That's when Starship reignited one of its six Raptor engines for a brief burn to make a minor adjustment to its flight path. The combustion lasted only a few seconds and the impulse was small—only a change in speed of 77 km/h, or delta-V—but it showed that the ship can safely exit itself on future missions.
With this achievement, Starship will soon be cleared to orbit Earth and deploy Starlink internet satellites or conduct in-orbit refueling experiments, two of the near-term goals on SpaceX's Starship development roadmap.
Launching Starlinks aboard Starship will allow SpaceX to more quickly expand the capacity and reach of its commercial consumer broadband network, which in turn will generate revenue for Musk to reinvest in Starship. In-space refueling will enable spaceship travel beyond low Earth orbit, fulfilling SpaceX's multibillion-dollar contract with NASA to deliver a human-rated lunar lander for the agency's Artemis program. Likewise, transferring cryogenic propellants into orbit is a prerequisite for sending spaceships to Mars, making Musk's dream of creating a settlement on the red planet a reality.
Until now, SpaceX has deliberately launched spacecraft at speeds just below the blistering speeds needed to stay in orbit. SpaceX wanted to test the Raptor's ability to reignite in space during the third Starship test flight in March, but the ship lost control of its orientation and the vehicle canceled its engine firing.
Before making a full orbital flight, officials had to confirm that Starship could send itself back into the atmosphere for re-entry so that it would not pose any risk to the public in an unguided descent over a populated area. After Tuesday, SpaceX can check this off its to-do list.
“Congratulations to SpaceX on Starship's sixth test flight,” NASA Administrator Bill Nelson wrote on Starship's success is Artemis'success. Together we will return humanity to the moon and set our sights on Mars.”
Although it lacks the pizzazz of a fiery launch or landing, reigniting the engine unlocks a new phase of the spaceship's development. SpaceX has now proven the rocket is able to reach space with a reasonable degree of reliability. Then the engineers will fine-tune how to reliably recover the booster and ship, and learn how to use them.
Acid test
SpaceX appears to be well on its way to doing this. Although SpaceX was unable to capture the Super Heavy booster with the launch tower's mechanical arms on Tuesday, engineers demonstrated that they can. The challenge of catching the ship itself back on the launch pad is more difficult. The spaceship will begin its reentry thousands of miles from Starbase, traveling at about 17,000 miles per hour, and must close the gap between the tower's capture arms within a few inches.
