SpaceX's unmanned Falcon 9 rocket broke apart on Sunday as it tried to land on a floating platform in the Pacific, marking the fourth such failure in the company's bid to recycle rockets.

However, the primary mission of the launch from Vandenberg Air Force Base in California went as planned, propelling into orbit a $180 million US-French satellite called Jason-3 to study sea level rise.

"Well, at least the pieces were bigger this time!" said Elon Musk, the CEO of the California-based company.