Human Space Travel: Medical Challenges Present and Future Diane Byerly, Ph.D. NASA Johnson Space Center Houston, TX Contributors • • • • • • • • • • • Neal Pellis, Ph.D. Marguerite Sognier, Ph.D. Diana Risin, MD., Ph.D. Lalita Sundaresan, Ph.D. Thomas Goodwin, Ph.D. Steve Gonda, Ph.D. Dennis Morrison, Ph.D. Diane Byerly, Ph.D. Mark Clarke, Ph.D. John Charles, Ph.D. Tacey Baker, M.S. • J. Milburn Jessup, MD. • Gordana Vunjak-Novakovoc, Ph.D. • Lisa Freed, M.D., Ph.D. • Robert Akins, Ph.D. • Timothy Hammond, M.D. • Lelund Chung, Ph.D. • Anil Kulkarni, Ph.D. • Arthur Sytkowski, M.D. Space exploration imposes new challenges on human systems and terrestrial life in general. Challenges • Present – Orbital Missions • • • • Known medical risks Communications Access to Earth Minimum autonomy • Future – Moon (Short duration) • Mostly known medical risks • Communications • 2-3 day to access Earth facilities • Greater autonomy necessary • Future (con’t) – Moon (Long duration) • Many known medical risks, others unknown but anticipated • Communication • 2-3 day to access Earth facilities • Greater autonomy necessary – Mars • Many medical risks (known, unknown, unanticipated) • Communications difficult • Probably no access to Earth facilities • Autonomous medical care absolutely required Human Mars Mission Trajectory Flight Profile Mars Departure Jan. 24, 2022 Transit out: 161 days Mars surface stay: 573 days Return: 154 days 3 1 Mars Arrival June 30, 2020 2 4 Earth Arrival June 26, 2022 Earth Orbit Mars Orbit Piloted Trajectories Stay on Mars Surface Earth Departure Jan. 20, 2020 Physical factors that influence nature • Life evolved on earth while the force of gravity has been constant for 4.8 billion years. • Therefore, there is little or no genetic memory of life responding to gravitational force changes. • As we transition terrestrial life to low gravity environments and study the adaptive processes in cells, our understanding of the role of gravity in shaping evolution on Earth will increase. • The response of higher organisms to this ‘new’ environment may be less ordered than the response to say, thermal change. Risks to Humans in Microgravity • • • • • • • • • • • • • Exposure to ionizing radiation Bone density decrease Muscle Atrophy Cardiovascular Deconditioning Psychosocial impacts Fluid Shifting Vestibular Dysfunction Hematological changes Immune Dysfunction Delayed wound healing Gastrointestinal Distress Orthostatic Intolerance Renal stones What happens to humans in space? • Early response (<3 weeks) – – – – • Intermediate (3 weeks to 6 months) – – – – – – • Cephalad fluid shift Neurovestibular disturbances Sleep disturbances Bone demineralization Radiation exposure Bone resorption Muscle atrophy Cardiovascular deconditioning GI disturbances Hematological changes Long Duration (6 months to 3 years) – – – – – – Radiation exposure Muscle atrophy Cardiovascular deconditioning GI disturbances Hematological changes Declining immunity • Long Duration (6 months to 3 years) – – – – – – – Radiation exposure Muscle atrophy Cardiovascular deconditioning GI disturbances Hematological changes Declining immunity Renal stone risk Impacts of Extended Weightlessness Physical tolerance of stresses during aerobraking, landing, and launch phases, and strenuous surface activities Bone loss no documented end-point or adapted state countermeasures in work on ground but not yet flight tested Cardiovascular alterations pharmacological treatments for autonomic insufficiency Neurovestibular adaptations Muscle atrophy resistive exercise under evaluation vehicle modifications, including centrifuge may require auto-land capability Radiation • Different from ionizing radiations on Earth • Two types – Galactic cosmic radiation (GCR) dominated by neutrons – Solar particle events (SPE)- sun storms dominated by protons • Earth is protected by the magnetosphere (van Allen Belt) Radiation Issue: Radiation Environment • Attenuation of GCR and SPE by atmosphere and bulk of planet • Possible risk from neutron backscatter from surface • TBD shielding for vehicle and habitat • Shielding high energy particles is difficult Radiation effects (possible synergy with hypogravity and other environmental factors) • Early or Acute Effects from Radiation Exposure (esp. damage to Central Nervous System) • Carcinogenesis Caused by Radiation • Immune system compromises Bone Loss in Weightlessness Change from pre-flight (%) 5 2 years post-menopause, n=13 (for comparison only) Space flight n=22 0 -5 -10 -15 -20 ? -25 (months) 6 12 18 24 30 36 Causes of bone loss • No load because of low gravity • Poor muscle performance • Metabolic and hormonal changes • Fluid dynamic changes in the bone marrow sinusoids – Decreased hydrodynamic shear – Loss of hydrostatic pressure gradient 1G mG Countermeasures for bone loss • • • • Resistive Exercise Loading Nutrition Bisphosphonates Muscle • Disuse Atrophy – Most locomotion achieved with the upper body – No load – No position based use and deployment of muscle activity akin to 1G environment – Unusual uses of selected muscle groups • Countermeasures – Exercise, exercise, exercise – Before, during, and after the mission Physical Challenges Gravity G-Load Earth Launch up to 3 g Transit Mars Landing Mars Surface Mars Launch Transit Earth Landing 0g 3-5 g 1/3 g TBD g 0g 3-5 g boost phase 4-6 (8min); months TMI (min) Notes Acceleration 18 aerobraking months (min); parachute braking (30s); powered descent(30s) 4-6 aerobraking boost phase months (min); (min); parachute TEI (min) braking (min) Cumulative hypo-g 0 4-6 months 22-24 months 26-30 months G transition 1 g to 0 g 0 g to 1/3 g 1/3 g to 0 g 0 g to 1g TMI: trans-Mars injection TEI: trans-Earth injection Transitions in G levels Physical tolerance of stresses during aerobraking, landing, and launch phases, and strenuous surface activities • Musculo-skeletal atrophy – Inability to perform tasks due to loss of skeletal muscle mass, strength, and/or endurance – Injury of muscle, bone, and connective tissue – Fracture and impaired fracture healing – Renal stone formation • Cardiovascular alterations – Manifestation of serious cardiac dysrhythmias and latent disease – Impaired cardiovascular response to orthostatic stress and to exercise stress • Neurovestibular alterations – Disorientation – Impaired coordination – Impaired cognition Human Behavior and Performance Issues: •Small group size •Multi-cultural composition •Extended duration •Remote location •High autonomy •High risk (to health and mission) •High visibility (e.g., high pressure to succeed) Behavior and Performance • Sleep and circadian rhythm problems • Poor psychosocial adaptation • Neurobehavioral dysfunction • Human-robotic interface • Episodic cognition problems Human Behavior and Performance • Human intrinsic rhythm = 24.1 + 0.15 hr – synchronization not assured – may require (chronic) intervention? • Synchronization successful (best case): Unknown efficacy in maintaining circadian health – Daylight EVA ops: safety, efficiency – Complicated Earth-based support • Failure to synchronize (worst case): – Crew awake during Mars night every 41 days (40 sols) • Well-rested “night-time” ops vs. fatigued daylight ops • Limited visibility: increased risk of accident, trauma – Radiation minimized: reduced SPE influence at night (?) Clinical Problems Medical care systems for prevention, diagnosis or treatment – Difficulty of rehabilitation following landing – Trauma and acute medical problems – Illness and ambulatory health problems – Altered pharmacodynamics and adverse drug reaction • Expected illnesses and problems – Orthopedic and musculoskeletal problems (esp. in hypogravity) – Infectious, hematological, and immune-related diseases – Dermatological, ophthalmologic, and ENT problems • Acute medical emergencies – Wounds, lacerations, and burns – Toxic exposure and acute anaphylaxis – Acute radiation illness –Development and treatment of decompression sickness – Dental, ophthalmologic, and psychiatric • Chronic diseases – Radiation-induced problems – Responses to dust exposure – Presentation or acute manifestation of nascent illness Illness and injury during space flight Incidence Common (>50%) skin rash, irritation foreign body eye irritation, corneal abrasion headache, backache, congestion gastrointestinal Conceptualization of crew disturbance healthcare & exercise cut, scrape, bruise facilities musculoskeletal strain, sprain fatigue, sleep disturbance space motion sickness post-landing orthostatic intolerance post-landing neurovestibular symptoms Data from R. Billica, Jan. 8, 1998 Incidence Uncertain infectious disease cardiac dysrhythmia, trauma, burn toxic exposure psychological stress, illness kidney stones pneumonitis urinary tract infection spinal disc disease unplanned radiation exposure Projected Rates of Illness or Injury Based on U.S. and Russian space flight data, U.S. astronaut longitudinal data, and submarine, Antarctic winter-over, and military aviation experience: Past Incidence of significant illness or injury is 0.06 per personExperience year as defined by U.S. standards requiring emergency room (ER) visit or hospital admission Subset requiring intensive care (ICU) support is 0.02 person 0.06 person/year per year For DRM of 6 crewmembers on a 2½ year mission, expect: 0.9 persons per mission, or ~one person per mission, Mars DRM to require ER capability 0.3 persons per mission, or ~once per three missions, to require ICU capability 0.90 person/mission ~80% require intensive care only 4-5 days ~20% do not. Note: Decreased productivity, increased risk while crew reduced by 1-2 (including care-giver) Data from R. Billica, January 1998, and D. Hamilton, June 1998 Autonomous Clinical Care Crew Health Care Facility non-invasive diagnostic capabilities for medical/surgical care “smart” non-invasive systems imaging systems definitive surgical therapy including robotic surgical assist devices and surgical simulators blood replacement therapy laboratory support Telemedicine preventive health care diagnostic/therapeutic capabilities from groundbased consultants Mars Surface Stay Requirements Autonomous facilities Crew health care Radiation Protection Medical Surgical care Nutrition - Food Supply Psychological support meaningful work surface – – science planetary biomedical simulations of Mars launch, trans-Earth injection, and contingencies progressive debriefs, sample processing, etc. housekeeping communications HRET: human-robotic exploration team capability Habitat Maintenance/housekeeping – workshop with HRET capabilities Exercise supplemental to Mars surface activities Recreation Privacy Risk Elements & Categories Space Medicine in-flight debilitation, long-term failure to recover, clinical capabilities, and skill retention Medical Care Advanced Life Support atmosphere, water, thermal control, logistics, waste disposal Environmental Health atmosphere, water, contaminants Planetary Extra-Vehicular Activity dust, suit design, serviceability Environment & Technology Radiation Effects carcinogenesis, CNS damage, fertility, sterility, heredity Human Performance psychosocial, workload, sleep Human Behavior & Performanc e Human Health & P erformance Risk Elements & Categories Bone Loss fractures, renal stones, osteoporosis, drug reactions Cardiovascular Alterations dysrhythmias, orthostatic intolerance, exercise capacity Food and Nutrition malnutrition, food spoilage Immunology & Hematology infection, carcinogenesis, wound healing, allergens, hemodynamics Muscle Alteration mass, strength, endurance, and atrophy Neurovestibular Adaptations monitoring and perception errors, postural instability, gaze deficits, fatigue, loss of motivation and concentration Human Health/ Physiology Human Health & P erformance Mars Transit Requirements Facilities must be mostly autonomous (one-way Earth-Mars communications time is 3-22 min.) Health care functions Nutrition Exercise Psychological support planned activities entry/landing simulations housekeeping refresher training cruise science (rover operations/site preparation, microgravity, astronomy, and biomedicine) communications reliable contact with mission control, family, & friends Health Care autonomous care telemedicine Habitat facilities Exercise & conditioning for Mars surface activities Recreation & privacy Maintenance & housekeeping (including workshop) artwork from Constance Adams and Kris Kennedy for the JSC TransHab Team Conclusions Mars Design Reference Mission requires novel technologies that allow human adaptation to: interplanetary space travel planetary habitation The medical and physiological challenges associated with interplanetary space travel will depend upon mission duration propulsion system The integration of human and robotic activities will be a critical determinant of the success of planetary exploration • 6o head tilt down Bed Rest Studies • Remain in bed continually for various time intervals; i.e., 60 days • Mimics many alterations that occur in microgravity due to fluid shift to head and lack of weight bearing lower limbs; i.e., bone loss & muscle atrophy •Often involved in countermeasure testing ESA, WISE NASA Microgravity Analog Cell Culture System Manufactured by Synthecon, Inc.
