A SpaceX Falcon 9 poised for the March 2017 launch of SES-9 from Cape Canaveral's SLC-40 launch pad. Credit: SpaceX

WASHINGTON — More than a year after suffering significant damage in a Falcon 9 explosion, a Florida launch pad is ready to return to service, incorporating improvements that will allow a higher flight rate.

The first launch from Space Launch Complex (SLC) 40 at Cape Canaveral, Florida, since a September 2016 pad explosion is scheduled for Dec. 12, when a SpaceX Falcon 9 launches a Dragon cargo spacecraft to the International Space Station. The rocket’s first stage performed a successful static fire test there Dec. 6, the first major activity at the pad since the accident.

SpaceX spent about $50 million rebuilding the launch pad after the accident, in the process incorporating improvements to the pad based on lessons learned from launches there and at two other launch pads in Florida in California that will support “many years” of Falcon 9 launches, a company official said.

“We really looked at this as an opportunity to not only rebuild the pad, but to make it better,” said John Muratore, director of SLC-40 at SpaceX, in a call with reporters Dec. 8.

That work, he said, included taking steps to make hardware on the pad more robust and thus less likely to suffer damage during a launch. Much of the support equipment that was above ground and exposed to launches has been moved below ground, protected by concrete and steel and thus less likely to be damaged in a launch or even in the event of an explosion.

“That’s critical to our rapid flight strategy,” he said. “If you don’t take damage on the pad then you can fly more often.” It should be possible, he said, to turn the pad around between launches in a week or less.

Among the changes to the pad is a “really augmented” water system to protect the pad from damage to the launch, and improvements to the flame trench to limit erosion of the concrete there. Those particular changes, he said, can allow for much longer static-fire tests there, which would enable the company to do things like testing a previously-flown first stage after replacing one of its engines.

Muratore said another change at SLC-40 was making the pad interfaces common with those at neighboring Launch Complex 39A at the Kennedy Space Center, as well as SLC-4E at Vandenberg Air Force Base in California. “That is a really a big advantage for us since we can move people around as we hit normal surges of lots of activity, or gaps in activity,” he said.

SLC-40 was built in the 1960s for launches of the Titan 3 and 4 rockets, then transferred to SpaceX, which started launching Falcon 9 rockets from the pad in 2010. As the rocket’s flight rate increased, there was little opportunity to do upgrades to the pad prior to the accident last year.

“We sort of put the equipment wherever we could fit it on the pad,” Muratore said. “The idea of digging up all the concrete and all the steel, that was something we couldn’t do and continue to the make the manifest. In this tragedy, we had an opportunity to rebuild.”

Rebuilding SLC-40 took longer than originally anticipated. SpaceX executives, including Chief Executive Elon Musk and President Gwynne Shotwell, previously said they expected SLC-40 to be ready to resume launches in the spring or summer of 2017.

Muratore said work didn’t start until February because the pad was on “lockdown” after the September accident until late November or early December 2016, after which some environmental remediation work was required before the company could start rebuilding.

“In any large construction project like this, whether you’re doing an upgrade to your house or building a launch pad, it’s really hard to predict from the start what’s going to happen,” he said. One issue he said SpaceX encountered was that the 50-year-old documentation from the pad’s original construction didn’t reflect where plumbing and wiring was actually located.

“It’s sort of a combination of things we discovered along the way that slowed us down, combined with, as we got into it, opportunities to really improve the pad,” he said.

SpaceX could take its time to rebuild SLC-40 because LC-39A, which started hosting Falcon 9 launches in February, could take over the workload of Florida launches. That allowed the company to incorporate all the changes it wanted. “We could have gotten the pad back in operation sooner,” Muratore said, “but we wouldn’t have had the pad we wanted to keep for the next 10 to 20 years.”

With SLC-40 in service, the company will have flexibility to schedule launches both there and at LC-39A. Some missions, such as Falcon Heavy launches and those of the Dragon v2 spacecraft, will only take place at 39A. SLC-40 will only host “single-stick” Falcon 9 missions, with no plans to add support for the Falcon Heavy.

“[Pad] 40 will be set to just run single-stick missions as fast as we can,” he said.

Jeff Foust writes about space policy, commercial space, and related topics for SpaceNews. He earned a Ph.D. in planetary sciences from the Massachusetts Institute of Technology and a bachelor’s degree with honors in geophysics and planetary science...