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Italian Astronaut Brews, Sips First Fresh Espresso in Space Options
Posted: Wednesday, May 6, 2015 5:00:00 AM
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Italian Astronaut Brews, Sips First Fresh Espresso in Space

The first Italian woman in space is now the world's first orbiting barista. Over the weekend, astronaut Samantha Cristoforetti fired up the first espresso machine in space. She posted a photo of herself on Twitter from the International Space Station ... More...
JUSTIN Excellence
Posted: Wednesday, May 6, 2015 7:34:55 AM

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Joined: 6/25/2014
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Location: Veinau, Baden-Wuerttemberg Region, Germany
``When you discover new things every minute and your mind is absorbing so many experiences, it feels like time expands.’ ’

Samantha Cristoforetti

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Space life sciences is a young science, having come into existence with the first studies carried out on animals during the first suborbital flight less than 60 years ago. Since then, people have visited the Moon and have lived in space for about the period planned for a mission to Mars. Still, our understanding of how spaceflight affects living organisms remains rudimentary.

The ISS [International Space Station] now fully operational with a permanent crew of 43, should prove an ideal platform for studying fundamental biological processes in microgravity. This will undoubtedly lead to the growth and development of a new science: gravitational physiology.

Gravity affects some materials and fluid dynamics. It is required for convective mixing and other weight-driven processes, such as draining of water through soil, and assuring that what goes up comes down. One might predict that plants would grow taller without gravity, yet the lack of gravity might facilitate increased levels of growth-inhibitory or aging environmental factors around the plants, thereby causing them to dwarf. Gravity also has a role to play in development of load-bearing structures. The scaling effect of gravity is well known: the percentage of body mass contributing to structural support is proportional to the size of a land animal (e.g., 20 g mouse = ~5%, 70 kg human = ~14%, and 7,000 kg elephant = ~27%). This scaling effect in land animals would likely change in space and could result in a static scale comparable to marine mammals on Earth (~15% of mass as supporting tissues over a wide range of weights). Legs are bothersome in space and not only get in the way but also are involved in the fluid shifts that occur early in-flight. Whether legs would disappear over time without gravity (perhaps similar to the extra-terrestrial ET) or become more like grasping talons is unknown. Form follows function, and as function changes, so will form. How much change and what form organisms will assume over time in space is unknown.

Data to date suggest that certain biological structures have evolved to sense and oppose biomechanical loads, and those structures occur at the cellular level as well as at the organism level. There is evidence that the musculo-skeletal system of vertebrates change following acute exposure to space. What will happen over multiple generations is speculative. The "functional hypothesis" theory suggests that what is not used is lost. If this theory holds over multiple generations in space, then gravity-dependent structures may ultimately disappear or assume a very different appearance in space.

Another example is plants. Plants are the first organisms to be raised to the point of producing seeds in space, from seeds that were themselves raised in microgravity. We now know that plants can grow in space, but the ISS studies have indicated that air and water require special management in microgravity. Further studies in this area are of paramount importance if one wants to move from the current physical-chemical to ecological closed life support systems.

Carrying out research in space often comes at a considerable cost (sometimes human, as demonstrated by the Columbia tragic event). The most striking difficulties are the small subject pool available, the lack of adequate controls, and the fact that science is, by necessity, secondary to mission safety when conducting experiments in such a hostile environment. Nevertheless, the success of the manned space program is dependent on the concomitant success of life sciences research in microgravity to solve the considerable dangers still faced by crewmembers on long-duration missions.

In this respect, the human Mars mission represents another fascinating challenge for space medicine. Such a mission, when it is undertaken, will probably be the longest period of exposure of any person to a reduced gravitational environment, and probably the longest period away from Earth, too. A recent report also suggested that radiation on Mars might be at much higher levels than previously believed. So high in fact, that it would make living there almost impossible. All together, these conditions make a human Mars mission a challenge from both the physiological and psychological points of view.

The historical record offers a rich set of examples of exploration – Christopher Columbus in his discovery of the New World, Vasco de Gama sailing directly from Portugal to India, and Lewis & Clark in the first overland expedition undertaken by the United States to the Pacific Coast, for example. These expeditions to unknown territories and back rank as some of the greatest voyages of discovery in human history. Because of the scientific and geographical discoveries that were made at the time, they stand in significance along the planned human exploration of Mars. They are many parallels between these jumps into terra incognita --- unexplored land. All these historical expeditions took the necessary equipment, collective skill set, and vision to go into an unknown world in search of many things. The expeditions redefined, literally, a quest for scientific understanding about Earth and set the foundation for colonization. The small number of vessels and time frame are quite similar for the Mars mission and for the Vasco de Gama and Lewis & Clark’s expeditions. However, the crew size was much larger and many lives were lost in the historical expeditions.

The public is presumably not ready for paying such a price in human lives for the Mars mission. Hence, more advances in research and technology are needed before the human exploration of Mars can be achieved with minimal risk. There is no doubt, however, that like the historical expeditions, the exploration of Mars will be extremely influential in terms of our knowledge of the world and satisfy the desire of humanity to explore and expand.

What is life?

It is generally admitted that, for scientific purposes, an object must meet six criteria to be considered alive: (1) movement (even plants move: stems shoot upward, flowers open and close, and leaves follow the movement of the Sun); (2) organization ( animals and plants have organs, whose structure is nearly identical within the same species); (3) homeostasis (the ability to maintain constant conditions within the body); (4) energy (all living things absorb and use energy); (5) reproduction; and (6) growth (during the growth process, cells not only increase in number but they also develop into different types of cells that are needed to form the organs and tissues of the new individual)

Life on Mars

Without exception, life in Earth's biosphere is carbon-based and is organized within a phase boundary or membrane that envelops reacting biomolecules. Every documented terrestrial cellular life form is a self-replicating entity that has genetic information in the form of nucleic acid polymers (DNA) coding for proteins. Biologically active systems require at a minimum liquid water, carbon, nitrogen, phosphate, sulfur, various metals, and a source of energy either in the form of solar radiation or from chemosynthetic processes.

The conditions that nurtured early self-replicating systems and their transition into microbial cells are speculative. In contrast, it is much easier to model the early stages of evolution. Origins-of-life experiments have outlined the synthesis of the basic building blocks of life, including amino acids, nucleotides, and simple polypeptides and polynucleotides. Yet creation of self-sustaining, self-replicating biological entities capable of evolution has not yet been achieved in the laboratory. Even if successful, this achievement would not necessarily mimic how life started on Earth or in other parts of the universe.

For life to originate, the presence of liquid water and a source of usable free energy are necessities. The synthesis and polymerization of basic organic building blocks of life on Earth eventually led to self-replicating nucleic acids coding for proteins, but the earliest replicating systems were not necessarily composed of amino acids and nucleotides. If extraterrestrial biological systems exist, their modes of information storage, retrieval, and processing and their enzymatic activity may not be identical to those of biological entities on Earth. Understanding this prebiotic evolution is one of the major goals of the astrobiology program, which is the study of biology of the early Earth and elsewhere in the universe.

In the search for extraterrestrial life, microbes are far more likely than multi-cellular organisms to retain viability on small Solar System bodies because they can adapt to a much wider range of environmental conditions. As mentioned already, single- cell organisms such as bacteria have infiltrated virtually every corner of Earth’s biosphere and still constitute the bulk of Earth’s biomass. They grow in temperate marine and terrestrial settings, within other microbial or multi-cellular organisms, in deep subsurface niches, and in extreme environments that would be lethal for other life forms. They often influence geochemical reactions within the biosphere and frequently play key roles in food chains and complex ecosystems.

A 4.5 billion-year-old rock that is a portion of a meteorite (ALH84001) that was dislodged from Mars and fell to Earth in Antarctica about 16 million years ago. It is believed to contain fossil evidence that primitive life may have existed on Mars more than 3.6 billion years ago. The small grains have formed in fractures inside this rock in the presence of liquid water or other fluid. There is considerable debate about the origin of these carbonates. These grains are the sites of the three types of evidence that McKay and his colleagues [McKay et al., 1996] suggest represent fossil life on Mars.

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The Neuro-Sensory System in Space

To be aware of the environment, one must sense or perceive that environment. The body senses the environment by the interaction of specialized sensory organs with one aspect or another of the environment. The central nervous system utilizes these sensations to coordinate and organize muscular movements, shift from uncomfortable positions, and adjust properly. One relevant question is “what is the relative contribution of gravity to these sensory and motor functions?” We will review the effects of microgravity on the functioning of the sensory organs primarily used for balance and spatial orientation.

The problem: space motion sickness

The neuro-vestibular system consists of organs sensing the acceleration environment, nerves transmitting this information to the spinal cord and brain, and the central nervous system (CNS) that integrates this information so that we can determine our position and orientation relative to the environment. The vestibular organs in the inner ear detect and measure linear and angular accelerations. These responses, already complex, are further integrated with visual and proprioceptive inputs. In microgravity, some of these signals are modified, leading to misinterpretation and inadequate responses by the brain. One of these responses is space motion sickness (SMS).

SMS is a special form of motion sickness that is experienced by some individuals during the first several days of exposure to microgravity. The syndrome may include such symptoms as depressed appetite, a nonspecific malaise, lethargy, gastrointestinal discomfort, nausea, and vomiting. As in other forms of motion sickness, the syndrome may induce an inhibition of self-motivation, which can result in decreased ability to perform demanding tasks in those persons who are most severely affected. Gastrointestinal symptoms have their onset from minutes to hours after orbital insertion. Excessive head movement early on-orbit generally increases these symptoms. Symptom resolution usually occurs between 30 and 48 h, with a reported range of 12–72 h, and recovery is rapid.

Even if someone doesn’t literally get sick to their stomach, they may feel a less dramatic motion sickness effect known as “sopite syndrome”, characterized by lethargy, mental dullness, and disorientation. Many astronauts have noticed this effect, which they call "mental viscosity," "space fog," or "the space stupids."

There were no reports of SMS in the Mercury and Gemini programs, while 35% of the Apollo astronauts exhibited symptoms. The incidence during the Skylab missions increased to 60%. About two-thirds of the space shuttle astronauts and Soyuz cosmonauts experienced some symptoms of SMS. There are no statistically significant differences in symptom occurrence between pilots versus non-pilots, males versus females, different age groups, or novices (first time flyers) versus veterans (repeat flyers.) An astronaut’s susceptibility to SMS on his/her first flight correctly predicted susceptibility on the second flight in 77% of the cases. In other words, one astronaut who has been sick during his or her first flight is likely to be sick again during subsequent flights.

SMS affects a similar percentage of both U.S. and Russian crews. Symptom recurrence at landing, also called “Mal de Débarquement,” reportedly afflicts 92% of Russian cosmonauts returning from longer missions. No reports of mal de débarquement were noted in the space shuttle program. However, many astronauts returning to Earth after long-duration stay on board the ISS now experience this syndrome. The severity of the symptoms and the functional recovery after the flight seem to be directly proportional to the time on orbit.

Microgravity by itself does not induce space sickness. There were no reports of motion sickness during the Mercury and Gemini spaceflights. As the volume of spacecraft has increased, allowing for more mobility, the incidence of SMS has increased as well. Movements that produce changes in head orientation seem necessary to induce SMS symptoms. In particular, many crewmembers report that vertical head movements (rotation in the pitch or roll planes) are more provocative than horizontal (yaw) head movements. However, once sickness has been well established, head movements in any plane are generally minimized by the affected crewmember. Indeed, movement of any kind is frequently restricted until the astronaut is on the road to recovery.

Head or full body movements made upon transitioning from microgravity to a gravitational field less than that on Earth, and vice versa, may not be as provocative. It is interesting to note that of the 12 Apollo astronauts who walked on the Moon, only 3 reported mild symptoms, such as stomach awareness or loss of appetite, prior to their EVA. None reported symptoms while in the one-sixth gravity of the lunar surface, and no symptoms were noted upon return to weightlessness after leaving the Moon surface.

Other issues related to the adaptation of the central nervous system through the vestibular pathways include: (a) the perceptual effects and illusions of free-falling, visual reorientation illusions, and acrophobia episodes (fear of height) during EVA; (b) decreased sensorimotor performance and visual scene oscillation (oscillopsia) during re-entry; (c) disequilibrium and ataxia when standing and walking after landing; and (d) g-state flashbacks during unusual stimulation of the vestibular system during the re-adaptation period following landing.

Vestibular function

The gravity vector is a fundamental factor in human spatial orientation, which results from the integration of a complex of sensory inputs coming from the vestibular organs in the inner ear, the eyes, mostly from peripheral retina, and tactile and proprioceptive receptors located in the skin, joints, muscles, and viscera.

The vestibular end organs

The vestibular system’s main purpose is to create a stable platform for the eyes so that we can orient to the vertical – up is up and down is down – and move smoothly. The inner ear contains two balance-sensing systems: one is sensitive to linear acceleration, the other to angular acceleration.

The linear acceleration sensing system sends messages to the brain as to how the head is translated or positioned relative to the force of gravity. It contains two tiny sacs filled with fluid, the saccule and the utricle, lined along their inner surface with hair cells of various lengths. Overlying the hair cells is a gelatinous matrix (the otoconia) containing solid calcium carbonates crystals (the otoliths, meaning “ear stone” in Greek). During linear acceleration, the crystals, being denser than the surrounding fluid, will tend to be left behind due to their inertia. It has been demonstrated that the resultant bending of the cilia causes cell excitation when the bending is toward the kinocilium (the longest hair cell), and inhibition when away from the kino-cilium. During head motion, the weight and movement of the otoliths stimulate the nerve endings surrounding the hair cells and give the brain information on motion in a particular direction (up, down, forward, backward, right, left) or tilt in the sagittal (pitch) or the frontal (roll) plane.

The angular acceleration sensing system comprises three semicircular canals. The system detects angular acceleration through the inertial movement of the liquid (the endolymph) within each canal and provides the brain with information about rotation about the three axes: yaw, pitch, and roll. The semicircular canals do not react to the body’s position with respect to gravity. They react to a change in the body’s position. In other words, the semicircular canals do not measure motion itself, but change in motion. Not surprisingly, the semicircular canals are not affected by spaceflight, as shown by the absence of changes in the perception of rotation or in the compensatory eye movements in response to rotation both in-flight and after flight.

Linear acceleration and gravity

When our head is horizontal the hair cells in the utricles are not bent and this stimulation is interpreted as signifying “normal posture”. If our head is tilted forward, the otoliths shift downward under the action of gravity, bending the hair cells. If we translate backward, again there is a shift of the otoliths forward due to the inertial forces. Thus, an equivalent displacement of the otoliths (and consequently the same information is conveyed to the central nervous system) can be generated when the head is tilted 30° forward, or when the body is translating at 0.5 g backward. This example simply illustrates Einstein’s principle stating that, on Earth, all linear accelerometers cannot distinguish between an actual linear acceleration and a head tilt relative to gravity.

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The other senses

In common speech, five different senses are usually recognized: sight (vision), hearing, taste, smell, and touch. Of these, the first four use special organs – the eye, ear, tongue, and nose, respectively, whereas the last uses nerve endings that are scattered everywhere on the surface of the body, as well as inside the body (visceral sensations). Proprioceptive sensations arise from organs within the body, from muscles, tendons, and joints. To what level these five senses are affected by spaceflight is uncertain.


The visual environment in space is altered in several ways. First, objects are brighter under solar illumination. Earth’s atmosphere absorbs at least 15% of the incoming solar radiation. Water vapor, smog, and clouds can increase this absorption considerably. In general, this means that the level of illumination in which astronauts work during daylight is about one-fourth higher than on Earth. Second, there is no atmospheric scattering of light. This causes areas not under direct solar illumination to appear much darker.

Early anecdotal reports that orbiting astronauts were able to see objects such as ships, airplanes, and trucks with the naked eye suggested improved visual acuity in space. Extensive testing of Gemini astronauts was performed using a small, self-contained binocular optical device containing an array of high- and low contrast rectangles. Astronauts judged the orientation of each rectangle and indicated their response by punching holes in a record card. Another method, taking into account the particularity of the visual environment of space described above, also used large rectangular patterns displayed at ground sites in Texas and Australia. Astronauts were required to report the orientation of the rectangles. Displays were changed in orientation between passes and visual performance of astronauts on preceding passes. Results with both measurement methods indicated that visual performance was neither degraded nor improved during spaceflight. The astronauts’ reported ability to detect moving objects (airplanes and ships) was probably based on the detection of turbulence or waves behind the vehicles. Also, the color contrast might improve the ability to identify features, as Astronaut William Pogue described it during his Skylab mission “We were able to see icebergs about a hundred yards in diameter quite easily because of the higher contrast of white ice with the dark blue sea.”

More refined visual testing has been performed on several shuttle flights using a specially-designed visual test apparatus to assess contrast sensitivity, phoria, eye dominance, flicker fusion frequency, stereopsis, and acuity. With the exception of reduced contrast sensitivity, no significant changes due to weightlessness were found. These changes were too small to impact operational performance. However, if contrast sensitivity continues to change during longer exposure to weightlessness, the decrement could become operationally significant.

It is also worth noting here that the light flashes perceived by the astronauts in the absence of normal visual stimulation were caused by heavy ionized cosmic particles passing through retinal cells. Although no performance disturbance has been associated with these light flashes, it is likely that the flashes mask transient visual stimuli.

An experiment currently in progress on board the ISS seems to indicate that the astronauts underestimate distance for the intermediate range of 100–1,000 m. Also, the perception of distance in the vertical direction, which is clearly overestimated on the ground (e.g., when on top of a building, the people in the streets look small), become as accurate as in the horizontal direction after 1 month in orbit. It is unclear if these illusions are direct effects of reduced gravity on the neuro-vestibular system, as seen in vestibular patients on Earth or due to other factors of the space environment, such as high contrast, confinement to cramped quarters, and the absence of known landmarks in the crewmember’s intermediate space. Nevertheless, these errors in visual perception and misperceptions of size, distance and shape could represent potentially serious problems. For example if a crewmember does not accurately gauge the distance of a target, such as a docking port or an approaching vehicle, then the speed of this target could also be misevaluated. In addition, disturbances in the mental representation of objects and the surround may influence the ability of astronauts to accurately perform perceptual-motor and perceptual-cognitive tasks such as those involved in robotic control.

Suspicions are that daylight is not bright on the surface Mars. The sunlight on Mars is about one-half of the brightness of that seen on Earth. The sky of the Red Planet does not appear blue, but pink due to suspended dust, which means that the surface of Mars is, in fact, darker than what is experienced on Earth.

Also, on Mars, the terrain may be more sloped than that explored by the Apollo astronauts. The astronauts may be traversing areas of deep shadow, possibly requiring the use of lights. Scientists are also investigating options for EVA sensory supplementation. Although vibrotactile and electrodermal cueing systems have been demonstrated in patients, these techniques appear encumbering and impractical, and require that the suit also incorporate a capable inertial attitude and heading reference system. Night vision sensor imagery, an artificial horizon, and a navigation display could also be incorporated into an add-on external heads-up display.

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“In space, no one can hear you [scream].” This cliché, which is commonly used in science fiction movies, has apparently not attracted the interest of scientists for studying hearing during spaceflight, since very little data is available yet.

The ISS is a noisy place. To better characterize the acoustic environment, a sound measurement survey is performed once every 2 months to measure the acoustic spectral levels at specified locations. An acoustic engineering evaluation is performed to diagnose acoustic abnormalities, investigate crew complaints, and evaluate effectiveness of newly installed noise reduction measures. Noise exposure levels are measured by crew-worn dosimeters complemented by dosimeters deployed at fixed locations to determine work, sleep, and 24-h noise exposure levels (with a microphone on the shirt collar). Recent data indicate that noise levels on the ISS, even during sleep periods, can average more than 70 dBA, and that the recordings have “maxed out” at over 90 dBA during scheduled sleep intervals.

Several aspects of spaceflight can have an impact on hearing capability: (a) life support equipment is continuously running (ranging from 64 dBA for the air conditioning to 100 dBA for some vent relief valves) and the noise reverberates through the spacecraft’s structure; (b) astronauts spend 24-h a day in the office, always close to noise sources; and (c) there is no privacy, with a constant interaction with other crewmembers. Thus quietness periods such as on Earth do not exist: earplugs can reduce noise but not vibrations.

Spaceflight raises a spectrum of noise questions: its effect on perception and performance, adaptation effects, the fatiguing and annoying aspects of noise, and individual sensitivity differences. The degree to which noise and environmental disturbances affect sleep during spaceflight missions remains to be determined. Because certain minimum noise levels are always present, spaceflight potentially constitutes a more stressful noise environment than a simple consideration of decibel levels would imply.

Although very stringent noise requirements for ISS result in a noise environment comparable to home and office, intelligibility of hearing as noise increases may vary across individuals. For example, it is known that both the lack of language proficiency and the reverberance in a room impair hearing. The performance of a native English speaker on board the ISS at 60 dBA therefore must to be compared with that of a non- native English speaker at 68 dBA! In addition, low noise levels can also be annoying and affect individual and group (communication) behavior.

The investigation of hearing in astronauts is difficult to conduct during spaceflight because classical hearing assessment techniques do not work in the noisy environments often found in spacecraft (no soundproof laboratory). Because crewmembers are at risk for hearing loss due to noise levels often encountered during spaceflight, techniques and investigation to track this loss are needed during and after the mission.

Auditory brain stem response recordings were investigated during shuttle flights. No significant differences were observed between mean latency values for any potential on the ground or during flight, suggesting that the auditory function is not altered in microgravity. Another experiment performed on Mir showed that the localization of a sound source in microgravity was within the same range as on Earth, i.e., between 1° and 2°. Since the faculty of localizing sound sources depends on normal binaural hearing, it was concluded from this study that hearing was not altered in cosmonauts.

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Smell and taste

It is well known that during spaceflight, astronauts ask for more spices and condiments to add taste to the prepared food. Diminished sensitivity to taste and odor could result from the passive nasal congestion reported in conjunction with the headward shift of fluid. Taste, particularly the non-volatile component mediated by the taste buds, may be susceptible to threshold shifts in microgravity, because of a reduced mechanical stimulation as a result of changes in the convection process.

Evaluation of olfactory recognition using paper impregnated with lemon, mint, vanilla, or distilled water, and taste recognition using solution of solutions of sucrose, urea, sodium chloride, and citric acid, demonstrated no subjective changes in smell or taste function postflight. However, there were large differences among individuals. Some of them could have been due to the reminiscence of space motion sickness symptoms!

Materials used in spaceflight are subjected to testing for odor as well as for flammability and toxicity. Odor evaluations are made by panels of test subjects who rate materials on a scale from 0 (undetectable) to 4 (irritating) with a score of 2.5 (falling between "easily detectable" and "offensive") considered as passing. Nevertheless, because particulate matter does not settle out in weightlessness, odor problems in a space habitat may be more severe than under similar terrestrial conditions.

Also, responses to odors can be accentuated by the presence of visual cues. For example, during the earlier Spacelab missions, crewmembers complained of disturbing odors, which they attributed to the primates and test rats which shared their facilities and which were in view . In later missions, the animal cages were placed in visually separated areas and no odor problems were mentioned.

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The absence of gravity modifies the stimuli associated with proprioception and impact spatial orientation, including knowledge of position in the passive limb, difficulty of pointing accurately at targets during voluntary limb movement, modification of tactile sensitivity, and changes in the perception of mass. However, the nature of proprioceptive changes in microgravity has been poorly studied. There is almost no space study of neck and joint angle sensors, and on the role of localized tactile cues in the perception of body verticality.

When crewmembers point at remembered target positions with their eyes closed, they make considerable errors and tend to point low. When they are asked to reproduce from memory the different positions of a handle, the accuracy of setting the handle to a given position is significantly lower with an error towards a decrease of handle deflection angle. Also, when trying to touch various body parts, they usually note that their arms are not exactly where expected when vision is restored. The problem is that these examples are suggestive of either degradation in proprioceptive function, or an inaccurate external spatial map, or both.

An elegant way to evaluate changes in the proprioceptive function is to measure the subjective sensation generated by the stimulation of proprioceptive receptors. A classic technique consists in vibrating a muscle tendon to elicit illusory limb movement. Using this technique, it was observed that the illusion of body tilt forward or backward was less pronounced in-flight than postflight during vibration of lower leg muscles. One interpretation of this result is that the utricles and saccules are unloaded in microgravity and decrease their descending modulation of alpha and gamma motoneurons, resulting in decreased tonic vibration reflexes.

A nice illustration of an alteration of proprioceptive inputs during the early exposure to microgravity is the impossibility for an astronaut to maintain a “vertical” posture, perpendicular to the foot support, in absence of visual information. The large body tilt observed in these conditions reveals an inaccuracy in the proprioceptive signals from the ankle joint (or in their central interpretation). After flight day three, however, the astronauts are able to maintain an upright posture, suggesting that adaptive processes take place quite rapidly.

Among the somato-sensory systems projecting to the neuro-vestibular system, the position receptors of the cervical column (neck receptors) play an important role. During the Spacelab-D1 mission, the trunk of a crewmember was passively bent sidewards or forwards, while keeping his head fixed to the floor of Spacelab, thus stimulating the neck receptors. The crewmember reported an illusory rotation of a head-fixed target cross seen in the monitor of his helmet, which was entirely due to the stimulation of the cervical position receptors, since the otoliths were not stimulated.

Another interesting feature of microgravity is that it allows separation between two distinct physical concepts, mass and weight, which both produce similar sensations of heaviness. On Earth, weight can be judged passively through the pressure receptors in the skin, if the object is placed upon a supported limb. Weight can also be judged actively, if the object is held against the force of gravity by the muscular effort, or is repeatedly lifted. Mass can only be judged actively, derived from the force required to produce a given acceleration, or from the acceleration produced by imparting a given force. Thus, active weight perception usually includes mass perception. It is therefore difficult to investigate weight without mass during active movement, except in weightlessness. Using balls of various masses that the astronauts shook up and down moving their arms, it was found that the process of discriminating the mass of objects in microgravity was less accurate than in normal gravity. Weight discrimination was impaired for 2 or 3 days postflight, while crewmembers felt their bodies and other objects to be extra heavy. The impairment in-flight was partly due to the loss of weight information (a reduction in the pressure stimulation), and probably also to incomplete adaptation to microgravity. The increase in apparent heaviness of objects reported for static weight judgment after the flight suggests that some central re-scaling of the static pressure systems had occurred.


Before a mission to Mars can safely be undertaken, the adaptive processes of the sensory, motor, and cognitive systems to microgravity need to be better understood, and countermeasures must be devised for a faster re-adaptation of the CNS functions that are expected to occur following the transitions between various gravitational environments. In particular, future investigations should address the following issues:

(a) Motion sickness upon return to a gravitational environment, including postflight motion sickness, needs to be better understood and mitigation strategies developed.

(b) The dynamic range of the adaptation of sensorimotor responses in various gravitational environments needs to be identified. This may be accomplished by using a centrifuge on board the ISS or in a Moon habitat. Accurate predictions of the effects Mars gravity may be accomplished via modeling.

(c) It is not known if permanent functional deficits result from the decrease in afferent input to the vestibular, proprioceptive and somatosensory systems as a function of the adaptation associated with long exposure to 0 or 0.38 g.

(d) Morphological or structural changes in CNS and neuromuscular functions that may account for these deficits need to be identified.

(e) The procedures that produce rapid and complete adaptation to Martian gravity and Earth’s gravity after exposure to microgravity must be validated. This may be accomplished using Martian gravity simulation by executing parabolic flight maneuvers on Earth, or using a centrifuge on board the ISS or in a Mars habitat.


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NASA (2009) Human Exploration of Mars: Design Reference Architecture 5.0. Houston, TX: NASA

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McKay DS, Gibson EK, Thomas-Keprta KL, Vali H, et al. (1996) Search for life on Mars: Possible relic biogenic activity in Martian meteorite ALH84001. Science 273: 924–930

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Godwin R (1999) Apollo 12 NASA Mission Reports. Burlington, Canada: Apogee Books, CG Publishing Inc

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Oman CM (2003) Human visual orientation in weightlessness. In: Levels of Perception. Harris L, Jenkin M (eds) Springer Verlag, New-York, pp 375–398

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Fukuda T (1983) Statokinetic Reflexes in Equilibrium and Movement. University of Tokyo Press, Tokyo
Posted: Wednesday, May 6, 2015 12:22:24 PM

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Daemon wrote:

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Italian Astronaut Brews, Sips First Fresh Espresso in Space

The first Italian woman in space is now the world's first orbiting barista. Over the weekend, astronaut Samantha Cristoforetti fired up the first espresso machine in space. She posted a photo of herself on Twitter from the International Space Station ... More...

Applause Il primo caffè espresso nello spazio!!!!!!!!!!!!!!! Applause

Caffè italiano. Il più buono!

Cara Samantha sei troppo forte Applause Dancing Applause
Posted: Wednesday, May 6, 2015 2:22:24 PM

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Location: Tbilisi, T'bilisi, Georgia
I sincerely respect Ms Cristoforetti, but I do not like espresso. I would not take it if I were on the orbit. Ordinary coffee is better, imho. Anyway, glory to Samantha, she is great lady!
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