fundamentally different and need careful analysis. The evidence reports need to clearly distinguish EVAs during planetary surface exploration from in-orbit EVAs.
|
From page 31... ...
During a typical hum space mi d man ission, the connditions condducive to DCS could occur during an EVA w o d g when astronau are asked to uts don an then manip nd pulate and ammbulate in gass-pressurized space suits thhat operate at lower am mbient pressu levels than the vehicle or habitat. Su ure n uit operating pressure is reduced to minimize suit rigidity and maximi t ize mobili ity -- the soft suit materials stiffen when pressurized making it d s n d, difficult to articulate the suit joints and causing significant astronaut exe t t g ertion (a frequently injury)
|
From page 32... ...
that needs to be addressed in future human space missions.
|
From page 33... ...
DCS 2. We do not know the contribution of specific DCS risk fac tors to the development of DCS in the spaceflight explora tion environment.
|
From page 34... ...
Knowing that the EVA represents the "altitude" phase of the decompression cycle (when DCS risk is at its highest) , ex pected exertion for EVA tasks needs to be well understood, as it may affect the type and duration of EVA operations that are fea sible (or add additional requirements for suit mobility)
|
From page 35... ...
As discussed earlier regarding the EVA evidence report, advanced mobility suit concepts such as MCP suits offer significant ad vantages over gas-pressurized suits (and can potentially be oper ated at higher pressures with less effort, decreasing both the difference between vehicle and suit pressure and the energetic cost of EVAs, thereby doubly decreasing DCS risk)
|
From page 36... ...
. Currently it is not known how an individual's specific DCS risk changes as they decondition or how much var iance there is in individual risk for a given change in these phys iologic systems.
|
From page 37... ...
. The committee concurs with these risk factors, and volunteers additional relevant interactions based on other evidence reports compiled by NASA, including • Risk of Injury and Compromised Performance Due to EVA Op erations (Chappell et al., 2015)
|
From page 38... ...
This term has also been written without the negative sign in previous evidence reports (Gernhardt et al., 2009, p.
|
From page 39... ...
As described earlier, due to the significant effect of both space suit architecture and EVA task selection on DCS risk, the committee encourages the DCS community and EVA suit and operations communities to continue working closely to mitigate this risk. Further, because of the difficulty and uncertainty in assessing and treating DCS in situ, the authors are encouraged to more closely interact with the medical and space technology communities on sensing (e.g., in-suit wearable technologies such as venous gas emboli Doppler sensors, or reliable biomarkers)
|
From page 40... ...
Evidence of constraining food system resources was also presented. Does the Evidence Report Provide Sufficient Evidence, as Well as Sufficient Risk Context, That the Risk Is of Concern for Long-Term Space Missions?
|
From page 41... ...
One common factor that has not been adequately addressed in this evidence report is the relationship between any of the factors discussed and the level of performance of required tasks. A concerted coordinated effort is needed.
|
From page 42... ...
Additionally, the models indicate that several of the existing foods deemed acceptable for current space missions will not be acceptable for longer duration missions. This justifies the need for exploring alternative technologies for preparing, processing, packaging, and storing foods and also developing more accurate models for predicting the shelf life of products.
|
From page 43... ...
Understanding Food Safety and Processing Technologies Although inadequate food safety was listed as a concern, it has not been listed as one of the areas of fundamental research that should be conducted in the list of gaps at the bottom of page 5 of the evidence report. Perhaps there was a typo or some duplication between gaps 2 and 3 (p.
|
From page 44... ...
on shelf life should also be considered. One of the issues that was mentioned in the report is the potential for partial gravity to affect heat and mass transfer for preparation or processing of foods.
|
From page 45... ...
Utilization of Waste Research on the use of waste generated in space, especially on planetary surfaces, should be conducted. This includes both food waste and packaging waste.
|
From page 46... ...
Further, communications between the Food Systems and Nutrition Research evidence report teams could improve the joint focus on food and nutrient intake on human performance and behavior.
|
From page 47... ...
Does the Evidence Report Provide Sufficient Evidence, as Well as Sufficient Risk Context, That the Risk Is of Concern for Long-Term Space Missions? The focus of answering this question shifts to whether the evidence report (Smith et al., 2015)
|
From page 48... ...
Overall deficient caloric intake or water intakes seem to be dominant risks. One suggestion would be to focus on those nutrients with intakes on space missions of some duration shown in the tables in the evidence report's appendix that are either above (sodium, phosphorous)
|
From page 49... ...
Research gaps are presented without any attempt to prioritize their importance. The report would be strengthened by stripping out data that are not corroborated by long-term studies.
|
From page 50... ...
• Effects resulting from studies of timing of food intake relative to exercise, and nutritional effects of circadian shifts and sleep habits Are There Any Additional Gaps in Knowledge or Areas of Fundamental Research That Should Be Considered to Enhance the Basic Understanding of This Specific Risk? Behavioral health is not adequately covered in the report, and additional understanding is needed of the inflight biochemical and psychosocial factors that contribute to appetite, palatability and taste perception, satiety, and astronauts not consuming available foodstuffs completely.
|
From page 51... ...
Thus, the addition of interactions with the risks of altered immune function and altered microbial physiology and virulence would be useful. Further, the potential for interactions with the risks noted in other evidence reports could be added, including • Risk of Impaired Performance Due to Reduced Muscle Mass, Strength, and Endurance (Ploutz-Snyder et al., 2015)
|
From page 52... ...
A more holistic view of nutrition and the factors that influence it, particularly for long-duration missions, will profit from including expertise in behavioral science and contemporary molecular biology that affects human metabolism, especially in the area of responses to diverse stresses. Understanding of the relationship between individual nutrient intake and overall individual diet patterns would benefit from contributions by behavioral health researchers.
|
From page 53... ...
60) SUMMARY This is the third of five letter reports that will review the entire series of NASA's evidence reports on human health risks.
|
From page 54... ...
Masys, Vice Chair Committee to Review NASA's Evidence Reports on Human Health Risks
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.