SpaceX's Starship prototype is on a streak of successes, at a key moment for the spacecraft's development. The Starship SN4 (so-named because it's the fourth full-size prototype) tester managed to pass a test of its Raptor engine firing while installed on the test stand. SN4 previously passed a crucial low temperature pressure test designed to emulate conditions in space, and now seems ready to take on the next phase: a short flight demonstration.The static test fire occurred late Tuesday night in Texas, where SpaceX is developing Starship at its facilities in Boca Chica. The SN4 Starship prototype had one Raptor mounted which is far fewer than the six engines that the spacecraft will eventually have once it achieves full operational status. SpaceX is going to be adding more as it continues its testing and development program, however, with one planned for this iteration in order to demonstrate a short, roughly 500 feet controlled flight similar to the one achieved by the sub-scale Starhopper testing vehicle last year.That test flight could happen relatively soon, as SpaceX has been pursuing the required clearances to perform it for a few weeks now. Pending successful completion of that test, SpaceX is also already in process of developing the next iteration of its Starship prototype, which is designed to be outfitted with three Raptor engines and perform a higher altitude flight, paving the way fo the first ever orbital demonstration, which the company still wants to achieve sometime later this year.The stakes for Starship were already high, considering how much SpaceX has invested in the vehicle, and how it hopes to eventually use it to replace both its Falcon 9 and Falcon Heavy launchers for all mission activities. But they were recently raised higher still, as NASA has selected SpaceX and Starship as one of the approved contractors for its human lander development program. That means the agency will be looking to Starship as a means of transporting astronauts to the surface of the Moon, which it aims to do by 2024.