Lightning strikes and storms delayed earlier launch attempts
Astronauts have been building the space station for more than 10 years now and it's about the size of a four-bedroom house.
The shuttle launched on Wednesday, just hours before the 40th anniversary of the launch of the space mission which led to man's first moon landing.
And it made it just in time... if the shuttle hadn't taken off by Thursday, it would have had to have waited until the end of the month to make way for a Russian cargo ship.