LONG BEACH, Calif. — Space Exploration Technologies Corp. (SpaceX) aims to field a fully reusable version of the Falcon 9, the expendable rocket the company is getting ready to send to the international space station (ISS) on a crucial demonstration mission now expected to be delayed until January.

SpaceX founder and chief executive Elon Musk disclosed the demo mission’s latest delay in a Sept. 29 speech in Washington unveiling plans for a redesigned Falcon 9 featuring first and second stages that would fly back to the launch site under their own power.

“It’s a very tough engineering problem,” Musk said during a webcast speech at the National Press Club. “[But] I’ve come to the conclusion that it can be solved and SpaceX is going to try to do it.

“Now, we could fail. I’m not saying we are certain of success here, but we are going to try to do it. We have a design that on paper, doing the calculations, doing the simulations, it does work. Now we need to make sure those simulations and reality agree because generally, when they don’t, reality wins,” Musk said.

SpaceX is seeking an experimental permit from the U.S. Federal Aviation Administration (FAA) to fly a technology test bed called Grasshopper that is essentially a single-engine Falcon 9 main stage equipped with landing legs.

Grasshopper’s existence was first disclosed in a Sept. 22 draft environmental impact statement the FAA’s Office of Commercial Space Transportation posted on its website and published in the federal register. According to the document, SpaceX plans to conduct suborbital flights of Grasshopper at the company’s McGregor, Texas, test site.

In addition to obtaining a permit, SpaceX will need to build a new launch pad at McGregor to fly Grasshopper.

To enable the Falcon 9 stages to land under their own power, SpaceX will have to equip them with heat shields and landing legs. The Grasshopper project is intended to give the company an opportunity to test some of that technology in flight.

“Grasshopper continues our path toward reusability,” SpaceX President Gwynne Shotwell said Sept. 27 at the Space 2011 conference here hosted by the American Institute of Aeronautics and Astronautics.

Shotwell said Grasshopper would serve as a “test bed” for reusable technologies but declined to discuss the project’s status, expected cost or schedule.

SpaceX spokeswoman Kirstin Brost Grantham would not say whether the company has begun construction of Grasshopper, which is described in the FAA documents as a 32.3-meter-tall vertical takeoff and landing rocket equipped with four landing legs and a single Merlin 1D engine.

SpaceX cannot get the FAA approval it seeks until the company builds Grasshopper because “before FAA issues an experimental permit, the company must make the vehicle available to FAA for inspection,” FAA spokesman Hank Price told Space News. Price said that the agency does not comment on the status of individual applicants.

Musk did not talk about Grasshopper during his National Press Club speech, which was billed as a discussion of the future of human spaceflight.

He said there are no guarantees that SpaceX will succeed in making Falcon 9 fully reusable. But if it does, the cost reductions would be dramatic.

“If it does work, it’ll be pretty huge,” Musk said. “If you look at the cost of a Falcon 9 … it’s about $50 [million] to $60 million. So obviously, if we can reuse the rocket, say, a thousand times, then that would make the capital cost of the rocket for launch only about $50,000.”

SpaceX holds a NASA contract to begin space station cargo runs in 2012 using Falcon 9 and its reusable Dragon capsule. However, it must first complete a demonstration mission to the space station under NASA’s Commercial Orbital Transportation Services program.

SpaceX had hoped to fly that mission in late November, but the Aug. 24 failure of a Russian Soyuz rocket and subsequent loss of a Progress cargo module bound for ISS mean that SpaceX likely will not get to send its Dragon space capsule to the space station until “more like January,” Musk said.

Dan Leone is a SpaceNews staff writer, covering NASA, NOAA and a growing number of entrepreneurial space companies. He earned a bachelor’s degree in public communications from the American University in Washington.