SpaceX CEO Elon Musk offers details on Starship SN11 explosion

Ignition and liftoff of Starship test articles are normally clearly visible from this LabPadre live feed, but for the Starship SN11 flight, the dense morning fog presented only an eerie glow. Credit: Louis Balderas Jr. / @LabPadre
The latest SpaceX Starship prototype, Starship SN11, met a fiery demise last week, like the three iterations before it. However, hopes were high it would’ve been the one to survive a landing attempt long enough for eventual reuse after SN10 very nearly did so, if not for a slightly hard landing.
Starship SN11’s flight ended up making what seemed like backward progress as it was the first one of the entire program to explode mid-air, immediately after beginning to relight its three Raptor engines for the landing-flip procedure.

A view of Starship SN11 the day before its March 30 test flight. Credit: Nicholas D’Alessandro / Spaceflight Insider
Adding a layer of mystery to the situation was the thick zero-visibility fog in the Boca Chica, Texas, area that made any visual assessment of the launch and failed landing impossible.
After the onboard cameras on SpaceX’s livestream suddenly froze, the only ground-based cameras in the area to capture the subsequent events were cameras positioned at the launch site perimeter, which captured the orange glow of the explosion followed by a heavy downpour of shattered stainless steel debris.
SpaceX CEO Elon Musk recently offered clarity on the situation on Twitter, as he usually candidly does after these incidents.
According to Musk in a post early Monday, it was a “relatively small” methane leak that led to a fire on Raptor engine No. 2, which in turn destroyed part of the avionics and created a hard start in the methane turbopump.
In rocketry, a “hard start” is a term for an overpressure event within the combustion chambers caused by an excess of propellants upon ignition of the engine, which can lead to an uncontained explosion.
Musk ended with the sentiment that the problem is getting fixed every possible way for the next flight.
Starship SN15, the next prototype in the queue, now aims to stick the first healthy landing of the 10-kilometer high-altitude hop program with a slew of new design upgrades, many of which directly address issues from the failed landings of earlier flights.
SpaceX was so confident in these revisions that SN12-SN14 have been scrapped with their existing sections being recently donated to a new nose cone test stand structure and even being made into ground support equipment tanks for the quickly sprouting orbital Super Heavy booster launch complex.
Rollout and testing of Starship SN15 is set to begin as early as this coming Thursday with Highway 4 road closures now in place for Thursday and Friday as well as the following Monday and Tuesday.

The final frame from a camera on SpaceX’s Starship SN11 during the company’s livestream of the event. Credit: SpaceX
Nicholas D'Alessandro
Nicholas D'Alessandro was born and raised in Southwest Florida. The seeds of his interest in Space Exploration were planted when the Shuttle's sonic boom upon re-entry would reverberate through his childhood home even across the state; the knowledge that a real life spacecraft was passing overhead and could have that effect was fascinating to him. A middle school field trip to the Kennedy Space Center cemented that fascination, and with an additional interest in the bleeding edge of automotive technology and Teslas, it was the story of Elon Musk's path to Cape Canaveral with SpaceX that finally led Nicholas to move to the Space Coast and, after joining Spaceflight Insider in 2020, begin documenting the dawning era of commercial spaceflight.
But why did you launch in the fog? Haven’t heard anyone answer that yet.
What is so hard about containing cryogenic material that allows these leaks? I’m sure I’ve seen other cryogenic leaks in other SpaceX testing videos.
Critical issues being identified for attention during these tests, keep pushing SpaceX!