We are still learning about the potential effect that long periods of time in space could have on the human body. A new health threat has now been identified that could put life at risk on long journeys across space.
The problem lies in the internal jugular vein (IJV), the major blood vessel flowing around the neck of the brain. A study of 11 astronauts who spent time at the International Space Station (ISS) found that six of them developed stagnant or backward blood flow in that particular vein within just 50 days.
One crew member was found to have developed thrombosis or obstruction of the internal jugular vein, the first time this was recorded as a result of a space flight.
According to the team behind the new discoveries, this problem must be investigated before we start sending astronauts on long trips to Mars. It is not yet clear what the consequences of this type of thrombosis may be, but the consequences can be severe and perhaps even fatal.
"Exposure to a non-gravity environment during space flight results in a chronic change of fluid in the blood and tissues compared to the upright posture on Earth, with unknown consequences for cerebral venous outflow," the researchers wrote in their published paper.
] Here on Earth, of course, gravity takes care of the work of extracting blood from the head to the rest of the body ̵
Up in the mix The ISS's gravitational environment is a different story – and blood flow problems are not the only health risks to worry about.
"Moving fluid to the head during prolonged weightlessness causes a swollen face, reduced leg volume, increased stroke volume and decreased plasma volume, "the researchers wrote.
Medical experts used readings and images collected aboard the ISS to identify a potential problem with the IJV while the astronaut who developed the occlusive tr MB, treated with anticoagulants for the remainder of the mission (identity of astronauts retained for confidentiality reasons)
More research is needed to determine how big the problem really is and how we could mitigate it in future space flights ; but the large number of astronauts who have developed some kind of blood flow problem is worrying.
We already know that time in space can reduce bone density, change the makeup of our intestines and drain our brains. At least we are working to detect these effects before we try to get further than the moon, so we have a better chance of developing potential solutions.
"[These] are new discoveries that can have significant human health implications for civilian space flight as well as future exploration missions, such as a mission to Mars," the researchers conclude.
The study was published in the JAMA Network Open .