CTolbert 062412 Mars

American Military University

SPST619

The Psychology and Physiology of Space

Mission to Mars: The Human Perspective

BY

Carl Lee Tolbert

Student ID # 4172687

16 June 2012

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CONTENTS

Scenario……………………………………………………………………………………...……3

Temperature Extremes……..……………………………………………………………………3

Extravehicular Activity................…………………………………………………………3

Circadian Dyssynchrony………………………………………….………………………..……5

High Vacuum………….................…………………………………………………………….…7

Effect of Vacuum on the Human Body…………………………………………...……….7

Ionizing Radiation………………………………………………………………………...……...8

Radiation Countermeasures………………………………………………………..…….10

Micrometeoroids and Space Debris……………………………………………………..…….12

Plasma Interaction……………………………………………………………………...………12

Microgravity……………………………………………………………………………...……..13

Sensing Gravity and Space Motion Sickness……………………………………….……13

Muscle Atrophy……………………………………………………………….…………15

Bone Loss………………………………………………………………………….……..16

Muscle and Bone Loss Countermeasures………………………………………………..17

Cardiovascular System Damage…………………………………………………………18

Cardiovascular Countermeasures……………………………………………..…………20

Psychological Factors…………………………………………………………………..………20

Pre-flight Preparation…………………………………………………………...………..22

Summary and Recommendations……………………………………………….……………..24

The “Show Stoppers”………………………………………………………...…………..24

The Minutia………………………………………………………………………………24

Need for Further Research on New Experimental Fronts………………………………..25

Final Recommendation…………………………………………………………………..26

Notes…………………………………………………………………..………………...…...…..27

Works Cited………………………………………………………………………………......…35

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Scenario

This paper is in response to the following hypothetical scenario: The President of the

United States must make a critical decision – whether or not to start the mission planning process

needed to send astronauts on a 2.5-year round-trip journey to explore the planet Mars. You have

been tasked to write a paper for the President, introducing him/her to the physical and mental

challenges of human space travel and exploration.

The response to this scenario is a broad topic that is better served by dividing up the

information into several smaller sections, with a summary at the end to bring the information

back together. The divisions will consist of the following: temperature extremes, circadian

dyssynchrony, high vacuum, ionizing radiation, micrometeoroids and space debris, plasma

interaction, microgravity, and psychological factors.

Temperature Extremes

To gain an understanding of the extremes in space, consider the common astronaut’s

experience of a spacewalk from a spacecraft in low earth orbit (LEO). The spacecraft in question

is traveling at a speed of Mach 25 (around 5 miles per second) and circles the earth once every

1.5 hours.1 Inside the spacecraft, the ambient temperature is 69.8 to 73.4*F (21 – 23*C), as

opposed to the extreme temperatures of -212 to 212*F (-100 to 100*C) found outside the

spacecraft.2 In addition to the mechanical wear and tear on the outer hull of the spacecraft, the

primary challenge related to the extreme temperatures of space appears when astronauts need to

venture outside.

Extravehicular Activity

As with the trip to Mars, it is imperative that the deployment of a spacewalk, also known

as an extravehicular activity (EVA), is operationally planned and that emergency procedures are

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established when required. With a typical workload of up to several hours performed outside the

spacecraft, the astronauts have very specific medical and environmental concerns. The workload

accounts for 800-1500 calories burned per hour during the EVA deployment.3 This very draining

work may exacerbate the already-deconditioned state of astronauts via increased heart rate and

possible dehydration.4 One of the other observed aggravations is irregular heart rhythm during

the EVA and during post-flight recovery.5

With microgravity, simple functions like loosening a bolt must be planned beforehand

because any force applied through the tool to the bolt will send the crewmember hurtling through

space unless the optimal tethering or holds are utilized.6

As mentioned earlier, the work is arduous and generates 10 – 20 times the heat of a crew

member at rest. If the generated heat exceeds the suits ratings during an EVA, then physiological

hazards become a possibility, including heat stress and heat stroke.7 It is important to understand

that although the suit design provides for active cooling, heating is passive based on body

temperature.8 The passive heating design becomes problematic when temperatures inside the suit

drop lower than expected because the suit can only decrease cooling and the temperature is slow

to increase. The hands of the astronaut are of specific concern in the extreme temperatures, and

provisions must be made for their individual active heating and cooling, including specially

made thermal mittens.9

Decompression sickness (DCS) is also a concern for EVA deployments because any

change in atmospheric pressure surrounding the body could cause nitrogen bubbles to form in the

blood and tissues.10 Type II DCS (the more severe version) can cause stroke, vestibular stress,

and paralysis, especially from a right to left shunt (a genetic bridge that can allow bubbles to

move from the venous system to the arterial system.)11 Note – A right to left shunt is a genetic

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defect that cannot be fully screened out and is present in 15 – 20% of the population.12 Exposure

to 100% oxygen usually clears the less severe symptoms, such as the “bends,” in little time and

also acts a preventive measure (pre-breathing) to reduce nitrogen levels.13 If type II DCS is

diagnosed, then the crew member would be treated again with 100% oxygen and the drug

lidocaine. The crew member would also need to be evacuated and possibly treated by a

hyperbolic chamber on Earth; however, on a trip to Mars, type II DCS will have potentially

deadly consequences due to the lack of treatment options and evacuation plans. The good news,

based on the history of space flight, is that there have been no reported cases of DCS in

American astronauts since Gemini.14

Note – The pressure inside the two different types of suits deployed for an EVA are 29.5

kPa for the NASA extravehicular mobility unit (EMU) and 40 kPa for the Russian Orlan space

suit.15 It makes sense to decide which type would be the best to use in order to consolidate

training and operations for EVA deployment for the trip to Mars.

In addition to the countermeasures mentioned, researchers believe that fitness and

cardiovascular training are useful. Obviously, pre-screening for predispositions to specific issues

associated with EVA is warranted as well.16 Lastly, monitoring nitrogen levels and other factors

will aid the crew in the safe and effective deployment of any EVA endeavor.17

Circadian Dyssynchrony

Again, considering the LEO example mentioned earlier, astronauts can experience 16

sunsets and sunrises per 24 hour period.18 Natural sleep patterns (circadian rhythms) can be

disrupted on missions conducted in LEO and the proposed Mars trip based on light/dark

irregularities and other factors.19

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Humans and other life forms on Earth have developed several mechanisms that allow

synchronization between the life form and the environment.20 The primary synchronization

method concerning the trip to Mars is the circadian clock (the molecular-level mechanism that

prepares the life form for pre-emptive environmental stimuli/events).21 Researchers have

determined that circadian functions are found in almost all organisms and are located in cells,

tissues, organs, and elsewhere.22

Circadian clocks have been found in almost all organisms investigated to date, with a few

notable exceptions.23 When astronauts perform their duties, even everyday activities, which go

against the natural rhythm of the sleeping and waking process, disruption occurs. The disruption

of the circadian function can be caused by light, temperature, sound (60 dBA average on

spacecraft), movement/physical activities, diet, light flashes (corona discharges are seen even

with the eyes closed while in space), and electrical fields.24 25 The loss of synchronization with

the environment can create many short-term and long-term functional and medical problems for

astronauts.26

The most challenging short-term effect of circadian dyssynchrony is a lack of natural

sleep. Researchers equipped with a very large database of 1.116 million Americans (age ≥30

years; mean = 57 years for women and 58 years for men) determined that 52.5% of respondents

reported an average of less than 7.5 hours of sleep.27 The effects of sleep deprivation include

oculomotor activity (eye movement changes), reduced waking cognitive performance, and

reduced behavioral alertness.28 Other corollary short-term effects can include irritability and a

weakened immune system.29 The long-term effects of sleep deprivation can include obesity and

type II diabetes.30 In modern society, it is obvious that people are statistically sleep deprived in

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their normal lives; however, it is imperative to maintain proper operations so that astronauts

during the Mars mission have optimal natural sleep.

High Vacuum

The vacuum outside the spacecraft is severe and naturally poses a deadly hazard for

unprotected astronauts. Inside the spacecraft, normalized pressure is maintained at 101.54 kPa

(14.7 psi) for an optimal crew habitat.31 Great care, complete with operational protocols, must be

maintained for operations that can expose the inside of the spacecraft to the vacuum of space. In

1997, the space station Mir collided with a supply module, which created a rapid

depressurization of the space station.32 No crew members were hurt; however, the accident

shows the need for absolute safety and emergency procedures for the trip to Mars.

Effect of Vacuum on the Human Body

Most of the data associated with exposure to vacuum comes by the way of human

accidents or animal testing. The research consensus is that the survivability of an unprotected

astronaut would be 5 to 15 seconds for the astronaut to help themselves clear the hazard or up to

90 seconds for others to remove the astronaut from the hazard.33 Many myths surround exposure

to the vacuum of space. The astronaut does not freeze, and the astronaut’s blood does not boil;

however, gas expansion does create a problem if the breath is held because the lungs can be

damaged.34

Explosive decompression is a far more deadly circumstance than those mentioned above.

When two different air masses come into contact, such as the spacecraft opening up

unexpectedly to the vacuum of space, an explosive noise can be heard.35 This type of event is

significant different that exposure to vacuum via a slow leak in an EVA glove. The mechanical

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expansion of gas in the body during decompression can affect the gastrointestinal tract and the

lungs and can create DCS, hypoxia, and burns.36

Ionizing Radiation

The key to understanding radiation hazards aboard spacecrafts is to understand the basics

of radiation on earth and beyond earth’s protectionary boundaries and the ways radiation can

affect human physiology.

The earth has natural protection from radiation based on the earth’s mass, atmospheric

layers, and magnetic field.37 The idea of creating shielding from radiation beyond Earth’s

boundaries creates a significant challenge for spacecraft designers and the space crew that will be

operating the spacecraft, especially since all human space missions have been within 600km of

the Earth, with the exception of Apollo.38

Ionizing radiation takes place at the atomic level and is divided into two forms based on

the type of radiation. The first form of radiation is photon-based, like x-rays and gamma rays,

and the second is particle-based, like protons and neutrons.39

Basic particle physics dictates that when an ion is created by energy bombarding an atom,

the excess electron (free electron) is ejected.40 A free radical is created from the resulting ion or

free electron. Free radicals can and will disrupt and harm other molecules, such as DNA.41 The

higher the energy level in the ionizing radiation, the more damaging the radiation can be to

molecules.

The magnitude of the high-energy radiation can be quantified in electron volts (eV).42

Medical x-rays are measured in thousands of eVs, whereas cosmic radiation is measured in

millions of eVs. Another way to measure the magnitude is by measuring the energy that is

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distributed through the cells by the radiation. The measurements are called linear energy transfer

(LET).43 Particles like photons can create more ionization based on the distance travelled and

when the particle stops. This stopping event can also affect other nuclei and lead to secondary

damage.

Solar flares present a specific catastrophic form of radiation that astronauts and

spacecrafts can be subjected to.44 Even with planning and prediction, the storms happen quickly

and can bombard the spacecraft and any space crew members outside the inherent shielding of

the craft (EVA).

Note – Since the prediction models for solar events need to monitor both sides of the sun,

it is essential that any Mars trip have adequate prediction models. Although research and

modeling has improved over the last 40 years in terms of space weather prediction, the fact

remains that there are only a few minutes of warning before a solar event.45

Galactic cosmic radiation is the constant flux of high-energy radiation that is always

present in space. Galactic cosmic radiation consists of 87% high-energy protons produced by the

nuclear disintegration of stars and secondary neutrons; 12% alpha particles (helium nuclei); and

1% heavy nuclei ions, ranging from lithium to iron, with high charges and high energies (1020eV,

HZE.)46 The damage this type of radiation produces in cells is directly proportional to the atomic

number of the particle of radiation and has a high LET.

Physiological damage from ionizing radiation can be divided in two overlapping

categories, acute and long-term damage, based on dosage. The acute damage from radiation and

radiation sickness-induced nausea and vomiting includes skin effects; the graying and loss of

hair; eye lens opacification (cataracts); decrease in blood cells counts (weakness, anemia, and

infection); and the loss of non-dividing cells.47 Long-term damage can include sterility; cancer in

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the blood-forming organs (the bone marrow, thymus, and spleen), stomach, colon, and bladder;

and genetic effects that arise from cell chromosome aberrations and translocations (DNA strand

break.)48

The average human on Earth receive a dose of less than .005 Sieverts (Sv) annually. As

humans travel higher in altitude, away from the Earth, the dosage levels increase.49 Commercial

airline pilots are exposed to .3 to 5.7 µSv per hour.50 Crew members onboard the international

space station (ISS) receive .3Sv per year, while astronauts average a total dose of 1 Sv in their

careers.51 A round trip to Mars will expose crew members to an unacceptable level of 5 Sv.52

Radiation Countermeasures

Shielding is the primary means of protecting the astronauts from the harmful effects of

solar and cosmic radiation and can be divided into passive and active designs. The solution for a

passive radiation shield seems simple from the cost and deployment perspective. The idea is to

create a wall behind which the astronauts are protected. The major challenge is that not all

radiation is deflected by any one type of material, and furthermore, some radiation that is

absorbed can produce secondary radiation, also known as bremsstrahlung, meaning “braking” in

German, which researchers have observed to be more detrimental to astronauts than primary

radiation in some cases.53 54 The passive shield designers must take the secondary radiation into

account, as well as the weight and onboard space (room) design constraints.

The National Council on Radiation Protection and Measurements (NCRP) estimates that

2 g/cm2 of aluminum and, in some cases, based on cosmic events, shielding up to 50 g/cm2 are

required for basic protection.55 The consensus, from various sources, is that conventional

shielding will be inadequate for Mars travel on this practical point.

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Two materials should be considered for Mars travel due to the weight and mass

constraints. The first is a polyethylene-based material called RXF1. This material is somewhat

immune to secondary radiation because it is composed entirely of lightweight carbon and

hydrogen atoms.56 The weakness of the material is temperature and flame retardation.

Researchers have been using combinations of different types of carbon, boron carbide, boron

nitride, and other more temperature-immune materials in search of a remedy for the problem.57

Researchers are hopeful that the ongoing experimentation and reformulations will produce an

overall effective solution.

The second material is graphite nano fiber and other composites with specific densities

and platelet (crystal) orientation, which can be the answer to the current solution of large

amounts of water and metallic primary and secondary shielding sources but at a very low mass

and weight.58 Passive lightweight material shielding seems to be the most practical approach

based on volume requirements, mass, and current feasibility.

Active solar and cosmic radiation shields are being developed with multiple design

approaches. One approach is to create an artificial magnetosphere around the spacecraft,

emulating the one that surrounds the Earth in a dipole shape.59 The Earth’s magnetosphere, in

addition to the atmosphere, keeps most harmful forms of radiation away from humans. The idea

of creating a magnetosphere is a serious design challenge. The idea is to use super-conductors

and a large enough power supply to create a magnetic field by utilizing the natural state of space,

which is plasma.60 Testing is moving forward and researchers believe a possible working model

may be available at a later date.

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Micrometeoroids and Space Debris

Although there are 12,000 or so pieces of space debris of significant size orbiting the

Earth, there is little fear of collisions after the spacecraft leaves Earth; however, micrometeoroids

are still a threat in free space.61 Micrometeoroids are naturally occurring in space, and are left

over bits of asteroids and comets. The collision of micrometeoroids or space debris with the

Mars spacecraft could be explosive. Imagine the kinetic energy created by a 1kg micrometeoroid

colliding with the spacecraft at a velocity of 10 km/s.62 The resulting impact would be like a

35,000 lb vehicle colliding with a wall at 118 mph.63 The spacecraft traveling to mars will need

to have adequate external shields robust enough to handle anything that the spacecraft cannot

maneuver away from. Note – EVA operations are especially susceptible to micrometeoroid

damage due to the weak material that the EMU are made out of; however, no incidents of

collisions or suit penetrations have been recorded so far.64

Plasma Interaction

Plasma is the fourth state of matter and occurs when gas is heated enough (energy is great

enough) to allow atoms to be stripped of electrons.65 These “free” electrons and ions create

plasma and are found in space.66 It is easy to understand that space is a sea of plasma. For the

Mars trip (and any space travel), plasma can be detrimental to the spacecraft and to astronauts

performing EVA from an electrical discharge perspective.

For example, the International Space Station (ISS) produces 160 VDC via the solar arrays

and utilizes a distribution bus of 120 VDC (imagine a car’s 12 VDC battery system amplified 10

times.)67 The problem that plasma creates is based on the fact that the medium is super

conductive. The resulting interaction between the ISS and plasma is a stored -140 VDC charge.68

Without the two plasma contactors (very different from the industrial contactors that switch

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current loads for electric motors) acting as grounds, the substantial negative charge would create

arcing and be detrimental to the spacecraft electronics and personnel.69 EVAs utilize a grounding

tether so that during any work on the spacecraft or other devices in the plasma, the astronaut will

be protected from electrocution and burn damage caused by arcing.70 Any spacecraft going to

Mars will require a grounding arrangement like the plasma contactors (with redundancy) or other

devices in order to allow safe interaction with the surrounding plasma.

Microgravity

Gravity is the state of acceleration caused by the gravitational energy drawing bodies

towards the center of the planet. On earth, the nominal rate is 9.8m/sec2. In space, depending on

the orbit, the acceleration can be thousandths or even millionths of a G.71 This very low

acceleration in space is called microgravity and is also known by the incorrect term

weightlessness.

Sensing Gravity and Space Motion Sickness

The neurovestibular system is primarily the body’s controls (organs) that sense the

acceleration environment.72 Nerves transmit this information to the central nervous system for

processing and allow humans to determine orientation and position within the relative

environment.73

Linear and angular acceleration are detected and measured by neurovestibular organs

located in the inner ear.74 These measurements, combined with other inputs, such proprioception

(sensors from joints, muscles, and tendons that give feedback regarding position) and vision,

yield the orientation (gravity vector) to astronauts for balance.75

In microgravity environments like space, the neurovestibular information can be

augmented based on the environment and lead to misreading and inadequate responses by the

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brain in terms of controlling balance and motor function. One of the consequences of the

environmental changes on the neurovestibular system is space motion sickness (SMS), which

arises in two-thirds of space travellers.76

SMS symptoms can appear over the first few days of travel, usually lasting three days

after onset, and include symptoms like nausea, vomiting, stomach pains, and a general sense of

lethargy.77 SMS can also lead to Sopite Syndrome, which is a lack of motivation to work and

associate with others.78 These symptoms themselves can limit the performance of the space

travelers. Head movements can aggravate the symptoms. After recovery and adaptation,

crewmembers do not have reoccurrences of SMS; however, there is no adaptation for the 5% of

individuals with chronic motion sickness.79

Microgravity itself does not induce SMS; however, the mobility available to space crews

in combination with microgravity creates an environment that can.80 Even in an environment that

can induce SMS symptoms, individuals vary in terms of susceptibility.81

Two major theories to account for SMS exist. The theories are fluid shift theory and

sensory conflict theory.82 Fluid shift is based on linear acceleration. Linear acceleration is

measure by the saccule and the utricle (in essence how the head is translated with relation to

gravity.)83 The otoliths are crystals inside the saccule and utricle that ride on hairs suspended in a

gel-type liquid.84 When the head moves, the crystals have a different inertia and yield a

movement that is interpreted by the brain as linear acceleration. The idea that linear acceleration

can be interpreted as head movement or body translation based on gravity is important to SMS.

In microgravity environments, the absence of gravity will cause a misreading of head movement

versus translation. This hypothesis, which is debated, is called Otolith Tilt-Translation

Reinterpretation (OTTR).85

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Note -- Angular acceleration is measured by the three semicircular cannels of the inner

ear. When the liquid inside of the canals moves; angular motion is detected. This movement is

measured and then sent to the brain.86

Sensory conflict theory assumes that the neurovestibular inputs that induce SMS are

rearranged. In three-dimensional space, the central nervous system has four inputs.87 They are

linear and angular acceleration and visual and kinesthetic inputs. When microgravity is

introduced, the change alters the stored (known) pattern of the four inputs and induces SMS.88

The first countermeasure to SMS is knowledge and prediction.89 However, ground-based

testing and physiological research (questionnaires, patient histories, etc.) do not have a direct

correlation to SMS symptom onset in space. Still, countermeasures have been developed.

Pre-flight adaptation testing (PAT) has shown a significant reduction in the severity of

SMS.90

Head restraints have met with limited success.91

Drug therapies, such as promethazine, have been successful with some subjects, but not

all.92 93

Vestibular prostheses can be used to overcome proprioceptive inputs that cause SMS.94

Artificial gravity is still being research and has shown some adaptation enhancement

during pre-flight and inflight testing.95 96

Muscle Atrophy

Muscle atrophy and the excretion of nitrogen through the urinary system begin when the

human body is exposed to microgravity.97 The atrophy can range from 10 to 20 percent on short

missions to as much as 50 percent on longer missions, without mediation.98 The atrophy is

characterized by reduced muscle mass and is mostly isolated to the postural muscles required for

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walking and standing.99 A quick reference that can be used is muscle diameter measurements;

however, this measurement also entails fluid transfer from the lower to the upper extremities and

should only be used as an analog.100

Unlike muscle atrophy common to earthbound cases of non-use (after surgery or healing

from a broken bone with a cast), it is postulated that the atrophy is caused by changes in muscle

metabolism. The Mir space station has produced test results in which metabolism has been

reduced by 15% in microgravity environments.101

Reduced muscular strength in various parts of the body has also been noted based on the

muscle contractile response, in addition to fiber size reduction within the first six days of

exposure.102 This strength loss manifests during extension more so than during flexion.103

With these changes, nitrogen scavenging also affects the regenerative abilities of muscles

to heal themselves.104 This regenerative ability is the function that allows the muscles to grow

from the constant damage and healing that occurs.105 Imagine athletes complaining about sore

muscles after a workout.

The bottom line is this: The key for space travellers is to perform their operational

functions to the best of their abilities both cognitively and physically. This hindrance affects their

primary function, the ability to withstand the stresses associated with the acceleration and

deceleration of the launch and recovery phases of the mission, and the stamina needed to endure

them.

Bone Loss

Bone loss in microgravity is characterized by a 1-2 percent loss per month.106 Initially,

this does not seem to be that detrimental; however, losses do not cease over the long term. They

compile and last for several months after the space traveller returns to gravity.107

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Like the muscle atrophy, the lower extremities and load-bearing bone structures suffer

the largest amount of loss. Bone loss is attributed to demineralization through calcium

scavenging.108 The calcium must be excreted from the body through the kidneys and causes a

greater chance of kidney stones (a potentially deadly side-effect.)109 110 Effects on the bone

structure as well as the blood cell-forming marrow are great concerns because they can lead to a

greater risk of fracture and difficulty in recovering from other forms of damage to the body, such

as wounds.111

Bone and muscle mass (more than 30 percent of the body) show an overall reduction of 5

percent in the first two weeks of travel, including fluid loss.112 Conversely, the body weight

increases due to an increase in sodium and water retention.113 It is assumed that the contradiction

of fluid loss and fluid retention is caused by the different densities of the fluids.

Muscle and Bone Loss Countermeasures

Exercise is the first countermeasure that is discussed regarding any type of muscle and

bone loss.114 The results from the Mir and Skylab regiments of two hours per day of intense

exercise only marginally slowed the predictable bone and muscle degradation.115 Other studies,

focusing on hip loading, manifested similar results to the Mir station findings. Methods involved

in recent and past studies have been a combination of aerobic and anaerobic activities including

“penguin” suits, which are similar to power lifter singlets, utilizing high-tech fabric and materials

to cover the body and make even basic movements more taxing on the human body.116 Note —

Non-load bearing structures did maintain their density in the Mir studies.

Nutritional and pharmacological countermeasures have also been prescribed to crew

members, primarily to counteract the calcium depletion that leads to bone loss and

demineralization. Diet, in addition to supplemental calcium at a dosage of 1000mg per day, has

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been shown to improve the balance of calcium levels for up to three months, with increasing

dosage and long-term supplementation yielding diminishing returns.117 Like on earth, calcium is

synergistically coupled with magnesium. In this case, 350mg has been found to be the best

coupled dosage. Vitamin D (a problem due to the lack of sun light) and vitamin K are also

supplemented because they have been shown to help maintain bone mass balance.118

Pharmacological countermeasures have been studied for space and osteoporosis patients,

with varying results. From aids research, administering testosterone for men and estrogen for

woman, as well as human growth hormone (hGh), can be an option for bone loss and muscle

wasting.119

Other countermeasures, including prescreening for hypercalciuria, are also standard

practice for space flights.120 These measures are universal because of the host of stresses

involved. Monitoring is also deployed in order to measure the medical condition of the space

travellers.

Lastly, artificial gravity (AG) has been used as a countermeasure, with varying results

based on the lack of duration and the lack of a more effective means of producing artificial

gravity in space.121 Research continues, and many researchers believe that AG can be an

effective countermeasure in the near future.

Cardiovascular System Damage

The cardiovascular system is comprised of the heart, circulatory system, lungs, and

kidneys.122 The system is responsible for blood transportation to and from the heart.123 The

blood is the mechanism for the supply of nutrients to cells, the removal of waste, the regulation

of temperature, and the fluid balance in the body.124 Microgravity affects the cardiovascular

system in two broad paths: in-flight and post-flight responses.

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Orthostatic intolerance is determined by symptoms experienced after standing, such as

increased heart rate, blood pressure changes, and fainting.125 The physical manifestations of

orthostatic intolerance are diminished by exercise and physical activity.126 The conditions

manifest in flight and continue until after the travelers are returned to Earth or possibly Mars; the

intolerance is especially apparent immediately after landing.127 The recovery varies greatly with

regard to pre-existing conditions and the duration of the flight, with no data existing beyond nine

months of flight.128 The Russian cosmonauts who spent over twelve months in space have little

or no data associated to the cardiovascular system.129

Cardiac atrophy (a decrease in the size of the heart muscle) appears to develop during the

space flight, leading to diastolic dysfunction and orthostatic hypotension (a drop in blood

pressure upon standing).130 Such atrophy may have been a potential mechanism for the cardiac

arrhythmias (irregular heart rhythms) identified in some crewmembers after long-duration

exposure to microgravity aboard the Mir space station.131 Research has suggested that cardiac

atrophy and orthostatic hypertension may be significant problems during and after long-duration

space flights to Mars.

With the change in gravity, more blood is allowed to flow towards the upper portion of

the body, which makes the heart work harder because of the added pressure and the required

cardiac output.132 This is similar to the supine position induced during launch for proper

acceleration tolerance. The fluid shift is more obvious during the early stages of the flight (6 – 10

hours), with the subject’s face being fuller in appearance, also known as “Puffy face.”133 The

fluid shift also alters the thirst mechanism early on and may induce de-hydration.134 The other

obvious physical appearance change is size loss in the lower extremities, commonly referred to

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as “chicken leg syndrome.”135 After several days in orbit, total losses in the lower extremities are

from 10 - 15 percent to 2 – 4 percent, with a plasma reduction of about 22%.136

Cardiovascular Countermeasures

The countermeasures developed to combat the effects of microgravity on the

cardiovascular system are similar to some of the basic countermeasures used against other

challenges in the microgravity environment. Two of the common approaches would be pre-

screening for medical conditions and in-flight cardiovascular training.137 Low body negative

pressure (LBNP) chambers and bungee cord suits (“penguin suits”) can be utilized to either

increase the flow of fluid back towards the lower extremities in the case of the LBNP or to pull

the body together and create a pressure shift in the case of the other device.138 Monitoring is also

important in preventing cardiovascular stress and gathering data.139 Examples of the monitoring

devices that can be deployed in space include a portable Holter monitor, which measures the

heart rate continuously for extended periods; a Cardiopres, which measures blood pressure with

every heart beat; and two Actiwatches, one on an ankle and one on a wrist, to monitor and record

body movements.140

Psychological Factors

There are three key psychosocial issues associated with space travel. They are inter-

personal conflict, depression, and anxiety disorders.141 Each of these possible issues can be

exacerbated by what researchers call “Third Quarter Phenomenon.”142

Many factors contribute to these psychosocial issues. Note that the location of the

mission on its operational timeline may bring about the onset of symptoms. For example, a crew

member may be fine during the first part of the mission because the environment is new. After

the midpoint of a mission, the same crew member may experience what researchers call the

21  

“Third Quarter Phenomenon” because of the self-realization that an equal amount of arduous

time is left until the completion of the mission.143 This phenomenon has been seen in analogs,

such as Antarctic research stations and nuclear submarines, and in actual space missions

conducted to date; however, much of the data researchers use is anecdotal.144

Space missions consisting of six months or more, like the Mars trip, have a limited

amount space for people to leave stressful situations and allow a conflict to have a cooling off

period, as it would on Earth. All crew members must be conscious of conflict resolution

strategies so that the conflicts that arise do not interfere with mission goals, especially after the

mid-point of the mission timeline.145 During any mission, unresolved conflicts can have a

detrimental effect on group morale and function, resulting in the possible termination of the

mission. In addition to person-to-person conflict, person-to-control conflicts can arise between

the crew members and ground control.146 For example, in 1973, astronauts onboard Skylab went

on strike for one day to rebel against ground control because of the workload.147 The result of

the Skylab strike and several examples of such conflict on Russian and other NASA missions

was crew members having the ability to schedule as much of their own operational time as

possible.148

Depression can be a result of isolation and the frustration of not being able to change an

event, the environment (like low light levels), or a combination of all the factors to various

levels.149 Symptoms of depression can include lack of sleep, eating habit changes, and a lack of

motivation.150 Depression could terminate the mission based on the health of the crew members

and the overall effectiveness and safety of the team; however, during the long mission to Mars, it

will be very difficult to change course and evacuate crew members.

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Simulations, like the Mars 520 in Russia, in which a crew was isolated from the outside

with living conditions similar to the Mars mission, shed light on the problems associated with

long-term isolation.151 The results of the isolation tests make researchers believe that the trip to

Mars is viable from an isolation standpoint.152

Anxiety disorders manifest when worries or concerns about an event or circumstance

concerning the mission increase.153 Although rare on space missions because of screening and

training, the concern regarding anxiety attacks precipitated by fatigue and other physiological

factors is appropriate.154

Note – Asthenia is a Russian term used to describe the following symptoms: weakness,

fatigue, reduced endurance, irritability, lower attention span, and short-term memory reduction.

According to researchers, the periods of symptoms come in waves.155

1. First stage – irritability, fatigue in the evening, and increased apathy

2. Second – fatigue and sleep disturbances

3. Third – depression, conflict, and mission mistakes156

American researchers do not fully subscribe to this notion of asthenia (neurasthenia in the

US) as a full diagnosis of a disorder; however, the hypothesis given is that as prolonged stress

levels produce lower amines in the brain, this results in susceptibility to depression and

anxiety.157 The Russians treat this with pharmacological means prior to missions as a

countermeasure.158

Countermeasures for these disorders range from select-in and select-out criteria for the

initial crew formation to training, self-assessment, proper habitat, and the environment aboard

the spacecraft.159

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Pre-flight Preparation

Pre-flight preparation starts with functional training for individual team members and

team building exercises to develop team cohesiveness. Survival training and parachute training

deployed by Russian cosmonauts can also be employed to build confidence for the team

traveling to Mars.160

As the mission approaches, family counseling sessions should be scheduled to allow for

specific planning for the duration of the mission and to prevent any unforeseen circumstance that

can cause distress to crew members or families during the separation.161 Mutual group support

for the crew’s families is also a great way to combat these issues.162

Crew members should receive specific training for cultural differences, gender

differences, and conflict resolution as part of the team building process. Included in team

building, sports psychology techniques, such as self-hypnosis and visualization, should be

employed.163

Note on gender differences – According to research, the average differences between

men and women are smaller than the differences between individual men or individual

women.164 Therefore, many feel that this is a non-issue; however, the knowledge of specific

gender differences known by planners is important. Two specific examples would be upper body

strength limitations and possible endurance issues associated with EVA, regarding which men

have an advantage over women.165 Women, however, have an advantage over men in the case of

kidney stone formation.166 The key goal for mission planners is to take an objective approach to

selection based on meritocracy, with selections including men and woman and also single and

married personnel.

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Specific mission factors must also be taken under advisement. Although there is no data

showing that menstruation contributes to DCS, steps should be taken to coordinate timing prior

to EVA.167 Other mission factors such as sex or, more importantly, conception during the

mission, which would be detrimental to the mother and the fetus, should be taken into

consideration.168 Other factors, such as sexual tension, should be avoided by means of

professionalism and concentration on mission goals.169

Summary and Recommendations

There is vast amount of information to digest when determining the viability of a manned

mission to Mars. The information needs to be further divided into two parts: one for those

complications for which there is no technological solution or countermeasure associated with the

effects of traveling to Mars and the other for those complications for which current space travel

has viable protection or countermeasures.

The “Show Stoppers”

The two primary challenges regarding a trip to Mars are the effects of radiation and the

microgravity environment on the human body. Both of these challenges have short-term and

long-term implications for astronauts, as summarized in the body of the paper. Although, the

mission planners can perform screening, countermeasures, and a host of protectionary functions,

it may not be possible to overcome these challenges. The first reason for doubt is that there is not

a substantial track record of long space missions, with approximately 350 people going into

space in the last four decades.170 This lack of data and exposure makes the Mars trip

experimental. It has a great deal of unknowns. The second reason for doubt is the ineffectiveness

of certain types of countermeasures, such as radiation shielding and a means of counteracting the

physiological effects of microgravity for current missions inside the Earth’s protectionary mass.

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NASA and Russia have not ventured past the protectionary boundaries of Earth since Apollo.

Technology has improved drastically since Neil Armstrong’s walk on the surface of the moon;

moreover, the technology needs to be tested in an environment outside the ISS.

The Minutia

In addition to the primary challenges of radiation and microgravity, researchers cannot

forget about the other technology required for the trip, even though a great portion of it has been

tested during previous missions. Designs can always be improved or replaced with new designs,

provided that researchers invest the time and effort. Minor challenges, such as extreme

temperatures, vacuum, sleep patterns, habitat, plasma interaction, micrometeoroids, and others,

have been at least intermittently solved by current technology and a proven track record in space.

However, Dr. Krishen from the Johnson Space Center (JSC) points out that the minutia, such as

safer propulsion, power, temperature control, navigation, avionics, EVA, and logistics, cannot be

overlooked for the trip to Mars.171

Need for Further Research on New Experimental Fronts

Here is a very small list of somewhat far-reaching research being performed by scientists

and researchers that can offer alternatives to standardized mission beliefs for the trip to Mars:

Mini-Magneto Spheres for active shields protecting the spacecraft and

astronauts from radiation, including cosmic radiation.172

Nuclear propulsion research to propel a larger spacecraft carrying larger

alternative countermeasures for microgravity, such as an artificial gravity

apparatus or giant water tanks for radiation shielding.173

The research associated with launch planning to shorten the mission with

alternative propulsion, as well as non-Hohmann transfer launches and

26  

burns.174 175 (It is important to note that a shorter trip means less exposure to

radiation and microgravity.)

Researchers and mission planners must be conscious of the alternative research being

conducted and not be stymied by traditional beliefs. The mission to Mars is experimental in

nature, and all alternative must be considered.

Final Recommendation

The final recommendation is to invest the reported 30 years and $400 billion cost into a

workable plan with milestones.176 The milestones should be based on the development of

countermeasures for radiation and the effects of microgravity on the astronauts. This research

must be performed in parallel with that regarding the minutia mentioned by Dr. Krishen, as well

as a push for alternative (non-mainstream) research. If and when these research initiatives

provide viable countermeasures, an unmanned mission should be conducted with either

automated animal habitats or other analogs for humans in order to measure the effectiveness of

the research and the trip. Only when all the milestones are reached should the mission to Mars be

green-lit by the Office of the President and NASA.

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NOTES

                                                              1 David Williams et al., "The space-flight environment: the International Space Station and beyond," CMAJ: Canadian Medical Association Journal 180, no. 12 (June 9, 2009): 1216-1220, Academic Search Premier, EBSCOhost (accessed May 24, 2012), 1217. 2 Ibid. 3 Gilles Clement, Fundamentals of Space Medicine, El Segundo, CA: Microcosm Press, 2005, 156. 4 Ibid. 5 Ibid., 157. 6 Jay C. Buckey, Space Physiology, New York: Oxford University Press, 2006, 103. 7 Ibid. 8 David Williams et al., "The space-flight environment: the International Space Station and beyond," 1217. 9 Ibid. 10 Jay C. Buckey, Space Physiology, 104. 11 Ibid., 108. 12 Ibid. 13 Ibid., 110. 14 Ibid., 107. 15 David Williams et al., "The space-flight environment: the International Space Station and beyond," 1217. 16 Jay C. Buckey, Space Physiology, 115. 17 Ibid. 18 David Williams et al., "The space-flight environment: the International Space Station and beyond," 1218. 19 Ibid. 20 Martin E. Young and Molly S. Bray, "Potential Role for Peripheral Circadian Clock Dyssynchrony in the Pathogenesis of Cardiovascular Dysfunction," National Center for Biotechnology Information, http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2020822/ (accessed June 17, 2012). 21 Ibid. 22 Ibid. 23 Ibid.

28  

                                                                                                                                                                                                 24 Gilles Clement and Douglas Hamilton, Fundamentals of Space Medicine CD-ROM, Dordrecht, Netherlands: Springer, 2005. 25 David Williams et al., "The space-flight environment: the International Space Station and beyond," 1219. 26 Martin E. Young and Molly S. Bray, "Potential Role for Peripheral Circadian Clock Dyssynchrony in the Pathogenesis of Cardiovascular Dysfunction." 27 Siobhan, Banks and David S. Dinges, "Behavioral and Physiological Consequences of Sleep Restriction," National Center for Biotechnology Information, http://www.ncbi.nlm.nih.gov/pmc /articles/PMC1978335 /?tool=pmcentrez (accessed June 17, 2012). 28 Ibid. 29 Ibid. 30 Martin E. Young and Molly S. Bray, "Potential Role for Peripheral Circadian Clock Dyssynchrony in the Pathogenesis of Cardiovascular Dysfunction." 31 David Williams et al., "The space-flight environment: the International Space Station and beyond," 1218. 32 Ibid. 33 Geoffry A. Landis, "Human Exposure to Vacuum," http://www.geoffreylandis.com/vacuum.html (accessed June 17, 2012). 34 Ibid. 35 Ibid. 36 Ibid. 37 Jay C. Buckey, Space Physiology, 54. 38 Ruth Bamford, Robert Bingham, and Mike Hapgood, "Shields for the starship Enterprise," Astronomy & Geophysics 48, no. 6 (December 2007): 6.18-6.23, Academic Search Premier, EBSCOhost (accessed May 24, 2012), 618. 39 Ibid. 40 Ibid. 41 Ibid. 42 Ibid., 55. 43 Ibid. 44 Ibid., 56. 45 Ruth Bamford, Robert Bingham, and Mike Hapgood, "Shields for the starship Enterprise," 623. 46 Gilles Clement and Douglas Hamilton, Fundamentals of Space Medicine CD-ROM.

29  

                                                                                                                                                                                                 47 Ibid. 48 Ibid. 49 David Williams et al., "The space-flight environment: the International Space Station and beyond," 1218. 50 Ibid. 51 Ibid. 52 Ibid. 53 Ruth Bamford, Robert Bingham, and Mike Hapgood, "Shields for the starship Enterprise," 619. 54 Jerry John Sellers, Understanding Space, New York: The McGraw-Hill Companies, Inc., 2005, 95. 55 J.W. Wilson, "Optimized Shielding for Space Radiation Protection," Mars Journal, http://marsjournal.org/contents/2006/0004/files/Wilson2001.pdf (accessed May 22, 2012), 67. 56 Patrick L. Barry, "Plastic Spaceships," NASA, http://science.nasa.gov/science-news/science-at-nasa/2005/25aug_plasticspaceships/ (accessed May 22, 2012). 57 Eric Grulke et al., "Polyethylene/Boron Composites for Radiation Shielding Applications," AIP Conference Proceedings 969, no. 1 (January 21, 2008): 484-491, Academic Search Premier, EBSCOhost (accessed May 24, 2012), 484. 58 Eugene N. Parker, "Shielding Space," APUS, https://edge.apus.edu/access/content/attachment/184053/ Forums/e6febab5-247b-4738-afd6-563ca606bf49/Shielding Space Travelers.pdf (accessed May 22, 2012). 59 Ruth Bamford, Robert Bingham, and Mike Hapgood, "Shields for the starship Enterprise," 619. 60 Ibid., 621. 61 David Williams et al., "The space-flight environment: the International Space Station and beyond," 1219. 62 Ibid. 63 Ibid. 64 Ibid. 65 Ruth Bamford, Robert Bingham, and Mike Hapgood, "Shields for the starship Enterprise," 619. 66 Ibid. 67 David Williams et al., "The space-flight environment: the International Space Station and beyond," 1219. 68 Ibid. 69 Ibid. 70 Ibid. 71 Gilles Clement, Fundamentals of Space Medicine, 4. 72 Ibid., 92.

30  

                                                                                                                                                                                                 73 Ibid. 74 Ibid., 94. 75 Ibid. 76 Ibid., 92. 77 Ibid. 78 Jay C. Buckey, Space Physiology, 190. 79 Ibid., 191. 80 Gilles Clement, Fundamentals of Space Medicine, 94. 81 Ibid. 82 Ibid., 131. 83 Ibid., 96. 84 Ibid., 95. 85 Ibid., 97. 86 Ibid., 95. 87 Ibid., 132. 88 Ibid. 89 Jay C. Buckey, Space Physiology, 196. 90 Gilles Clement, Fundamentals of Space Medicine, 134. 91 Ibid., 135. 92 Ibid. 93 Jay C. Buckey, Space Physiology, 202. 94 Ibid., 136. 95 Ibid. 96 William B. Scott, "Artificial Gravity," Aviation Week & Space Technology 162, no. 17 (April 25, 2005): 62-64, Academic Search Premier, EBSCOhost (accessed May 24, 2012), 1. 97 Gilles Clement, Fundamentals of Space Medicine, 173. 98 Ibid., 174. 99 Ibid.

31  

                                                                                                                                                                                                 100 Ibid. 101 Ibid. 102 Ibid., 184. 103 Ibid. 104 Ibid., 192. 105 Ibid. 106 Ibid., 175. 107 Ibid. 108 Ibid. 109 Ibid., 176. 110 Jay C. Buckey, Space Physiology, 4. 111 Gilles Clement, Fundamentals of Space Medicine, 183. 112 Ibid. 113 Ibid. 114 Jay C. Buckey, Space Physiology, 25. 115 Gilles Clement, Fundamentals of Space Medicine, 196. 116 Ibid., 197. 117 Ibid., 199. 118 Jay C. Buckey, Space Physiology, 172. 119 Ibid., 8. 120 Ibid., 24. 121 Ibid., 25. 122 Gilles Clement, Fundamentals of Space Medicine, 139. 123 Ibid. 124 Ibid. 125 Ibid., 140. 126 Ibid.

32  

                                                                                                                                                                                                 127 Ibid. 128 Ibid., 141.   129 Ibid. 130 Jay C. Buckey, Space Physiology, 149. 131 Gilles Clement, Fundamentals of Space Medicine, 157. 132 Ibid.,148. 133 Ibid., 152. 134 Ibid., 153. 135 Ibid. 136 Ibid., 154. 137 Jay C. Buckey, Space Physiology, 162. 138 Ibid., 163. 139 Ibid. 140 Lori Meggs, "Astronauts Getting to the Heart of the Matter," NASA's Marshall Space Flight Center, http://www.nasa.gov/mission_pages/station/research/integrated_cardio_prt.htm (accessed June 17, 2012). 141 Jay C. Buckey, Space Physiology, 34. 142 Gilles Clement, Fundamentals of Space Medicine, 208. 143 Ibid. 144 Ibid., 209. 145 Jay C. Buckey, Space Physiology, 43. 146 Ibid., 36. 147 Anne-Marie Corley, "520 DAYS," New Scientist 211, no. 2830 (September 17, 2011): 39-43. Academic Search Premier, EBSCOhost (accessed May 24, 2012), 6. 148 Gilles Clement, Fundamentals of Space Medicine, 234. 149 Jay C. Buckey, Space Physiology, 37. 150 Ibid. 151 Anne-Marie Corley, "520 DAYS," 5. 152 Ibid., 6.

33  

                                                                                                                                                                                                 153 Jay C. Buckey, Space Physiology, 37. 154 Ibid. 155 Ibid., 38. 156 Ibid. 157 Ibid. 158 Ibid., 39. 159 Ibid., 50. 160 Gilles Clement, Fundamentals of Space Medicine, 234. 161 Ibid., 238. 162 Ibid. 163 Jay C. Buckey, Space Physiology, 50. 164 Ibid., 209. 165 Ibid. 166 Ibid. 167 Ibid., 215. 168 Ibid., 219. 169 Ibid. 170 David Williams et al., "The space-flight environment: the International Space Station and beyond," 1216. 171 Kumar Krishen, "Technology Needs for Future Space Exploration," IETE Technical Review 26, no. 4 (July 2009): 228-235, Academic Search Premier, EBSCOhost (accessed May 24, 2012), 234. 172 Ruth Bamford, Robert Bingham, and Mike Hapgood, "Shields for the starship Enterprise," 618. 173 J. E. Brandenburg, "Mars X: A Mars Mission Architecture with Lunar-Mars Synergy," AIP Conference Proceedings 813, no. 1 (January 20, 2006): 1178-1185, Academic Search Premier, EBSCOhost (accessed May 24, 2012). 1178. 174 M. Durante and C. Bruno, "Impact of rocket propulsion technology on the radiation risk in missions to Mars," European Physical Journal D -- Atoms, Molecules, Clusters & Optical Physics 60, no. 1 (November 15, 2010): 215-218, Academic Search Premier, EBSCOhost (accessed May 24, 2012), 215. 175 Mehdi Lali, "Analysis and Design of a Human Spaceflight to Mars, Europa, and Titan," AIP Conference Proceedings 1208, no. 1 (January 28, 2010): 557-565, Academic Search Premier, EBSCOhost (accessed May 24, 2012). 559.

34  

                                                                                                                                                                                                 176 Matthew Forney et al., "MISSION TO MARS, (Cover story)," Time 163, no. 4 (January 26, 2004): 42- 50, Academic Search Premier, EBSCOhost (accessed May 24, 2012), 42.

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