What sort of genetic manipulation will be needed in order to colonize space ?
I’m assuming that it will in the future be easier and more necessary to modify the genome than to modify the environment.
How to cope with the gravity on Mars, for instance ? Sci Fi films have artificial gravity but that seems like an impossibility now.
And also, at what point will future space migrant be deemed to be a separate species, unable to breed with Homo Sapiens Sapiens ?
From Packing for Mars, apparently degree of bone loss from inactivity (related to bone loss from zero g) is hereditary, as may be a propensity for kidney stones and reaction to cosmic rays. Although she may have been kidding about the last two, she had citations for black women (and, presumably, black men - the studies were being done for osteoporosis) being less susceptible to bone loss. You can add any genes that make any medical problem less likely.
She also mentioned that anosmia might be a benefit, due to the difficulties of hygene in zero g and close quarters.
From her descriptions of the difficulties of excretion containment systems in space, I’d say engineer a human that can poop like a sheep - in little, dry ovals that fall away easily, that can be easily entrained by air-flow, and that compost easily.
The current human form depends on gravity to regulate fluid through the body, so in zero g the current model tends to swell above the waist and get a little dry below it. You’d want to fix that.
Maybe change human skin so that it sheds in clumps or strips instead of single cells that float around and get into things.
The speciation thing, unless deliberately done, will depend on how cut off from bog standard humans they are for how long.
You wouldn’t need to cope with it. I’d say that humans as they are today could easily adapt to the lower gravity on Mars. The problem is the zero grav environment getting there. Well, and all the radiation, un-breathable atmosphere and such.
Same as any other species. When you are no longer able to breed with and form viable offspring that can also breed you have a separate species.
My WAG on this would be that it would vary depending on the planet. One thing that I think you’d need regardless is higher tolerance for radiation…just to get to another planet you’d need to have the crew survive, and radiation would be one of the show stoppers.
I think, however, that we are more likely to go for geo-engineering and terraform technologies, as well as engineering solutions for the space craft rather than trying to re-engineer humans for the huge range of environments we are likely to find out there in the greater universe. It makes more sense, to me at least, to terraform Mars, say, with genetically altered life forms and use artificial means to thicken the atmosphere and make it suitable for human habitation than to try and change a small subset of humans to fit the planet.
All of this of course assumes we ever get to that point at all. 
Surely we’ll be looking at terraforming AND genetic engineering ? Thing is though, is terraforming possible on planets that have a different orbit from Earth’s ? The basic factor of sunlight and heat wouldn’t support an Earthlike biome, I would think.
Are we talking “this sounds good on Star Trek” or is this thread meant to be a legitimate discussion about real science and engineering?
Because if it’s the former, you can make up whatever you want.
If it’s the latter, the answer, based on the best current knowledge, is obvious.
Riddle me this : what’s more likely to function for centuries (space travel is slow) in a high radiation environment :
A biological meat creature based on inefficient evolved Earth Biology
A self repairing artificial creature made of nanoscale subunits using all the diamondoid and CNT and rare earth elements and high end materials an optimal design needs.
More specifically, we can visualize number 2 pretty well. A reasonable estimate is that at current semiconductor densities, you would need ~60,000 square meters of chip surface to emulate all the complexity of a human mind with dedicated hardware. Obviously, a 60,000 square meter chip is impractical, but if the chips are stacked inside the same package thousands of times (to make a true 3 dimensional IC) you could fit this synthetic brain into about the same space as the current human brain. (by definition, you must be able to do so )
The individual circuits would use things like triplicate redundant logic and other things to be highly resistant to radiation. You’d also keep backup logs in some kind of 3 dimensional media where you would save the state snapshots of this synthetic mind periodically.
In short, this kind of technology would give you a being with human intelligence or better, but it would be de facto immortal and resistant to thousands or millions of times higher levels of radiation than a human. Also, while the hardware itself would wear over time, the fact you have state snapshots means that any time you can manufacture a new brain and migrate this being’s mind to brand new hardware.
TLDR : Terraforming and genetic engineering? That’s about as silly and dated as discussing using gunpowder cannons to reach the moon.
…and that’s not including the roles played cell membrane and the microtubules.
It’s hard to imagine a genetic fix that would make it possible for human-derived organisms – or any Earth-derived organisms at all – to live in space, with no air tanks or pressure suits.
I meant on planets/asteroids etc - but yeah what would have to be done to make us survive in just space ? Something pretty radical I would think.
Maybe engineer the gut bacteria to do that.
Something having to do with photosynthesis, perhaps.
And, for moving through space with nothing to grab on to . . . a far more gas-productive digestive system, and several extra ani strategically placed.
Beautiful.
There’s some throughput parameters, including membrane reabsorption, that gut bacteria can’t control. But you would want to manage the gut bacteria, at least. Maybe engineer them to do other things.
I think they’re maybe engineering us.
Nothing. We’re humans. We make the Universe adapts to our needs and wants. Not the other way round.
Both are pretty much in the realm of science fiction at this point. We don’t have the ability to genetically modify humans to fit into alien eco-systems OR the ability to terraform another world (we are currently doing open experimentation at terraforming THIS world for high levels of CO2 so I guess we shall see how that works out :p). Hell, we haven’t even been to any other worlds even in our own solar system outside of the Moon thus far, so the question you are asking is really putting the cart before the horse.
But my WAG is that IF we are ever able to serious contemplate colonization of another planet we will do so by tailoring that planet to our needs, not radically changing ourselves to fit the ecology of that planet. I doubt I’ll live long enough to find out if I’m correct or wrong, however, as at this point I’m simply hoping to live long enough for a manned mission to Mars. 
There’s a pretty severe objection to photosynthesis as a source of energy for animals. Even if we’re talking about artificial algal type symbionts, think about how many square meters of farmland a human being needs to grow enough food to live. That’s how many square meters of leaves intercepting sunlight a plant-man is going to need to have a human-like metabolism.
Having a symbiotic algae skinsuit is like having a tiny windowbox garden as your food source, except you have to carry it around with you all day. Wouldn’t it be easier to leave your garden at home when you need to run errands?
Reportedly some bacteria can actually live on electricity; and creatures like electric eels and rays show that biochemical activity can produce electricity. Conceivably a human could be genetically modified to be able to use electricity for their bodily energy needs. Presumably you’d still need to eat and eliminate some to cover the constant rebuilding of the body, and you’d want to be able to breath to enable speech (unless that could be replaced by radio waves, which is really out there). Raw electricity is much easier to come by in space than oxygen and food. And since warm-bloodedness is not that useful when the ambient temperature has to be artificially controlled anyway, one might as well eliminate endothermy. Those two taken together would drastically reduce the overhead of keeping humans alive beyond the earth.
However, since we still don’t know the limits of technology, it would be shortsighted to adapt our bodies rather than our technology. For all we know in a thousand years we’ll be able to wear personal forcefields that will completely protect and nourish our bodies as they are.
Terraforming Mars would be a fantastically large undertaking, and would take thousands of years, during which the surface would be a very hazardous place to live.
On the other hand genetic enginering is likely to start bringing results of a dramatic nature some time during this century. So I’d say that genetic engineering will probably beat terraforming hands down in the race to make Mars habitable. Even if we do terraform Mars the planet will probably need to have a toxic level of carbon dioxide, acting as a greenhouse gas to maintain that planet’s surface temperature. So the eventual inhabitants of a terraformed mars will need some tweaking anyway.
For space-dwellers in microgravity, Improved tolerance of radiation, a better waste-disposal system and better agility for living in freefall will all be useful. I imagine humans with more flexible necks to improve their three-dimensional awareness would fare better than unmodified humans, and gripping toes to retain a handhold where necessary.
But this last adaptation need not be necessary, if the interior of the microgravity environment is designed correctly - an environment could be constructed with automatic positioning devices that allow a person to remain anchored in position - hundreds or thousands of little Canadarms that hold you gently but firmly, and which respond to your slightest movement. Adapting humans to a freefall environment is all very well, but if you want them to be able to retain the ability to walk about on Earth, adapting the environment is generally preferable.
Nitpick: it must be possible to make a synthetic brain that’s as small as a human brain (because at the least we could “just” synthesize a perfect copy of a human brain).
It doesn’t follow however that stacking ICs could produce human-equivalent intelligence in the same volume, because that isn’t a copy; that’s a different structure/substrate with different limitations and requirements (e.g. cooling).
We’d need eyes or some kind of antenna with at least the same diameter/length as the relevant radio wavelength.