The private spaceflight company SpaceX is poised to launch a robotic capsule toward the International Space Station Saturday (May 19) on a test flight that, if successful, could be a watershed moment for the commercial space industry. But while SpaceX has a NASA contract to provide cargo deliveries to the space station, the company and other private spaceship developers are looking to a future beyond NASA funding.

The Hawthorne, Calif.-based SpaceX is one of several aerospace firms who are competing for NASA funding under the third and final phase of NASA's commercial crew development program. Proposals for this stage of the competition, called Commercial Crew integrated Capability(CCiCap), require companies to present a complete launch system — rocket and vehicle — for consideration.

SpaceX intends to use a version of its current cargo ship, the robotic Dragon capsule,to fly up to seven passengers to the International Space Station and other destinations in low-Earth orbit. The spacecraft will launch atop the company's own Falcon 9 rocket from the Cape Canaveral Air Force Station in Florida.

Private spaceships of tomorrow

SpaceX isn't alone in the private spaceship game. The company is facing some stiff competition from other aerospace firms, including Boeing and Sierra Nevada Corp. NASA is expected to announce at least two recipients for CCiCap funding awards in August.

A model of Boeing's CST-100 space capsule shows the crew-carrying craft's interior design. The CST-100, which can carry up to seven astronauts, could fly its first manned mission by 2015 or 2016, Boeing officials have said. (Image credit: Denise Chow/SPACE.com)

Some of the contenders have said they intend to forge ahead with the development of their spacecraft regardless of whether they receive NASA funding or not.

"At SpaceX, we definitely hope to go forward in partnership with NASA, not only for financial reasons, but just also it's been a very effective partnership during our cargo efforts as far as being able to tap into the great experience base in technology and know-how that NASA has," said Garrett Reisman, SpaceX's senior engineer for astronaut safety and mission assurance. [Gallery: Dragon, SpaceX's Private Spacecraft]

Reisman, Keith Reiley, deputy program manager of Boeing's commercial crew development, and Mark Sirangelo, chairman and vice president of Sierra Nevada, participated in a panel discussion about the future of human spaceflight at the inaugural Spacecraft Technology Expo, which was held May 8-10 in Los Angeles.

But even if SpaceX is not selected for the final round of NASA funding, a crewed version of the Dragoncapsule will not be mothballed, Reisman said.

"[I]f we are not selected in this next phase, would we continue to work on human spaceflight? Absolutely," he said. "We might proceed in different directions, we might proceed at a different pace with less resources available to us, but, oh yeah, we're going to keep going."

Other companies are not quite so sure.

U.S. space taxi evolution

Boeing is developing a gumdrop-shape capsule, called the CST-100, that could be ready to fly astronauts to the space station as early as 2015 or 2016, company officials have said. The spacecraft, which measures 14.8 feet (4.5 meters) across at its widest point, will be able to ferry up to seven astronauts to low-Earth orbit. [Photos: Boeing's CST-100 Capsule]

To date, NASA has provided Boeing with about $120 million for its commercial crew transportation work. Without further agency funding, Boeing officials are undecided about the future of the CST-100 capsule.

"It's a tough question," Reiley said. "I frankly don't know. We've thought about it, but there's not anything official that we've done. Obviously NASA would be providing a significant amount of money. Would the Boeing Company be willing to continue that at that level? I doubt it — maybe at some lower level, but I really don't know."

Alliant Techsystems (ATK) announced its bid for CCiCap funding at the Spacecraft Technology Expo, presenting the Liberty rocket and capsule. Kent Rominger, ATK's vice president and program manager for Liberty, told SPACE.com that the company will not stop developing the launch system if they are not selected by NASA.

The goal of executing the first crewed test flights of the Liberty system by 2015, however, would become much less realistic without CCiCap funding, he added.

A space market beyond NASA

Still, NASA is not the only client being considered by commercial spaceflight companies, which may mean other markets could be suitable for these vehicles, Sirangelo said.

At Sierra Nevada, Sirangelo and his team are developing a space plane, called Dream Chaser, to fly up to seven astronauts or other paying passengers to low-Earth orbit.

An artist's depiction of the Dream Chaser vehicle landing on a conventional runway at the end of its mission. (Image credit: Sierra Nevada)

"We look at it from two perspectives: one is that NASA is certainly providing a lot of funding, but the destination of the ISS also adds a lot of complexity, and that complexity, if it weren't there, there could be other destinations, other activities that are going on," he explained.

Sirangelo pointed to Boeing's X-37B spacecraft as an example of an unmanned, winged lifting body that could be used for other purposes.

"We think there are other markets that we can explore and look at, but clearly it's like having an anchor tenant in a mall, and you can continue to have stores, but whether or not that mall gets built as quickly is, I think, the issue here."

You can follow SPACE.com staff writer Denise Chow on Twitter @denisechow. Follow SPACE.com for the latest in space science and exploration news on Twitter @Spacedotcomand on Facebook.