WASHINGTON — An astronaut told U.S. lawmakers July 25 that the greatest impediment to research and science aboard the international space station (ISS) is the limited amount of time crew members can devote to these pursuits.

“Currently, I believe the great limiting resource for doing scientific research on station is the availability of crew time,” astronaut Donald Pettit said at a hearing of the Senate Commerce, Science and Transportation science and space subcommittee. “We have more scientific apparatus on space station, more equipment waiting to be used, more science experiments in the queue than we have crew time in the [U.S. segment] with three crew members that we can spend working on this.”

Pettit, who returned July 1 from a six-month expedition to ISS, said that crew members typically work 13- or 14-hour days on orbit. They can spare about six-and-a-half of those hours for “mission programs,” which might include either government or nongovernment research. The rest of the time, the crew is doing maintenance work “just to keep the machinery going and keep it possible for human beings to be there,” Pettit said.

ISS can support a six-person crew. With the retirement of the U.S. space shuttle fleet, crew members arrive three at a time aboard Russian Soyuz capsules and typically stay for six months. If there are logistical constraints, as there were last year when a Russian cargo freighter bound for ISS crashed due to a launch vehicle failure, the station operates with a three-person skeleton crew. NASA’s top human spaceflight official, William Gerstenmaier, has said ISS could expand to seven-person crews if the agency’s plan to spur development of privately operated space taxis is successful. NASA’s Commercial Crew Program targets a 2017 start date for private flights, but the agency says insufficient funding threatens that date.

Moreover, the total time available for ISS research depends upon how long the outpost stays in space. The official end-of-life is 2020, but Congress could approve an extension. Sen. Kay Bailey Hutchison (R-Texas), a longtime advocate for space station research, asked Gerstenmaier whether that could be done safely.

“We’re looking technically to make sure that there’s not any problems extending space station,” Gerstenmaier replied. “We think from a physical standpoint, station could be operable probably to 2028.”

Gerstenmaier urged a continued focus on station utilization, suggesting there might be more interest in continuing ISS operations if NASA can demonstrate a return on the government’s investment so far.

“I think it’s important at this point to focus … on utilizing the station and showing some benefit and return back,” Gerstenmaier said. “If we can do that, in the next couple of years, then I think the discussion about ‘Do we continue beyond 2020?’ becomes a little bit of an easier discussion.”

NASA estimates it will end up pitching in about half of the station’s estimated $100 billion lifecycle cost. To justify the great expense for the only human presence in space, lawmakers have pushed NASA to utilize the space station as a research platform for improving life on Earth. In 2005, through legislation introduced by Hutchinson, Congress designated the U.S. segment of ISS a National Laboratory. In 2010, again at Hutchison’s insistence, Congress ordered NASA to set aside half the ISS National Lab’s capacity for nonagency science. It further ordered NASA to pick a nonprofit organization to manage these projects.

A Florida-based organization, the Center for the Advancement of Science in Space (CASIS), was selected for that role in 2011. The group is planning to send its first payload into space in 2013 and, in the meantime, is trying to get the private sector interested in ISS-based research.

CASIS is particularly interested in biomedical experiments, specifically those targeting osteoporosis, a degenerative bone disease, and the human immune system. The station’s microgravity environment makes ISS well suited for such research, said James Royston, interim executive director of CASIS.

“We can be the organization that allows [potential users] to think of the [ISS] lab as just another lab,” Royston told lawmakers at the July 25 hearing. “You don’t have to worry about rockets, and all kinds of different paperwork and science advisory panels, and everything else. We’re there to do that for you.”

CASIS has not identified which companies want to do ISS-based research, but it says several have expressed interest.

Meanwhile, CASIS is still trying to patch up a lingering controversy that in March led the group’s first executive director, space scientist Jeanne Becker, to resign.

The proposal that led to the establishment of CASIS was sponsored by, among others, Boeing Co.; Space Florida, that state’s aerospace economic development corporation; and a Malvern, Pa., company called ProOrbis. Prior to the competition to select an ISS National Lab manager, ProOrbis provided NASA with a blueprint for a “national lab management entity.” ProOrbis and others then used this blueprint as the basis for CASIS, which ProOrbis planned to serve as a consultant.

CASIS’ interim board of directors, led by Space Florida President Frank DiBello, maintain that there is nothing improper about ProOrbis’ helping to craft the CASIS proposal, or collecting revenue as a consultant for the nonprofit.

In written testimony published July 25, Royston said, “[T]he Interim Board has identified the first group of permanent Board of Directors candidates, all of whom represent the best American minds in the fields of scientific research and management from academia, government, and industry.” Royston did not say when the permanent board will be established, or how long it will take to appoint an executive director.

It cannot be soon enough for Hutchison, who told Royston she is “anxiously awaiting the appointment of the board so we can see CASIS get up and go and start showing results.”

Dan Leone is a SpaceNews staff writer, covering NASA, NOAA and a growing number of entrepreneurial space companies. He earned a bachelor’s degree in public communications from the American University in Washington.