June 21, 2011 Space Weather Enterprise Forum Human Safety and Response Preparedness John R. Allen, PhD NASA Headquarters Space Operations Mission Directorate

NASA Is Concerned With Two Main Types Of Radiation Risk: Short-term consequences of relatively high levels of radiation, Short-term consequences of relatively high levels of radiation, Caused by a Solar Particle Event (SPE), Caused by a Solar Particle Event (SPE), Repeated exposure during passage of the South Atlantic Anomaly Repeated exposure during passage of the South Atlantic Anomaly Radiation risk is mainly due to cell depletion of sensitive tissues: Radiation risk is mainly due to cell depletion of sensitive tissues: bone marrow, bone marrow, intestinal epithelium, intestinal epithelium, skin, etc. skin, etc. May lead to conditions affecting crew health and performance May lead to conditions affecting crew health and performance Long-term exposure to expected levels of solar and galactic cosmic radiation Long-term exposure to expected levels of solar and galactic cosmic radiation Enhanced probability of cancer Enhanced probability of cancer Possibly changes in the cells of the brain, reproductive organs, other tissues. Possibly changes in the cells of the brain, reproductive organs, other tissues.

South Atlantic Anomaly Double Strand Breaks

Basis of a Radiation Protection Program Principles of Radiation Protection: Principles of Radiation Protection: Define risks Define risks Define acceptable levels, leading to exposure limits Define acceptable levels, leading to exposure limits Justify activity involving radiation exposures in terms of benefits to society Justify activity involving radiation exposures in terms of benefits to society As Low As Reasonably Achievable (ALARA) requirement As Low As Reasonably Achievable (ALARA) requirement Implementation Implementation Establish risk projection methods and limits Establish risk projection methods and limits Train workers and specialists Train workers and specialists Dosimetry Dosimetry Maintaining records Maintaining records ALARA documentation ALARA documentation

ALARA The population involved in space activities is of limited size; thus, genetic effects would not play a role. The population involved in space activities is of limited size; thus, genetic effects would not play a role. The benefit of space flight exceeds substantially the risk. The benefit of space flight exceeds substantially the risk. Radiation hazards analysis conducted before each mission. Radiation hazards analysis conducted before each mission. Radiation exposure monitored by individual/area dosimeters Radiation exposure monitored by individual/area dosimeters Records of radiation exposures maintained (including those from medical procedures). Records of radiation exposures maintained (including those from medical procedures). Formal protocols, including the use of calibrated active and passive measurement radiation systems, Formal protocols, including the use of calibrated active and passive measurement radiation systems, Flight rules covering any radiation exposure contingency have been developed and documented. Flight rules covering any radiation exposure contingency have been developed and documented.

Radiation Protection Standards Ground-based Regulations Inappropriate Ground-based Regulations Inappropriate Permissible Exposure Levels (PELs) - NASA Space Flight Human System Standard – Volume 1 Crew Health Permissible Exposure Levels (PELs) - NASA Space Flight Human System Standard – Volume 1 Crew Health Reviewed by National Council on Radiation Protection and Measurements (NCRP Reports No. 132, No. 137, No. 142) Reviewed by National Council on Radiation Protection and Measurements (NCRP Reports No. 132, No. 137, No. 142) Space Permissible Exposure Limits Space Permissible Exposure Limits “…primary functions of preventing in-flight risks that jeopardize mission success and limiting chronic risks to acceptable levels based on legal, ethical or moral, and financial considerations.”

Mitigation of Risk Use of countermeasures Use of countermeasures Five approaches of which only the first two are currently practical Five approaches of which only the first two are currently practical Operational Operational Shielding Shielding Screening Screening Prevention Prevention Intervention Intervention

Operational Countermeasures Limitation of exposure and resultant risk through: Limitation of exposure and resultant risk through: Projection of mission radiation exposure and risk Projection of mission radiation exposure and risk Space Radiation Analysis Group Space Radiation Analysis Group Radiation Health Office Radiation Health Office Selection of older crew members Selection of older crew members Avoiding EVAs during passage through the SAA Avoiding EVAs during passage through the SAA Using spacecraft transfer trajectories that minimize the duration of interplanetary travel Using spacecraft transfer trajectories that minimize the duration of interplanetary travel

Shielding Countermeasures Earth’s magnetic field is protective in LEO Earth’s magnetic field is protective in LEO Estimates of GCR within 15% Estimates of GCR within 15% Shielding materials have been tested on ISS Shielding materials have been tested on ISS Computational tools have been developed to estimate interaction of radiation with materials Computational tools have been developed to estimate interaction of radiation with materials Standard approach for estimating shielding for spacecraft Standard approach for estimating shielding for spacecraft Computational models validated with dosimetry Computational models validated with dosimetry Personnel dosimetry worn by crew Personnel dosimetry worn by crew Detectors mounted internal and external to the spacecraft Detectors mounted internal and external to the spacecraft CAD Model of US Lab Radiation Area Monitor & ISS Tissue Equivalent Proportional Counter

Other Countermeasures Screening: Potential methods to screen for a genetic predisposition that results in an increased susceptibility or resistance to radiation Screening: Potential methods to screen for a genetic predisposition that results in an increased susceptibility or resistance to radiation Prevention: Development of pharmaceuticals that can be used as radioprotectants and genetic methods to enhance an organism’s ability to repair damage Prevention: Development of pharmaceuticals that can be used as radioprotectants and genetic methods to enhance an organism’s ability to repair damage Intervention: Interventions may be required to address acute radiation effects resulting from solar particle events. Biological interventions such as gene therapy methods to enhance cell repair or apotosis may be possible in the future. Intervention: Interventions may be required to address acute radiation effects resulting from solar particle events. Biological interventions such as gene therapy methods to enhance cell repair or apotosis may be possible in the future.

Missions Beyond Low Earth Orbit Significant risk to crew and mission from space radiation Significant risk to crew and mission from space radiation No geomagnetic protection No geomagnetic protection Space weather events Space weather events Mission durations Mission durations ~x10 compared to ISS ~x10 compared to ISS Determination of an acceptable level of risk for exploration underway Determination of an acceptable level of risk for exploration underway NASA has chartered reviews by the NCRP NASA has chartered reviews by the NCRP NCRP Information Needed to Make Radiation Protection Recommendations for Space Missions Beyond Low-Earth Orbit NCRP Information Needed to Make Radiation Protection Recommendations for Space Missions Beyond Low-Earth Orbit SC 1-13: Impact of Individual Susceptibility and Previous Radiation Exposure on Radiation Risk for Astronauts SC 1-13: Impact of Individual Susceptibility and Previous Radiation Exposure on Radiation Risk for Astronauts SC 1-15: Radiation Protection and Science Goals for Short-Term Lunar Missions SC 1-15: Radiation Protection and Science Goals for Short-Term Lunar Missions

Information Needed as published in NCRP 153 Space Radiation Environment Space Radiation Environment Develop SPE forecasting and prediction capabilities Develop SPE forecasting and prediction capabilities Develop realistic models of the largest expected SPE fluence rates Develop realistic models of the largest expected SPE fluence rates Continue to improve the GCR environmental models used for risk assessment Continue to improve the GCR environmental models used for risk assessment Space Radiation Physics and Transport Space Radiation Physics and Transport Develop and validate space radiation transport codes Develop and validate space radiation transport codes Improve existing nuclear interaction databases Improve existing nuclear interaction databases

Information Needed (Cont.) Space Dosimetry Space Dosimetry Develop, certify and fly reliable rugged monitoring equipment Develop, certify and fly reliable rugged monitoring equipment Improve neutron spectrometers Improve neutron spectrometers Validation of transport and dosimetry models Validation of transport and dosimetry models Improved understanding of Tissue Equivalent Proportional Counter (TEPC) response Improved understanding of Tissue Equivalent Proportional Counter (TEPC) response Measures radiation dose and dose equivalent in fields containing a mixture of particle types Measures radiation dose and dose equivalent in fields containing a mixture of particle types Improved organ dose assessment Improved organ dose assessment TEPC

Information Needed (Cont.) Space Radiation Biology Space Radiation Biology Late radiation effects (cancer/non-cancer) Late radiation effects (cancer/non-cancer) Early radiation effects Early radiation effects Thresholds for neurovestibular, cardiac, prodromal and other CNS efffects Thresholds for neurovestibular, cardiac, prodromal and other CNS efffects Hematological, dermal and immune issues Hematological, dermal and immune issues Dose rate effects Dose rate effects Countermeasure development Countermeasure development Goal: Improved Risk Assessment Model → Acceptable Level of Risk

Designing Vehicles with Current Knowledge Communicating importance of radiation protection Communicating importance of radiation protection Radiation System – part of Vehicle Integration Office – Spacecraft Design Radiation System – part of Vehicle Integration Office – Spacecraft Design Allocation of PELs to vehicle design Allocation of PELs to vehicle design Human System Integration Standards Human System Integration Standards Currently a “work in progress” Currently a “work in progress” Flexibility in the future will be required Flexibility in the future will be required

Design and Response Operations The best opportunity for implementing ALARA inside vehicles and habitats is during the design process The best opportunity for implementing ALARA inside vehicles and habitats is during the design process Mass/volume penalty Mass/volume penalty GCR difficult if not impossible to shield GCR difficult if not impossible to shield Design Design Use of physics codes to model vehicle Use of physics codes to model vehicle Multi-use materials and geometry optimization Multi-use materials and geometry optimization Radiation protection as design element Radiation protection as design element Provide baseline shelter Provide baseline shelter Operations Operations Concept of Operations development ongoing Concept of Operations development ongoing Risk minimization Risk minimization Mission flexibility Mission flexibility “Worst Case” “Worst Case” Courtesy of the Space Radiation Analysis Group

Implications for Commercial Ventures Same concerns and planning as NASA Same concerns and planning as NASA Mission length, destination, exposure, shielding, craft design, monitoring, PREDICTION, etc. Mission length, destination, exposure, shielding, craft design, monitoring, PREDICTION, etc. Duration and destination may be different – initially Duration and destination may be different – initially Participants vs Crewmembers Participants vs Crewmembers Frequency of exposure Frequency of exposure Commercial Aerospace Commercial Aerospace Polar routes Polar routes

Questions ?