(Business 2.0) - Let's not wax sentimental about our space exploits thus far. The Apollo era was heroic, but beating the Soviets to the moon never provided a compelling economic reason to return. (We didn't even get Teflon or Tang as spinoffs--both were invented before 1960.)

The shuttle and the international space station continued this record of dismal return on investment. Small wonder, then, that most private-sector investors have focused instead on more earthly pursuits. Only one thing will prod us into the cold, hard vacuum of space, and that's the prospect of earning cold, hard cash.

More from Business 2.0 Live chat: your new online salesperson The hijack-proof truck Server farm goes solar Fastest Growing Tech Companies Current Issue Subscribe to Fortune

Photo Gallery See more photos

Profits set to soar in outer space Out-of-this-world opportunities The Silicon Valley of spaceflight Cashing in on Mars Millionaires on the launchpad The 62,000-mile elevator ride Building zero-G boomtowns Why space needs you

Fortunately, there's now a lot of that to go around. Worldwide government spending on space is soaring to $50 billion a year, a 25 percent jump over 2000. NASA represents only $16 billion of that total, but during the next 20 years, the U.S. space agency is likely to sign contracts totaling as much as $400 billion to launch a human mission to Mars.

We are also well into the commercial space age. In 1998, private-sector spending on space applications began to exceed government spending, and the gap is widening. A critical mass of entrepreneurs -- some with familiar names like Bezos and Branson -- have been backing space-related companies for years. In the coming months, their efforts will reach blastoff stage (quite literally). Some of the markets they're targeting, like the $4 billion satellite launch business being pursued by PayPal founder Elon Musk, are ripe for competition. But most, such as suborbital tourism, space hotels, and solar satellites, don't yet exist. All, however, have the potential to generate astronomical returns during the next decade.

Building infrastructure is the first step, and here historical analogies abound. The federal government is poised to begin contracting with the private sector to deliver cargo into orbit, a trend that could nurture a market for civilian spaceflight in much the same way that airmail contracts from the Post Office spurred the development of civil aviation a century ago. Prize money -- the incentive that launched Charles Lindbergh -- is now being offered for everything from building a machine to extract oxygen from lunar soil ($250,000) to building an aircraft capable of delivering tourists to orbit by 2010 ($50 million).

Meanwhile, new technologies are opening up new possibilities. Consider the space elevator, which is enabled by the advent of lightweight carbon nanotubes; a 62,000-mile elevator to the heavens would reduce orbital freight costs by 98 percent and open up space just as the railroads opened up the Wild West.

The long-term possibilities are even more celestial. Ever heard of 3554 Amun? It's a space rock about 2 kilometers in diameter that looks as if it might have fallen straight out of The Little Prince. There are three key things to know about 3554 Amun: First, its orbit crosses that of Earth; second, it's the smallest M-class (metal-bearing) asteroid yet discovered; and finally, it contains (at today's prices) roughly $8 trillion worth of iron and nickel, $6 trillion of cobalt, and $6 trillion of platinumlike metals. In other words, whoever owns Amun could become 450 times as wealthy as Bill Gates. And if you time your journey right -- 2020 looks promising -- it's easier to reach than the Moon.

That doesn't mean it's easy, of course; nothing worthwhile ever is. The automobile, commercial air travel, the PC, the Internet, the cell phone -- all took decades to reach their full potential, and none would have taken root without stubborn entrepreneurs who refused to heed conventional wisdom. The greatest barrier to the open markets of space isn't physical or technological; it's psychological. But for those who have the right stuff, the rewards may prove greater than anything the Apollo astronauts ever imagined.

________________________________________

Click here to send a letter to the editor.