"Nasa rides 'bucking bronco' to Mars"

"It weighs almost a tonne, has cost more than $2bn and, in 2013, it will be lowered on to the surface of Mars with a landing system that has never been tried before.

The Mars Science Laboratory will "revolutionise investigations in science on other planets", says Doug McCuistion, director of Nasa's Mars exploration programme.

It will, he says, lay the foundations for future missions that will eventually bring pieces of the Red Planet back home to Earth.

"The ability to put a metric tonne on the surface... gives us the capability to undertake sample collection," says Dr McCuistion. "To collect and launch samples back into orbit will require that size of a vehicle."

But it has been a rather bumpy road to revolution."