Studies recently concluded on astronauts who have flown long-term missions that could point to serious problems with prolonged exposure to microgravity. This adds to the list of physical concerns NASA is addressing when considering long-term space travel.
Astronauts who had flown Shuttle or ISS missions anywhere up to 108 days came back reporting changes in eyesight — some worse, some better.
MRIs completed in the astronauts showed surprising results. Over a sampling of 27 astronauts who had flown long-term, they had a mix of problems ranging from deformities in their eyeballs and swelling of the optic nerves to changes in the pituitary glands.
These conditions mimic symptoms caused by a rare problem called intracranial hypertension, where pressure inside the skull rises and presses on the brain and eyes. For those astronauts who were already near-sighted, the pressure or flattening of the eyeballs actually corrected their vision. For others they weren't so lucky.
A sampling of the group showed the flattening of the eyes created vision problems. Others had swelling of the optic nerve, which left unchecked could cause permanent damage. Even more compelling was the fact that the issues seem to get worse and more frequent the longer the stay in space was.
Doctors from the University of Texas Health Sciences Center in Houston, led by Dr. Larry Kramer performed the study and published their results in the journal Radiology.
In a press release Kramer notes: "Microgravity-induced intracranial hypertension represents a hypothetical risk factor and a potential limitation to long-duration space travel." His hope is that by studying the problem now we can better understand just what causes it. By assessing the cause and risks, then scientists can determine whether the condition could be avoided or at best, treated.
These new findings are added to the list of problems that NASA medical teams have been aware of for some time — bone loss and muscle shrinkage have been well documented.
And while NASA has not pulled any astronaut out of rotation due to these findings, it is taking a cautious approach. The space agency knows there are many physical issues that will need to be studied further before understanding how to deal with long-term space travel.
William J. Tarver, M.D., M.P.H., chief of flight medicine clinic at NASA/Johnson Space Center, noted in a press release: "NASA has placed this problem high on its list of human risks, has initiated a comprehensive program to study its mechanisms and implications, and will continue to closely monitor the situation."
Fortunately, astronauts from Europe, Russia, Japan and Canada will also be studied before and after flight missions so the research will be ongoing as we dream of missions to Mars and beyond.