QUESTION:
I read about the possibilities in the future of creating a race of
humans that can be
genetically altered to live on Mars's surface.  Is there any truth to
this?

ANSWER from Geoff Briggs on January 4, 1999:
Presumably the idea is for a genetically-altered human to be able to
tolerate the cold martian temperatures, low pressure CO2 atmosphere and
heavy ultraviolet radiation without a spacesuit.

I think this would probably not be possible as stated since we don't
even
know of a terrestrial microbe that can tolerate those conditions except
maybe in a desiccated state of hibernation.

The cold temperatures would quite rapidly freeze solid an unprotected
human
and it is the inability of water to stay liquid at such cold
temperatures
that is a key stumbling block to expecting there to be any life forms at
the surface of Mars.  Note that humans on Earth have to wear insulating
garments to survive in very cold conditions.  So, maybe these
genetically
altered humans would be allowed to wear insulating clothes.

Regarding the heavy ultra violet radiation (because Mars has no
protective
ozone layer), again we terrestrials wear hats and sunscreen to protect
against the UV and so, again, maybe the Martian humans would be allowed
to
proect themselves.

Probably the real question is whether a human animal could breath the
Martian atmosphere, extracting oxygen from the CO2.  There would seem to
be
two problems -- 1) getting enough breathable air from an atmosphere
whose
density is equivalent to 100,000 ft plus and 2) extracting the oxygen
from
the CO2.

The second task is something that plants can do so I suppose it doesn't
violate any laws of physics to imagine the genetic transformation of a
human to breathe CO2 -- though it seems implausible to me (not a
biologist).

The first task -- coping with an atmosphere that is almost a vacuum --
seems to stretch one's credulity.  A human has to be able to generate
enough energy to maintain vital functions and perform work.  That
requires
burning a certain volume of oxygen with food -- so getting at the oxygen
really seems like a fundamental problem.   It would seem to me that the
human would always need some kind of machine (an oxygen tank or a
machine
to extract oxygen in sufficient quantity from the CO2) to deal with this
problem.  Note: an oxygen tank is an expendable source and a machine
would
require an energy supply that would also be expendable so in both cases
the
human is still a highly dependent being.

Also the problem of maintaining the human's interior integrity against
the
near vacuum has to be considered.  I suppose you could imagine a human
developing a very thick skin that would act as a pressure suit.

However, you could perhaps engineer a human to take advantage of the
lesser
gravity there -- less powerful limbs, say.  However, I would think that
humans on Mars would appreciate their ability to lift large loads
unaided
(and leap over tall buildings) and probably wouldn't choose to
deliberately
engineer away muscle mass.

Geoffrey Briggs
Center for Mars Exploration