The last two Starship test flights ended with explosive failures near islands just east of Florida.
An investigation into the most recent mishap in March is ongoing.
But SpaceX says it knows what went wrong.
The Super Heavy booster, which provides the initial burst of power at liftoff, and the upper 171-foot (52-meter) Starship spacecraft took off with no obvious issues.
After the Super Heavy burned through most of its fuel, it separated from the Starship and landed successfully in the arms of SpaceX’s “Mechazilla” launch tower.
But a few engines flamed out on the way home. SpaceX said the “most probable cause” was an ignition issue caused by abnormal thermal conditions, the company said in a May 22 statement.
Separately — and more significantly — an engine of the upper Starship spacecraft, often referred to as just the “ship,” exploded just minutes after separating from Super Heavy. Ground controllers lost contact with the vehicle, likely triggering the vehicle’s automatic, emergency self-destruct feature.
The likely cause of the mishap, according to SpaceX, was “a hardware failure” in one of the ship’s six engines. That issue likely led to “inadvertent propellant mixing and ignition” — setting off an explosion in that engine.
The March failure occurred at a similar point in Starship’s flight path to that of the January mishap. That’s when a fire broke out in the vehicle’s “attic” section that led to the vehicle to explode over Turks and Caicos.
But SpaceX said the issues affecting the March and January test flights were different: January’s issues centered on “harmonic response” — or harsh vibrations — and “flammability.” Those problems were mitigated during the March test flight, according to SpaceX.
The fixes implemented before today’s flight, however, included putting “additional preload on key joints.” That basically means tightening up some screws.
