EVIDENCE BOOK OVERVIEW

I. BACKGROUND AND DOCUMENTS

The HRP, within the NASA Human Exploration and Operations Mission Directorate (HEOMD), is a directed and applied research program that addresses NASA's needs for human health and performance risk mitigation strategies in support of space exploration missions. These exploration undertakings include missions to Near Earth Asteroid (NEA), including the Moon, and Mars. Although all of these mission types involve some of the same human health and performance challenges, each also includes specific challenges that depend on the nature of the mission and the mission development schedule. HRP research and technology development are focused on the highest-priority risks to crew health and safety, with the goal of ensuring mission success and maintaining long-term crew health.

The development of HRP content has been formulated around the management architecture of “Evidence to Risk to Gap to Task to Deliverables”. In other words, evidence indicates that a risk exists to the human system, and gaps in our knowledge about the risk or how to mitigate it indicate what tasks need to be carried out in order to produce the deliverables needed to fill these gaps. Three core documents thus describe the HRP: 1) the Program Requirements Document (PRD), 2) the Evidence Book, and 3) the Integrated Research Plan (IRP). These documents are updated regularly and provide relevant information that can be used to manage the program.

The HRP PRD defines, documents, and allocates the high-level requirements to each of the HRP Program Elements: Behavioral Health and Performance, Exploration Medical Capability, Human Health Countermeasures, ISS Medical Project (as an implementing Element, no risks assigned), Space Human Factors and Habitability, and Space Radiation. These requirements are derived to satisfy the exploration mission requirements of the HEOMD and the Office of the Chief Health and Medical Officer (OCHMO) and are essentially the set of spaceflight human health and performance risks and standards of acceptability for these risks upon which the HRP is focused [NASA Standard (STD) 3001, Space Flight Human System Standard - Volume 1: Crew Health, and Volume 2, Human Factors, Habitability, and Environmental Health, available on the Standards and Technical Assistance Resource Tool (START)]. In addition, NASA/SP-2010-3407, Human Integration Design Handbook (HIDH) was published as a compendium of human space flight history, lessons learned, and design information for a wide variety of disciplines to serve as a companion document to NASA-STD-3001, Volume 2, Human Factors, Habitability, and Environmental Health.

The Evidence Book provides a record of the state of knowledge from research and operations for each risk currently in the PRD. The book consists of an evidence-based report or collection of citations for each individual risk. Each report is essentially a brief review article, written for a scientifically-educated, non-specialist reader.

The IRP documents what implementation activities are necessary to fill the knowledge and mitigation gaps associated with each risk listed in the PRD and supported by the Evidence Book. It also details when those activities will be accomplished, where they will be accomplished (for example, the International Space Station or a ground analog), who will accomplish them (investigators within a specific project or organization within the HRP), and what is being produced (risk uncertainty reduction, candidate health or performance standard, countermeasure strategy, etc.). The Human Research Roadmap is the web-based tool for communicating the IRP content.

II. RISKS

The Bioastronautics Roadmap (BR) documents the health and performance risks and areas of concerns of a wide cross-section of the professional space life sciences community, but it does not have the level of detail necessary to prioritize risks across physiological disciplines or to compare strategies for how to manage a given risk across mission operational architectures. In order to identify missing risk details, organize the diverse risk information needed and facilitate mission-focused analysis and communication of risks, the NASA Space Life Sciences Directorate (SLSD) developed the Risk Mitigation Analysis Tool (RMAT). It provides a method to consolidate information such as identified risk and evidence base; the standard level of acceptable risk; likelihood and consequence of risk; current and proposed mitigation strategies for risk; and potential costs and benefits of mitigation strategies for risk. Further, all of the information in the RMAT is provided in the context of specific mission architectures, which vary in duration, degree of autonomy (due to distance from Earth), onboard capabilities, etc. In total, this tool permits analysis of risks in a manner based on evidence and provides a platform for comparison within and between risks.

The HRP 2008 PRD risk list, which has no cross-risk prioritization, was generated from an extensive discipline-by-discipline Program Review of risks held in 2006. This review began with the BR risk list, continued with an extensive assessment of medical observations and research findings, and finally led to the identification of a slightly narrowed and more operationally-focused series of risks and risk factors. During this review, teams of discipline experts analyzed the current evidence for each risk and presented their assessments to HRP management. Each HRP element then evaluated the available information from the discipline teams and determined whether the risks were relatively high priority and operationally relevant. For many risks, the data to generate information regarding the likelihood and consequences of a risk were not yet available. Although probabilistic risk methodology was currently being used to provide this information, most of these analyses had not yet been completed; therefore cross-risk prioritization is not yet possible. However, the HRP expects to have this capability in the near future. As more mission experience and space and ground-based evidence become available, new risks may be identified and added to the PRD, while other risks and contributing factors may be taken off the PRD requirements list. The HRP shall thus periodically review the available evidence and revise the lists of risks and contributing factors in the PRD as appropriate.

III. EVIDENCE BOOK

A. Evolution of the Evidence Book

The original Evidence Book, the 2008 Evidence Book, is a collection of evidence reports created from the information presented verbally and discussed within the NASA HRP in 2006. In April of 2008, the 2008 Evidence Book was reviewed by the members of the Committee on NASA's Research on Human Health Risks, established by the Institute of Medicine (IOM). The resulting thorough Review of NASA's Human Research Program Evidence Books: A Letter Report (2008) provided guidance for both the revision of the current Risk Reports and for the development of future versions. It is publicly available via the National Academies Press website.

As per the recommendations of the IOM Review, risk report information was made publicly available. The method was either to publish the content of selected reports in multiple specialized journals or to publish a subset of the reports in a collection, forming a NASA Special Publication entitled the HRP Evidence Book 2008. The reports revised for presentation in the HRP Evidence Book 2008 incorporate the recommendations from the IOM Review as much as possible. The specialized journal publications containing the evidence report information are being revised and reviewed as per the specifications of the particular journals in which they are to be published.

Since this original publication, the HRP elements continue to update each evidence report given results from ongoing research and technology development tasks. The Human Research Roadmap contains the most up-to-date evidence reports in the above table..

Note that the evidence for two risks, Risk of Reduced Physical Performance Capabilities due to Reduced Aerobic Capacity and Risk of Unnecessary Operational Limitations due to Inaccurate Assessment of Cardiovascular Performance, has been provided in a single evidence report with the overall heading, Risk of Cardiovascular Effects on Performance and Operational Limitations.

B. Spaceflight and Ground-Based Evidence

Each risk report contains a narrative discussion of the risk and its supporting evidence. Every declarative statement concerning the risk is supported by a description of the evidence. All cited publicly-available references are listed at the end of the report. In addition, data that are significant or pivotal are summarized in text, tables, and charts in sufficient detail to allow the reader to critique and draw conclusions. The authors also indicate whether the data are from human, animal, or tissue, cellular, or molecular studies. The reports discuss evidence from both spaceflight (including biomedical research, Medical Requirements Integration Document [MRID] data, and operational performance or clinical observations) and ground (including space analog research and non-space analog biomedical or clinical research). When providing evidence from ground-based studies, authors discuss why these results are likely to be applicable in the space environment, offering any available validation information for the use of these ground-based systems.

C. Categories of Evidence

To help characterize the kind of evidence provided in the reports, authors were encouraged to label evidence according to the "NASA Categories of Evidence." These categories indicate whether data are from two possible types of controlled experiments, are observational, or are expert opinion. As shown below, the NASA categories are compared to a more familiar version of a scale for levels of evidence. The use of a coordinated data categorization system is new to many NASA life scientists, but authors were encouraged to use such a system to help clarify the type of evidence presented and thus provide some additional information about the strength of interpretations derived from those data. They were not required to use the categorization system hierarchically.

D. Computer-Based Simulation Information

Mathematical modeling and computer simulation provide another type of information distinct from experimental evidence, observation, and expert opinion that can support decision making, including the identification of risks. In the evidence reports, authors presented the results of simulations, the types of models used, and the reasoning that supports the acceptance of the modeling and simulation results as valid and appropriate in the situation of interest. Appropriate references to papers or reports describing the types of verification to which models were subjected and the validation methods used were also provided.

E. Risk in Context of Exploration Mission Operational Scenarios

In each evidence-based risk report, the qualitative likelihood and physiological consequences of a risk were presented within the context of a relevant space exploration mission or scenario, such as a short or long mission to the moon or a mission to Mars, and risk factors were discussed. If a risk was due to the possibility of exceeding a current physiological standard during a certain mission scenario, that fact was stated. If the standard existed but was incompatible with the evidence, then the standard was restated in appropriate terms. Alternatively, if a physiological limit was needed but not available, a measure or level beyond which risk was present could be proposed. In any case, a clear rationale for the use of standards or limits in the discussion of likelihood or consequences of a risk during a particular mission scenario was given.