https://wccftech.com/musk-blows-the-lid-off-starship-exolosion-says-spacex-loaded-it-with-too-much-fuel/
According to Musk, the explosion took place because SpaceX had to vent excess oxygen out of the ship. Testing new rockets typically sees companies use a mass simulator for a payload to simulate flight conditions, and Musk added that the explosion could have been avoided had SpaceX used an actual payload for orbital delivery.
Musk revealed the reason behind the anomaly in SpaceX's company talked. A little over a third of the talk shared by SpaceX on its X page covered Starship. SpaceX's future depends on Starship since not only is the rocket essential for the firm to build out its Starlink internet satellite constellation, but it will also conduct lunar missions for NASA and eventual crewed Mars flights.
SpaceX's latest Starship test took place in December, and while it saw the rocket successfully lift off and complete stage separation, the rest of the test saw both the first and second stages explode at different times and far away from each other.
Musk shared details about the second stage's explosion, revealing that the cause of the anomaly was SpaceX itself. He outlined that during liftoff, SpaceX had fully filled the Starship's second stage with liquid oxygen and methane. Once the firm tried to vent this oxygen during flight, the Starship's second stage exploded, explained the executive.
According to Musk:
So, flight 2 actually almost made it to orbit. So, in fact, ironically if it had a payload, it would have made it to orbit because the reason that it actually didn't quite make it to orbit was we vented the liquid oxygen. And the liquid oxygen [inaudible] led to fire and an explosion, because we wanted to vent the liquid oxygen because we normally wouldn't have that liquid oxygen if we had a payload. So, ironically, if it had a payload, it would have reached orbit. And so I think we've got a really got shot of reaching orbit with flight 3, and then a rapid cadence to achieve full and rapid reusablity.
Flying Starship's second stage with the weight to represent a payload was necessary for SpaceX's December second Starship test flight since it had to test the correct thrust specifications for lift-off and stage separation. A lighter rocket requires less power whenever engines are involved. For test launches, depending on the objectives, it has to match flight specifications to ensure performance at the correct requirements.