(TheVerge): SpaceX is hoping to get back to launching — and landing — its rockets again, a little over four months after one of its Falcon 9 vehicles exploded on a Florida launchpad. The company’s vehicle is slated to take off from Vandenberg Air Force Base in California at 12:54PM ET, carrying 10 satellites into orbit for the communications company Iridium. And as is the norm with Falcon 9 launches these days, SpaceX will attempt to land the majority of the rocket upright on one of its drone ships in the Pacific Ocean following takeoff. But most of all, the launch itself needs to go smoothly if SpaceX wants to move forward and accomplish its many goals that lie ahead.
It’ll be the first flight that SpaceX has attempted since August, since the company was forced to go on a hiatus from spaceflight after the September launchpad explosion in Cape Canaveral. The vehicle was being loaded with propellant in preparation for a static fire test — a routine procedure that SpaceX does prior to flight, in which the rocket engines are turned on while the vehicle is constrained. During this fueling process, the vehicle suddenly went up in a spectacular fireball, destroying the Falcon 9 and the Israeli Amos-6 satellite that it was supposed to carry into space just a few days later.
SpaceX has spent its time grounded trying to decipher what happened, finally coming up with an official cause for the explosion two weeks ago. The source of the failure originated within the rocket’s upper liquid oxygen tank, which stores the vehicle’s super chilled liquid oxygen propellant. Also housed inside this tank are three smaller tanks called composite overwrapped pressure vessels, or COPVS. These vessels store cryogenic helium, which is needed to fill up and pressurize the liquid oxygen tank when the propellant is used up during flight. SpaceX determined that the materials making up the COPVs had a bad reaction with the liquid oxygen in the tank, ultimately causing the propellant to ignite.
With the official cause decided, SpaceX originally said it was aiming to return to flight on January 8th, but the launch was ultimately delayed until tomorrow due to rain and heavy winds this past week. The company conducted a static fire test of the Falcon 9 vehicle January 5th in preparation for the flight, and the company finally received approval from the Federal Aviation Administration to launch and land its Falcon 9 vehicle for the upcoming mission. In fact, the FAA launch license gives SpaceX permission to launch the next seven rockets for the Iridium NEXT mission — an endeavor that will put 70 satellites into orbit for Iridium.