So far, SpaceX has done three test flights to heights greater than 10 km with prototypes of their Starship system, with the third flight resulting in the first successful landing, albeit with the prototype exploding shortly after landing due to damage sustained. SpaceX continues the development of the Starship vehicles.
When will the fifth SpaceX Starship flight be?
This question resolves to the time of the fifth Starship flight, with the December SN8 flight considered to be the first. A "flight" is defined as a testflight that reaches an altitude of at least 1 km intact by firing its engines, and a Starship is defined as a SpaceX vehicle meeting the following criteria:
- Not an existing member of the Falcon family (Falcon 9/Heavy) or a Falcon derivative
- Intended to be fully reusable, with every stage returned to Earth (smaller portions such as fairings may be expended)
- The vehicle must have a stated payload to LEO of at least 20,000 kg (of pure payload, e.g. the Space Shuttle Orbiter would not count as payload mass). This is very conservative, so Starship would qualify even if it were greatly scaled down from today.
- The vehicle should be representative of a vehicle intended to carry a payload to Mars at some point, according to public statements of SpaceX or its representatives.