Ice buildup may be to blame for the fiery botched landing of a SpaceX Falcon 9 rocket at sea on Sunday, the company said.
The rocket blasted off from Vandenberg Air Force Base in California to put the U.S- and European-owned Jason 3 climate-monitoring satellite into orbit. It then returned to Earth, attempting to land upright on an ocean barge.
Video showed the rocket had descended with pinpoint accuracy onto the drone ship before a landing leg buckled, causing the booster to tip over and explode. The lockout collet on one of the rocket's four legs didn't latch, leading to the mishap, SpaceX CEO Elon Musk wrote in a post on Twitter and Instagram.
"Root cause may have been ice buildup due to condensation from heavy fog at liftoff," he said.
The failed landing was a setback for the Hawthorne, California, company's plan to reduce space launch costs by reusing rockets rather than having them fall into the ocean.
A successful ocean landing would have marked a second milestone for the company, a month after it nailed a spaceflight first with a successful ground landing in Florida.
The feat of having the rocket touch down on the tiny platform won accolades from fellow tech entrepreneur Jeff Bezos, the Amazon.com chief executive whose Blue Origin space company is pursuing similar technology.
"SpaceX will soon make Falcon 9 landings routine," Bezos posted on Twitter. "Kudos SpaceX!"
Blue Origin landed a suborbital rocket during a November 2015 test flight.
SpaceX's landing attempt on Sunday was the third time the privately owned firm had tried to recover a rocket on an ocean platform.
"At least the pieces were bigger this time," Musk said on Twitter. "Am optimistic about upcoming ship landing."
Last month, a Falcon 9 booster touched down on a landing pad at Cape Canaveral Air Force Station in Florida after dispatching 11 small communications satellites into orbit.
SpaceX wants to be able to land rockets on ocean platforms as well as on the ground to accommodate a wide variety of space missions. It has more than 60 launches on its schedule, worth more than $8 billion.