Mars, Page 21: [Previous Page] [Next Page] [Syllabus] Textbook pages 160 - 168

Where do we Begin??


Clearly, we need to increase the average temperature, decrease day/night temperature variations, increase pressure, and introduce O₂ and N₂ into the atmosphere. Possible starting points include:

Increase Greenhouse Gases
We can't rely on CO₂ alone. Mars being further out than Earth, and working alone, requires a toxic level (for humans, NOT plants) for adequate warming. To do it with CFCs would require a trillion tons per year, which is a million times more than the current million tons per year being produced on Earth! Ammonia, NH₃, is an efficient greenhouse gas, but it would need to be created on Mars, or perhaps brought on an icy outer planetary body. Both methods would be extremely difficult.

Push an Instability
Presently, the very low atmospheric pressure means heat is quickly lost to space and the ice caps get REALLY REALLY cold, condensing out still more of the atmosphere. If we increased the pressure just a few 10s of mbars, the polar regions would retain more heat, leaving more CO₂ to warm the atmosphere. More CO₂ would be released from the polar ice caps, increasing pressure and retaining more heat. A new equilibrium of 100 to 1000 mbar (like Earth) might be reached.

This requires that there is enough CO₂ to be released! The Carbon may be locked up in rocks, which would need to be broken up or heated to release the CO₂. Even if this did work (and it would make the atmosphere TOXIC for humans), the very high concentrations of CO₂ would cause it to absorb into any liquid water on the surface.. removing it as a greenhouse gas, in the form of carbonates. No Carbon Cycle! Why?

Is Terraforming Mars Feasible?
We don't know how much CO₂ or H₂O is in the surface ices and regolith. We don't understand the complex instabilities inherent in the Martian climate system. However, Mars did at one time have a dense atmosphere, when geological activity was high and impacts were often, heating the surface and keeping the atmosphere full of CO₂ and H₂O. These molecules were lost to space or went into the crust.

The role of geological activity (for carbon-cycle and maintaing a magnetic field) is frequently ignored by advocates of Mars Terraforming!