After two technical delays, will SpaceX be able to launch Falcon 9 Sunday?

A new rocket fuel feature appears to be causing technical problems. But even if the glitch is fixed for Sunday's launch, the big question still remains: Will the Falcon 9 be able to land back on Earth in one piece?

After postponing the launch of a telecommunications satellite into orbit aboard its Falcon 9 rocket twice this week, SpaceX says it will likely try again Sunday at 6:46 pm Eastern time, reserving Monday as a backup day.

SpaceX called off two attempts to launch the rocket this week from Cape Canaveral, Fla. because of technical problems; first on Wednesday, about a half-hour before the launch, and then again on Thursday, less than two minutes before blastoff.

The problem appears to be with a new feature of the Falcon 9: cryogenic propellant, a liquid oxygen propellant mixed with a type of kerosene and nearly frozen to make it more dense, and thus compact.

SpaceX founder and CEO Elon Musk said this technique gives the rocket more power and allows it to carry more fuel.

“There are a number of improvements in the rocket, and one of the things we’re doing for the first time – the first time I think anyone’s done it – is deeply cryogenic propellant,” Mr. Musk said at the American Geophysical Union meeting in December, reported Spaceflight Now.

Though it aims to make the Falcon 9 more efficient, the new propellant appears responsible for the delays, as the company struggles to nail down the timing of chilling the liquid oxygen and loading it onto the rocket within a 30-minute window before launch.

“Preliminary (information) is that we were … looking at how much time we had left in the count to finish loading the liquid oxygen, and at that time the launch team decided that we would need to hold the countdown,” SpaceX commentator John Insprucker said during a live webcast of the Thursday launch attempt, according to Reuters.

The denser fuel will make the rocket more powerful, says SpaceX, so it can lift heavier communications satellites into orbit. It also will allow the rocket to store more fuel to guarantee that it has enough to power its trip back to Earth for landing.

Bringing rockets back to Earth is a primary goal and major hurdle for space exploration. SpaceX – a private company that has billions of dollars worth of space-cargo delivery contracts with satellite operators and with NASA – is among the private companies that are trying to make spaceflight more affordable by making rockets reusable.

“If one can figure out how to effectively reuse rockets just like airplanes, the cost of access to space will be reduced by as much as a factor of a hundred,” says SpaceX on its website. “A fully reusable vehicle has never been done before. That really is the fundamental breakthrough needed to revolutionize access to space,” the company says.

Out of several attempts, SpaceX has only once been able to land a rocket successfully, in December at Cape Canaveral, the first time a large rocket delivered a spacecraft to orbit and landed on Earth intact, reported Florida Today.

Blue Origin, the space company owned by Amazon CEO Jeff Bezos, a month before that landed a smaller rocket after a test flight in Texas.

SpaceX has also tried several times to land a rocket on a barge called "Of Course I Still Love You," floating about 400 miles off Florida's coast. But those attempts were not successful. Each time the rockets were able to return to the barge, but then tipped over and burned after they touched down.

Sunday’s landing attempt will come after Falcon 9 delivers into orbit SES-9, a 12,000-pound hunk of machinery built by Boeing and owned by Luxembourg-based satellite operator SES. It is the heaviest load that a Falcon 9 rocket has yet tried to deliver more than 22,000 miles over the equator, and SES’s largest satellite to provide high-speed Internet and television services to the Asia-Pacific region.

If Falcon 9 is able to drop off the satellite in space on Sunday, a piece of the rocket, the launch booster, will break off and attempt to land about 10 minutes later on SpaceX's barge. The company warned in a mission overview that it does not expect a successful landing.

Despite this, simply returning the booster to a barge in the middle of the ocean would be a success, say some space industry observers.

"The simple ability to bring it back to that point in the ocean is a major achievement," Frank DiBello, head of aerospace economic development agency Space Florida, told the Orlando Sentinel recently.

"The more they can do that, the more they can demonstrate to anyone that they have that capability," he said.