All those different potential applications and the “stakeholders” who want them make it difficult to set priorities for using scarce station resources. Since the orbiting lab was completed, those problems have sometimes overshadowed the promise that the station is just beginning to show.

In practice, NASA and the Russian space agency, Roscosmos, keep track separately of how they use their station assets, dividing the six-member crew in half. On NASA's end of the station—home to the European, Japanese and U.S. laboratory modules—the three non-Russian crewmembers spend a collective average of 35 hr. per week on research. The rest of their time is spent on exercise to counter the effects of microgravity on their bodies, as well as station maintenance, operations and housekeeping, sleep and personal time.

“We're at full utilization in terms of certain parameters,” Robinson says. “For example, we're getting the full utilization crew time that the system was designed for, and we're filling that completely and have things on the reserve list and have ready to go if we get a little extra time because of a launch slip or something like that.”

Research has been underway on the station from the beginning, when the first crew arrived in November 2000. As more and more scientific gear was delivered and installed, crew members began using it for experiments when they were not needed for assembly and maintenance tasks. By October 2011, Robinson says, NASA had run 475 investigations on the station, and the partnership as a whole had done 1,251. That number is rising rapidly now that the station is finished, but perhaps not as rapidly as planners had hoped when they promoted the station as an orbiting laboratory for ground-breaking science.

Officially, NASA has three priorities for the space station: 1) meeting its international commitments; 2) conducting research in the life sciences and spacecraft technology that can feed its own goals in human space exploration; and 3) conducting research “in the national interest” using the U.S. National Laboratory organization mandated by Congress in 2005.

A space-station conference in Berlin last month highlighted some of the funding issues and other problems that all of the ISS partners are facing as they move into the utilization phase of their grand joint project (AW&ST May 21, p. 22). But it also highlighted some early research successes in orbit that have significant applications on the ground (see p. 42).

In the U.S., work is picking up on the human-exploration part of the portfolio. With the station in operation, astronauts are spending more time in space, growing the pool of human subjects against which to measure the effects of long-duration exposure to microgravity on the human body. One of them appears to be vision changes in some long-duration crewmembers. Station research has pointed to intracranial hypertension induced by microgravity as a potential cause (AW&ST March 19, p. 26).

Now, additional work on the station suggests there may be a nutritional factor, perhaps involving the dependent one-carbon metabolic pathway that is part of the process the body uses to make DNA. Station crewmembers provide samples of blood and urine that is preserved in the Minus-Eighty-deg. Laboratory Freezer for ISS for eventual analysis on the ground. Work based on those samples, published in the March edition of The Journal of Nutrition, may help screen astronauts who are susceptible to intracranial hypertension in microgravity, or point the way to changes in the ISS cabin atmosphere that could mitigate it. Because intracranial hypertension in the terrestrial population is poorly understood and potentially serious, the space-based studies may have a beneficial application on Earth.

“We clearly have identified a piece of the vision puzzle,” says Scott Smith, a Johnson Space Center nutritionist who co-authored the published paper. “We now need to go another step forward to assess whether it is a small piece among many others, or a large piece that is a primary cause of this problem.”