There are a number of "cash and carry" suborbital craft under development by such groups as: Armadillo Aerospace, Blue Origin, Masten Space Systems, Virgin Galactic, as well as XCOR Aerospace.

What's the attraction?

The attraction for investigators at the meeting was to gauge use of suborbital craftto carry out a variety of high-altitude science studies, including access to three to four minutes of microgravity for experimentation, discovery and testing.

Suborbital flights up to 62 miles (100 km) above Earth could serve numbers of disciplines, such as astronomy, the life sciences, microgravity physics, or to plumb a little-known atmospheric region dubbed "the ignorosphere."

Lori Garver, NASA's deputy administrator, said that the government is keen on stimulating the suborbital market, seeing it as bridge building to orbital flight.

To this end, Garver noted that the space agency is seeking Congressional approval in their fiscal year 2011 budget for $75 million in planned funding over five years forNASA's Commercial Reusable Suborbital Research (CRuSR) program.

"Suborbital puts us on a sustainable, step-by-step path to building an industry that evolves to low cost access to orbit," Garver said. "We're really on the cusp of an exciting new capability for our country and for our economy."

Charles Miller, senior advisor for commercial space and program executive for CRuSR at NASA Headquarters, Washington, D.C. told SPACE.com: "Industry will pick the point design. Some of them will succeed, some of them will fail. Over time it's vastly superior at accelerating innovation in the nation."

Miller said the backing by NASA's CRuSR program is akin to the government becoming an anchor tenant customer for air mail delivery in the 1920s. That relationship, he said, helped the industry close their business case and raise private capital.

"We see the same thing happening in commercial suborbital research," Miller continued. "NASA is going to be an early customer," with other federal agencies, universities and the private industry becoming customers too, he suggested.

Flight rates: still to be proven

Yet to be demonstrated is the hoped-for flight rates of suborbital vehicles. Quick turnaround of these craft is central to realizing the profit-making potential of over-and-over sojourns by piloted and unpiloted vessels to the suborbital heights.

As pointed out in a handout from Masten Space Systems of Mojave, California: "Reusable Launch Vehicles – Just Gas 'Em Up and Go!" The company said it intends to begin precursor flights later this year, flying an unpiloted reusable craft up to 22 miles (36 km) in a beta testing program. The California-based company won $1 million last October in a NASA contest to build reusable rocket-powered craft designed to mimic lunar landers.

From the scientific perspective, for the story to close for science, flight rates have to be high, said Alan Stern, chair of the scientific organizing committee for the conference and associate vice president of the Southwest Research Institute's Space Science and Engineering Division in Boulder.