A third SpaceX Starship prototype was destroyed early April 3 during a tanking pressurization test with cryogenic nitrogen to simulate flight temperatures and pressures.

“This may have been a test configuration mistake,” SpaceX CEO and chief engineer Elon Musk wrote in response to a video of the failed test on Twitter. “We will see what data review says in the morning.”

SpaceX reportedly was aiming to launch the prototype, referred to as SN3, on a 490-ft. (150-m) hop as early as next week.

Starship is a completely reusable, two-stage, heavy-lift transportation system designed to fly people and cargo to and from Mars. 

A Starship prototype made two hops in July and August 2019, testing the methane-burning Raptor engines during 66-ft. and 490-ft. flights, respectively.

The company is aiming for an orbital flight test with the fourth or fifth prototype this year. 

SN3 is the third prototype lost during pressurization tests. The Mark 1 test article was destroyed during a tank pressurization test in November 2019. Mark 3, later renamed Starship SN1, was destroyed in February 2020 while undergoing pressurization. 

SpaceX built a stripped-down version of the next prototype, SN2, to serve as a testbed to address problems revealed during the SN1 test, then built another full-scale prototype, SN3. That vehicle successfully completed a pressurization test on April 2 using ambient-temperature nitrogen. 

But during a second test with chilled nitrogen, the vehicle was destroyed. The test took place shortly after 2 a.m. local time/3 a.m. EDT at SpaceX’s privately owned complex near Brownsville, Texas.