The space shuttle Discovery will blast off on Wednesday, despite recent damage to a panel on the spacecraft.
A window cover fell off the craft and damaged two heat shield tiles, but it has been quickly fixed and poses no threat to the shuttle, says Nasa.
The shuttle is set to take off from the Kennedy Space Center at 8.51pm UK time, and will be the first US space mission since the Columbia disaster in 2003.
It broke up when re-entering Earth's atmosphere, killing all seven on board.
The soft window cover which fell off is made of plastic with a foam edge, and is taped in place to protect the windows and keep them clean before launch.
The damage to the carrier panel of the Orbital Manoeuvring System pod, which allows the shuttle to move in orbit, was repaired in less than an hour.
Earlier Nasa officials said they have done everything they can to make the flight as safe as possible.
At least 107 cameras have been positioned on the ground, on planes and on the shuttle, to monitor the flight.
They will film different stages of the journey, and transmit them back to base to allow engineers to make further safety improvements to space flights.
Discovery even has a special extended arm with a camera on, so it can swing round and check the underside of the shuttle at any time.
The mission will take 12 days, during which time Discovery will carry a crew of seven to the International Space Station with supplies and parts.
Storms following Hurricane Dennis have threatened the launch, but experts hope the bad weather has now moved on.