On their third voyage, which began four years ago, the crew size had increased to six, and Dr. Whitson, a trained biochemist, was finally able to spend much of her time as a scientist.
"I've done everything from soybeans to superconducting crystals, but on this last mission I had to do a lot of stem cell and cancer studies as well as bone studies," said Dr. Whitson. "The quality and quantity of the science we did has really improved."
The station is slated to remain in orbit until at least 2024, and Mr. Suffredini is now trying to apply what he has learned to commercial space stations. He is President and CEO of Axiom Space, a Houston company that NASA selected in January to build a commercial module for the International Space Station.
When the current space station is decommissioned, the Axiom module becomes the core of an Axiom space station. "Our entire company is built on the premise that we can do this much more cheaply," said Suffredini.
Nanoracks, Mr. Manber's company, is also developing a concept for a commercial outpost that is robotic and therefore cheaper most of the time. It would also allow for experiments and manufacturing in space that would be too dangerous if humans were around. Astronauts could visit regularly.
Mr Suffredini said the current life path in orbit follows the path of previous exploration of new areas. "Every government exploration in human history, you send out a couple of government-funded people to do something relatively risky just to see what's there," he said.
If there is anything of value, the pioneers follow and eventually the settlers. "In order to reach low-earth orbit," said Suffredini, "we have to get to the pioneering stage, which is what we really do."