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Hi all,
I repost here in a more appropriate and new topic.
A real problem might be pregnancy on Mars. Days are 24 hours 5minutes, gravity is 0.38 g, food is testricted (only vegetal), etc. This raises many issues regarding people health on Mars, and more precisely about the female hormonal signals and their ability to carry children in those conditions: For example, would those hormonal signals be deregulated and shifted well above or below the 9 months gestation period, forbidding any normal delivery ?
What about Embryonic Neural tube closure / Brain growth at 0.38g ? Will the fetal brain be overgrowth, undergrowth, No one knows.
For 500 millions years, the vertebrate body has adapted his fetal growth at 1g gravity, I doubt the shift at 0.38 g will be without concequences.
Doctors and molecular biologists will be required to fix expected problems like: high rate of miscarriage during pregnancy, grossly developmentaly abnormal babbies (those who survive), growth and mental retardation after birth etc. Systematic delivery by Caesarean might be the rule, at least for a couple of generations, before a normal adaptation takes place. Other problems could be hypertension, heart disease, calcium or other ions defficiency. Maybe Molecular Biology could help by using transgenesis or "genetic therapy" techniques by using Adenovirus or retrovirus to express useful genes to delay or accelerate pregnacy, for example.
Another example, I completely disagree that because of the low gravity, the martian children will be necesseraly tall (as in KSR trilogy and in the recent poem sent by Ms Zubrin: "... they grow taller and taller...").
Body growth is a function of hormonal signal, food income (check the size of nordic population in the starving middle age: were they all 6 feet tall giants ?).
It might well be that under low gravity and no McDonalds available, the children hormonal system won't be very stimulated, they won't produce enough growth hormone like for "small size people", this in addition to the calcium/bones depletion. If nothing is done, I would predict disastrous effects, just for the gravity only, during embryogenesis and early infancy and especially for human, because of the long gestation that the brain requires in our specie. In that regards unfortunatly, the translife experiment (see the Mars Society web site) is partly informative, I mean that mice doing well at 0.38g won't mean human doing well at 0.38 g, but that abnormal mice born at 0.38g will probably signify that it's gonna be worst for us. I hope to be wrong.
Small versus tall... I think the issue could be different if we consider the new martians (or neoMartians) as Terran neotenics. Neotenic organisms are animals similar to their ancestor's fetal stage, likewise it has been said that Humans are neotenic Chimps because they look like chimp fetus. Neomartian could look like terran kids. Being smaller at 4/5 feet, they would request less food, only the brain size and metabolism would be unchanged and they might be better adapted than the 7 or 8 feet tall people described in the KSR trilogy. They might have more cartilages, less calcified bones, less muscular fibers, different heart beating frequency, different cardiavascular system, different gonads and renal apparatus, they might also be less sexually differentiated than we are, they might weight only 30 kgs (on earth) with a 1 or 3 kg brain, who knows ? but if they survive, that would be all right. All those differences don't have to be genetically acquired through mutations, they might be part of the natural capability of the vertebrate body to adapt in the low gravity, which brings me to the next point:
I want to criticise another KSR statement (even if I liked that book): that mutant like Nirgal, with a higher metabolism to resist the cold, would arise spontaneously in the martian conditions. This is pure Lamarckism. Everybody knows this typical Darwinist example: the giraffe neck did not extend over generation because the giraffe needded to reach higher and higher leaves, generation after generation, but because long neck mutants potentially already present in the population were preferentially selected to survive. But the environnent can drive the evolutionary path in many other way than just mutations, fetal development, as cited above, is one possibility. Personnaly, I don't expect the martians to become furry after several generation because it's cold outside, but rather, I expect a tendancy to follow the genetic drift that have started the first humanoids millions of years ago, a trend towards a smarter, highly skilled and brainy humanoid which seems to have stop recently, at least on Earth, but maybe that trend will continue on Mars.
Now that's a lot of new topics: medicine, genetic, evolution... Let's see if people in that list are interested.
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still nobody to describe the new Homo Sapiens Sapiens Marineris of his dream ? I am disapointed.
Use that web site to querry informations :
http://www.ncbi.nlm.nih.gov/entrez/quer … ?db=PubMed
It's PUBMed, the nec plus ultra database in the field of medicine/biology etc, even applied to space biology,medicine or chemistry.
Enter any key word in the search field, like "Mars" or "Coriolis + low gravity" etc, anything you like to think about.
Copy the abstract and reference in the forum and after that, start a great discussion about biology on Mars !!!
ka !
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For example, a simple search with "coriolis + artificial gravity" leads to alsmost 40 published paper, included this one that I copied the abstract below. It says that human could endure until 7 rpm. That absolutely great ! no need to tethered spaceships anymore, a 30 meters radius torus rotating at 4 rpm provides 0.5 g. (cf that site:
http://www.labcentrifuge.com/gforce5.ht … ce5.html.)
I think a torus of 30 meters radius is an acceptable structure in a spaceship, right ?
no comment ?
"J Neurosci Res 2000 Oct 15;62(2):169-76
Artificial gravity as a countermeasure in long-duration space flight.
Lackner JR, DiZio P.Ashton Graybiel Spatial Orientation Laboratory, Volen Center for Complex Systems, Brandeis University, Waltham,Massachusetts 02454, USA. Lackner@brandeis.edu
Long-duration exposure to weightlessness results in bone demineralization, muscle atrophy, cardiovascular deconditioning,altered sensory-motor control, and central nervous system reorganizations. Exercise countermeasures and body loading methods so far employed have failed to prevent these changes. A human mission to Mars might last 2 or 3 years and without effective countermeasures could result in dangerous levels of bone and muscle loss. Artificial gravity generated by rotation of an entire space vehicle or of an inner chamber could be used to prevent structural changes. Some of the physical characteristics of rotating environments are outlined along with their implications for human performance. Artificial gravity is the centripetal force generated in a rotating vehicle and is proportional to the product of the square of angular velocity and the radius of rotation. Thus, for a particular g-level, there is a tradeoff between velocity of rotation and radius. Increased radius is vastly more expensive to achieve than velocity, so it is important to know the highest rotation rates to which humans can adapt. Early studies suggested that 3 rpm might be the upper limit because movement control and orientation were disrupted at higher velocities and motion sickness and chronic fatigue were persistent problems. Recent studies, however, are showing that, if the terminal velocity is achieved over a series of gradual steps and many body movements are made at each dwell velocity, then full adaptation of head, arm, and leg movements is possible. Rotation rates as high as 7.5-10 rpm are likely feasible...."
etc
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