[KevinDavis]

[Aetius]

Governor Schwarzenegger terraformed Mars in a matter of minutes in "Total Recall."

But seriously, this is very interesting.

[Calvin Locke]

Not to rain on her sqaure kilometer, but what about all those long lasting dust storms?

In addition to all the technical problems.

[Pontiac]

The concept calls for 300 reflective balloons, each 150 metres across, arranged side-by-side to create a 1.5-kilometre-wide mirror in orbit around Mars.

Somehow I just don’t get the concept of balloons in space. Why would you use balloons in space?

If the mirror is in space it does not need to be buoyant.

It also seems to me a balloon would have a convex shape which would disperse light rather than focus it on a specific area.

[Brett66]

This sounds practical, I could imagine setting up a dome structure in a large crater and focusing the sunlight on it. It would make it quite warm.
I seem to remember the Russians attempting to do this over some of their colder regions of the country a few years ago. I believe it failed to deploy properly in space.

[SunkenCiv]

...but some experts say the mirrors may be hard to deploy.

elsewhere in the news, the Elephant Man had a little puffiness around the eyes. For that kind of money, the Sahara could be refoliated.

[nuke rocketeer]

Gotta get a magnetic field going there too to help radiation protection.

[mwyounce]

If they're trying to warm up the surface, they don't need "space mirrors"... they just need a space heater! :-)