SpaceX aims to launch the Falcon 9 again this Sunday

Now with less explosive helium tanks

SpaceX rocket takes off

Orbcomm Takes Flight

SpaceX's Falcon 9 takes off. (Photo taken December 2015)SpaceX

SpaceX is ready to resume launching again, a little more than four months following the September 1 explosion that destroyed a Falcon 9 rocket, its payload, and the launch pad it was sitting on. The company identified the cause of the explosion, has a short-term fix in place, and is targeting January 8 for its return to flight.

Although SpaceX originally planned to be back in action in November, the failure turned out to be the most complex the company has ever faced, according to CEO Elon Musk.

A statement from SpaceX detailed the findings of the investigation that followed the explosion. Kenneth Change at The New York Times provides a nice breakdown of what happened.

After analyzing massive amounts of data, the investigation panel (which included folks from SpaceX, NASA, the Federal Aviation Administration, and the U.S. Air Force) concluded that the explosion originated with the helium tanks that sit inside the oxygen tanks on the rocket's second stage. The helium helps to keep the oxygen under pressure while the engine burns.

The helium tanks are made of two layers: a carbon composite wrapper and an aluminum liner. As these layers came into contact with the Falcon 9's super-cooled oxygen and helium during the fueling process, the rapid temperature change may have caused the two layers to shrink at different rates, causing buckling and opening gaps for the surrounding oxygen to flow in. With oxygen trapped in between the flammable layers, just a little bit of friction is all that would be needed to start an inferno. Just 0.093 seconds after anomalies appeared in SpaceX's data, the entire rocket was engulfed in flames.

To correct the problem, SpaceX will use warmer helium and return the system to a previous configuration. Over the long-term, some design changes to the helium tanks will hopefully prevent buckling.

If all goes according to plan—which is never guaranteed in rocketry—the Falcon 9 will lift off again on Sunday carrying 10 Iridium telephone relay satellites into orbit.

Seeing as SpaceX's launch pad at Cape Canaveral was destroyed in September, Sunday's launch will take off from Vandenberg Air Force Base in California. But later in January, the company aims to launch another communications satellite from the historic Launch Complex 39A—the launch pad from which most of the Apollo and many space shuttle missions blasted off. The company hopes to resume carrying supplies to the International Space Station later this month.