When the end came, years of work meant little beside the loss of seven lives.  After the space shuttle Columbia broke apart upon reentry Feb. 1, Kimberly O’Brien set aside worries about her own research to join the nation in mourning the seven astronauts who perished. “It was really a tragedy,” says O’Brien, PhD, International Health associate professor.
O’Brien served as a co-investigator for an experiment carried out by the astronauts on the Columbia STS-107 mission. The study sought to explain why and how space flight leads to bone loss in astronauts by tracking the movement of calcium in the body—a process called calcium kinetics. “Many people think bones are static; that’s very inaccurate,” says O’Brien, a researcher at the School’s Center for Human Nutrition. “Bone is an incredibly dynamic tissue.” If the human body is immobilized for a long time (as in the case of a spinal cord injury), up to 40 percent of bone mass can be lost within During weightlessness, the bones release calcium and the body decreases absorption of the mineral, causing a net bone loss that averages 1.5 percent per month. The Columbia study was designed to gather data on the phenomenon and discover factors that predict susceptibility to bone loss. O’Brien has collaborated with NASA for six years. In one experiment aboard Russia’s Mir space station, two cosmonauts and an astronaut participated in a calcium study similar to Columbia’s. Data from that study will be published later this year. It’s too soon to talk about future experiments in space, according to O’Brien. “We really need to wait for results from the committees studying why this accident happened before anyone can really say what’s going to happen next,” she says.
—Brian W. Simpson PHOTO: Space Shuttle Columbia’s final flight (Photo: NASA) | 
