Ticket to Mars

Many scientists believe that all the chemical prerequisites for life like water, nitrogen, carbon dioxide and other carbon compounds are bound in its polar ice, writes Prakash Chandra.

Mediterranean-pink skies, wooded hills and rivers running through lush green valleys… imagine this promise of a vacation -- on Mars! Humans are not there yet, but this is how the Red Planet would look once greened, or ‘terraformed’. So what if Martian equatorial temperatures barely touch 20º C at midday, and dip to a bone-chilling 90º C at night? Terraformers, or scientists who use planetary engineering to landscape inhospitable, alien worlds, will modify its temperature, surface and atmosphere so that it can support life.

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Sci-fi author Jack Williamson coined the term ‘terraform’ in his 1942 classic, Collision Orbit. Arthur C Clarke and others later published stories based on the idea, terraforming everything, from Jupiter’s exotic moons to Venus and its sulphuric acid rains. It is Mars, though, that has caught terraformers’ attention as data sent back by the Mariner, Viking and Pathfinder missions indicate it was a very wet place once. Many scientists believe that all the chemical prerequisites for life like water, nitrogen, carbon dioxide and other carbon compounds are bound in its polar ice, permafrost and carbonate rocks. On Earth, early volcanic activity constantly recycled these atmospheric elements, but on a less active young Mars, falling temperatures trapped them and they grew thinner and thinner, freezing into the planet’s fabric.

Defreezing this requires heat, but Mars gets only 40 per cent of the Sun’s energy unlike Earth because of its distance. One solution is to darken its polar ice caps and reduce albedo -- the Sun’s heat reflected back into space. Terraformers calculate a 4 per cent albedo reduction is enough to raise temperatures, release trapped CO2 and trigger a runaway greenhouse effect. This can be achieved by covering the ice caps with a thin layer of dark dust, mined on Mars. Plants and bacteria ‘imported’ from Earth would then photosynthesise, with help from nitrogen in the atmosphere, and release oxygen. Mirrors can also help warm the planet. Nasa plans to have a 75-mile diameter solar mirror behind Mars in a stationary position, from where it would reflect enough sunlight to raise the temperature of the South Pole by five degrees. The Russian Znamia project that successfully tested the first space mirrors in Earth orbit proves how easy it is to build these in the weightlessness of space.

But even the best planetary engineering skills may only ensure that early human settlers on Mars walk around without pressure suits and without instantly freezing to death. For scientists reckon it’ll take around 10,000 years for its atmosphere to be oxygen-rich. So for that Martian getaway, don’t forget your oxygen backpack.