It weighs almost a tonne, has cost more than $2bn and, in 2013, it will be lowered onto the surface of Mars with a landing system called a sky crane that has never been tried before.
And after one launch delay and a budget that has slipped by almost $800m, Nasa's Mars Science Laboratory (MSL) project appears to have turned the corner.
The US space agency says it is on track to launch the rover on its journey to the Red Planet in 2011.
This animation shows the technology that will, hopefully, set MSL down safely on the surface of Mars.
(Footage courtesy NASA/JPL and Caltech)