Human Space Travel: Medical Challenges Present and Future

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Human Space Travel Medical Challenges Present
and Future

• Diane Byerly, Ph.D.
• NASA Johnson Space Center
• Houston, TX

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Contributors

• 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.

• 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.

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Space exploration imposes new challenges on
human systems and terrestrial life in general.
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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 (cont)
• 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

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Human Mars Mission Trajectory
Mars Departure Jan. 24, 2022
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Earth Departure Jan. 20, 2020
1
Mars Arrival June 30, 2020
2
4
Earth Arrival June 26, 2022
Earth Orbit Mars Orbit Piloted Trajectories Stay
on Mars Surface
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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.

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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

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What happens to humans in space?

• Early response (lt3 weeks)
• Cephalad fluid shift
• Neurovestibular disturbances
• Sleep disturbances
• Bone demineralization
• Intermediate (3 weeks to 6 months)
• 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

• Long Duration (6 months to 3 years)
• Radiation exposure
• Muscle atrophy
• Cardiovascular deconditioning
• GI disturbances
• Hematological changes
• Declining immunity
• Renal stone risk

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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
• vehicle modifications, including centrifuge
• may require auto-land capability

• Muscle atrophy
• resistive exercise under evaluation

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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)

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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

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Bone Loss in Weightlessness
2 years post-menopause, n13
Space flight
5
(for comparison only)
n22
0
-5
-10
Change from pre-flight ()
-15
-20
?
-25
(months)
6
18
12
24
30
36
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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

m G
1 G
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Countermeasures for bone loss

• Resistive Exercise
• Loading
• Nutrition
• Bisphosphonates

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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

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Physical Challenges
Gravity
Acceleration
Mars Launch TBD g boost phase (min) TEI
(min) 22-24 months 1/3 g to 0 g
Mars Landing 3-5 g aerobraking (min) parachute
braking (30s) powered descent(30s)
Mars Surface 1/3 g 18 months
Earth Launch up to 3 g boost phase (8min) TMI
(min) 0 1 g to 0 g
Earth Landing 3-5 g aerobraking (min)
parachute braking (min) 26-30 months 0 g to
1g
Transit 0 g 4-6 months
Transit 0 g 4-6 months
G-Load Notes Cumulative hypo-g G
transition
4-6 months
0 g to 1/3 g
TMI trans-Mars injection TEI trans-Earth
injection
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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

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Human Behavior and Performance

• Behavior and Performance
• Sleep and circadian rhythm problems
• Poor psychosocial adaptation
• Neurobehavioral dysfunction
• Human-robotic interface
• Episodic cognition problems

• 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)

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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 (?)

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Clinical Problems

• 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

• 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

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Illness and injury during space flight

• 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

• Incidence Common
• (gt50)
• skin rash, irritation
• foreign body
• eye irritation, corneal abrasion
• headache, backache, congestion
• gastrointestinal disturbance
• cut, scrape, bruise
• musculoskeletal strain, sprain
• fatigue, sleep disturbance
• space motion sickness
• post-landing orthostatic intolerance
• post-landing neurovestibular symptoms

Data from R. Billica, Jan. 8, 1998
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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
• Incidence of significant illness or injury is
  0.06 per person- 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 per year

Past Experience
0.06 person/year

• For DRM of 6 crewmembers on a 2½ year mission,
  expect
• 0.9 persons per mission, or one person per
  mission, to require ER capability
• 0.3 persons per mission, or once per three
  missions, to require ICU capability
• 80 require intensive care only 4-5 days
• 20 do not.

Mars DRM
0.90 person/mission
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
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Autonomous Clinical Care

• Crew Health Care Facility
• non-invasive diagnostic capabilities for
  medical/surgical care
• smart systems
• non-invasive 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
  ground-based consultants

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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 capability

• Habitat
• Maintenance/housekeeping
• workshop with HRET capabilities
• Exercise supplemental to Mars surface activities
• Recreation
• Privacy

HRET human-robotic exploration team
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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
• Radiation Effects
• carcinogenesis, CNS damage, fertility, sterility,
  heredity

Environment Technology
Human Behavior Performance

• Human Performance
• psychosocial, workload, sleep

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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
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artwork from Constance Adams and Kris Kennedy for
the JSC TransHab Team
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)
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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

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Bed Rest Studies

• 6o head tilt down
• 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
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NASA Microgravity Analog Cell Culture System
Manufactured by Synthecon, Inc.
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