Aerospace and defense giant Boeing has tossed its hat into the space-tourism ring, announcing that it has agreed to market future rides into Earth orbit to paying customers. The company announced the private-spaceflight initiative, in concert with Space Adventures, on September 15.

The future of private spaceflight remains speculative—no one can say with any certainty which companies will manage in the coming decades to get more than a handful of customers off the ground, in which crew capsule, and aboard which rocket. Space Adventures can lay claim to delivering seven customers to orbit, but those fliers each bought seats on Russian Soyuz spacecraft rather than on wholly commercial vessels.

So far, space tourism has been the territory of smaller start-ups such as Space Adventures and Armadillo Aerospace. (Richard Branson's Virgin Galactic is a high-profile player in the game, but the flights his company sells do not reach orbit.)

Boeing's participation lends some corporate muscle to the private-spaceflight business, but its proposed contributions are still sketchy. A joint press release from Boeing and Space Adventures trumpets only an agreement to sell "anticipated transportation services" to private individuals, companies and even U.S. government agencies other than NASA. The rockets themselves might come from United Launch Alliance, co-owned by Boeing and Lockheed Martin, or from SpaceX, the company headed by PayPal co-founder Elon Musk.

But the "anticipated" space capsule that would fly those customers to orbit is even further from readiness than Boeing's long-delayed 787 aircraft, also known as the "Dreamliner." The seven-person CST-100 (pictured), which Boeing is developing with the help of $18 million from NASA, could be used to transport astronauts to the International Space Station (ISS) as early as 2015 (and presumably space tourists soon thereafter). Even that may prove to be an optimistic estimate, although Boeing Vice President John Elbon said in a press conference September 15 that the company had 80 to 100 full-time employees developing the craft, according to analyst and Space Politics blogger Jeff Foust, who reported from the press conference via Twitter.

If Boeing can realize its CST-100 capsule, it might even have a destination for orbital tourists beyond the ISS. The capsule is being designed to support private space stations in low-Earth orbit envisioned by Bigelow Aerospace, a company headed by hotel magnate Robert Bigelow.

Artist's conception of CST-100 crew capsule courtesy of Boeing