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Human Research Program Evidence Book

Welcome to the National Aeronautics and Space Administration (NASA)
Human Research Program (HRP) Evidence Book website.

The purpose of the HRP Evidence Book is to present the evidence base for potential astronaut health and performance risks on future exploration missions. The Evidence Book is a tool to communicate the HRP research content within the HRP, between HRP and other NASA programs, and for public knowledge about, and evaluation of, the HRP. Evidence Book website users can link to the evidence, as captured in 2008, for each of the HRP risks listed in the Table of Contents below. The evidence for a given risk is reviewed in evidence reports and journal articles (see newly-added citations and evidence reports).

HRP Evidence Book New!!! The Human Health and Performance Risks for Space Exploration Missions book, a collection of many of the evidence reports, is now available in an electronic .pdf format! Download a copy by clicking this link.

TABLE OF CONTENTS

INTRODUCTION

SENSORIMOTOR

BONE

  • Chapter 3: Risk of Bone Fracture

MUSCLE

EXTRAVEHICULAR ACTIVITIES

CARDIOVASCULAR

NUTRITION

  • Chapter 12: Risk Factor of Inadequate Nutrition

IMMUNOLOGY

BEHAVIORAL HEALTH AND PERFORMANCE

SPACE RADIATION

PHARMACOLOGY

EXPLORATION MEDICAL CAPABILITIES

SPACE HUMAN FACTORS AND HABITABILITY


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INTRODUCTION

I. PURPOSE

The NASA Human Research Program (HRP) Evidence Book is a collection of evidence-based risk reports or cited journal articles for each individual risk contained within the HRP Program Requirements Document (PRD). Thus, the book provides the current record of the state of knowledge from research and operations for each of the defined human health and performance risks for future NASA exploration missions. The evidence reports provide a brief review article containing the evidence related to a specified risk, written at a level appropriate for the scientifically-educated, non-specialist reader. The current HRP Evidence Book, containing information captured in 2008, is on this website.

A. Background

The HRP, within the NASA Exploration Systems Mission Directorate (ESMD), 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 as described in the Vision for Space Exploration, the U.S. National Space Policy and the NASA Strategic Plan. These exploration undertakings include both lunar missions and missions to 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.

B. HRP Core Documents

Three core documents 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, Space Human Factors and Habitability, and Space Radiation. These requirements are derived to satisfy the exploration mission requirements of the ESMD 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, NASA Space Flight Human System Standard - Volume 1: Crew Health and NASA STD-3000, in leiu of Volume II: Habitability and Environmental Health (available in spring 2009)].

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.).

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) has 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.

The identified risks in the 2008 PRD were listed according to the strength of the evidence supporting them. 2008 PRD Table 1 listed the items for which substantial evidence existed; 2008 PRD Table 2 listed items of concern that were deemed not yet supported or refuted by available information (see PRD Tables 1 and 2 below). 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.

PRD 2008 Table 1*
Risks with Substantial Evidence

Risk of Accelerated Osteoporosis
Risk of Orthostatic Intolerance During Re-Exposure to Gravity
Risk of Unnecessary Operational Limitations Due to Inaccurate Assessment of Cardiovascular Performance
Risk Factor of Inadequate Nutrition
Risk Factor of Inadequate Food System
Risk of Inability to Adequately Treat an Ill or Injured Crew Member
Risk of Compromised EVA Performance and Crew Health Due to Inadequate EVA Suit Systems
Risk of Error Due to Inadequate Information
Risk of Behavioral and Psychiatric Conditions
Risk of Performance Errors Due to Sleep Loss, Circadian Desynchronization, Fatigue, and Work Overload
Risk of Radiation Carcinogenesis
Risk of Acute Radiation Syndromes Due to Solar Particle Events
Risk Associated with Poor Task Design
Risk of Impaired Performance Due to Reduced Muscle Mass, Strength and Endurance
Risk of Operational Impact of Prolonged Daily Required Exercise

PRD 2008 Table 2*
Risks Not Yet Fully Supported or Refuted

Risk of Bone Fracture
Risk of Invertebral Disc Damage
Risk of Renal Stone Formation
Risk of Cardiac Rhythm Problems
Risk of Reduced Physical Performance Capabilities Due to Reduced Aerobic Capacity
Risk of Adverse Health Effects from Lunar Dust Exposure
Risk of Crew Adverse Health Event Due to Altered Immune Response
Risk of Impaired Ability to Maintain Control of Vehicles and Other Complex Systems
Risk of Therapeutic Failure Due to Ineffectiveness of Medication
Risk of Performance Errors Due to Poor Team Cohesion and Performance, Inadequate Selection/Team Composition, Inadequate Training, and Poor Psychosocial Adaptation
Risk of Acute or Late Central Nervous System Effects from Radiation Exposure
Risk of Degenerative Tissue or Other Health Effects from Radiation Exposure
Risk of Reduced Safety and Efficiency Due to Poor Human Factors Design

* Source: PRD Rev. B HRP-47052.

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.

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III. EVIDENCE BOOK

A. Evolution of the Evidence Book

The current 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 is being made publicly available. The method is 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.

Individual revised risk evidence reports and cited journal articles have been placed on this website in a format that allows a user to link to the evidence available for each risk. Future generations of the HRP Evidence Book are expected to be maintained on the HRP website in an electronic and rapidly updatable text format that promotes comment to the current evidence content and identification of previously unexplored data or interpretations.

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.

Broad "Experimental" Design Type Silagy & Haines Levels of Evidence* (for comparison only) NASA Categories of Evidence
Controlled Ia. Meta-analysis of randomized trials I. At least one randomized, controlled trial
Ib. At least one randomized trial
IIa. At least one controlled study without randomization II. At least one controlled study without randomization, including cohort, case-control, or subject operating as own control
IIb. At least one other type quasi-experimental study
Observational III. Non-experimental descriptive studies, e.g. comparitive correlation, or case studies III. Non-experimental observations or comparitive, correlation, and case or case-series studies
Opinion IV. Expert committee reports or opinions or clinical experiences of respected authorities IV. Expert committee reports or opinions of respected authorities based on clinical experiences bench research, or "first principles"

*Source: Silagy C, Haines A. Evidence Based Practice in Primary Care, 2nd ed., London: BMJ Books, 2001.

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.

IV. ACRONYM LIST

  • BR - Bioastronautics Roadmap
  • ESMD - Exploration Systems Missions Directorate
  • HRP - Human Research Program
  • IRP - Integrated Research Plan
  • MRID - Medical Requirements Integration Document
  • NASA - National Aeronautics and Space Administration
  • OCHMO - Office of the Chief Health and Medical Officer
  • PRD - Program Requirements Document
  • RMAT - Risk Management Analysis Tool
  • SLSD - Space Life Sciences Directorate

Contact Us

We would like your feedback to make this online Evidence Book better. Please CLICK HERE and fill out the form to submit your suggestions or comments about the web site structure or utility of the content.

 

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Last Updated: 2/5/10 3:15 PM