The astronauts will be lifted off into space on the Space Launch System (SLS) rocket.
The job of the SLS is to carry the Orion spacecraft – which sits at the top of the rocket with the astronauts onboard – to space.
The astronauts will spend 10 days in the Orion capsule, which is about 5m wide and 3m high.
They’ll exercise for 30 minutes every day with a small exercise machine, use water to rehydrate their food and use a toilet tucked under the floor.