The first stage of a SpaceX rocket that delivered a U.S.-European ocean-monitoring satellite into orbit Sunday made a hard landing on a floating barge in the Pacific and broke a support leg.

SpaceX announcers said the Falcon 9 was not upright after reaching the 91-by-52-metre landing pad in choppy seas about 322 kilometres west of San Diego.

Spacex botched landing

The Falcon 9 rocket, owned by SpaceX, is seen toppled on the ocean landing pad. (Elon Musk/Twitter)

"Well, at least the pieces were bigger this time! Won't be last RUD [rapid unscheduled disassembly], but am optimistic about upcoming ship landing," tweeted Elon Musk, who is the founder of SpaceX.

Liftoff occurred as planned at 10:42 a.m. PT Sunday from Vandenberg Air Force Base, northwest of Los Angeles, under mostly cloudy skies from the California coast. It sent its second stage and a Jason-3 satellite into orbit.

The failed landing is a setback for the California-based company's plan to reduce launch costs by reusing rockets rather than having them fall into the ocean. Two previous attempts to land a rocket on a barge in the Atlantic failed, but last month SpaceX succeeded in returning a rocket to a vertical landing at Cape Canaveral, Fla., after putting a cluster of satellites into orbit.

The mission of Jason-3, the satellite, is to continue an unbroken record of more than two decades of sea level measurements from orbit.

3-4-metre ocean swells at landing barge​

Hans Koenigsmann, vice-president of mission assurance for Space-X, said the current rocket would have been able to return to land but the company does not have environmental approval at Vandenberg yet.

Meteorologists predicted swells of three to four metres where the barge was waiting for the rocket landing attempt.

Ocean Satellite

The SpaceX Falcon 9 rocket is seen as it launches with the Jason-3 spacecraft onboard on Sunday, Jan. 17, 2016, from Vandenberg Air Force Base Space Launch Complex 4 East in California. (Bill Ingalls/NASA/Associated Press)

"The sea state is good for surfing and a little high for landing but we don't anticipate that that's going to be a major problem," said Koenigsmann before the landing. "I'm really hopeful. We had a really good landing last time."

$180M US price tag

Like its predecessors, Jason-3 is equipped with radar altimeter to bounce microwave energy off the ocean and a GPS system to identify the satellite's precise location.

The cost of the mission, including five years of operation, was put at $180 million US.

After years of testing, including two failed ocean landing attempts, SpaceX last month nailed a touchdown on land in Florida, a key step in founder Musk's quest to develop a cheap, reusable rocket.

The 550-kg Jason-3 satellite is the fourth in a series of ocean-monitoring satellites, which are taking center stage in monitoring Earth's climate.

"More than 90 per cent of all the heat being trapped in the Earth's system ... is actually going into the ocean," said Laury Miller, Jason-3 lead scientist with the National Oceanic and Atmospheric Administration.

"This makes the ocean perhaps the biggest player in the climate change story."

Ocean Satellite

The SpaceX Falcon 9 rocket before the launch. The rocket launched its satellite Sunday but made a hard landing, breaking a leg. (Bill Ingalls/NASA/Associated Press)

NOAA is one of five agencies partnering on the five-year Jason-3 program.

Once in position 1,336 km above Earth, Jason-3 will bounce radio waves off the ocean and time how long it takes the reflected signals to return.

Scientists can use the information to figure out ocean heights to within 0.5 cm, said Josh Willis, with NASA's Jet Propulsion Laboratory in Pasadena, Calif.

"We can really see the rise of the global oceans. This is one of the most important yardsticks we have for human-caused climate change," Willis said, adding that heat, plus runoff water from melting ice sheets, causes ocean levels to climb.

Jason-3 can also chart ocean currents, which affect weather phenomena such as this year's powerful El Nino system, monitor tsunamis and track oil spills.

with files from The Associated Press