atmosphere without oxygen, advanced plants
require about 1 mb and humans need 120 mb. While
Mars may have super-oxides in its soil or nitrates that
can be pyrolysed to release oxygen (and nitrogen)
gas, the problem is the amount of energy needed:
about 2200 TW-years for every mb produced. Similar
amounts of energy are required for plants to release
oxygen from CO
. Plants, however, offer the
advantage that once established they can propagate
themselves. The production of an oxygen
atmosphere on Mars thus breaks down into two
phases. In the first phase, brute force engineering
techniques are employed to produce sufficient
oxygen (about 1 mb) to allow advanced plants to
propagate across Mars. Assuming 3 125 km radius
space mirrors active in supporting such a program
and sufficient supplies of suitable target material on
the ground, such a goal could be achieved in about
25 years. At that point, with a temperate climate, a
atmosphere to supply pressure and
greatly reduce the space radiation dose, and a good
deal of water in circulation, plants that have been
genetically engineered to tolerate Martian soils and
to perform photosynthesis at high efficiency could
be released together with their bacterial symbiotes.
Assuming that global coverage could be achieved in
a few decades and that such plants could be
engineered to be 1% efficient (rather high, but not
unheard of among terrestrial plants) then they would
represent an equivalent oxygen producing power
source of about 200 TW. By combining the efforts of
such biological systems with perhaps 90 TW of
space based reflectors and 10 TW of installed power
on the surface (terrestrial civilization today uses
about 12 TW) the required 120 mb of oxygen
needed to support humans and other advanced
animals in the open could be produced in about 900
years. If more powerful artificial energy sources or still
more efficient plants were engineered, then this
schedule could be accelerated accordingly, a fact
which may well prove a driver in bringing such
technologies into being. It may be noted that
thermonuclear fusion power on the scale required
for the acceleration of terraforming also represents
the key technology for enabling piloted interstellar
flight. If terraforming Mars were to produce such a
spinoff, then the ultimate result of the project will be
to confer upon humanity not only one new world for
habitation, but myriads.
We have shown that within broad tolerances of
uncertainty of Martian conditions, that drastic
improvements in the life-sustaining characteristics of
the environment of the Red Planet may be effected
by humans using early to mid 21st century
technologies. While our immediate descendants
cannot expect to use such near-term methods to
"terraform" the planet in the full sense of the word, it
at least should be possible to rejuvenate Mars,
making it again as receptive to life as it once was.
Moreover, in the process of modifying Mars, they are
certain to learn much more about how planets really
function and evolve, enough perhaps to assure wise
management for our native planet.
Beyond such near-term milestones, the tasks
associated with full terraforming become more
daunting and the technologies required more
speculative. Yet who can doubt that if the first steps
are taken, that the developments required to
complete the job will not follow, for what is ultimately
at stake is an infinite universe of habitable worlds.
Seen in such light, the task facing our generation,
that of exploring Mars and learning enough about
the planet and the methods of utilizing its resources
to begin to transform it into a habitable planet, could
not be more urgent, or more noble.
1. C. McKay and W. Davis, "Duration of Liquid Water
Habitats on Early Mars," Icarus, 90:.214-221, 1991
2. C. McKay, J. Kastings and O.Toon, "Making Mars
Habitable," Nature 352:489-496, 1991.
3. M. Fogg, "A Synergistic Approach to Terraforming
Mars," Journal of the British Interplanetary Society,
4. J. Pollack and C. Sagan, "Planetary Engineering,"
, J. Lewis and M. Mathews,
eds, Univ. of Arizona press, Tucson, Arizona, 1993.
5. P. Birch,"Terraforming Mars Quickly" Journal of
the British Interplanetary Society, August 1992.
6. R. Forward, "The Statite: A Non-Orbiting
Spacecraft," AIAA 89-2546, AIAA/ASME 25th Joint
Propulsion Conference, Monterey, CA, July 1989.