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Advanced Topics in Space Studies: Commercial Barriers and Solutions. Human Factors/Space Medicine Dr. John M. Jurist Biophysicist CRM, Inc. What Happens to People Living and Working in Space?. The dream:. What Happens to People Living and Working in Space?. Reality:. Human Factors.

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Advanced topics in space studies commercial barriers and solutions

Advanced Topics in Space Studies: Commercial Barriers and Solutions

Human Factors/Space Medicine

Dr. John M. Jurist

Biophysicist

CRM, Inc.




Human factors
Human Factors Solutions

Space is a very, very hostile and unforgiving place:

  • None of the comforts of home unless brought along

  • It is largely empty (both blessing and curse)

  • Transport from Earth is very expensive

  • We don’t really know much about living there

  • Repairs and help are far away

  • Truism: Space can always hurt you more


Human factors1

862 gms O Solutions2

2,200 gms H2O

523 gms food

982 gms CO2

2,542 gms H2O

61 gms solid waste (min)

Human Factors

Consumables for a 70 kg Man (level flying) at 2,830 kcal/day on specific diet:

(after Hans G. Clamann, Problems of Metabolism in Sealed Cabins)


Human factors2

Air Solutions

Water/urine

Food/solid wastes

Toxic accumulations of whatever

Human Factors

Consumables requirements make recycling more attractive for longer missions and larger crews:


Human factors3
Human Factors Solutions

Considered in the context of mission parameters:

  • Suborbital

  • Orbital

  • Lunar

  • Solar System


Human factors4
Human Factors Solutions

Considered in the context of mission parameters:

  • Duration

  • Life Support

  • Consumables

  • Acceleration

  • Microgravity

  • Radiation

  • Other Considerations


Human factors5
Human Factors Solutions

Suborbital:

  • Duration – minutes

  • Life support – hypoxia – pressure suits

  • Consumables – minimal – no waste handling

  • Acceleration – multidirectional? – cardiac arrhythmias

  • Microgravity – nausea (in a pressure suit?)

  • Radiation – negligible


Human factors6
Human Factors Solutions

Orbital:

  • Duration – hours to weeks

  • Life support – + contaminants, noise

  • Consumables – +transported and stored

  • Acceleration – + tolerance after microgravity

  • Microgravity – +fluid shift, bone & muscle atrophy

  • Radiation – not negligible

  • Other – medical emergencies – can’t call 911


Human factors7
Human Factors Solutions

Lunar:

  • Duration – hours to weeks

  • Life support – + contaminants, noise

  • Consumables – +transported and stored

  • Acceleration – + tolerance after microgravity

  • Microgravity – +fluid shift, bone & muscle atrophy

  • Radiation – roughly 2x orbital, flares fatal

  • Other – dust, medical emergencies, procreation?


Pulmonary physiology
Pulmonary Physiology Solutions

Abating effects of altitude:

  • Pressurize the cabin – 8,000 feet airline standard

  • Supplemental oxygen


Pulmonary physiology1
Pulmonary Physiology Solutions

Pressurizing cabin to 8,000 feet results in inadequate oxygen saturation and need for additional oxygen for otherwise healthy people:

  • 44% of 65 year old

  • 27% of 55 year old

  • 14% of 45 year old


Pulmonary physiology2
Pulmonary Physiology Solutions

Breathing pure oxygen at altitude equivalent to:

  • Sea level air at 33,000 feet

  • 10,000 feet air at 39,000 feet

  • 20,000 feet air at 45,000 feet


Pulmonary physiology3
Pulmonary Physiology Solutions

Pressure suits:

  • Full pressure suit more than $1 Million

  • EVA capable suit more than $3 Million

  • Partial pressure suits uncomfortable -- Get me down alive !!

  • Poor heat dissipation especially with exercise

  • Heat stroke running from downed spacecraft?


Acceleration effects
Acceleration Effects Solutions

Acceleration duration:

  • Prolonged if more than 0.2 seconds

  • Fluid shifts important and dominate effects

  • Impact if less than 0.2 seconds

  • Viscoelastic nature of tissues

  • Delta-V or acceleration onset best indicator


Acceleration effects1
Acceleration Effects Solutions

Acceleration definitions:

  • Eyeballs down plus Gz

  • Eyeballs up minus Gz

  • Eyeballs in plus Gx

  • Eyeballs out minus Gx


Acceleration effects2
Acceleration Effects Solutions

Prolonged acceleration:

  • Normal blood pressure at heart 120/75 mm Hg

  • Pulmonary artery 20/7 mm Hg

  • Pressure drop to brain 35 mm Hg at 1 G

  • Pressure drop to brain of 105 mm Hg at 3 G

  • Venous blood pooling


Acceleration effects3
Acceleration Effects Solutions

Prolonged acceleration:

  • Grey out, loss of vision, loss of consciousness

  • Visual acuity decrease (deformation)

  • Compensatory mechanisms

  • Carotid sinus reflex dominates (5 seconds)

  • Respiratory difficulties


Acceleration effects4
Acceleration Effects Solutions

Abating effects of prolonged acceleration:

  • Decrease uphill heart-brain distance

  • Modify flight profile

  • Counter pressure suit to decrease blood pooling

  • Counter pressure by straining


Acceleration effects5
Acceleration Effects Solutions

Cardiac effects of prolonged acceleration:

  • Irregular heart beat 47% medical professionals

  • 4.5% potentially dangerous

  • Irregular heart beat 30-50% fighter pilots

  • 4.6% potentially dangerous

  • Aging effects poorly characterized


Consideration of failure
Consideration of Failure Solutions

  • Fundamental decisions:

    • Vertical or horizontal takeoff and landing

    • FAA/AST-2 essentially laissez faire

    • Definition of failure modes and probabilities

    • Passenger education and training


Consideration of failure1
Consideration of Failure Solutions

  • Ejection seat utility:

    • Part of atmospheric flight

    • HTO vehicle in early flight

    • Limited at high speeds

    • Limited at high stagnation temperatures


Consideration of failure2
Consideration of Failure Solutions

  • Ejection seat upper envelope:

    • Mach 0.9 at sea level

    • Mach 3.7 at 65,000 feet

    • High stagnation temperatures above 65,000 feet


Consideration of suborbital failure
Consideration of Suborbital Failure Solutions

  • Cabin depressurization:

    • Unstrap for short time in microgravity?

    • Emergency egress for landing mishaps

    • Lawyers have 20-20 hindsight

    • So do congressional committees


Radiation exposure
Radiation Exposure Solutions

  • Sources of exposure:

    • On board fluid level sensors

    • Cosmic photons (includes gamma bursts)

    • Cosmic particulate radiation

    • Solar photons

    • Solar particulate radiation (includes flares)

    • Trapped particulate radiation belts (Van Allen)

    • Terrestrial background


Radiation exposure1
Radiation Exposure Solutions

  • Units:

  • Energy/Mass Bioeffect

    • 100 Rad times Q(RBE) 100 Rem

    • 1 Gray (Gy) times Q 1 Sievert (Sv)


Radiation exposure2
Radiation Exposure Solutions

  • Short term acute whole body exposure (rems):

    • 10-50 Minor blood changes

    • 50-100 5-10% nausea (1 day), blood, survivable

    • 100-200 1/4-1/2 nausea (1 day), blood, GI, survivable

    • 200-350 Most nausea (1 day), blood, GI, 5-50% die

    • 350-550 450 LD50 Most nausea, blood, GI, 50-90% die

    • 550-750 Nausea (hours), blood, GI, almost all die

    • 750-1,000 Nausea (hours), blood, GI, fatal (2-4 weeks)

    • 1,000-2,000 Nausea (hours), fatal (2 weeks)

    • 4,500 Incapacitation (hrs), fatal (1 week)


Radiation exposure3
Radiation Exposure Solutions

  • Living and medical:

    • Polar airline flight 0.10-0.23 mSv per day

    • 2 view chest X-ray 0.06-0.25 mSv

    • Bone scan 0.15 mSv

    • Chest CT 0.3-30 mSv (typical 10 mSv)

    • Billings MT background 1.2 mSv per year (quiet sun)

    • Typical US background 2.4 mSv per year

    • Typical US medical 0.6 mSv per year



Radiation exposure5
Radiation Exposure Solutions

  • Based on HTO suborbital:

    • Upper limit 0.0053 mSv per flight

    • Polar airline flight 0.10-0.23 mSv per day


Radiation exposure6
Radiation Exposure Solutions

  • Based on orbital and beyond:

    • 0.6-0.9 mGy/day (Skylab)

    • 0.2-1.3 mGy/day (Apollo landing flights)

    • ~0.06 mGy/day (STS)

    • 0.049-1.642 mGy/day (STS-2, STS-31)

    • 0.053 mGy/day 0.146 mSv/day galactic cosmic

    • 0.042 mGy/day 0.077 mSv/day trapped belt


Radiation exposure7
Radiation Exposure Solutions

  • The problem:

    • 2 view chest X-ray 0.06-0.25 mSv

    • Public limit 1 mSv per year

    • NASA classifies astronauts as radiation workers

    • Worker whole body 50 mSv or 0.05 Sv per year

    • Worker organ limit 0.5 Sv per vear

    • Worker organ limit 0.25 Sv per month


Radiation exposure8
Radiation Exposure Solutions

  • Career limits for radiation workers (1994):

    • Blood-Forming Organs

    • Limit at Lens Skin Male Female

    • Age 25 4.0 Sv 6.0 Sv 1.5 Sv 1.0 Sv

    • Age 35 4.0 Sv 6.0 Sv 2.5 Sv 1.75 Sv

    • Age 45 4.0 Sv 6.0 Sv 3.2 Sv 2.5 Sv

    • Age 55 4.0 Sv 6.0 Sv 4.0 Sv 3.0 Sv


Radiation exposure9
Radiation Exposure Solutions

  • Radiation carcinogenesis:

    • 0.5/106/mSv/year Breast

    • 0.4/106/mSv/year Thyroid

    • 0.3/106/mSv/year Lung

    • 7-17/106/mSv/year All cancers

    • 100 mSv/105 800 deaths added to 20,000 w/o radiation (4% increment/10 rads)

    • 10 mSv/year cont. 5% increment/1 rad lifetime increase


Radiation exposure10
Radiation SolutionsExposure

Is radiation a show-stopper for a trip to Mars?

  • Minimum energy transfer roughly 9 months each way

  • Assume STS-like free space galactic radiation exposure of 0.146 mSv/day

  • 270 days times 0.146 mSv/day = 39.4 mSv for 1 way

  • Is it legal? 50 mSv/year whole body worker limit

  • Is it legal? Compare to career limits (3 Sv age 55)

  • Boost cancer death risk 1.7% for baseline trip to Mars

  • Boost cancer death risk 25% for continuous 0.146 mSv/day

  • Flares and Mars orbit time, surface time

  • Radiation issues become significant


Radiation exposure11
Radiation Exposure Solutions

  • The conundrums:

    • Are long term space missions legal?

    • Informed consent vs. legal limitations

    • Conceive and raise children?

    • Remember planets shield by geometry

    • Large variability in exposure (flares)

    • Large variability in response


Weightlessness
Weightlessness Solutions

  • Based on HTO suborbital:

    • Maximum of 3½ minutes of microgravity

    • Greatest risk is nausea (other risks in orbit)

    • Familiarization aircraft flights

    • Minimize head movements

    • Medication

    • Avoid vomiting into oxygen mask or closed helmet

    • Nausea is contagious (smells and sounds)


Discussion

Discussion Solutions


Suborbital human factors status
Suborbital Human Factors Status Solutions

Alt.space awaremess is dismal:

  • Assumption that it is accomplished and can be ignored

  • Lack of appreciation of risks

  • Aging normative population undefined

  • Suborbital floating free in shirt sleeves?

  • Buy a Russian space suit on EBAY


Orbital and beyond human factors status
Orbital (and Beyond) Human Factors Status Solutions

Alt.space awaremess is even more dismal:

  • Assumption that it is accomplished and can be ignored

  • Lack of appreciation of risks

  • Aging normative population undefined

  • Minimal gravity level is undefined

  • Radiation issues become significant

  • Working is microgravity is hard


Orbital and beyond human factors status1
Orbital (and Beyond) Human Factors Status Solutions

Why? Culture shock (engineering vs. biomedical):

Engineers look for limiting parameters

Engineers design to limiting parameters

Engineers minimize variables

Human responses vary enormously

Human responses probabilistic

Human responses – many variables

Human responses poorly characterized

Never say never in medicine


Orbital and beyond human factors status2
Orbital (and Beyond) Human Factors Status Solutions

Medical issues related to living in space and going to Mars:

  • Outside assistance is impossible or very difficult

  • Life support degradation – toxin accumulation

  • Acute urinary retention -- renal lithiasis

  • Cardiac event

  • Cancer (Antarctica example)

  • Drug shelf life (accelerated degradation with radiation)

  • Medical/surgical infrastructure -- how much is enough?


Opportunities
Opportunities Solutions

What we don’t know can hurt us or provide opportunities for play/research:

  • Microgravity – musculoskeletal, cardiovascular, reproductive, and immune systems; embryogenesis, fetal development; aging; optimization

  • Radiation – shielding (mass, electrostatic, or magnetic), abatement (pharmaceutical, antioxidants, modification of humans – genetic engineering)

  • Long term exposure to different gas mixes vs. standard air

  • Other – lunar dust and urban/rural pollution effects


Opportunities1
Opportunities Solutions

Role for small business niche operations:

  • Training MDs in aerospace medicine

  • Training passenger candidates

  • Screening passenger candidates

  • “Space Camp” for passengers

  • Life support equipment – esp. pressure suits

  • Ever present consulting


Opportunities2
Opportunities Solutions

Role for academic operations:

  • Training MDs in aerospace medicine

  • Training passenger candidates

  • Education – public outreach

  • Research – specialized – intradepartmental

  • Research – interdisciplinary – multidepartmental or multischool

  • Ever present consulting


Solutions
Solutions Solutions

Becoming a spacefaring culture:

  • Drive down cost to LEO and beyond

  • Find and exploit commercial opportunities

  • Justification for manned presence

  • Technology (microgravity, radiation, life support)

  • Technology (shorten trip times)

  • Motivation (national security?, lifeboat?)


Solutions1
Solutions Solutions

Becoming a spacefaring culture:

  • Time

  • Money

  • Research

  • Technology

  • Management

  • Motivation


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