Dream High

I am probably one of a very limited number of people in the world who think punning references to Korean "Glee" knockoff series with regard to space exploration are funny.  We call it "Huffman Humor" around my house, and it consists of jokes that require lengthy explanations before anyone even realizes that they are jokes, and then only get pity laughs.

But, despite the pun, my topic this week is serious.  In fact, it may be the most important thing I ever write on this blog.  The inspiration was a documentary, or rather the kickstarter trailer of a documentary in the making, which will discuss why the US space program is in a long, terrible decline.  The reality of it breaks my heart.  So, I am going to take a break from my normal, lackadaisical, semi-scientific, semi-sarcastic approach, and really speak plainly.  Honesty is something we don't see too often these days, and I think it is time for some.

We need hope. But right now, we do not have it.

At this moment, I am speaking of America, as an American, so for any international readers, I apologize, but this might not really pertain to you.

America needs hope.  We can delude ourselves with lies about our own greatness for only so long before the delusions stop working, and we must face reality.  And that reality is that we are a nation fallen from glory, a glory once undeniable, once the envy of the world, and the source of our pride as men and women.  In the past, we could be proud, because we were part of something great.  Now, America is not great.  It's not even good, unless we are generous, or blinded to reality by the mythology we are taught our whole lives.

Honesty.  I promised I would give it.  So here it is: I have no patriotism for America, at least not as it is now.  In fact, as recently as last week, I was considering renouncing my citizenship and immigrating to someplace else permanently.  And the simple reason is that I think America is going to fail, to crash and burn because it grew too used to living rich, and forgot how to work for its money.  America has forgotten the most important thing it ever knew: How to dream.

There was an America though, once, which knew how to dream, and dream big.  I never experienced the 1960s and 70s, so I don't know the full depth of the fervor, the patriotism, and the true, honest belief that American hard work, innovation, and ingenuity could carry mankind off of this world.  But, I have seen the look in my father's eyes, on days when he remembers it, and that is enough.  From that look, I know the dreams he held.  I know from his recollections of his school days how he wished to be a scientist, how as a boy he dreamed of being an astronaut.  I know from the Buck Rogers stories he told me at bedtime, when I was young, that the dream of space was buried deep in him, and that it had never let go.  It was a dream he passed to me, wittingly or not.

I also know he was not alone in his fervor.  During the space race, millions of children wanted to learn science and engineering.  Why?  Not because it was important to their country, or they had good career opportunities, but because they wanted to go out into the night sky and see what was there.  Kennedy's dream of landing on the moon lit a fire in the hearts and minds of the whole nation, a fire that fueled the technological advances of the next two decades, keeping America on the razor edge of advancement.

And then they reached the moon, said the immortal words "A giant leap for mankind," and etched in the memories of the world an event that would never be forgotten.  We left our planet.  We succeeded.  Surely, nothing would prove impossible for us, and a new era would dawn.  With baited breath, mankind waited for that future to come....

And it didn't.  We made the giant leap, we found a cold, dead rock, and then we leapt right back again.  And then, nothing.  We didn't try to tame the rock, not even to live on it.  After a couple short walks, we left and never returned.  And that fire in the hearts and minds of America burned down, to a sizzle.  In the younger generation, the fire was never planted.  Instead of scientists, they became investment bankers.  And slowly, we lost our technological preeminence, and our pride went from a well-earned right to stand tall amongst our fellow men to hollow platitudes.

We need that fire again.  We need a project that inspires us to be better than normal human beings, that drives us, instills in us a passion and a belief in the possibility that humanity, and America, truly can be great.  We need another goal, a new symbol for the strength and resilience of our people, a symbol that shines in this dark night of our country and says that even now, from the pit of our woe, we have within us the strength to touch the stars.

Mars can be that symbol.  Not walking on Mars and coming back, but living on Mars.  Staying there.  Making Mars a place for humanity.  And not just Mars, but all of space!  We should be on Deimos, on Io, mining asteroids, building space stations at the opposite side of the sun from our orbit.  The solar system is ours for the taking, and all we need to do is grasp it.  That is a dream that people, no matter their political affiliation, can agree on.  A dream to light a fire in their hearts, the way this picture did, almost half a century ago.

What stands in our way?  Two things.  First, money.  Politicians win few votes by giving NASA money, and therefore they seldom do so.  As a result, NASA gets only half a percent of our tax dollars, and still some argue it is too much in a time of economic crisis.  As Neil Degrasse Tyson says in this keynote speech, there are a bunch of arguments for going to space (I talked about many of them in my first post), but they are tired and old, and people don't listen to them very well.  They take more than an elevator ride to explain, and people these days therefore don't have the attention span to hear them

The second problem is the root of the first: we don't think past our own lives.  As human beings, we concern ourselves with the here and now, think fuzzily a few years into the future, but past a decade we don't make any plans.  That mistake leads to the argument that "There are problems on Earth.  We shouldn't worry about space until those problems are solved."  Why not?  The fact that one problem exists doesn't mean we shouldn't solve another.  Humanity needs to become a planning species, a species that controls their own fate, homo evolutis, the human that determines the next step in his own evolution.  

Is this happening?  Slowly.  We have the environmental movement.  We have people realizing that the actions of the last hundred years are going to drastically affect the realities of the next hundred.  People are starting to see the need to be careful about long term effects.  But with regard to space, people aren't thinking of it as the excellent investment that it is, they are thinking of it as a waste.  Politicians are mocked for suggesting that we can live on the moon, when we could have done it twenty years ago if we wanted.  Government in the USA deprioritizes the space program.  The shuttles are gone.  The budget gets cut as costs increase.  People are still more concerned with the here and now than what the future will hold, when the fact is that the current here and now was determined twenty years ago by the way people then thought about (or didn't think about) the future.

The same will be true as time goes on.  We can't fix the present, because the present is an effect of the past.  So we should stop trying.  What we can do is fix the future.  Our decisions now will affect the fate of humanity for millions of years, which is a great responsibility.  Will they look back on us as uncivilized fools who didn't even know enough to plan a century in advance?  Will they look back on us as the technologically stagnant era of man between our initial forays into space and the beginning of widespread colonization?  Or will they not exist to look back at all, because we did not build a place for them to survive if Earth dies?

Not if I can help it.

Magnetic Fields and You

Magnets are cool.  Seriously.  They are one of the coolest things ever.  You can stick them to metallic surfaces, you can make them bend electricity, you can use them to MAKE electricity, you can make them hover.  If you have a round one, you can roll it down a whiteboard.  Just ask any five to ten year old what the coolest thing in science is, and magnets will rank right after dinosaurs and lasers (which, let's be honest, shouldn't even be considered in the same league, they reek so thoroughly of coolness).  Another cool thing about magnets: They prevent everyone on Earth from dying horribly of cancer.

Let's look at how this works.  First, it should be noted that the correct answer to the question "How does Earth's magnetic field work?" is "We don't know, but we have a hunch that might be right, assuming our theories about the inner parts of the planet are correct."  That hunch is as follows (according to HowStuffWorks.com here):  The core of the Earth is made of super hot, super pressurized, solid crystallized iron.  Outside the core, Earth's rotation causes some other, slightly less hot, slightly less pressurized, liquid molten iron to spin around the solid iron core, creating a bit electricity and thus a bit of magnetic field.  I'm sure there are much more sciency explanations than this one, but that's the gist.

This magnetic field is really weak (only half a Gauss on Earth's surface, and only 1/8 of that 8000 miles up (which is the diameter of the Earth)), but still strong enough to deflect a large part of the harmful solar wind, forcing it to bend out around the Earth.  Without it, solar wind would annihilate our ozone layer, expose us to the full brunt of solar radiation, and slowly strip away our atmosphere until nothing was left, a process which, on Mars, is currently in its third step.

Which leaves us with a problem.  Mars has no ozone.  Well, actually, that's not too big a problem; we'll be forced to live in domes anyway to trap a useful atmosphere, and the domes will need to be glass so that plants beneath them get light to grow.  Fortunately, normal glass will block most UV rays on its own, and we've already invented various films and treatments (check one of them out here) that can cut out those remaining few rays and leave us safe and sunny.  So, really, the ozone issue is not an issue.  And, since we will be distilling our own atmosphere to fill all of these domes, an atmosphere which the sun cannot strip away, the whole solar wind stealing our air thing isn't too important either.

However, the matter of high energy cosmic rays is still a big problem.  A lot of this problem will occur in space on the way to the planet, but I will deal with that in a later entry on spacecraft design.  For now, I want to limit my inquiries to the colony itself.  According to the Mars Radiation Environment Experiment (MARIE), radiation on the surface of Mars should be roughly equal to that on the International Space Station, at about 100-200 mSv (microSieverts) per year.  To give some context, the maximum recommended lifetime dose of radiation is about 1000 mSv, which would be 10 years on Mars, not counting the radiation the first colonists would experience on the way there.  Cancer risks increase by about 5.5% per Sievert, so at 1000 mSv you have a 5.5% chance, at 2000 mSv an 11% chance and so on.   On Earth, we get about 0.4 mSv of cosmic radiation annually (this does not include Earth-bound radiation sources, like nuclear power plants, and bananas.  Read here for more information.)  So, if we want to live on Mars, chronic radiation is a problem we'll need to solve.

It gets worse.  Not only is chronic radiation a possibility, but without the protection of a magnetic field, the extremely intense radiation from solar flares will hit Mars (and our poor fledgling colony) head on.  Radiation during these events is sometimes over 100 times background levels.  That's a ridiculous 2000 mSv per day, and sometimes these flares last a week of more!  In that week, the lifetime risk of radiation induced cancer for every exposed citizen of Mars would go from 0% to 77%.  A 77% chance of getting cancer.  This radiation dose (.14 Gray in a week) is also high enough to cause chronic radiation syndrome, which is basically all of the nastiness that comes from working in Chernobyl on the wrong day, except drawn out over the course of a year or two.  Not a pretty sight.

Okay, so things are grim.  How do we fix it?  Well, since things will probably take some setting up once we arrive on Mars, the first solution will probably be digging.  Mass blocks radiation.  Lead, as most of us know, is the best single radiation absorber, but 2 meters of dirt or stone will accomplish the same goal as eighteen centimeters of lead, and won't need to be mined carefully or processed before use.  Two meters underground is almost 22 halving thicknesses of dirt, which means that if a solar flare scorches the martian soil with 2000 mSv a day for two weeks, our underground explorers will feel only 0.0005 mSv.  Which is completely harmless.  So, at least at first, humans can escape the radiation on Mars by building and living in caves, which also have the advantage that they do not require the humans to bring too many construction materials with them to Mars (yay saving money!).

But who wants to move to another planet just to become a cave man?  Not me.  I like living on the surface, and seeing the sun once in a while.  Plus, plants need light to grow, and light tends to be scarce in caves.  Of course we can grow our crops underground with full spectrum light bulbs, but it costs energy, energy we could get from the sun, for free, if we could keep the radiation from killing us in our pretty little domes.  How can this happen?  Well, we could make our own magnetic field.  Some people suggest digging into the core of Mars and blasting away with nuclear weapons trying to start a dynamo effect and make a field like Earth's, but I don't buy into the idea; feels too much like Armageddon (an excellent story, but not really related to actual science). So it seems like we should make a whole lot of small magnetic deflectors.  After all, it is a very weak magnetic field that repels the solar wind on Earth, right?

Wrong.  The magnetic field on Earth works because it has a lot of space to work with.  An average deflection of only one degree per thousand miles will mean that everything misses the whole planet if the field takes effect 25,000 miles from the surface (because the diameter of the Earth is less than 25 degrees on a circle with radius 25000 miles, so shifting radiation by 25 degrees in any direction will make it miss Earth).  At that height, Earth would have a field strength of .00098 Gauss, which is very weak, but not negligible.  But, we don't have the ability to make a field that big.  Magnetic fields lose power as a cube of distance, meaning that if you double distance, power drops to 1/8th.

Let's take as an example the strongest electromagnet on Earth, which is 45 Tesla, or 450,000 Gauss, about 900,000 times stronger than the Earth's magnetic field at a range of 0, with a diameter of about two meters.  To put that in perspective, this magnet will literally rip a pacemaker out of your heart from ten feet away.

BOOYAH!

So, how strong is it from 25000 miles away?  25000 miles is 40250 km, or 40,250,000 meters.  This is  very roughly 2m^26 (rounded to nearest power of 2), so the diameter of the magnet doubles 26 times to reach that distance.  That means the strength would be 450000/8^26 Gauss, which leaves you with an infinitesimally small charge (1.5*10^-18 Gauss).  (Note: Only the field strengths at given distances in this section are actually real values.  One degree per thousand miles is a number drawn from thin air.  Actual deflection is not linear, but exponential because as the beam approaches the magnet, the magnetic field gets stronger, and as the angle changes from perpendicular, it also becomes easier to change because there is less momentum fighting against the magnetic field.  The energy of each radioactive particle also greatly affects how much it is swayed, and those energies vary hugely.  So, these numbers are meant only as an example to illustrate the problem, not as actual mathematical solutions to it.)

A possible solution is produce a lower magnetic field, but with a much bigger radius.  Suppose we built an electromagnet with a power rating of 2 Tesla, or 20000 Gauss, but a diameter of 50 miles.  At 25000 miles (roughly 50*2^9), this would yield a force of .00015 Gauss, which is more than 1/6th that of Earth.  So, wider magnets with smaller charges might work.  If you make the magnet with superconductors, then you can run it on much less electricity, and a cooling system is a lot cheaper on a planet which is already quite cold.  It would certainly cost a fortune, and take a very long time to build, probably a decade or more of concentrated effort since the crew would be so comparatively small.  The thing I don't know is how much power it would take to generate a magnet like this; it could require billions of megawatts to just get the thing going.  If the final power input is less than the constant several megawatts required by smaller magnets, then this sort of thing would be a worthwhile project.  If the smaller magnets take less power in the long run, then they are probably the better investment, and in any case it seems likely that they will be employed as a short term solution.  Whatever else is true, it looks like a good number of years on Mars before the magnetic deflector shields are fully up and running.

Plastics: Make it Possible!

A day or two later than I wanted this week, due to vacationing and teaching small children to write essays.  But, now I am back, sun burnt, with a broken phone, and a waterlogged ear, wondering how we can make plastics on Mars.

Really, the answer is: We can't.  There are no oil deposits to use in plastic creation.  We can recycle plastics we bring to Mars with us, but with no major local sources, plastic making via petroleum will be prohibitively expensive.  And, since we use plastics in pretty much everything, this is a pretty big deal.  So, we need a functional replacement.

There are several potential replacements being developed by people who figure that Earth is going to run out of oil pretty soon, and be in a similar situation (which is true, and will make plastic alternatives, especially biodegradable ones, a pretty decent investment direction starting around 2020 or so, when rising oil prices make them the cheap alternative.)  Let's look at these one at a time, and see if we can choose the best option.

One option is using mycelium.  In this TED talk, Eben Bayer outlines a way to create new plastic-like materials.  His company has developed a way to grow mycelium, which is basically mushroom roots, into a replacement for styrofoam, moldable into any shape, growable, and 100% compostable.  It uses farm wastes like rice hulls and mulched corn husks for food, and the mycelium as a glue and polymer to provide shock or acoustical absorbency.  It is fire resistant, light weight, and uses all materials with no waste, since it incorporates any un-eaten corn husks or whatnot into the structure of the end product. It makes great insulation, and they are even researching how to use this mycelium glue to replace things like particleboard and fiberboard, which are wood byproducts and thus won't be available on Mars for a long time after colonization.  Really, one of the coolest companies I found, so check them out here!

It's cool, but not a complete solution.  Styrofoam is only one style of polymer based material, and the process takes a bit more time and storage space than normal plastic manufacturing, since each product in a run requires a separate mold, and takes about five days to grow.  That decreases turnover time, limiting capacity somewhat with regard to Earth bound use.  But, on Mars, quantity won't be too important for the next hundred years or so, and mycelium has the added benefit of improving soil quality, meaning that littering with this stuff would actually help the colony out, rather than polluting.  A further advantage is the fact that since this process involves growing fungus to fit a mold, the factory equipment involved is pretty simple (mulcher, cleaner, pasteurizer, and some way to mix in the fungus), and would not take up too much space on the colony ship. 

So, these shrooms should definitely make the trip, but more is needed for the more diverse, high-tensile uses of plastics.  You can't use Styrofoam to replace a heart valve, or as a microwaveable dish, or as the external shell of your laptop.  So we look at other alternatives.  One promising alternative is starch plastics, which are biodegradable, and can be worked into a wide variety of strengths and flexibilities, allowing them to substitute for most other types of plastic easily.  The main drawback here is that they usually use high soil depletion food crops, such as corn, as the source of the starch.  This is a double whammy on the new colony, because not only will using these crops to make plastic reduce the available food supply, growing this kind of crop in the first place will deplete nutrients from soil which is already in desperate need of enriching.  Corn requires constant application of fertilizer or it will deplete soil in only a few harvests, and constant fertilizer is something that should not be counted on, on Mars.  Other crops with lower soil impact will be preferable for the first few years.

The last option I want to explore is algae.  Several US companies are already starting to create plastics out of algae, and although some of them use petroleum based additives the technology for pure algae plastic is not at all distant.  Algae is cheap and easy to grow, hydroponic, which means it doesn't deplete soil nutrients at all, and inedible, so it doesn't have a tendency to drive up food costs on Earth, or make colonists on Mars choose between getting food or the container to put it in.  It can be used almost exactly like starch to make plastics, with only slightly more processing, and can create the same wide variety of products.  The one problem is that in its current incarnations, algae based plastics are not biodegradable; in other words, they are just like normal plastics.  If we go to Mars, it would seem intelligent to live green from the very start, and thus never need to deal with the problems we made for ourselves on Earth.  Of course, biodegradable algae plastics are not out of the question, and in fact are under development currently (see here to read more).

This is algae! It's your friend!

Really, some combination of the three is likely to be the answer to the question of Mars plastics.  Algae and mycelium will be needed just to fill out the biosphere, whether we make plastics out of them or not, and corn is a food crop that we should certainly bring along, even if we don't grow it for a few years while we build up soil quality (which is a whole issue in itself, to which I will probably devote an entry at some point).  Mycelium manufacturing takes the least equipment, making it most economical, but the low variety of present uses is limiting, and I wouldn't really want to drink from a styrofoam cup made of fungus, even though it would probably be very safe.

Oh, yeah, and the algae factories apparently smell like a fish market.  Ah well, that's the price you pay, I suppose.

Regarding Germs

There is an amazing opportunity waiting for us on Mars:  The chance to escape, once and for all, from disease.  However, is it really an opportunity?  Or is it a temptation best avoided?

At first glance, Mars with it's completely sterile environment, devoid of all life, and therefore all germs, viruses, and the like, seems like a boon to humanity.  We can go live there, and as long as the colonists are detoxed before flight, they will never again catch a cold, a flu, or indeed any other dangerous germ borne illness.  When we move to Mars, we can simply leave germs behind, for the most part.   Of course, no antibacterial soap is perfect, and no matter what, humans and their livestock will carry some pathogens into space, however, a short term quarantine before flight should allow the astronauts immune systems to finish off anything that they were carrying, and avoid picking up anything new.

When they get on board ship, their bodies will already be accustomed to defeating all the diseases they carry with them.  By the end of their journey to Mars, some of those strains may have died out completely in the absence of new, defenseless hosts.  Any strains that do remain are benign, and have lost the ability to hurt us without mutation.

Mutation is possible, but is a matter of odds.  On Earth, bacteria populations are estimated to be 5*10^30, or 5,000,000,000,000,000,000,000,000,000,000,000.   That's a lot.  A whole, whole, lot.  Of course this is an estimate (found here: http://www.sdearthtimes.com/et0998/et0998s8.html ), but the obvious thing is that with so many bacteria the odds of a mutation are very, very high, probably happening every second or so.   Some of those mutations make deadly diseases, others might create new, useful medicinal treatments.  But, now consider Mars.  Presumed bacteria population: 0.  How much will we bring with us?

An average human has roughly 10^14 bacteria living in and on their body (so says wikipedia here: http://en.wikipedia.org/wiki/Human_microbiome ), about 1000 species.  We need these bacteria to live, so getting rid of them completely is out of the question.  If we assume at least 100 people are going to Mars (I'd rather have a thousand, but that's rather unlikely), that means 10^16 bacteria.  Let's double that number, to include livestock (rabbits, perhaps, and goats, maybe a few cattle), and then double it again to account for topsoil traveling with the plants on board ship (roughly a trillion bacteria per kg of soil, and I expect they will need to carry at least 20 tonnes of topsoil to create a ground layer that can grow crops for 100 people), and we can estimate 4x10^16 bacteria on board our colony ship.  That means that a mutation with good odds of happening once every second on Earth will probably only happen once every five million years in our Mars colony.

That's a very big deal, because it means that Mars will probably have roughly the same strains of bacteria for the first few thousand years after colonization, since population growth after landing will be limited to the size of human settlements, and even at a very high rate of settlement, it is not likely that we will ever reach Earth-like microorganism populations.  Humans will almost certainly adapt to beat all of them, and then will almost certainly not need to adapt any more, which is a problem.  See, if we don't adapt, it is like our immune systems using outdated software.  Imagine if you didn't update any of your computer's software for five thousand years, and then plugged into the internet.  Your computer would explode.  That's what it would be like for humans who live on Mars their whole lives, always exposed to the same bacteria and viruses, and then come back to Earth.  They will suffer extreme immune deficiencies, which could make any Earth tourism very dangerous.

This is why I said that the lure of a disease-free Mars is a temptation.  While it is true that we could solve a lot problems for individuals by eliminating disease on Mars, we would lose the ability to return safely to Earth in two generations or so.  Longevity and health on Mars would come at the cost of isolation.  Soon, even trading with Earth would become risky, because there is no knowing when some chance germ will ride along against which the Martian humans have no immunity.  An epidemic could easily cripple the young colonies, where every person will be necessary, and one death might mean that suddenly nobody on the planet knows how to fix the air purifiers.

To some extent, this separation is unavoidable, and will almost certainly occur.  There is simply no way that the Mars biosphere can keep up with the robustness of the Earth biosphere.  And for some diseases, there is absolutely no reason to let them travel to Mars.  For example, simple screening can completely eliminate all sexually transmitted diseases from the Martian population.  AIDS will be a non-issue on Mars.  Depending on how many people are willing to go, it may even be possible to be selective and create a population devoid of most genetic risk factors.  Similarly, parasites and certain diseases can be done away with.  For example, there is no reason to bring malaria to Mars, or any disease for which a vaccine is available, since Earth can simply send the vaccine instead and immunity can be achieved without an outbreak taking place.

But, if Mars and Earth mean to be in contact with each other, it will be necessary to intentionally expose Mars to at least the more mild Earth germs.  Martian children will still need to be immunized against Earth illnesses, like tuberculosis and tetanus, and for these diseases a simple vaccine should solve the problem.  The really unfortunate part is that Martian humans will also need to be exposed to incurable but common diseases as well, so that if they ever return to the home world they aren't at a physical disadvantage.  The flu, the cold, and perhaps the occasional stomach bug will all be necessary ailments to make sure that Martian immune systems stay up to date.  In essence, there will need to be annual germ deliveries from Earth to make sure that Mars gets sick.

And now, I am certain that my name will be cursed forever on Mars, as the one who suggested an annual "Disease Day."  It's sort of a holiday.  Like Christmas, except that instead of presents, you get the flu.

I Think I'll Try Defying Gravity

This post will be weird.  I talk about childbirth.  Also, my idea is weird.  But enough said.  Let's begin.

One major problem on Mars (or, anywhere else, for that matter) is that the gravity will be different.  As in, you will weigh just over one third of your Earth weight on Mars.  This....could create some problems.

The largest problem, at first glance, is the same problem experienced by astronauts in the microgravity of space: loss of muscle and bone mass.  A person who lives on Mars for too long, and anyone born on Mars, will probably not be able to return to Earth gravity without extreme discomfort and danger, because our bodies only grow strong enough for our environments.  If my muscles think I weigh 52 lbs. and suddenly I go back to earth and weigh 140, my muscles won't be able to cope.

A related problem is bone growth.  I might be born on Mars, but my genes are still designed for  Earth gravity. Most of you will know that bones grow faster at night, because they are not being pressed by gravity and activity as much.  As a result, the lower pressure from Mars gravity poses a major problem.  Our bodies, normally programmed to grow only when we rest, may be convinced that we are always resting, and therefore that we should always be growing.  Giantism could thus become epidemic, along with all of its related health problems.  The effects of low or micro gravity on children have not been studied thoroughly, since all the people who have spent substantial time in space were fully grown adults.  So, really, we don't know how bad this might get.  It could be that just standing upright is enough to convince your bones not to go into growth mode, and if so, this is a non-issue.

Another potential problem is childbirth.  Not being female, I'm not an expert, but I do know that kids skulls are subjected to some very intense pushing and smooshing on the way out, and that their skulls are soft enough on Earth that forceps delivery can sometimes cause skull fractures.  If, as I suspect, low gravity means more fragile bones for the fetus, then mothers giving birth could potentially crush the skulls of their babies with the force of the muscles required to push them out.  Lower gravity could also lead to an increase in breech births.  The exact causes of breech births are unknown (We don't even know why most babies come out head first: I read everything from "the baby gets top-heavy" to "it's instinct" to "the mother just needed to role on the floor"), but it seems likely that there is a gravitational component involved in aiding babies when they determine which way is down.  If that is the case (and I should stress again, I don't really know for sure), then lower gravity would make it harder, increasing complications.

All other complications aside, the real issue is bone and muscle mass and density.  This is the problem we KNOW is real, and it would mean that Mars-born humans would have a lot of trouble making trips to Earth, which we know that someday they will probably want to do.  Ergo, we must try defying gravity (teehee).

To get ideas for this, I looked into possible spacecraft designs.  One major school of thought regarding interplanetary and interstellar spacecraft is to build torus shapes as habitations, and spin them to simulate gravity via centrifugal force.  Build a big ring, spin it at the right speed, and stand people inside it, and they are pulled outward by exactly the same level of force that pulls us downward on Earth.  The bigger the circle, the fewer the rpms need to be.  Voila, microgravity problem solved.  People can now stay in space as long as they want without getting all weak and breakable.

On a planet this becomes more difficult, because the planet is pulling down at the same time that the torus is pulling outward.  You might have experienced a carnival ride where you stand in a padded, circular room, the room spins, and then the floor falls away.  You don't fall out because you are pinned to the wall by centrifugal forces, but you can't move either, because the force needed to pin you to a wall safely is perhaps 2 Gs, and pulls you heavily into that padded wall.  Less force, and you might fall out of the ride, because Earth's gravity is still present.  We can only use centrifugal force to ADD gravity, we can't get rid of the existing gravity.

Mars gravity, however, is less.  So we can reach Earth gravity if we can add the right amount.  What we need to do is build a spinning house.  Specifically, a spinning house with a curved floor.  You see, the addition of two forces in different directions (in this case, one outward force, and one downward) can be seen as a single force that is their sum, a new vector, in a new direction that averages the old ones.  So, if I spin a torus to add .62 g of force at a certain radius, while Mars pulls downward with .38 g, there will be a certain, perfect angle at which I can tilt the floor, where gravity will pull exactly 1 g perpendicularly.

The problem with this is that at all other radii, the force from the rotation will be different, and the angle will change.  To account for this, the floor will need to be curved such that "down" is always perpendicular to the floor.  If you make the radius big enough, and the rotation slow enough, the difference in angle becomes gradual, leading to a gentle upward slope away from the entrance to the building in the center.  As you walk outward and up the slope, you will get heavier and heavier, but down is always directly beneath your feet.  You can walk perpendicular to the slope of a hill, and a ball on the floor won't roll back down.

In fact, if the designers built the slope right, the ball would roll upward.  You see, a human being sticks up off the floor, and a human's center of gravity is not at floor level.  To optimize balance, it would be best to build the curve so that it fits a radius just under 1 meter less than the actual radius, so that our feet, below 1 m, are slightly heavy, and our heads, above 1 m, are slightly light, and on the whole, an average height person comes out to be Earth weight.  This means objects at floor level will have more outward pull than the floor angle compensates, and will roll upward.  Unfortunately, this also means that rolling office chairs will be a bad idea.

(WARNING: This paragraph may contain math type stuff.)  The building itself will need to be HUGE, and the bigger it is, the better, because the bigger it is, the slower it can spin, and the less difference in weight and angle from one point on the radius to the next.  At a radius of 50 m, .62 g is a rotation of 17.439m/s, a little less than 3 rpm, which, at a radius of 51 m will cause a velocity of 17.787m/s, for .632 g, increasing or decreasing by roughly 2% (.0124 g) per radial meter.  So, a person 2 meters tall would have feet that were 4% heavier than his head, which might be dizzying, but would be tolerable.

This will be quite a construction project.  Basically, it means building a spinning football stadium on Mars.  And it can never stop, either.  If the spin stops, all the furniture goes sliding down the slope.  A difficult feat for engineers.  This will have to be built with on-site martian materials, as shipping costs would render it completely impractical to build on Earth.  Only the outer edges will really be good for human habitation.  The center would make a very nice little park or low gravity playground or gymnasium.  It will need a VERY reliable and substantial power supply, probably fusion, although current fission reactors would work, and I would want a triple fail-safe on the machinery, and would probably still bolt my furniture to the floor.  It probably won't exist for a couple years after original Mars landing, due to all of these concerns.

However, aside from fusion power (which we could skip, but I don't want too), all of the technology is already achievable, it just needs a bit of scaling up in terms of size.  Once that is done, gravity problems go away, and this can be the first apartment building on the red planet.