A Mars Mission Simulation to Determine the Efficacy of 0.38 G as a by nyut545e2

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									    A Mars Mission Simulation to
  Determine the Efficacy of 0.38 G
as a Countermeasure to Microgravity




                 Or…….
Lawrence Kuznetz, PhD, USRA
Lanny Rudner, MD, Baylor College of Medicine
Roger Kram, PhD, University of Colorado
                      Mars Mission Gravity Profile

                                  M ars M issio n G ravity P rofile S chem atic
                  8
                                     c
                  6
g- L o a d in g




                  4
                                                                                 f
                                                                    e
                          a
                  2                           Mars…..0.38 G
                          Zero G                          d             Zero G
                              b                                           b
                  0
                      0               6         12         18        24     30
                                          M issio n E lap sed T im e (M onths)
                   Artificial Gravity Systems




                              Rotate the person in the spacecraft
Rotate the Spacecraft




          Rotate the person while asleep in the spacecraft
              Issues with these techniques
•   Rotating Spacecraft
     – Complexity
     – Cost
     – Safety
         • Spinup
         • Spindown
         • EVA
         • Correolis forces
•   Rotating Countermeasure Device (UTMB)
     – Duty Cycle, ie duration and magnitude of G exposure
     – Vibration Isolation
     – Correolis forces
•   Rotating Bed
     – Same as above
     – Will anyone sleep on a rotating bed for 6 months?
Are we really asking the right question ?
 • These systems are designed for the transit
    – Conjunction class mission
       • Outbound transit = 6 months maximum
       • Mars surface stay time = 18 months at 0.38 G
       • Inbound transit = 6 months maximum
 • We’ve done 6 months in zero G many times
    – ISS, Mir experience
       • Minor , not major problems are the rule
    – Countermeasures largely successful
       • Exercise
       • Pharmacokinetics
       • G suit, LBNP, Penguin suit, etc
 • Bottom Line:
    – AG probably not needed for transits
     What is the right question?
• What happens on Mars?
   – Will it help, hinder or maintain homeostasis


 Asked anotber way, is Mars

• Hostile (H1)
• Habitable (H2), or
• Hospitable (H3)
Atmospheric Composition
                    H1, H2




                          H1
                          H2
                          H2


                          H2
     Soil composition                     H3
•   49.5% SiO2                  50
•   16 % FeO                    45
•   8.5 % Al2O3                 40
•   7.7 % MgO                   35
                                30
•   6.5 % CaO                                          %
                                25
•   5.5 % SO3                                          makeup
                                20
•   2.3 % Na20                  15
•   1.2 % TiO2                  10
                                 5
•   0.6 % Cl
                                 0
•   0.3 % K2O

Unlike the air, the soil is similar to Earths, probably formed
 from the weathering of rocks by flowing water or seas that
existed on early Mars.
H2


???

H2


H2, H1
    Overview of Experiment
• Problem Statement: Is 0.38G = H1, H2 or H3
  – Does gravity on Mars help, hinder or maintain homeostasis?
• Hypothesis
  – Bone loss is the primary issue
  – If Bone loss can be stopped, gravity becomes a non issue
     • Artificial G in transit or on the surface is not necessary
• Design an experiment to test the above
                Bone Loss:
       The Potential “Show-Stopper”


• Skylab/Shuttle-
  Mir/ISS
• Bedrest
          The latest bone loss data
           N = 16 ISS crew subjects*
• Spine
  – Trabecular bone loss average = 0.8% month
  – DEXA spine loss average = 1%
• Hip
  – DEXA 1.1 -1.5 % month
  – QCT trabecular 2.5 – 2.7 %**

**Extrapolated to a Mars Mission = 16% for each transit in zero G,
                  and ?? % loss at Mars 0.38G))
  *Courtesy, Thomas Lang, PI, UCSF
     Implications of Bone Loss
• Increased risk of fracture
• Affects crew health and safety
• May affect mission success



•Conclusion:
         Knowledge of bone loss on Mars
          is critical for mission planning
      Experiment Assumptions
• Bone loss occurs primarily due to a lack of
  mechanical stress placed on the longitudinal
  skeleton
• Modeling reduced bone loading should
  model bone changes in 0.38 G
       Experiment Guidelines
• The effects of microgravity on bone are
  well-documented
  – corresponds to outbound and inbound legs of
    Mars mission
• The effects of Mars gravity (0.38 G) on
  bone have not been documented
  – must be known in order to make
    countermeasure prescriptions for Mars mission
       Bone loss for a Mars Mission:
           Possible Outcomes
                Mission Elapsed Time (Months)
 0              6    10.5    15    19.5   24                              30
                                                                               0.5
                                    1G Baseline
                                                                               0
                             H3




                                                                                      BMD (T-Score)
                                                                    Inbound
                                                                               -0.5
     Outbound                         Surface Stay
                                                          H2                   -1
                                                                               -1.5
                 Clinical Threshold (4 x normal risk of fracture)
                                                                               -2
                 (WHO standard, healthy 30 yr old population)                  -2.5
                                                                               -3
                                                            H1                 -3.5
                                                                               -4
Conjunction class mission: 6 month transits, 18 months on surface
                          The Experiment---
                  Simulate this and see what happens
                                  M ars M issio n G ravity P rofile S chem atic
                  8
                                     c
                  6
g- L o a d in g




                  4
                                                                                 f
                                                                    e
                          a
                  2                           Mars…..0.38 G
                          Zero G                          d             Zero G
                              b                                           b
                  0
                      0               6         12         18        24     30
                                          M issio n E lap sed T im e (M onths)
            The Challenge
How do you simulate a Mars Mission on Earth?

 Step 1. Start with the tasks and activities
 Step 2. Reproduce the daily timeline
 Step 3. Model the postures and loadings
 Step 4. Design a facility to impose those loadings
 Step 5. Run the experiment until trends evolve
Step 1. Tasks and Activities
EVA Exploration
Maintenance and Construction
Geology and Science
IVA tasks
    Step 2: Reproduce the Daily Timeline
          Simulating Mars on Earth
                Sample Daily Schedules
•EVA Hours         Table:Mars Activity Schedule - for EVA crew
Determine          Event                      Location   Total Time (hours)
Schedule           Sleep                      Habitat             8
                   Meals                      Habitat             2
• 3 Schedule       EVA Prep                   Habitat             2
                   Meals                      Surface            0.5
Types              Rest                       Surface            0.5
                   Exobiology, Geology, or    Surface             7
                   Construction EVA
   •EVA            Recreation                 Habitat             2
                   Exercise                   Habitat             1
   •EVA-           Data Management,
                   Tracking, Communications
                                              Habitat             0

   Monitoring      Overhead                   Habitat             1


   •Non-EVA
Step 3. Model the Postures and Loadings
      Simulating Mars on Earth
          Categorizing Activities
                    Table: Earth Analogs for Mars
• Posture and       Activities
  Loading Profile   Mars Activity    Posture

                    Sleep            horizontal
                    Meals            sitting
                    Computer work    sitting
                    Science          sitting or standing
                    Maintenance      walking
                    EVA              combination
                    Exercise         combination
                    Overhead         combination
   Simulating Mars on Earth
Posture and Loading Candidates
Sleep -- Bedrest
Meals and Computer Work:
  Seated Weight Relief
Science – Standing Weight Relief
Supine Exercise
Surface EVA
EVA Simulation Methods




              Suspension
EVA -- Horizontal Suspension
EVA – Neutral Buoyancy
Methods of Simulating Postures on Mars
            Pros and Cons
Simulation Methods    Pros                                           Cons
lower body positive   -simulates different levels of bone loading    -limited mobility
pressure              -can be used in conjunction with a treadmill   -cannot be used to
                                                                     simulate sitting
                                                                     position
tilt table            -models gravitational acceleration in the      -limited mobility
                      longitudinal direction                         -limited variety
centrifugation        -mimics gravitational force with centripetal   -subjects cannot
                      force                                          perform activities
submersion            -uses buoyancy, ballast is used to simulate    -limited duration
                      different levels of gravitational pull
                      -can use underwater treadmills
                      -can perform seated and standing activities
parabolic flight      -simulates microgravity                        -short duration
                                                                     simulation
suspension            -unloads skeletal system via a harness
                      attached at the waist
                      -mobility with overhead rail system
                      -can simulate seated position
      Selected Modalities
    Simulating Mars on Earth
       Weight Relief Simulators




                Meals, Maintenance,
Overhead        Science               EVA - 1
Simulating Mars on Earth




  Work Station        Sleep Station
EVA – Trolley Suspension, NBL
  Validity of Simulators
Modeling Human Skeletal System




      z
                   1.)hip
                   2.)femur
          y        3.)knee
                   4.)tibia,
  x                   fibula
                   5.)ankle
Load (% of Body Weight)
                          Validity of Simulators - Sitting
                          30%               Sitting in 1 G
                          25%
                                            Sitting in 0.38 G
                          20%
                                            Seated Weight
                          15%               Relief

                          10%

                          5%

                          0%
                                Fz         Fx     Fz         Fz     Fx     Fz       Fz       Fx
                                     Hip        |Thigh I          Knee   | Shin |    Ankle        .
                                                       Load Location
                          Validity of Simulators - Standing
                          50%
                                Standing in 1 G
                          45%   Tilt Table
Load (% of Body Weight)




                          40%   Standing in 0.38 G
                          35%   Weight Relief

                          30%
                          25%
                          20%
                          15%
                          10%
                          5%
                          0%
                                Fz      Fx       Fz        Fz          Fx      Fz        Fz      Fx
                                       Hip     I Thigh I        Knee        I Shin   I   Ankle
                                                       Location of Load
          Simulating Mars on Earth
  Selected Postures, Activities and Simulators
Table: Earth Analogs for Mars Activities

Mars Activity     Posture               Method of Simulation on Earth

Sleep             horizontal            Bed rest
Meals             sitting               Sitting weight relief
Computer work     sitting               Sitting weight relief
Science           sitting or standing   Tilt table and/or Sitting weight relief
Maintenance       walking               Track weight relief
EVA               walking               Trolley standing weight relief
Exercise          combination           Exercise station
Overhead          combination           Combination of above
 Step 4. Design a facility to impose
      the postures and loadings

• Outbound leg transit simulation
• Mars G surface simulation
• Inbound leg return transit simulation
                Possible venues
• Shuttle + ISS + 0.38 G Simulation Facility
• Bedrest + 0.38 G Simulation Facility

     What is this 0.38G Simulation Facility ???
Integrity
Integrity Schematic
            Integrity Schematic



                                  Exercise
                                  and Data
                                  Collection
                                  Lab
                                  To EVA
Sleep and
                                  Practice
Commons
                                  Sites
Area
                                  Overhead
Exercise Pool for EVA simulation

Pool for EVA
Rockpile/Workstations for Traverse Simulations

          Geology Traverse
     Benefits of Multi-Station
            Approach
• More Accurate Simulation
• Psychological Benefits
  – Antarctic Experiences
  – Task Performance and Skills Retention Testing
• Subject Comfort
• Long-Duration Testing
            Piggyback Benefits
• Add-on experiments can be run concurrently
  –   Nutrition
  –   Vitamin D and UV
  –   Psychosocial Interactions
  –   others
      Benefits of Using Integrity
           Things You Don’t Need
•   Life Support Systems
•   Pressurized Suits
•   Big Monitoring Crew
•   Thermal Vacuum Chamber
•   Controlled Mars or Thermal Environment
     Benefits of Using Integrity
              Things You Do Need
• Extended Period of Time for Testing
• Pre-Test Protocol of Simulated or Actual
  Microgravity Exposure (Spaceflight or Bedrest)
• Crew of Returning ISS Astronauts or Bedrest
  Subjects
• Work Stations
• Monitoring Personnel
   – Medical, Engineering, Test Management
• Consumables, Equipment, Etc.
          Benefits of Using Integrity
            Integrity vs. “One Can” Design
   • Large Living/                 • Small Living Space
     Simulation Space
                                   • Conditions dictate shorter
   • Allows for Long                 duration studies
     Duration Studies
                                   • Closed Setting
   • Open Setting*


*Depending on time to impact clinical horizon and transport time,
subjects may be permitted to sleep at home to simulate sleep on Mars
(i.e. normal work day)
Step 5: Run the Experiment
Experiment will be run in 3 phases

1.) O.38 G Simulation for 17 weeks
  – Effect relative to 1 G and bedrest
2.) Bedrest then 0.38 G simulation
  – Recovery Period
3.) ISS Stay then 0.38 G simulation
  – Best Mars mission simulation
  – Continue experiment until data trends stabilize
Primary Objective: determine the trend
                 (run as long as it takes)
                 Mission Elapsed Time (Months)
  0              6    10.5    15    19.5   24          30
                                                            0.5
                           1G Baseline
                                                            0




                                                                   BMD (T-Score)
      Outbound                               Inbound        -0.5
                             Surface Stay
                                                            -1
                                                            -1.5
                                                            -2
             Clinical Threshold
                                                            -2.5
                                                            -3
                                                            -3.5
                                                            -4
Biological Data Collection
•   Bone Markers
•   DEXA + MRI
•   EKG
•   VO2 max
•   Neurological Function
•   Psychological Health
•   Etc.
         Metabolic load profile
Impose Metabolic Expenditures for each activity

  • Metabolic Rates at Mars G
    – Average data from 1 G and 1/6 G EVA’s
    – POGO Walkback test series at Mars G
    – NBL, NEEMO data for Mars G
                    Data
          Data Collection/Analysis

• Plot Data Against Mission Timeline
• Maintain Subject Safety
• Draw Conclusions on the Effects of 0.38 G
  and the need for alternative countermeasures
                          Current State
            The Good                                 The Bad


• We have a mandate for Mars         • Use of Integrity for post-flight
                                       functional testing will be a battle
• Funding will increase as the
                                        – Comprehensive strategy required
     Shuttle winds down              • Management commitment needed
• Integrity is an extraordinary tool • Politics likely involved
   – Dynamic testing environment
• Mars mission simulations will
  be required sooner or later
   – ESA, RSA are calling for subjects

								
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