Terraforming Mars and Venus

transcript

Reasons to Terraform

Henceforth I spread confident wings to spaceI 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 BrunoOn 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 PlanetsEarth Mars Venus

Atmosphere% O2 20.94 0.13 0% N2 78.08 2.7 3.5

% CO2 0.04 95.32 96.5

Pressure 1 atm 0.006 atm 90 atm

Temperature -15 C to 40 C -140 C to -15

C 450 C

Water liquid/frozen frozen noneGravity 1.0 g 0.38 g ≈ 1.0 gMagnetic Field adequate none none

Length of Day 1 day ≈ 1 day 117 days

Conditions on the Sister PlanetsEarth Mars Venus

AtmosphericChemistry

% O2 20.94 0.13 0% N2 78.08 2.7 3.5

% CO2 0.04 95.32 96.5

Pressure 1 atm 0.006 atm 90 atm

Temperature -15 C to 40 C -140 C to -15

C 450 C

Water liquid/frozen frozen noneGravity 1.0 g 0.38 g ≈ 1.0 gMagnetic Field adequate none none

Length of Day 1 day ≈ 1 day 117 days

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)

“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 + H⇒ 2O

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 altera 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?

Terraforming Mars and Venus

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