As if mankind would like to the stars, if it does not develop a way to obtain huge amounts of energy almost effortlessly, his nearest significant cosmic perspective will territorialnye of Mars. Remind: to get to him, enough to accelerate to 1/10 000 light speed, and then would slow down - and this is unrepresentable easier than travelling with light velocity. Because fuel vehicle in space have to bear with me. Therefore, the growth speed of travel in 10 thousand times causes the same increase of fuel stocks, which in turn calls... And so on! But still it will be necessary to brake...

Mars and the four stages of TERRITORIALNIY. Although at the beginning of the need bombardment by comets, high temperature can still get to keep only with the help of saturation of the atmosphere by chlorofluorocarbons. (Here and below Fig. Wikimedia.)

How to start territorialnye Mars - evident. You need to make in the atmosphere of greenhouse gases. Carbon dioxide is not ideal: its greenhouse opportunities too weak; methane will quickly break down under the action of sunlight. The ideal candidate (known chemistry) lowest chlorofluorocarbons (CFCs), practically non-toxic to humans. It is believed that they may be responsible for 13-25% of current greenhouse effect, only twice, four times less than the guilt of carbon dioxide - by incomparable concentration in the atmosphere.

By the way, in the case of Mars and do not need much: CFCs will play the role of a trigger anthropogenic warming. A huge mass of carbon dioxide in the form of ice at the poles of Mars with warming of only tens of degrees will melt, and ("dry ice") immediately to the gas - and it would be enough to secure a more powerful greenhouse effect and warming.

Most importantly, CFC not arise in the course of natural processes. In other words, it's almost a litmus test for the detection of advanced intelligent life.

Easy and detect CFCs in the atmosphere of other worlds: they absorb the light not as common substances that occur naturally. Yes, today's telescopes is not yet capable of it, but the orbiters next generation may well provide astronomers.

"Artificial heating of [greenhouse gases] body outside habitability to still make it habitable, may also be a sign of intelligence, thinks astrobiology Sanjay Soms (Sanjoy Som) NASA involved in the scientific community Blue Marble Space Institute of Science. - Assume that a few thousand years later people terraforming Mars... Then the alien [reasonable] types will find our Solar system, and you will find the Ground, and in addition they are investigating the composition of the Martian atmosphere of the planet, which must be outside the habitable zone of Sun, and will record the increased concentration of greenhouse gases (except for water vapor and oxygen). This duplanty system is a serious indicator of reasonable civilization, a busy extension of your crib beyond the home planet".

Based on the materials Astrobiology Magazine.