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NASA expects humans – not robots – to be exploring the surface of Mars within the lifetime of students now walking the CSU campus.
But before it can achieve its goal of landing astronauts on another planet, the agency needs to better understand the physical toll long-distance space travel takes on the human body.
Colorado State University researchers are working on that.
Led by Christian Puttlitz, associate professor of mechanical and biomedical engineering, the CSU team is entering the final year of a three-year, $1.2 million project to study the impact of extended exposure to microgravity on human bone density. The team also includes researchers and students from CSU’s De- partment of Health and Exercise Science and Department of Clinical Sciences.
The goal of the NASA-funded study is threefold: Develop a new ground-based model that simulates bone density loss and can help estimate the risk of fractures in space; determine how bone breaks heal in microgravity; and identify potential in-flight treatments.
Why Study Bone Density?
Space travel, with its increased exposure to radiation, varying oxygen levels and lack of gravity, can have serious effects on the human body.
Microgravity is particularly hard on bones, which are meant to support weight. Bones weaken when they do not bear weight for several weeks – whether it’s due to microgravity or a limb being immobilized in a cast.
Data from extended missions in low gravity show that astronauts can lose 1 percent to 2 percent of bone density a month – or 10 percent to 20 percent a year. (For comparison, women can lose up to 20 percent in the five to seven years following menopause.)
The loss adds up when a mission spans sever- al years. NASA hopes to develop rocket technology that will cut the travel time to Mars to under a year before sending humans on an interplanetary mission.
Bone weakening coupled with high-impact forces humans can encounter in space put them at risk of fractures, according to NASA’s Human Research Roadmap, which identifies research “gaps” that need to be addressed.
NASA has long known astronauts lose bone density while in space. But what the agency hasn’t had is a way to accurately simulate space-related bone loading on Earth, Puttlitz said.
Results So Far
During the first year of the study, Puttlitz and his team built a new computer model that simulated 12 months of space-travel-related bone loss in five to six weeks.
To develop the model, CSU researchers attached a brace – similar to those orthopedic surgeons use to stabilize human bones – to the legs of sheep to keep them from bearing weight, simulating the effects of microgravity. Since sheep’s bone makeup resembles that of humans, the results are expected to be more applicable than past studies, which mostly used rodents.
Results from the study’s second year indicate that microgravity not only reduces bone density but also severely inhibits healing of fractures.
These preliminary results, which were presented at the 2013 NASA Human Research Program Investigator’s Workshop and the 2013 ASME Summer Bioengineering Conference, will be published in the Journal of Biomechanical Engineering early next year.
The study is now in its third year and Puttlitz and his team are focused on potential treatments to aid healing and techniques to overcome the effects of microgravity on human bones. They are looking at pulsed ultrasound and other treatments.
The results could have implications beyond space travel. They could be applied to treating postmenopausal women and bedridden patients who are also at risk of bone density loss.
“There are a lot of potential applications for this beyond helping astronauts in space,” Puttlitz said.