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What is gravity?
What can you tell me about pursuing a career with NASA or in space biology?
What roles do centrifuges play in research?
What are the conditions necessary for life on other planets?
Why do we conduct research in space and what value does it have for people on earth?
What safety precautions are taken to protect the astronauts?
Ask an Astrobiologist
What significance would it have to us on earth if we found that life once existed on Mars?
"Ask an Astrobiologist" features Astrobiology related questions and answers.
Human Issues
How does one maintain balance in a weightless environment?
How does the heart and cardiovascular system react to space
conditions?
What effect does microgravity have on the human skeletal
system and muscles?
Why and how do people exercise in microgravity?
Does a woman's menstrual cycle change with spaceflight?
How are cancer patients affected by the cosmic radiation
in space?
What effect do changes in gravity have on DNA replication?
What is the longest time a human has spent in space?
Other than geriatrics, what other health benefits can we
gain through space exploration?
Have astronauts experienced heartburn in microgravity? It seems that without
gravity, the effects of hearburn would be intensified. 
Plant Biology
Does gravity have different effects on different kinds of plants?
How do plant roots and shoots know which way is up and down?
Can plants grow in space?
What is phototropism?
The Future of Space Travel
What medical supplies would be necessary for a hypothetical 9 month trip to Mars for a crew of 25 people?
What does the future hold for the space program?
With the technology that we have now, can colonization
of space begin?
How would future colonies on Mars grow crops, and what would
be the human diet?
Exercise Guide
How do I determine which exercises in the "Exercise: A Guide from the National Institute on Aging and the National Aeronautics and Space Administration" are right for me? What do I do if my doctor or physical therapist recommends something different?
Physics
What determines the shape of water during free fall?
General
What biological effects does space travel have on humans, animals, and plants?
Try looking up specific interests on the SpaceBio site found at http://www.spacebio.net. This site contains information and photos, diagrams, etc. on all these topics.
For information about the human body in space, visit the on-line textbook found at http://www.nsbri.org/HumanPhysSpace/index.html published by the National Space Biomedical Research Institute.
For photos and information about specific missions, try the Life Sciences Data Archives found at http://www.lsda.jsc.nasa.gov. The best way to find the information you want is to use the "advanced search" function and pick a species or topic under the "research area", "experiment", or "keyword" scroll down menus. For example, under "photo gallery" then "research area", pick "plant biology" and get a series of photos of plants, experiments, and astronaut activities related to growing plants in space.
What is gravity?
Gravity is the force of attraction between two objects. Mathematically, it is expressed by Newton's Law of Universal Gravitation which states that F = G *m1*m2/r^2 where G is the Universal gravitational constant, m1 is the mass of object 1, m2 is the mass of object 2, and r is the distance between the centers of gravity for both objects.
Why do we conduct research in space and what value is it for people on earth?
For information on NASA research and applications to solving problems on earth, please visit the following web sites:
http://www.nasa.gov
http://www.nasa.gov/news
http://www.sti.nasa.gov/tto
http://spaceresearch.nasa.gov/general_info/pressrel.html
What safety precautions are taken to protect the astronauts?
For information on NASA Safety Programs, please visit:
http://www.hq.nasa.gov/office/codeq/safety/index.htm
What can you tell me about pursuing a career with NASA or in space biology?
If you are open to living in different parts of the US, you should review on-going NASA research to determine who is doing the type of work you would like to become involved in. Refer to the Office of Biological and Physical Sciences Task Book found at http://research.hq.nasa.gov/taskbook.cfm for a list of grant-funded investigators and their research topics. The task book is searchable by keyword, location, investigator name, etc. We suggest you contact the researchers directly to network and discuss opportunities of interest to you.
Alternately, to increase your understanding of currently funded NASA space biology research, you can attend scientific meetings to network with investigators and learn about upcoming opportunities. The largest organization of space biology investigators can be found at http://www.asgsb.org - the American Society for Gravitational and Space Biology (ASGSB). ASGSB holds an annual meeting in the fall (November 12-15, 2003 in Huntsville, Alabama). In Europe, you may wish to visit http://www.elgra.org and check out the European Low-Gravity Research Association (ELGRA). Another space-themed society of interest is online at http://www.aiaa.org - the American Institute of Aeronautics and Astronautics (AIAA).
Also consider reviewing the meetings covered by societies in your specific field, cell biology, plant biology, molecular biology, etc. By searching meeting agendas, papers and abstracts, membership rosters, etc., you should be able to determine if the society will be a good place to network. Several societies are beginning to offer workshops and seminars related to space biology and are a good place to network. The ASGSB website lists a variety of other scientific meetings in the "other meetings" section.
Finally, check out NASA center websites (or ESA, DLR, NASDA, etc. depending on your nationality) for where research is occurring, who is performing the work, and what contractors are hiring. Centers with significant research in the fields of space biology include Ames, Johnson, Kennedy, and Marshall. Visit http://www.nasa.gov to find links to each of the NASA centers (and enterprises).
When you check out a NASA center website, search the site for a list of contractors. Links should bring you to descriptions of what companies are doing what. For example, the Kennedy website http://www.ksc.nasa.gov brings you to the home page. Click on "Information Center" then on "KSC Contractors" then search and review sections that seem applicable to you. Contractors provide a lot of the workforce at each center and list openings independently. Contractor positions are not listed at the "NASAjobs" website. Visit http://www.nasajobs.nasa.gov to serach for Federal work. Federal jobs are hard to come by and are generally not open to non-US citizens.
Human Issues
How does one maintain balance in a weightless environment?
In order to understand how our bodies maintain balance in a weightless environment,
it is essential to discuss first how we maintain balance here on Earth. The ability
to sense motion and position can be attributed to the vestibular organs, or the
vestibular apparatus collectively, located in each inner ear. Three membranous
semicircular canals and two large sacs, the utricle and saccule, make up the vestibular
apparatus, and they all share a common sensor - the hair cell. Inside a widened
area of each canal called the ampulla resides fluid and hair receptor cells, which
are surrounded by a fragile membrane called the cupula. With each movement, no
matter how slight, the ampulla pushes the cupula, which in turn nudges against
sensory hairs. The movement of sensory hairs stimulates the hair cells, and consequently
sends sensory impulses down the vestibular nerve to the brain. Each canal is located
in one of three planes of space, thus acquiring a sense of all possible head movement
combinations.
The utricle and saccule are also encased in membranous sacs, and each are lined
inside with a bed, or macula, of hair cells. The hair cells are layered with small
flat piles of calcium carbonate crystal, themselves embedded in a gel-like substance.
Those crystals are called otoliths, which give the utricle and saccule the common
name otolith organs. Normally, the hair cells in the utricle lie flat on the horizontal
plane, but when the head tilts, the crystals slide in that direction and bend
the sensory hairs. Again, the movement of the hair stimulates the hair cells,
which send impulses to the brain. A similar scenario occurs with the hair cells
in the saccule. Here, the hair cells are normally oriented vertically, and any
head movement will cause the same result as described with the utricle.
In space, astronauts must take some time to lose the disoriented feelings associated
with weightlessness. Because of the lack of gravity, the otolith organs no longer
play the same role; they can sense linear acceleration (forward/backward, up/down,
and left/right), but cannot establish a vertical reference signal to the brain.
Adaptation to this new environment involves learning to use nonvestibular signals
that are more visual, proprioceptive, and tactile. Currently taking place are
investigations into the role gravity plays in specialized sensory organ development,
the neural connections associated with vestibular systems in altered gravity,
and the areas of the brain responsible for reversible adaptation.
How does the heart and cardiovascular system react to
space conditions?
When the human body is first exposed to microgravity, blood shifts from the lower
body towards the heart and head in what is called a headward fluid shift. This
initially causes the central venous pressure to drop and the heart to temporarily
enlarge, but as soon as the body senses what it interprets as an increase in total
blood volume, it works to eliminate the excess fluid via urination. Within 2 days
and after more frequent urination, the heart shrinks in order to pump a smaller
volume of blood. Once an astronaut returns to Earth, the heart has difficulty
adjusting to an environment in which it has to pull blood up to the brain against
the force of gravity.
Does gravity have different effects on different kinds of plants?
Yes. In fact, there are some plants that have been discovered that do not respond to gravity. These are being used in research to determine how various plants sense and respond to gravity.
What effect does microgravity have on the human skeletal
system and muscles?
Several studies have been done to assess the effects of microgravity on the human
body with the goal of preventing muscle atrophy and a decrease in bone density
that is common among astronauts. In space, bone density tends to decrease as the
bone mineral turn-over rate decreases, and this results in a greater chance for
broken bones upon return to Earth. Similarly, muscles undergo weakening in a microgravity
environment. Muscles consist of one-celled fibers of various lengths that may
be of two types: slow-twitch or fast-twitch. The slow-twitch fibers are responsible
for continuous movement, total body support, and resistance to gravity. The fast-twitch
fibers produce the force needed during rigorous or intense activity. In a microgravity
environment, the leg and back muscles, which are used to resisting gravity, no
longer have to provide support, and consequently the fibers become smaller, or
atrophied. This decrease in muscle mass poses a major problem upon return to the
1G environment of Earth and often leads to difficulties in performing routine
activities. Fortunately, this state has been shown to be temporary after short-term
duration flights. As for longer flights, the reversibility of muscle atrophy is
currently under investigation. A similar situation exists with the analysis of
the skeletal system in microgravity.
Why and how do people exercise in microgravity?
Working against the force of gravity is what causes the muscles, bones, and cardiovascular
system of the human body to maintain strength and build mass. In order to prevent
their bodies from adapting to microgravity and consequently losing body mass and
strength, astronauts must maintain a strict exercise program while in space. Without
such discipline, the potential for broken bones, reduced work capacity, loss of
balance, and other problems upon return to Earth greatly increases.
To work the muscles, astronauts use a stationary bike, which also provides
a good cardiovascular workout. Treadmills do the same, although they are more
cumbersome to use - the astronauts must be strapped down in place. Resistive exercises,
those that supply loading forces, are currently being developed in order to help
build bone mass.
Does a woman's menstrual cycle change with spaceflight?
So far there have been no studies done on how microgravity affects the human menstrual
cycle, on the hormonal level or otherwise. Scientists have, however, studied the
reproductive system of the rat in microgravity, specifically during pregnancy
and birth.
How are cancer patients affected by the cosmic radiation
in space?
Currently, no missions have flown with a cancer-bearing patient. However, scientists
have conducted preliminary studies on the effects of exposure to radiation in
space. Since high levels of radiation are known to cause higher-than-normal mutation
rates (which can lead to cancer) within a living cell, the levels of cosmic radiation
experienced outside of Earth's protective atmosphere will be a large concern in
the coming era of longer manned spaceflights. Many experiments that have been
performed to address this concern can be browsed online through NASA's Life Sciences
Data Archive link http://lsda.jsc.nasa.gov
What effects do changes in gravity have on DNA replication?
The major point of concern regarding the fidelity of DNA replication in space
is not microgravity itself, but rather cosmic radiation. The average dose of radiation
received by an astronaut while on the Shuttle is significantly higher than what
they would experience on Earth in a year. A radiation biology experiment performed
on C. elegans, a microscopic worm, flown on the Shuttle showed the rate
of mutagenesis to be significantly higher in space than in the ground controls.
Studies have also been done on the effects of microgravity on cell division and
DNA replication. Cells with chromosome breaks, bridges, and double nuclei were
found in space samples and quantified. None of these abnormalities were evident
in the ground controls. However, it is not known if these effects were due to
microgravity or radiation exposure.
What is the longest time a human has spent in space?
During the 10 years Mir has been orbiting earth, it has been home to 62 people
from 24 crews, from more than a dozen countries. The current record holder for
the most consecutive days on the station is Russian cosmonaut Dr. Valeri Polyakov,
who has spent 418 days in space.
Other than geriatrics, what other health benefits can
we gain through space exploration?
There are numerous other health benefits to be obtained through space exploration.
Experiments being conducted today can either focus directly on a physiological
aspect, or they can seek answers through the study of related fields such as pharmacology,
botany, and biochemistry. Quite often, technological advances and increased understanding
of the human body come from cross-functional studies. For example, the Left Ventricular
Assist Device that aids patients with heart disease could not have been developed
without additional research in materials science, microminiaturization, fluid
dynamics, and engineering.
What roles do centrifuges play in research?
Centrifuges play important roles in research both here on Earth and in space.
On Earth, they are used with humans, animals, and plants in experiments designed
to test the effects of differing levels of hypergravity. The centrifuges are usually
constructed with cabs attached to a rotating arm. By placing the test subject
in different positions within the cab, the experimenter can assess the forces,
or gravity gradients, that act upon various parts of the subject. In addition,
the experimenter can vary the centrifugal force felt by the subject by moving
the cab closer or farther away from the center of rotation.
The International Space Station plans to house a 2.5 meter in diameter centrifuge
that can support several biological specimen habitats. The number of revolutions
the centrifuge makes per minute can be varied to simulate different levels of
gravity; for example, 28 revolutions/minute would simulate 1 G, or Earth's gravity.
This centrifuge will prove to be very useful in allowing scientists to conduct
experiments in space and keep the effects of gravity separate from other space
environment conditions. In the long run, the need for artificial gravity during
extended life science missions can be determined, and if needed, can accurately
predict the level of gravity and the duration of exposure necessary to maintain
health.
Have astronauts experienced heartburn in microgravity? It seems that without
gravity, the effects of heartburn would be intensified.
"Heartburn" is not a common problem with crew. For one thing, they are a healthier than normal group, with strong exercise and eating habits, and do not have any significant incidence on the ground. On orbit, it is not a common complaint. For one thing, "GERD" (gastro-esophageal reflux disease) is often associated with large meals. On orbit, the crew tends to eat light. Occasionally, the ever-popular shrimp cocktail (popular because it's
spicy) has been implicated as a culprit, with simple antacids and simethicone used to resolve the problem. Again though, gastric reflux is not high on the list of reported on-orbit medical problems. That is not to say if a GERD prone person flew it would not be worsened. We have all probably suffered acute reflux after a spicy meal. The symptoms can be kept at bay by sitting up, or laying on your right side. These maneuvers work due to gravity pulling the stomach contents away from the gastro-esophageal junction. This would not be available to someone in a weightless environment, making avoidance and treatment the only available treatment options.
The condition is usually attributed to "acid reflux." Basically, dinner reacts with the acids in the stomach as part of the normal digestive process. Under normal conditions, though, the sphincter valve located at the top of the stomach allows food to go from the esophagus into the stomach and supposedly only in that direction. In acid reflux, the sphincter valve gets irritated in some manner and opens up at an inopportune time allowing the acidic contents of the stomach up into the esophagus thus burning the inside of the esophagus. Because of the proximity of the esophagus to the heart, this burning sensation is called "heartburn."
One sure-fired way to avoid acid reflux at night is not to eat for a few hours prior to going to bed. Lying down puts the stomach contents against the sphincter valve which is one method for irritating the sphincter valve into opening up. Of course, some people can tolerate this type of irritation, but others can't, so some people can eat right before bedtime
without problems, while others can't tolerate it all or need to watch out for foods that cause them to burp or stimulate acid buildup in the stomach.
In microgravity, buoyancy forces are greatly diminished and the digestive juices climb out of the "bottom" of the stomach and up the walls of the stomach via capillary forces or surface tension. Thus the sphincter valve at the top of the stomach gets coated with a thin film of digestive juices. Some astronauts can tolerate this irritation without any problems,
others can't and get to taste dinner a second time in a less than appetizing manner.
Ask an Astrobiologist
What significance would it have to us on earth if we found that life once existed on Mars?
Finding life on Mars would excite researchers for a variety of reasons. Firstly, it would just be interesting to know that life did (or does) exist elsewhere in the universe. Humans have been wondering about this question almost as long as we have been in existence. Finding evidence that suggests that we may not be alone, that Earth is not the only planet capable of sustaining life, would be an amazing revelation. As for scientists, many want to know how and why life was created on Earth. Finding evidence of life on Mars may help elucidate the issue. Finding out why life no longer exists on Mars may also give scientists insights as to geologic and planetary changes that may be of importance to life on Earth.
Life on Mars is really part of the discipline called "Astrobiology", which is somewhat different from space biology. For more information about astrobiology, visit the official NASA site http://www.astrobiology.arc.nasa.gov. They have an "Ask an Astrobiologist" feature which has questions and answers in a wide variety of astronbiology related fields. The direct link to the FAQ/Ask an Astrobiologist page is http://nai.arc.nasa.gov/astrobio/index.cfm. Be sure to mouse over the buttons under "select a category" to see all of the choices available. Specifically for your question, you will want to focus on the "Origin of Life" and "Life on Other Planets" sections.
Exercise Guide
How do I determine which exercises in the "Exercise: A Guide from the National Institute on Aging and the National Aeronautics and Space Administration" are right for me? What do I do if my doctor or physical therapist recommends something different?
The "Exercise" guide was developed to provide general advice concerning health, exercise, aging, and other health related matters. The book/website is not intended as a substitute for a doctor's diagnosis or care; in fact, before engaging in a new exercise or diet regime, you are urged to consult with your physician.
As each person has differing medical histories and conditions, the advice of your personal doctor or physical therapist should always supercede the suggestions made in the manual. Therefore, we suggest that you follow the advice of your regular health care provider who is unquestionably in the best position to recommend (or to discourage) specific exercises for your situation. Most physical therapists have access to a wide variety of websites, handouts, brochures, videos, etc. that demonstrate exercises that are most appropriate for you.
You may see the complete guide online and you may email SpaceBiology@ksc.nasa.gov to order a printed copy of the exercise guide.
Please include your mailing address when requesting materials.
Plant Biology
How do plant roots and shoots know which way is up and down?
The phenomenon known as gravitropism enables plants to sense and respond to gravity.
How the shoots respond to gravity is not entirely clear at this point, but scientists
do have a plausible explanation for the roots. When a seed germinates, or sprouts,
cells at the tips of the root called statocytes release specialized starch containing
plastids, or statoliths. The aggregation of the statoliths towards the end of
the root causes a redistribution of calcium and the release of a plant hormone
called auxin. Calcium and auxin settle at the lower side of the root and prevent
cell elongation. The cells on the upper side of the root continue to elongate,
and, as a result, the root bends downward as it grows.
Can plants grow in space?
Several flight experiments have been performed on plants, particularly on wheat.
Part of the grass family, wheat is known as a cereal crop and typically used in
making bread. In a microgravity environment, germinating seeds tend to grow normally
with the shoots growing towards the light (positive phototropism). The roots do
not exhibit phototropism, and they tend to grow whichever way they please. They
will, nonetheless, usually stay within the moist medium in which the plant is
growing.
Problems have been discovered in plants' reproductive systems; that is, in
their ability to flower and produce seed. It is not clear whether this failure
to complete a life cycle is due to the weightless environment of space or other
complicating factors. In microgravity, fluids do not have density because fluid
and air convection is absent. Water moves only by capillary action and air moves
very slowly by molecular diffusion. These factors prove to be extremely detrimental
to the plant during flowering and seed-set, as the stagnant air is lacking in
oxygen. This state is called carbon dioxide narcosis. To prevent these situations,
it is necessary to have a forced convection at both the roots and the shoots during
all stages of a plant's life. This can be accomplished with plant-growth units
that attend to the light, atmosphere, temperature, mineral nutrient, and water
conditions essential for a successful plant life.
What is phototropism?
Phototropism describes the process by which plants respond to the light in their
environment. The light-sensing hormone responsible for the curvature of plant
shoots towards light is auxin. Upon release from the cells in the apical meristem,
auxin collects primarily on the darker side of the stem and stimulates cell elongation.
Thus, the cells on the side not directly exposed to light will grow much faster
than the opposing side, and the stem will curve towards the light source.
Physics
What determines the shape of water during free fall?
Due to surface tension, a property that minimizes surface area, liquid would become
spherical if allowed to free fall without the Earth's gravity. On Earth, gravity
overpowers surface tension, and liquids form flat surfaces. However, in very small
areas (capillary tubes less than 5 mm in diameter, such as thermometers) surface
tension dominates and liquids form spherical (convex or concave) surfaces.
Two microgravity research scientist burst water balloons in a reduced gravity
plane to see if they could deploy large liquid drops. Although the water did not
start out free flying, the end results were the same; the water eventually took
the shape of the sphere.
Exobiology
What are the conditions necessary for life on other
planets?
When we ask about life in the universe, we have one point of reference: terrestrial
life. Terrestrial life is entirely DNA based. But, when we search for life beyond
Earth, we do not necessarily go looking for DNA-based life. We look for things
that exhibit the common features of our life; that is, a self-organized, catalytic
system capable of replication and evolution. Living systems require some discernible
structure that maintains the integrity of the body plan while using energy and
other materials from the environment to sustain it and to produce subsequent generations.
One common indicator of life is that it changes its environment in ways that non-biological
processes do not. In the search for life on other planets, scientists will look
for disequilibria signatures, or chemicals in an environment that should not be
there unless something biological was producing them.
The Future of Space Travel
What medical supplies would be necessary for a hypothetical 9 month trip to Mars for a crew of 25 people?
There are essentially two types of medical issues, those peculiar to space and those common to any small, isolated community.
Space-peculiar issues include the need for exercise, space motion sickness, preparation for and adaptation to return to gravity at Mars and/or Earth, etc. These issues depend critically on the duration of the voyage, and thus on the form of propulsion available.
For a nine month trip with 25 people you would need many common medications (antibiotics, analgesics, motion sickness medications, drugs required for advanced life support, intravenous fluids, sedatives, stimulants (for critical mission performance in an emergency), topicals, bandages and dressings, medical examination equipment, etc. One usually would only carry one or two medications of each type, but in sufficient quantity to treat several people.
For a related PowerPoint presentation visit: http://medic.ksc.nasa.gov/edu/presentations/mars.ppt
and also visit http://medic.ksc.nasa.gov/edu/project.html
Regarding the treatment of medical problems on an isolated vessel, generally the medical equipment and personnel required for a prolonged space voyage are fairly similar to those required for a sea voyage of similar crew size and duration. To give you a general picture of the considerations required you may find the Coast Guard online publication "The Ship's Medicine Chest and First Aid at Sea", helpful.
Now, obviously not all the issues addressed in this publication would occur in space or would be handled exactly the same way in space, but we have far more real-world experience in medical problems in the sea travel environment.
Finally, there are a lot of ideas available on the web, including pages on medical equipment on the shuttle and space station.
Many of these include considerable speculation, so do not assume any reference is completely accurate.
What does the future hold for the space program?
NASA plans to further human occupation of space on a more long-term basis through
the International Space Station. A commitment to exploration of Mars is also in
the near future. Realizing these dreams would require a focus on developing new
technologies for adaptation to the environment of space.
With the technology that we have now, can colonization
of space begin?
Right now we have all that is required to colonize the Moon and Mars, including
rocketry and technology to conduct experiments in microgravity. Colonization of
space will be most prevalent during the lifetime of the next generation.
How would future colonies on Mars grow crops, and what
would be the human diet?
Due to the thin atmosphere and the consequent exposure to space radiation and
particle bombardment, the first human and agriculture habitats on Mars will be
underground. Light will eventually be generated by a nuclear reactor, but will
initially have to be piped down from solar collectors. Greenhouses that make excellent
use of the high levels of CO2 found in the Martian atmosphere and long
cycles of continuous light will be constructed to facilitate fast crop growth.
Until the content of Martian soil is known, crops will be grown solely with water,
in a process called hydroponics. This will prove to be more efficient anyway,
because scientists can control the concentration and variety of nutrients each
plant needs, thus encouraging faster growing and healthier crops.
The human diet will probably consist mostly of cereal (wheat and/or rice) and
legumes (peanut, soybean, and/or cowpea) for protein; sweetpotato and/or white
potato for complex carbohydrates; and vegetables (lettuce, tomato, broccoli) and
herbs (onion, garlic). Sources of fat will be limited; hence, peanuts and perhaps
small amounts of animal food sources will be required.
If you have other questions email us at SpaceBiology@ksc.nasa.gov
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