The space shuttle Endeavour has begun its journey home after leaving the International Space Station.
Endeavour is coming home a day earlier than planned because of Hurricane Dean, which is threatening parts of the US.
Mission control for the shuttle is in Houston, Texas and there is a chance that Dean could hit there around the time planned for Endeavour's landing.
Nasa bosses have also decided that there is no need to repair some damage on the bottom of the shuttle.
This picture of Hurricane Dean was taken from the space shuttle
During launch on 8 August a piece of foam broke off and hit the bottom of the shuttle, but tests suggest it won't be a problem.
Damage from foam has been a big worry for Nasa ever since 2004, when the shuttle Columba was destroyed when returning to earth.
The shuttle had been damaged by foam when it was launching, and all seven crew on board were killed.