Mars science laboratory Curiosity set for lift off

[popeyespappy]

I doubt if launch weight was an issue. The Atlas V that launched the MSL this morning was configured with 4 SRB’s. It’s capable of using 5 so they could have added an additional 300,000 lbs of thrust if needed. The problem isn’t getting more weight off earth and to Mars. It’s landing something that heavy where you want it soft enough for it to survive.

There’s an interesting article here that discusses some of the issues with landing larger payloads on Mars.