Is space the final investing frontier? I'm wondering that today, after privately held Space Adventures, which puts wealthy tourists into orbit for a staggering fee, agreed to buy Space Launch for an undisclosed sum.

To this point, Space Adventures' trips have been to the International Space Station, conducted in cooperation with the Russian Space Agency. Now, with Space Launch, Space Adventures will expand its horizon by creating its own vehicles for commercial space travel. That could put the company squarely in conflict with Sir Richard Branson's Virgin Galactic and founder Jeff Bezos' Blue Origin.

All of this has me wondering: Are we witnessing the birth of the first space lines? Will Virgin, Blue Origin, and Space Adventures be to us in 50 years what United (NASDAQ:UAUA), AMR's (NYSE:AMR) American, and Delta are to us today? Certainly Space Launch founder Jacob Lopata seems to think so. He told that space tourism is expected to be a billion-dollar business within the next 10 years.

There's some evidence to suggest he's right. For example, a recent study by the Australian Graduate School of Management found that 20% of consumers would be willing to pay $50,000 for a suborbital flight. Only 10% would pay $200,000, which is roughly what Branson's Virgin Galactic proposes as a fee. Still, Branson has publicly said that his space venture boasts a lengthy waiting list.

Frankly, I have my doubts about space tourism as a destination for my investment dollars. But that doesn't mean opportunities aren't available. SpaceDev (OTC BB: SPDV.OB), for example, has already built the propulsion system that carried SpaceShipOne to the Ansari X Prize. It would be a perfect candidate to build needed equipment for any spaceliner. There's also SPACEHAB (NASDAQ:SPAB), which says it specializes in enabling space commerce, whatever that means.

Investing in space has a natural Rule Breaking feel to it. But it also carries huge risks. Micro-cap stocks like SpaceDev can burn supernova-hot or eat your returns faster than a black hole. That's why we study the industry carefully at Motley Fool Rule Breakers. Our active board covering space-faring stocks is a great place for Foolish beginners or experts. You're welcome to poke around free for 30 days if you'd like, and there's no obligation to buy.

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Fool contributor Tim Beyers wants to see Earth from orbit once before he dies. But then again, don't we all? Tim owns shares of SpaceDev. You can find out which other stocks he owns by checking Tim's Fool profile . The Motley Fool has an ironclad disclosure policy .