Download S Roberts - Anaesthesia and Spaceflight

13 July 2012
No. 23
Anaesthesia and Spaceflight
SM Roberts
Commentator: D Naidoo
Department of Anaesthetics
Moderator: S Tarr
CONTENTS
INTRODUCTION ................................................................................................... 3
CONTEXT ............................................................................................................. 3
PHYSIOLOGY ...................................................................................................... 5
SURGICAL AND ANAESTHETIC CONCERNS ................................................. 11
CONCLUSION .................................................................................................... 16
APPENDIX .......................................................................................................... 17
REFERENCES.................................................................................................... 19
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INTRODUCTION
The primary goal of this text is to outline interesting information and published
literature on the topic of Anaesthesia and Spaceflight. From a South African
perspective, on 25 April 2002, Mark Shuttleworth became the second self-funded
space tourist and the first African in space [1], and this year on the 2nd May 2012,
Virgin Galactic announced that Virgin Atlantic (Johannesburg) became one of the
140 international space agents to sell commercial space flights in South Africa [2].
It is understandable that a reader could question the relevance of the topic of
Anaesthesia and Spaceflight. These reasons include: the absence of a national
space program; the likely perception that the practice of anaesthesia in space is
futuristic and non-clinical to the majority of anaesthetists in Africa; and that in light
of the global financial situation, funding for space programs would likely be
reduced. Hopefully, as secondary goals, this text will also reveal that the topic is
not so “far-fetched”, that the ongoing contribution to medical knowledge from
experiments during spaceflight is significant, that research and development of
anaesthesia in this context is important and, lastly, to acknowledge our
international colleagues who are demonstrating passion, bravery and intellect for
human exploration.
CONTEXT
The context of the topic of Anaesthesia and Spaceflight first needs to be
established. Without an interest in spaceflight, there is little common knowledge of
participating countries, the complexities of spaceflight and establishing a space
station, current expeditions and experiments, and spaceflight crew structure and
training.
Probably the most globally known organisation is the National Aeronautics and
Space Administration (NASA) in the United States of America. However, currently
there are 17 other countries represented by 37 agencies, administrations and
organizations (Appendix 1). Facts, figures and quotes below are from the official
NASA website [3].
NASA conducts its work through three mission directorates:
 Aeronautics: which pioneers flight technologies to improve the ability to
explore space and have practical applications on earth
 Human Exploration and Operations: which focuses on the International
Space Station (ISS) and human exploration beyond low Earth orbit
 Science: which explores the Earth, solar system and universe beyond.
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Even though the NASA space shuttle program has ended, some of the future
plans of NASA listed below will require the field of Anaesthesia to continue to
provide input into the establishment of medical care in space:
 NASA is designing and building capabilities to send humans to explore the
solar system, working toward a goal of landing humans on Mars.
 The ISS remains fully staffed with a crew of six, with humans living and
working in space 365 days a year.
 Commercial companies are on their way forward to providing cargo and
crew flights to the ISS.
 NASA is part of the team working on the Next Generation Air Transportation
System, to be in place by 2025.
As space travel develops into flights of longer duration reaching further locations
and possibly even one day habitation on another planet, the need for surgical
intervention, anaesthesia and critical care in space is inevitable [4].
NASA expeditions and the ISS will serve as the prototype for spaceflight in this
text.
Some facts about the ISS are given below, with more in Appendix 2, to get a
better idea of what was required to establish it. The ISS marked 10 years of
human occupation in 2010. The space station has been visited by 202 individuals.
At the time of the anniversary, the station’s odometer read more than 1.5 billion
statute miles (the equivalent of eight round trips to the Sun), over the course of
57,361 orbits around the Earth. As of August 2011, there have been 135 launches
to the space station since the launch of the first module, Zarya, Nov. 20, 1998: 74
Russian vehicles, 37 space shuttles, two European and two Japanese vehicles.
The final space shuttle mission delivered 4 & 1/2 tons of supplies.
A total of 161 spacewalks have been conducted in support of space station
assembly totaling more than 1,015 hours. The space station, including its large
solar arrays, spans the area of a U.S. football field, and weighs 861,804 pounds
(390,907 kg), not including visiting vehicles. The complex now has more livable
room than a conventional five-bedroom house, and has two bathrooms, a
gymnasium and a 360-degree bay window.
Research is continually underway aboard the ISS. These can be categorized as:
 Biology and Biotechnology: study of biological processes in microgravity
 Earth and Space science: at an average altitude of 400km, details of the
Earth’s surface and space can be studied
 Human research: “The space station is being used to study the risks to
human health that are inherent in space exploration. Focal research
questions address the mechanisms of the risks and develop test
countermeasures to reduce these risks.
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Research on space station addresses the major risks to human health
from residence in a long-duration microgravity environment. Results from
this research are key enablers for future long-duration missions beyond
low Earth orbit.” [3]
 Physical sciences: the study of the long term physical effects in the
absence of gravity
 Technology: the study and testing of technologies, materials and systems
needed for longer-duration exploration.
Some of the current human experiments underway can be seen in at the specific
referenced NASA link [5].
Who makes up the six man crew? On the latest expedition, Expedition 31, there is
a commander and five flight engineers. The selection criteria to enter astronaut
training include:
 Any adult man or woman
 Excellent physical health
 Bachelor’s degree in engineering, science or mathematics from an
accredited institution, with three years experience, and an advanced degree
is desirable
 Pilot astronauts need 1000 hours jet aircraft experience and certain vision
requirements.
There is an average of 4000 applicants for 20 openings every two years.
Each crew will include a crew medical officer (CMO) who currently, however, may
have no medical background before entering astronaut training [4]. The CMO
training thereafter approximates 80 hours only. We can now explore the
physiology, surgical and anaesthetic concerns of spaceflight. Most of the text will
come from five good review articles [4, 6-9] and Miller’s Anesthesia [10] , which
reference much of the current literature.
PHYSIOLOGY
The phases of spaceflight can be described as Launch, Flight (short or long
duration), Landing and the Post flight period. Each phase requires acclimation,
which is the acute change in normal physiology by a complex multisystem
response to an abnormal environment. Recovery in the post flight period may be
longer than the actual mission and some physiological effects like bone
demineralization after long-duration flights may be permanent. Countermeasures
pre-, intra-, and post-flight can be taken which reduce the health risks to the crew.
The fact that spaceflight requires physiologic acclimation centers round the
changes in gravity. During launch and landing, gravitational effects on the body
increase compared to the gravitational effect on Earth (the crew experience “G
forces”), whereas during flight, the body is exposed to microgravity (the literature
seems to use the terms “microgravity”,” zero gravity” and “weightlessness”
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interchangeably). Other factors of the abnormal environment include isolation and
confinement which may have psychological and psychosomatic implications. All
organ systems can be affected to varying degrees. Table 1 [6] outlines acclimation
related to phases of spaceflight and flight duration, and table 2 [6] outlines
countermeasures to reduce risk.
Table 1: Timeline of physiologic acclimation experienced by astronauts from launch to the post
flight period.
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Table 2: Countermeasures to minimize risk to astronauts
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Cardiovascular response and shift in body fluids
The cardiovascular response to microgravity is complex and there are many
published articles studying aspects of the physiology. Models have been
developed based on studies in real and simulated microgravity which show the
immediate and delayed changes in intravascular volume, neurohumeral
responses and cardiovascular reflexes, vascular tone, water and electrolyte
composition, circadian rhythm and muscle mass. One such model is shown in
figure 1 [7] and outlines many of the major components of the cardiovascular
acclimation to microgravity.
Figure 1: Suggested cardiovascular response to weightlessness
The primary cause of the acclimation is the redistribution of body fluids, with an
increase in the central blood volume as the blood and tissue fluid accumulates in
the torso and head from the lower legs (“Puffy face-bird leg” syndrome), with
resultant neurohumeral responses.
Prior to launch, the astronauts are in a supine position with the legs elevated,
initiating the redistribution of body fluid. During Launch, the body is exposed to an
increase in G force due to the Earth’s gravity and the speed of ascent (typically 34G), which likely would contribute to this redistribution.
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Once in space, the microgravity environment and loss of a hydrostatic gradient in
the cardiovascular system maintain this increase in central blood volume. The
increase in central blood volume leads to a baroreceptor response inhibiting the
renin-angiotensin-aldosterone system and the release of atrial natriuretic peptide.
Thus there is increased renal excretion of salt and water, and a reduction in
plasma volume of approx 17% by 24 hours. With this reduction in plasma volume
is a transient increase in the haematocrit, leading to a decrease in erythropoeitin
secretion, a reduction in red cell mass and a net overall reduction of
approximately 10% in total blood volume.
Aerobic capacity with the reduced total blood volume can be maintained in the
microgravity environment in space. However, in the presence of this reduced total
blood volume (with a central distribution), combined with altered cardiovascular
receptor responses (e.g. enhanced eNOS expression, down regulation of alphaadrenergic receptors) and reduced myocardial and somatic muscle mass after
long-duration flights, astronauts face an orthostatic stress on landing and in the
post flight period. On landing, the G forces experienced are increased (typically
1.5-4G). In the post flight period, astronauts typically experience some degree of
orthostatic hypotension (with its associated symptoms of light-headedness,
syncope, palpitations, sweating and nausea vomiting) and 1 out of 4 astronauts
cannot stand quietly for 10 continuous minutes on the first day of landing without
symptoms.
Countermeasures to cope with the cardiovascular acclimation are being
developed and include exercise, pressure suits (negative and positive pressure for
different phases of spaceflight), fluid therapy, positioning during phases of travel
and drug therapy (alpha-1 agonist midodrine [11], as shown in Table 2).
Respiratory
Cabin pressure in the ISS is 760mmHg. However, when the astronauts venture
out of the pressurized cabin (extravehicular activity (EVA) or “spacewalks”), not
only is acclimation required for the microgravity, but the space suit pressure is
only 222mmHg, which is similar to the ambient pressure at the top of Mount
Everest at 8 848m (Figure 2 [10]).
This results in a decreased alveolar partial pressure of oxygen and hypoxia is
prevented by the astronauts breathing 100% oxygen. The astronauts are at risk of
decompression sickness (the formation of gas bubbles in tissue and blood), and
possibly features of acute mountain sickness, high-altitude cerebral oedema, and
high-altitude pulmonary oedema.
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Figure 2: Ambient pressure as a function of altitude and depth. Note the NASA space suit
pressure in the left graph. AMS-acute mountain sickness, HAPE- high altitude pulmonary
edema, HACE- high altitude cerebral edema.
Space motion sickness
Space motion sickness is a syndrome of facial pallor, cold sweating, stomach
awareness, nausea and in some cases vomiting. It represents neurovestibular
acclimation to the first 48hours in space and again on landing and the first
48hours in the Post flight period. The physiological components include visual and
vestibular perception discordance in the three dimension space environment as
well as body fluid redistribution affecting gastrointestinal afferents and intracranial
hypertension. This important syndrome may impact on crew performance,
particularly during landing. Countermeasures include neurovestibular
preconditioning and medications as in table 2.
Muscle atrophy
The loss of gravitational loading, suboptimal nutrition and stressful working
conditions contribute to the known loss of muscle mass, in particular of the
postural muscles. The amount of loss is related to the duration of flight, with up to
30% muscle loss on missions of 3-6 months duration. Studies have looked at
muscle fibre number, fibre size and fibre types that are affected. With the loss of
muscle mass, there is loss of muscle strength, fatigueability, loss of explosive
contractile force and various other changes in motor unit recruitment and the
contractile apparatus. In the post flight period, astronauts can report muscle pain,
plantar fasciitis and tight hamstrings and calves.
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Countermeasures hinge around exercise programs and most astronauts fully
recover within 2 months after landing.
Bone demineralization
During spaceflight, the absence of gravitational loading on bones is absent which
leads to bone reabsorption and loss of bone density (osteoporosis). The lower
levels of light (leading to vitamin D deficiency) and higher ambient carbon dioxide
levels (with a respiratory acidosis) may contribute. The rate of decline in bone
density is approximately 1-2% per month in microgravity in weight bearing bones.
There is marked inter individual variation. There is marked (60-70%) increases in
urinary and faecal calcium.
Countermeasures include peri-flight bone density assessments, exercise
programs, nutrition and the restriction of high fracture-risk activities in the recovery
period, but the focus is on prevention of bone loss during flight. Recovery can take
up to three years, but in some may not be complete and the remodelled bone may
not have the same structure or mineralization.
Psychosocial and Immune function
There is much literature on the psychosocial effects and changes in immune
function with spaceflight. Suffice to say, there are highly detailed processes for
selection and training of the crew members with numerous support measures in
place and being developed to optimize crew psychosocial stability and
performance. Immune suppression occurs during spaceflight and in the recovery
period with impaired cellular immunity, and reactivation of latent herpes virus.
Numerous components of the immune system have been studied showing global
dysregulation.
The pathophysiology is complex including the effects of psychological and
physical stress, nutrition changes, changes in circadian rhythm, neurohumeral
(especially glucocorticoid and catecholamine) changes for microgravity
acclimation, and confinement.
SURGICAL AND ANAESTHETIC CONCERNS
As yet, a surgical procedure has not been performed on a human in space and
clinical experience is very limited. Currently on the ISS, there is an Advanced
Cardiac Life Support (ACLS) pack and an Advanced Trauma Life Support (ATLS)
pack, allowing ventilation and defibrillation. There is also a Shuttle Orbital Medical
System Pack, with components of a minor surgical kit for lacerations. These
include local anaesthetics as well as minimal-skill laceration closure techniques
(e.g. steri-strips, dermabond adhesive). The capability to perform major surgery
on the ISS is currently not available. The current approach would be to stabilize as
far as possible and return to earth for definitive care.
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The time to definitive care on the ISS is 6 to 24 hours making use of a medical
evacuation spacecraft (the Crew Return Vehicle).
On earth, even though a certain surgical procedure may be considered simple, we
know that the provision of safe general or regional anaesthesia and critical care
can be complex. This is even more so when one wonders how to provide
anaesthetic care in space due to the physiological and technical challenges
related to spaceflight. Studies are being done in simulated environments (like
water immersion and parabolic flight), however these simulations have short
comings and the best information will come from studies in actual spaceflight.
Even though, through the rigorous crew selection process, the persons involved in
spaceflight are in excellent physical condition, a pattern of disease can be
predicted during spaceflight which may require medical care involving
anaesthesia. Principally mentioned in the literature are urological procedures (to
manage nephrolithiasis due to altered calcium metabolism) and trauma. However,
using analog environments (such as submarine cruises) to extrapolate to
spaceflight, a wide spectrum of disease could occur. As mentioned previously,
with the goal of longer duration and further location spaceflights, it is safe to
assume that the medical care in general, and anaesthetic capabilities in particular,
would have to be able to manage a wide range of disease and injuries in the
future.
Technical challenges
There are many technical challenges to the provision of medical care and
anaesthesia in spaceflight. These relate to the limited space, closed environment,
cost, available equipment and stock, information technology and backup, CMO
skills, and the microgravity environment.
 The station or shuttle is a tightly closed environment, sealed off from the
outside for obvious reasons. However, this requires a tightly controlled and
unpolluted cabin atmosphere. Drugs used must not contaminate the
atmosphere or the water systems. Flushed oxygen may increase the fire
hazard in the cabin. The safe use of volatile anaesthesia would be difficult.
 The choice of equipment, drugs, disposable vs. reusable stock, fluids, blood
products, item shelf life, cold chain storage, etc. requires careful planning,
and cost-benefit analyses will be complex. It approximately costs US$22
000 to take 1kg material (e.g. a vacolitre) into orbit. Storage restrictions are
significant.
 As discussed previously, the single CMO is generally not from a medical
background, has limited hours of medical training during the astronaut
training program and would not have the necessary skills for major surgery
or anaesthesia. Crew composition would need to include two CMO’s with
the appropriate surgical and anaesthetic skills to perform surgery in space.
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Some studies have looked at telemedicine support and remotely guided
diagnostic ultrasound. Robotic surgery with the operators on earth has been
considered, but with current technology, even robotic surgery performed on
earth with the robot and operator at different locations has limitations with
the system time delay. These advanced remote-support possibilities as well
as on-board information systems would need further investigation.
 Microgravity has many implications for the functioning of a “theatre
environment”:
o The need for restraint: The patient, operating staff and equipment
needs restraint in microgravity otherwise physical actions are made
more difficult and awkward. Currently on the ISS, is a Crew Medical
Restraint System at the level of the floor. Careful planning is needed
to have all necessary equipment within arm’s length of the restrained
operators. Sharp objects can be inserted into a Styrofoam block to
prevent them floating around the surgical area until they can be stored
safely. Securing an airway has been described using a technique to
restrain the operator and mannequin, and a technique with the CMO
stabilizing a free floating mannequin’s head between one’s knees
(Figure 3. [10])
o Cleaning, draping and preventing contamination: Investigators
propose a closed system around the surgical site to manage the dual
issues of maintaining sterility and preventing contamination of the
ambient environment with blood, pus and/or tissue particles. A canopy
prototype is depicted in Figure 4 [8] which has a patient interface and
ports through which the operators arms can protrude to operate.
o Fluid and vaporizer management: There is no separation of gases and
fluids due to different densities in microgravity, with the absence of airfluid levels and fluids being similar to a foam with numerous air
bubbles (Figure 5 [4]). This makes administering IV fluids, drawing up
IV drugs, providing total intravenous anaesthesia and managing
intercostals drains extremely difficult. Conventional volatile
anaesthetic vaporizers do not function in microgravity as they depend
on the gravity-induced separation of gases and liquids. New devices
would need to be developed to deal with these challenges.
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Figure 3: Tracheal intubation in microgravity stabilizing a mannequin’s head between one’s knees.
Figure 4: A surgical containment canopywith ports for the operators arms.
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Figure 5: A bag of normal saline in orbital flight with numerous gas bubbles.
Physiological challenges
An outline of the physiological changes of acclimation to spaceflight was given in
the previous sections. One can accept that these changes need to be taken into
account for the provision of anaesthesia during flight or in the post flight period, in
particular the cardiovascular changes. In one animal experiment (Bion 11 mission)
described in Miller’s Anesthesia [10]and Norfleet’s review article [4], two primates
were administered general anaesthesia (ketamine, isoflurane) within 24 hours
after landing, having spent 14 days in space, by competent veterinary
anaesthetists for minor surgical procedures such as muscle biopsies.
One animal aspirated during emergence and could not be resuscitated and the
other developed lethargy and facial oedema in recovery 3 hours later. Anaesthetic
techniques cannot be assumed to be safe in humans during flight or in the postflight period, and the physiological challenges to the provision of anaesthesia are
mentioned below:
 Airway: The majority of crew members will experience space motion
sickness in flight and the post flight period. An increased risk of gastrooesophageal reflux with reduced gastric motility has been shown in space
motion sickness, possibly placing the crew member at an increased risk of
aspiration on induction and awakening from general anaesthesia. Not only is
a crew member at a possible increased risk of aspiration, but due to the
body fluid redistribution in microgravity, they may be at risk of difficult bag
mask ventilation, laryngoscopy or rescue airway placement due to facial and
airway tissue oedema.
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The laryngeal mask airway (LMA), intubating LMA, combitube and cuffed
endotracheal tubes have been successfully placed in simulated
microgravity.
 Hypovolaemia and autonomic dysfunction: The cardiovascular acclimation
to microgravity results in hypovolaemia and adrenergic hyporesponsiveness,
particularly in the post flight period resulting in orthostatic intolerance. This
has many implications for the provision of anaesthesia, both regional and
general, in flight or in the post flight period. Similarly, the resuscitation and
transfer of a cardiovascularly unstable trauma or medical patient for
definitive care is made even more difficult due to the compound effects of
the baseline hypovolaemia and autonomic dysfunction, the new pathology,
as well as the increased gravitational forces on landing. The cardiovascular
status (a 10% reduction in total blood volume) of an uninjured crew member
is similar to a Class 1 haemorrhage. After trauma and during landing, a true
class 1 haemorrhage may in fact behave as a Class 2 or 3 haemorrhage.
 Neuromuscular physiology: Long duration flights theoretically induce similar
receptor changes at the neuromuscular junction as prolonged bedrest. The
will have implications for the use of suxamethonium and a hyperkalaemic
response as well as the duration of action of non-depolarising
neuromuscular blocking agents and further studies are needed.
 Electrolyte changes: Reductions in serum potassium and magnesium, as
well as other electrolytes, may place patients at risk of arrhythmias.
 Anaesthetic agents: Little is known about the pharmacokinetics and
pharmacodynamics of intravenous and volatile anaesthetic agents and other
medications in microgravity as yet. Animal experiments are underway, and
total intravenous anaesthesia may hold promise for performing general
anaesthesia in space [12].
A more detailed discussion on the theoretical choice between regional versus
general anaesthesia in space is covered in an good article by Silverman and
McCartney [9].
CONCLUSION
The ongoing existence of the ISS and plans by NASA and other international
space agencies to pursue longer duration spaceflight and even habitation on other
planets, will require the ability to provide medical and surgical care for a wider
variety and greater severity of pathologies. There will be many challenges in
achieving this and, even though there is already some guiding literature, further
studies in microgravity and the development of new technologies and devices will
be needed to make the provision of general and regional anaesthesia safe.
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APPENDIX
Appendix 1: International
organizations [3].
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space
agencies,
administrations
ARGENTINA
National Commission on Space Activities (CONAE)
AUSTRALIA
Commonwealth Scientific Industrial Research Organization (CSIRO)
BRAZIL
Instituto Nacional de Pesquisas Espaciais (National Institute for Space Research) (INPE)
CANADA
Canadian Space Agency
FRANCE
Centre National d'Etudes Spatiales (CNES)
Office National d'Études et de Recherches Aérospatiales (ONERA/CERT)
French Ministry of Research
GERMANY
German Aerospace Center (DLR)
Max Planck Institutes
GFZ
INTERNATIONAL ORGANIZATIONS
International Telecommunications Satellite Organization (INTELSAT)
International Maritime Satellite Organization (INMARSAT)
European Telecommunications Satellite Organisation (EUTELSAT)
North Atlantic Treaty Organization (NATO)
NATO / Research and Technology Organization
International Standards Organization (ISO)
Organization for Economic Cooperation and Development (OECD)
United Nations Office for Outer Space Affairs
ITALY
Italian Space Agency (ASI)
JAPAN
Institute of Space and Astronautical Science (ISAS)
Japan Aerospace Exploration Agency (JAXA)
Ministry of International Trade and Industry (MITI)
Electrotechnical Laboratory (ETL)
Ministry of Education, Culture, Sports, Science and Technology
Japanese Patent Office
THE NETHERLANDS
The Netherlands Agency for Aerospace Programmes (NIVR)
Space Research Organization Netherlands
RUSSIAN FEDERATION
Russian Space Science Internet
Russian Academy of Sciences (RAS)
Space Research Institute (IKI)
SOUTH KOREA
Ministry of Science and Technology (MOST)
Korean Aerospace Research Institute (KARI)
NORWAY
Norwegian Space Centre
SPAIN
Instituto Nacional de Técnica Aeroespacial (INTA)
SWEDEN
Swedish Space Corporation
TAIWAN
National Space Program Office of Taiwan
UNITED KINGDOM
British National Space Centre (BNSC)
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and
Appendix 2: More facts about the International Space Station [3].
Size & Mass:
 Module Length: 167.3 feet (51 meters)
 Truss Length: 357.5 feet (109 meters)
 Solar Array Length: 239.4 feet (73 meters)
 Mass: 861,804 lb (390,908 kilograms)
 Habitable Volume: 13,696 cubic feet (388 cubic meters)
 Pressurized Volume: 32,333 cubic feet (916 cubic meters)
 Power Generation: 8 solar arrays = 84 kilowatts
 Lines of Computer Code: approximately 2.3 million
Other facts:
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The ISS solar array surface area could cover the U.S. Senate Chamber three times over.
ISS eventually will be larger than a five-bedroom house.
ISS will have an internal pressurized volume of 33,023 cubic feet, or equal that of a Boeing 747.
The solar array wingspan (240 ft) is longer than that of a Boeing 777 200/300 model, which is 212 ft.
Fifty-two computers will control the systems on the ISS.
More than 115 space flights will have been conducted on five different types of launch vehicles over
the course of the station’s construction.
More than 100 telephone-booth sized rack facilities can be in the ISS for operating the spacecraft
systems and research experiments
The ISS is almost four times as large as the Russian space station Mir, and about five times as large
as the U.S. Skylab.
The ISS will weigh almost one million pounds (925,627 lbs). That’s the equivalent of more than 320
automobiles.
The ISS measures 357 feet end-to-end. That’s equivalent to the length of a football field including the
end zones (well, almost – a football field is 360 feet).
3.3 million lines of software code on the ground supports 1.8 million lines of flight software code.
8 miles of wire connects the electrical power system.
In the International Space Station’s U.S. segment alone, 1.5 million lines of flight software code will
run on 44 computers communicating via 100 data networks transferring 400,000 signals (e.g.
pressure or temperature measurements, valve positions, etc.).
The ISS will manage 20 times as many signals as the Space Shuttle.
Main U.S. control computers have 1.5 gigabytes of total main hard drive storage in U.S. segment
compared to modern PCs, which have ~500 gigabyte hard drives.
The entire 55-foot robot arm assembly is capable of lifting 220,000 pounds, which is the weight of a
Space Shuttle orbiter.
The 75 to 90 kilowatts of power for the ISS is supplied by an acre of solar panels.
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REFERENCES
1. http://en.wikipedia.org/wiki/Mark_Shuttleworth.
2. http://www.timeslive.co.za/scitech/2012/05/02/virgin-appoints-south-africanspace-flight-agent.
3. http://www.nasa.gov/.
4. Norfleet, W.T., Anesthetic concerns of spaceflight. Anesthesiology, 2000.
92(5): p. 1219-22.
5.khttp://www.nasa.gov/mission_pages/station/research/experiments/experiment
shardware.html#Human-Research.
6. Williams, D., et al., Acclimation during space flight: effects on human
physiology. CMAJ, 2009. 180(13): p. 1317-23.
7. Pavy-Le Traon, A., et al., From space to Earth: advances in human physiology
from 20 years of bed rest studies (1986-2006). Eur J Appl Physiol, 2007.
101(2): p. 143-94.
8. Campbell, M.R., A review of surgical care in space. J Am Coll Surg, 2002.
194(6): p. 802-12.
9. Silverman, G.L. and C.J. McCartney, Regional anesthesia for the management
of limb injuries in space. Aviat Space Environ Med, 2008. 79(6): p. 620-5.
10. Miller's Anesthesia. 7 ed. Vol. 2. 2010.
11. Ramsdell, C.D., et al., Midodrine prevents orthostatic intolerance associated
with simulated spaceflight. J Appl Physiol, 2001. 90(6): p. 2245-8.
12. Chad G. Ball, M.A.K., Rosaleen Chun, Michelle Groleau, MichelleTyssen,
Jennifer Keyte, Timothy J. Broderick, Andrew W. Kirkpatrick, Anesthesia and
critical-care delivery in weightlessness. Planetary and Space Science, 2010.
58(4): p. 732-740.
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