4th LD Writethru: SpaceX launches cargo mission, rocket recovery test seems failed

After two delays, private U.S. firm SpaceX launched its fifth cargo mission to the International Space Station (ISS) early Saturday morning, but its rocket recovery test seemed to have failed.

The mission has generated a lot of interest because SpaceX was trying to realize a precise landing of the company's Falcon 9 rocket's first stage on a floating ocean platform for the first time.

SpaceX CEO Elon Musk tweeted about 30 minutes after launch that the rocket made it to the platform but "landed hard."

"Close, but no cigar this time," he said, "Ship itself is fine. Some of the support equipment on the deck will need to be replaced."

"Didn't get good landing/impact video. Pitch dark and foggy. Will piece it together from telemetry and ... actual pieces," he stated.

SpaceX has already demonstrated two successful soft water landings previously, but this time the company itself claimed before launch that the chances of success of landing the rocket on an unanchored ocean platform were no greater than 50 percent.

According to SpaceX, the concept of landing a rocket on an ocean platform has been around for decades but it has never been attempted.

In a related development, unmanned Dragon cargo ship lifted off at 4:47 a.m. EDT (0947 GMT) aboard the Falcon 9 rocket from Cape Canaveral Air Force Station in Florida for SpaceX's fifth of 12 planned station resupply missions under a contract with NASA.

The launch was originally scheduled for December but was delayed due to undisclosed rocket issues encountered during a preflight test.

Another attempt on Tuesday was scrubbed just before liftoff because of a problem with an actuator on the rocket's second stage.

The spacecraft carried about 2.5 tons of supplies and payloads, including materials to support 256 science and research investigations.

If all goes as planned, Dragon will arrive at the ISS Monday for an expected four-and-a-half-week visit.

"We are delighted to kick off 2015 with our first commercial cargo launch of the year," NASA Administrator Charles Bolden said in a statement.

"Thanks to our private sector partners, we've returned space station resupply launches to U.S. soil and are poised to do the same with the transport of our astronauts in the very near future."

Currently, NASA is totally dependent on Russian spacecraft to ferry astronauts to the ISS and back after retiring the space shuttle in 2011. It hopes to change this within the next three years by using commercial spacecraft currently under development, including a crewed version of Dragon. Endi