HOUSTON — Waves of rodents and fruit flies will soon join the astronauts, plants, microbes and robots that populate the International Space Station, as NASA steps up efforts aboard the six-person orbiting lab to meet the life science challenges of deep-space missions spelled out by the National Research Council (NRC).

The NRC’s priority-setting decadal survey, "Recapturing a Future for Space Exploration: Life and Physical Sciences Research in a New Era," prompted a fresh look at a range of ISS facilities available to researchers in the two broad fields, according to top space agency scientists.

"Veggie," one of the first responses, is a prototype plant growth chamber launched in April aboard the third SpaceX commercial re-supply mission to the ISS. Veggie has kicked off studies to determine if astronauts on long, deep-space missions can improve their nutrition by growing lettuce and other fresh foods. Pre-packaged vitamins and other supplements degrade with exposure to space radiation.

Twenty mice are manifested for the next SpaceX cargo delivery tentatively set for launch in the August/September time frame along with an upgrade to the animal enclosure modules once used to house rodents for one to two weeks aboard the now-retired space shuttle. The upgraded enclosures are another response to the 2011 NRC assessment.

Longer-term rodent studies are considered an essential part of predicting how humans will respond over missions that could span years. After months of weightlessness in transit to Mars, for example, the bones and muscles of astronauts must be healthy enough to re-encounter gravity, don heavy spacesuits and lug tools.

"One of the first things we did once NASA received the decadal survey was look through all the recommendations and some of the priority approaches," Julie Robinson, the agency’s chief ISS program scientist, told a recent ISS Science Forum at Johnson Space Center. "We identified new facilities we needed. One was facilities for flying mice and eventually rats on the station. We needed changes, especially to make it possible to allow studies for longer periods of time."

If the late-summer SpaceX ISS rodent delivery is successful, NASA plans to include up to 40 mice and eventually rats on future cargo deliveries. Station astronauts, meanwhile, are receiving training in the euthanization and dissection of the small mammals as well as the preservation of their tissues for return to Earth for study, Robinson says.

The rodent test subjects will be shared among peer-reviewed investigations selected by NASA as well as by the Center for the Advancement of Science in Space (Casis). Casis is the nonprofit established by the space agency to facilitate research in the National Laboratory wing of the station by scientists from the private sector, academia and other government agencies. Pharmaceutical companies are expected to be among the rodent studies sponsored by Casis.

"We will start fairly small so we are sure we have good animal husbandry, good characteristics in how we take care of the animals," Robinson said.

Fruit fly studies are also rising in prominence as researchers look deeper into the genetic consequences of spaceflight, especially as they affect health, Marshall Porterfield, NASA’s director of Space Life and Physical Sciences, told the forum.

"Fruit flies are an important biomedical model system," Porterfield said. "Out of the 900 documented genes known to be associated with human disease, about 700 are documented in fruit flies. You can grow them over multiple lifetimes and get a lot of valuable data."

The NRC assessment focused on fundamental physical and life science challenges faced by humans as they attempt to travel greater distances from Earth in confined engineered environments and how they translate into mission designs, said Elizabeth Cantwell, a Lawrence Livermore National Laboratory director of mission development who co-chaired the 400-p. NRC study.

"I think everyone knows there are some pretty grand challenges in taking the next steps to get a lot further away with humans," Cantwelll told the forum. "We need a science portfolio that begins now to get there."