But the weather may stand in the way.
A cold front that's making its way toward Florida is expected to bring rain and thick clouds by the weekend.
Forecasters are putting the odds of acceptable conditions at 60 percent for a Friday evening liftoff and only 40 percent for Saturday.
The chance of success goes up dramatically on Sunday.
The seven-member crew will deliver home-improvement equipment that is essential if NASA is going to double the size of the crew on the space station. There's an extra bathroom and kitchenette, two more bedrooms, and another exercise machine.
There's also a recycling system that will turn urine into drinking water.
