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 EarthMarsVenus Atmosphere % O % N % CO Pressure 1 atm0.006 atm 90 atm Temperature -15 C to 40 C-140 C to -15 C450 C Water liquid/frozenfrozennone Gravity 1.0 g0.38 g≈ 1.0 g Magnetic Field adequatenone Length of Day 1 day≈ 1 day117 days

Conditions on the Sister Planets EarthMarsVenus Atmospheric Chemistry % O % N % CO Pressure 1 atm0.006 atm 90 atm Temperature -15 C to 40 C-140 C to -15 C450 C Water liquid/frozenfrozennone Gravity 1.0 g0.38 g≈ 1.0 g Magnetic Field adequatenone Length of Day 1 day≈ 1 day117 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: (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,” date unknown but after

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 CO 2 and reduce pressure – Microbes to turn excessive CO 2 into carbohydrates – Capture in carbonates by introduction of magnesium and calcium metals – Direct liquifaction – Introduction of hydrogen H 2 + CO 2 ⇒ C + H 2 O

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?