speech 5

Terraforming Mars - 900 words
Mister toastmaster, fellow members and guests.
I'd like you to, if you can, imagine you're floating in space somewhere in our solar system.
In the far distance is the brilliant orange glow of the Sun and spinning nearby is the blue-green planet we know as the Earth.
The Earth is the third from the sun and is wrapped in an atmosphere rich in nitrogen and oxygen.
It has a cosy average temperature of about 14 degrees celcius.
The planet has abundant water and its surface is positively teaming with life, from the highest mountain peaks to the deepest oceans.
Its life forms range from the six billion human beings who have tamed its landscapes to countless plant and animal species and trillions and trillions of algae and bacteria.
Now turn your attention to the fourth planet from the sun: Mars.
It's a frigid world where temperatures can plunge to minus 160 degrees celcius and on an average day things don't get much above minus sixty.
The atmosphere is thin and made up mostly of carbon dioxide with a little argon thrown in.
Cosmic rays stream in from space, the air pressure is only about one one-hundredth that on Earth and the only water on the planet is frozen.
The polar ice caps are made mainly from carbon dioxide.
To human beings and every other form of life that we know of it is a toxic, hostile, deadly place.
But it doesn't have to be.
Humankind is now on the verge of our first manned missions to Mars - possibly as soon as 2025 - and in response science is proposing a host of ways to transform the red planet into a world like our own.
Under a process called terraforming or planetary engineering, over thousands of years man could give Mars a dense protective atmosphere and turn up the temperature to a level where plants could grow and people could live without space suits.
Eventually the atmosphere could also be made breathable.
There are two schools of ethical thought on terraforming.
Those for it say, transforming Mars would allow mankind to take a foothold elsewhere in the solar system, preserving our species in case of a catastrophe like a nuclear war or comet strike.
They say we have a right to alter Mars to suit our needs in the same way we've changed the Earth.
Opponents say mankind has no right to touch a pristine world and Mars should be left like the Antarctic as a national park.
They also argue, while it may seem sterile we may yet discover evidence of life on Mars and that should be preserved.
It's a debate that's sure to continue for some time to come.
If we do eventually decide to terraform Mars the main hurdles are going to increasing the surface temperature and thickening up the thin atmosphere.
Scientists say theoretically that's very possible and we can probably do both at the same time with something called the runaway greenhouse effect.
In the same way that grenhouse gases - things like chloroflurocarbon and carbon dioxide - are warming the Earth's atmosphere by trapping the Sun's heat, researchers say they say they could warm Mars.
If you can release a massive amount of the gases in the Martian atmopshere you would slightly increase the temperature which would melt some of Mars' frozen carbon dioxide.
This is turn would raise the temperature more and cause more CO2 to melt and so it would go on.
There are at least four proposals for to get the process started in the first place.
Number one would see massive mirrors built in space and placed a couple of hundred kilometres from Mars.
These would be used to bounce back the energy of the Sun and direct to the Martian surface where it would melt carbon dioxide and kickstart the greenhouse effect.
A second plan two would see massive greenhouse gas factories set up on the Martian surface, built from local materials.
These would work day and night churning out the most powerful greenhouse gases - CFCs - and so raise the temperature and thicken the atmosphere.
The third model involves smashing frozen deposits of ammonia into Mars.
Ammonia is a powerful greenhouse gas and scientists believe there are massive frozen supplies, stockpiled around the solar system, to which rocket engines could be attached.
The final option is even more dramatic.
Some scientists propose taking stockpiled nuclear weapons from Earth and detonating them at the Martian poles.
This would melt the frozen carbon dioxide at the poles and release it into the atmosphere.
Fall-out would blacken the planet surface meaning it would absorb more heat.
Opponents to the plan have some pretty serious reservations about contaminating the planet's surface in this way.
Whatever the technique chosen, it's likely that terraforming Mars would take thousands, perhaps tens of thousands of years.
But if the techniques work they could then be applied to other planets in the solar system - like Venus.
Unlike Mars, which is too cold, Venus is too hot for humans and its atmopshere is too thick.
While it's a long way off, I personally like the idea of terraforming.
I think its somehow comforting to think thousands of years from now our descendents might one day breathe in a lungful of Martian air, stroll beneath a Martian sky and raise kids on the red planet.