Most importantly, SpaceX will attempt to briefly reignite one of Starship's six Raptor engines in space. SpaceX tried this on Starship's third launch in March but aborted the engine restart after the rocket lost roll control during the flight's coast phase.

SpaceX’s Starship rocket will be launched for a sixth test flight next week, the latest experiment by the Elon Musk-owned aerospace firm to create reusable spacecraft after a previous test resulted in a “seminal moment” for the company.