Like countless entrepreneurial couples, Jane Poynter and Taber MacCallum started their business from home. It was 1993, and home was Biosphere 2, the 3.14-acre terrarium in which researchers spent two years testing self-sustaining ecosystems.

Six months before leaving the dome, Poynter and MacCallum started worrying about their second act. "Astronauts and others who have had seminal experiences tend to implode afterward if they don't have a plan," says Poynter. "There has been alcoholism. Suicide. We started a business so we would have something to throw ourselves into after this extraordinary, life-changing experience."

As to what the business would do, they weren't exactly sure. But their singular circumstances and events in the outside world provided an indication. Having shared close quarters with Biosphere's engineers, biologists, and ecologists, the pair was intimately familiar with the conflicts that prevented collaboration among those professionals. Meanwhile, plans for an international space station had just been announced. Poynter and MacCallum pondered creating a company that would bring together engineers and biologists, for whom they would act as cultural translators.

Sealed off from the world, Poynter and MacCallum had their attorney incorporate the business, which they named Paragon Space Development. They also acquired a business partner, an aerospace engineer named Grant Anderson, whom they encountered in a space-related group on Usenet, an early online forum. "We became partners with someone we'd never met in real life," says Poynter. They even attended their first trade show -- the Small Satellite Conference -- via videophone while still inside the dome.

Outside the Biosphere at last, Poynter and MacCallum relied on student loans and credit cards to stay afloat. The University of Arizona let them use labs and green- houses for free. The Biospherians were popular on the lecture circuit, which helped pay living expenses. Their experience designing air, water, and agricultural systems inside the dome attracted consulting contracts, amounting to several hundred thousand dollars.

Poynter and MacCallum, who married in 1994, had been experimenting all along with small ecosystems -- using $2 glass light covers to build miniature Biospheres capable of sustaining aquatic plants, snails, and shrimp with nothing but light and warmth. In 1995, NASA began sending flights to the Mir space station. It was a rare U.S. opportunity for long-duration space biology experiments. "We gave one sphere to a friend as a wedding present," says Poynter. "Someone from NASA saw it and said, 'Oh, my goodness! This is exactly what we need to fly to Mir!' "

JAXA, the Japan Aerospace Exploration Agency, wanted to observe simple aquatic animals undergoing entire life cycles in microgravity. NASA agreed to fund the flight, and JAXA provided Paragon with the use of expensive communications equipment. Paragon's spheres took a test flight on the shuttle, followed by two flights to Mir. Entire issues of scientific journals were dedicated to the experiments.

Paragon has since parlayed that fame into contracts with NASA, other government agencies, and industry. Many involve life-support and thermal control systems for spacecraft, diving suits, and other enclosed units. "At first, we wasted a lot of time just shotgunning around, saying, 'We have this passion for space,' " says MacCallum. "Maybe we had to do that to understand what our niche really was."

Company Dashboard: Paragon Space Development

Founders Jane Poynter, 47; Taber MacCallum, 44; Grant Anderson, 46

Location Tucson

2008 Revenue $8 million

Employees 65 Start-up Year 1993 Funding $75,000 in savings, student loans, and credit card debt

Start-up Costs A few thousand dollars for glass globes; $30,000 for computers and lab equipment; $600 a month for lab and office space

Breakeven Five years out on sales of $800,000

Biggest expense About $20,000 a year for travel

Qualifications Poynter is a biologist, MacCallum a chemist, and Anderson an engineer.

Red Tape Each space agency has its own safety requirements.