Vocabulary: rocket (n), top part/ bottom part (n), supplies (n), to land (v), ship (n).
For the first time, part of a rocket will return safely to the earth. Normally, all parts of a rocket are destroyed when they return to the earth because they travel very quickly.
SpaceX, a company from California, will send a rocket to the International Space Station on Tuesday. This rocket is called Falcon 9. The top part of the rocket contains supplies and experiments for the Space Station. This will arrive safely at the International Space Station. The bottom part, which contains the engine, will return to earth and land on a ship in the Atlantic ocean, near Florida.
This is the ship where the rocket will land.
This has never been tried before and it will be very difficult because the sea might move the ship. SpaceX says that there is only a 50% chance that the rocket will land safely on the ship.
Rockets are extremely expensive, so to land part of the rocket on the ship would be a great achievement. The rocket can then be recycled.