Thursday, May 27, 1999 Published at 10:46 GMT 11:46 UK
Perfect launch for Discovery
The start of a 10-day mission
A string of recent rocket failures in the US space programme had led to some nervousness at Nasa, but the countdown progressed normally to blast off and Discovery rose high into the Florida morning sunshine shortly after 0649 EDT (1149 BST).
On board are a crew of five Americans, one Russian and one Canadian. They are taking almost two tonnes of supplies to the ISS. This includes spare parts, tools, laptop computers and clothes for the ISS's first permanent residents, due to move in early next year.
Discovery will also deliver components for two cranes that are needed for future construction work on the embryonic station.
The astronauts will also attempt to repair the malfunctioning communications system linking the American-built Unity module to the control centre in Houston.
The Russians failed to meet their deadlines for completion of the service module which will act as the living quarters for the first ISS crew.
Although more than 40 missions will be required to complete the building work, it is possible Discovery's may be the only one to launch in 1999 if the service module does not go up as planned in November.
Discovery has other work to complete during its 10-day mission. It will deploy the Project Starshine satellite. This scientific project will help school children worldwide to measure the way the Earth's atmosphere responds to explosions on the Sun.
"By taking a simple little mirror and putting it up in space and having it be visible to kids on the ground by reflecting flashes of sunlight after sunset or before sunrise, we can actually measure the density of the upper atmosphere," Gil Moore, Director of Nasa's Project Starshine, said.
Children will monitor the satellite's progress in the night sky, and register their observations with Nasa via the Internet.