NASA and its international partners have announced an agreement to send two crew members to the International Space Station on a one-year mission designed to collect valuable scientific data needed to send humans to new destinations in the solar system.

The crew members, one American astronaut and one Russian cosmonaut, will launch and land in a Russian Soyuz spacecraft and are scheduled to begin their voyage in spring 2015.

The space station serves as a laboratory for technological demonstrations and scientific research, including experiments that improve understanding of how the human body reacts and adapts to the harsh environment of space.

Data from a year-long expedition also will help inform assumptions about crew performance and health, and will help reduce the risks associated with future exploration.

"In order for us to eventually move beyond low Earth orbit, we need to better understand how humans adapt to long-term spaceflight," said Michael Suffredini, International Space Station program manager.

"The space station serves as a vital scientific resource for teaching us those lessons, and this yearlong expedition aboard the complex will help us move closer to those journeys."

During the 12 years of permanent human presence aboard the space station, scientists and researchers have gained valuable, and often surprising, data on the effects of microgravity on bone density, muscle mass, strength, vision and other aspects of human physiology. This year-long stay will allow for greater analysis of these effects and trends.

"We have gained new knowledge about the effects of spaceflight on the human body from the scientific research conducted on the space station, and it is the perfect time to test a one-year expedition aboard the orbital laboratory," said Julie Robinson, NASA's program scientist for the International Space Station.

"What we will gain from this expedition will influence the way we structure our human research plans in the future."

The expedition also will serve as a test bed for future exploration technologies. Those innovative technologies, the logistics of the trip to and from the space station and the selection of the crew will be announced at a future time.