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.

SpaceX is trying to land its rockets back on Earth in order to re-use the parts in the future, trying to make spaceflight cheaper and more sustainable than before.

The firm succeeded in landing its Falcon 9 first stage - the long towering portion of the rocket - on solid ground at Cape Canaveral, Florida, in December.

Even though an ocean landing is more difficult, SpaceX wants to perfect the technique because ship landings "are needed for high velocity missions", Musk said.

"Similar to an aircraft carrier vs land: much smaller target area, that's also translating and rotating."

Currently, expensive rocket components are jettisoned into the ocean after launch, wasting hundreds of millions of dollars.

Competitor Blue Origin, headed by Amazon founder Jeff Bezos, succeeded in landing a suborbital rocket in November.

However, no other company has attempted the ocean landing that SpaceX is trying to achieve.