March 30 (UPI) -- A fourth Starship rocket prototype for Elon Musk's SpaceX launch company exploded after a test flight on Tuesday morning in South Texas.
As with previous test flights, SpaceX flew Starship -- model SN11 -- to over 6 miles high above the launch facility about 180 miles south of Corpus Christi. The rocket then glided on wing flaps back to the launch pad.
Heavy fog and problems with the video feed made it unclear exactly what happened, but SpaceX engineer John Insprucker confirmed the explosion.
"Well, looks like we've had another exciting test of Starship ... A reminder again, this is a test series to gather data," Insprucker said during SpaceX's live broadcast.
Previous test flights of the giant, stainless steel rocket ended in fireballs in December, February and March. The last attempt, on March 3, featured an upright landing but a fire on the rocket's base caused an explosion moments later.
The tests are part of SpaceX's rapid prototype development methods, which the company used to develop its highly successful Falcon rockets.
Landing and reusing the rocket is key to Starship's proposed interplanetary use, according to the company. The rocket is roughly the height of a 14-story building.
Starship is "designed to carry both crew and cargo on long-duration, interplanetary flights and help humanity return to the Moon, and travel to Mars and beyond," according to SpaceX.
Musk founded SpaceX in 2002 with a stated goal of reducing spaceflight costs to enable human exploration of Mars.
Starship is one of three spacecraft NASA has chosen as possible means to send astronauts back to the moon this decade. The space agency intends to choose two proposals for those crewed lunar missions by mid-2021.