BOULDER, Colo. — High flight rates, a degree of risk tolerance and demand from researchers and educators will be among the keys to success for several entrepreneurial ventures developing vehicles to carry paying passengers to suborbital space, according to government and industry officials.

These firms have been buoyed by the prospect of a steady stream of NASA funding to fly scientific payloads, perhaps accompanied by NASA astronauts. Speaking Feb. 18 here at the first Next-Generation Suborbital Researchers Conference, NASA Deputy Administrator Lori Garver unveiled the Commercial Reusable Suborbital Research (CRuSR) program, under which the agency proposes to spend $75 million over the next five years to make use of commercial suborbital vehicles.

The funding shows how “serious we are about developing and opening this market,” she said.

Separately, the independent Southwest Research Institute announced Feb. 18 it would allocate $1 million to develop science payloads for commercial suborbital rockets. The program is led by Alan Stern, associate vice president of the institute’s Space Science and Engineering Division in Boulder, Colo.

Suborbital flights to altitudes up to 100 kilometers could serve disciplines including astronomy, life sciences, microgravity physics and studies of a little-known region in the upper atmosphere often dubbed “the ignorosphere.”

“There are no less than five separate firms building suborbital systems,” Stern, who advocated utilizing commercial suborbital services during a stint as NASA associate administrator for space science, said at the meeting. “We’ve never had anything like that in human spaceflight.”

These firms, led in some cases by technology industry pioneers, include Virgin Galactic, Armadillo Aerospace, Blue Origin, Masten Space Systems and XCOR Aerospace.

Texas-based Blue Origin, bankrolled by founder Jeff Bezos, has begun a campaign to survey and select experiments to be taken aloft during its New Shepard flight demonstration program, said Gary Lai, who is responsible for the crew cabin on the planned rocket. The New Shepard vehicle is designed to take off and land vertically and carry three-person crews to suborbital heights.

Stern pegged today’s cost of sounding rockets at $2.5 million a flight.

Commercial suborbital vehicles have the potential to “take that down an order of magnitude to a couple hundred thousand dollars,” Stern said. “Space will be a commodity. It will be easy to access, not hard.”

Critical to getting to that price point is high flight rates.

“It’s the ability to fly a very large number of experiments and experimenters day in and day out,” Stern said. “We don’t think for a minute that the flight rates will go from zero to hundreds in a year. But over the course of this decade … we want them to get to those levels so we can really exploit this new capability.”

Jeff Greason, chief executive of Mojave, Calif.-based XCOR Aerospace, said the industry has strong motivations to fly frequently. “If we don’t have the flight rate, we don’t make money; it’s not optional.”

The emergence of private suborbital space transportation brings with it a measurable degree of risk-taking, said George Nield, associate administrator for commercial space transportation at the Federal Aviation Administration. Nield’s office regulates the commercial suborbital industry.

“Climbing aboard a rocket carries with it the potential for unfavorable results,” Nield said. Nevertheless, America’s space program is at a crossroads, he added, “where we can decide to make change an ordeal … or we can make it a better deal.”

Several NASA speakers said the CRuSR initiative mimics the government-industry-academia partnership of the National Advisory Committee for Aeronautics — the U.S. agency that became NASA in 1958.

“We like that model,” said Charles Miller, senior advisor for commercial space and program executive for CRuSR at NASA. “This is about stimulating an entire new industry. … Some of them will succeed, some of them will fail.”

Daniel Durda, a Southwest Research Institute space scientist, said there is a pent-up demand among space scientists to get “out in the field” the same way other researchers travel to Antarctica or the bottom of the ocean. “It’s the 21st century and it’s high time we get on with it in space as well,” he said.

Leonard David has been reporting on space activities for nearly 50 years. He is the 2010 winner of the prestigious National Space Club Press Award and recently co-authored with Apollo 11’s Buzz Aldrin the book “Mission to Mars — My Vision for Space...