The Weight of Gravity in Medical Research

by Jad Hilal

For those not involved in astrophysics, astronomy or engineering, the concepts and breakthroughs of the Space Age may not be much to get excited about. Now, however, as technologies of space exploration have become more extensive, the vast complexity of outer space has begun to pique the interest of other fields, including medical research.

Space exploration and medical research first intersected when astronauts began reporting a unique set of symptoms after long trips to space despite rigorous pre-flight training and preparations. The absence of gravity prevents the human body from properly orienting itself. This has proved to impact the functioning of many basic biological processes and has led to a deeper understanding of how diseases dealing with bone density are actually influenced by weight.

The International Space Station (ISS), the leading laboratory in space research, studies the impact of gravity on one’s well being. Within the ISS, research can be conducted under the exact conditions present in space. According to the National Institute of Health, ISS research determined how and why zero gravity caused a loss of bone and muscle mass in astronauts.  A study regarding the bone densities of crewmembers aboard Skylab, one of NASA’s earlier orbiting research facilities determined that by day 84 of spaceflight, a negative calcium balance of -300 mg/day was evident in the spine, femur, neck, trochanter and pelvis. In addition, there was a significant loss of bone mineral density (BMD). This condition is called Spaceflight osteopenia.

Both calcium deficiencies and bone mineral density are restored upon returning to Earth’s atmosphere. This phenomenon occurs because the body maintains bone density in response to stress. Thus, in a zero gravity environment or an environment such as Mars in which the gravity is approximately one-third of that on Earth, such stress is not customary. As a result, the researchers aboard the Skylab experienced a 1-2 percent decrease in BMD per month in space.

What researchers have found has expanded beyond astronaut health. According to Stephen I. Katz, M.D. Ph.D., director of the National Institute of Arthritis, Musculoskeletal and Skin Diseases (NIAMS) and National Institute of Health Liaison for NASA, “there are many new frontiers and considerable new knowledge that medical researchers can gain from using the space station.” Results of research in zero gravity atmospheres have helped shed light on how patients on Earth suffering from delicate bones or muscle-wasting diseases may be treated. In fact, research in non-gravity environments has informed research on diseases such as osteoporosis, which is quite similar to Spaceflight osteopenia but affects patients who have never set foot outside Earth’s atmosphere.  

Spaceflight research can expedite our understanding of biological conditions associated with gravity. It can also provide knowledge on diseases that affect individuals who haven’t been exposed to low gravity environments. As the ISS continues to uncover potential sources of disease, it is time we start looking deeper into not just what space is to us, but also what it can do for us.