​SpaceX’s Reusable Rocket Launch Delayed Again

​This morning, SpaceX was set to launch its Falcon 9 rocket—and attempt to land part of it on a platform in the ocean. But once again, the mission has been postponed.

Late into the count, at T minus 1 minute 28 seconds, a problem was detected and the launch called off.

At the end of a livestream of the launch on the SpaceX site, a spokesperson said that there was a problem with the second stage of the Falcon 9 rocket and that the mission would be delayed.

"What appears to have happened is some actuator drift fairly late in the count," explained a commenter on the NASA w​ebcast shortly after the cancellation, and added that this would have triggered the mission to abort automatically if it hadn't been caught by the team.

The SpaceX CRS-5 mission was scheduled to launch from Cape Canaveral at 6.20am EST. It's a resupply mission, set to send the Dragon cargo spacecraft to the International Space Station. The launch was originally scheduled for ​December, but got delayed due to an anomaly in a test. Now it's been pushed back again, but could try to launch once more as soon as Friday, January 9, at 5:09am EST—provided the problem that prevented launch this time is fixed.

The CRS-5 mission will be the first time anyone's tried to recover a rocket stage like this after launching it, and a step towards Elon Musk's goal of reusability—something that would help significantly reduce the cost of spaceflight.

SpaceX will attempt to get the first stage of Falcon 9 back after launch, aiming to land it on what they call "the autonomous spaceport drone ship," which is pretty much what is sounds like: a floating platform.

The​ drone ship measures 300 feet by 100 feet (extendable to 170 feet), which sounds like a lot until you consider that the Falcon 9 is 14 stories tall with a legspan of 70 feet. The rocket's speed is reduced to around ​two metres per second before landing.

You'd usually expect confidence ahead of a space mission—especially from someone with​ such grand ideas as Elon Musk—but even if the Falcon 9 launches to plan next time, the company has always been realistic about its chances of failure and success regarding the drone ship landing. Before the scheduled launch in December, it wrote ​that, "The odds of success are not great—perhaps 50 percent at best."

Let's hope next time it at least gets into the air.

Correction: An earlier version of this story said that the rocket is travelling at 250 metres per second at landing. Obviously it slows down more than this. The story has been updated.