Terraforming Mars and Venus
Reasons to Terraform
Henceforth I spread confident wings to space
I fear no barrier of crystal or of glass;
I cleave the heavens and soar to the infinite.
And while I rise from my own globe to others
And penetrate even further through the eternal field,
That which others saw from afar, I leave far behind me.
Giordano Bruno
On the Infinite Universe and Worlds, 1584
Reasons to Terraform
•
•
•
•
Extreme pollution of Earth
Extreme crowding on Earth
The imminent destruction of Earth by impact
Scarcity of raw materials; creation of
permanent mining operations
• Adventure; because it’s there
Conditions on the Sister Planets
Earth
Mars
Venus
% O2
20.94
0.13
0
% N2
78.08
2.7
3.5
% CO2
0.04
95.32
96.5
1 atm
0.006 atm
-15 C to 40 C
-140 C to -15 C
450 C
liquid/frozen
frozen
none
1.0 g
0.38 g
≈ 1.0 g
adequate
none
none
1 day
≈ 1 day
117 days
Atmosphere
Pressure
Temperature
Water
Gravity
Magnetic
Field
Length of
Day
90 atm
Conditions on the Sister Planets
Earth
Mars
Venus
% O2
20.94
0.13
0
% N2
78.08
2.7
3.5
% CO2
0.04
95.32
96.5
1 atm
0.006 atm
-15 C to 40 C
-140 C to -15 C
450 C
liquid/frozen
frozen
none
1.0 g
0.38 g
≈ 1.0 g
adequate
none
none
1 day
≈ 1 day
117 days
Atmospheric
Chemistry
Pressure
Temperature
Water
Gravity
Magnetic
Field
Length of
Day
90 atm
Do We Need Earth-Like Conditions?
• Not necessarily
• Obtaining the right oxygen level might
be very difficult
• With the right pressure and
temperature, humans could grow food
and mine without spacesuits (need
oxygen masks)
• Different term? -- ecosynthesis
(Macelroy, 1976)
Goals for Terraforming Mars
• Increase atmospheric pressure
• Warm terrain and atmosphere
• Prevent loss of atmosphere
Mars Ecosynthesis
• James Graham, Astrobiology, 4:
168-195 (2004)
• 1000-year process
• Probably have several hundred
thousand years before Earth is
uninhabitable
Schemes for Atmospheric Warming
• Pollution: manufacture and release
hydrocarbons to enhance greenhouse
effect
• Melt CO at the poles through to use of
space mirrors
• Steer ammonia-rich asteroids or comets
to impact -- decades of delay
James Graham’s Model (2004)
James Graham’s Model (2004)
James Graham’s Model (2004)
James Graham’s Model (2004)
James Graham’s Model (2004)
James Graham’s Model (2004)
James Graham’s Model (2004)
“It is concluded that a drastic modification of Martian conditions can
be achieved using 21st century technology. The Mars so produced
will closely resemble the conditions existing on the primitive Mars.
Humans operating on the surface of such a Mars would require
breathing gear, but pressure suits would be unnecessary. With
outside atmospheric pressures raised, it will be possible to create
large dwelling areas by means of very large inflatable structures.
Average temperatures could be above the freezing point of water
for significant regions during portions of the year, enabling the
growth of plant life in the open. The spread of plants could produce
enough oxygen to make Mars habitable for animals in several
millennia. More rapid oxygenation would require engineering efforts
supported by multi-terrawatt power sources. It is speculated that
the desire to speed the terraforming of Mars will be a driver for
developing such technologies, which in turn will define a leap in
human power over nature as dramatic as that which accompanied
the creation of post-Renaissance industrial civilization.”
Robert M.Zubrin and Christopher P. McKay, “Technological Requirements for
Terraforming Mars,” http://www.users.globalnet.co.uk/~mfogg/zubrin.htm; date
unknown but after 1994.
Goals for Terraforming Venus
• Reduce atmospheric temperature
• Eliminate most of dense CO
atmosphere
• Add breathable oxygen
• (Establish magnetic field by spin-up)
• (Push Venus further from the Sun)
Venus Ecosynthesis
• Reduce temperature
– Space-based solar shade (Paul Birch)
Venus Ecosynthesis
• Reduce CO2 and reduce pressure
– Microbes to turn excessive CO2 into
carbohydrates
– Capture in carbonates by introduction of
magnesium and calcium metals
– Direct liquifaction
– Introduction of hydrogen
H2 + CO2 ⇒ C + H2O
Venus Ecosynthesis
• Establish magnetic field
–Molten interior
–Spin-up
• Mass drivers ?
• Rocket assist ?
An Interesting Alternative to
Venus Ecosynthesis
• Floating colonies
–50 km altitude
–Pressure about 1 atmosphere
–Temperature: 0 – 50 C
Philosophical (Ethical?) Issues
Do we have the right to alter
a natural environment?
Philosophical (Ethical?) Issues
• Pros
– Ecosynthesis would allow free movement
with breathing masks
– Colonists could live off local biomass
– A unifying project for Earth’s people
– Would provide a survival colony in the
face of an Earth disaster
– Stimulate technological developments
– Better use of resources than building
military stockpiles
Philosophical (Ethical?) Issues
• Cons
–
–
–
–
Enormous time scales
Very long-term economic payback
Less attention to important terrestrial problems
Legal and administrative roadblocks
• Who gets to live there?
• Who owns it?
• Who controls it? Earth or the other planet?
– People’s physiology would evolve in different gravity of
Mars
• Bone structure
• Muscle mass
• Internal organs?