Traveling to space is certainly one of those ideas that cross every child’s head at some point. There is no greater feat than leaving the safety of planet Earth to explore the colossal vastness of the sky. However, it is not a simple journey. Only a few humans in our species’ history have journeyed to outer space and confronted the perilous threats that the dark void holds. According to one study, the extended stay of the human anatomy in outer space causes anemia because, for reasons unknown to scientists, red blood cells exhibit a deadly self-destructive tendency.

The dangers of outer space

Some of the obstacles experienced by astronauts going into space include vacuum, radiation, extreme cold, weightlessness, unanticipated impacts with particles traveling at great speeds, and isolation due to confinement in cramped space modules.

NASA’s Human Research Program has spent decades studying how the human body behaves in space. To accomplish this, it has tracked the biological activity of astronauts who have visited space for short, medium, and extended periods of time, such as those who live on the International Space Station for months. The program’s goal is to better understand the physiology and psychology of life in space in order to improve the quality of the astronauts’ experience and plan future manned trips to the Moon and Mars that emphasize contextual variables.

These factors include the distance from Earth (and thus the infrastructure required in the event of a medical emergency); prolonged exposure to radiation; the risk of developing behavioral disorders due to social isolation; and the effects of microgravity on bone and muscle tissue and organ function.

Added to all these concerns is a documented effect on astronauts: space anemia.

Space anemia

Guy Trudel is a medical physics scientist and co-author of an article published in Hematology that details the examination of 17,336 astronaut hemoglobin readings gathered during 721 space flights. He explains in a press release that space anemia is a common effect on space travelers. In response to the weightless environment, your body loses 10 percent of the fluid in your blood vessels. As a result, 10 percent of red blood cells are expected to be destroyed in order to preserve homeostatic balance. However, the findings of Trudel and his team astounded them: half of the astronauts returning from extended missions (5 months on average) displayed indications of a type of anemia in which red blood cells were destroyed at a rate greater than 50 percent of what was expected.

This is not a concern in a weightless environment because the decrease in fluid in the blood compensates for the depletion of red blood cells. Trudel and his colleagues observed that when astronauts returned to Earth, their bodies, unsurprisingly, recovered fluid. But even so, their blood continued to destroy red blood cells at the same rate as in space, causing space anemia.

Trudel examined five of the 13 astronauts he monitored throughout their stay on the ISS a year after they came back and found that their red blood cells continued to be destroyed at a rate 30 percent greater than acceptable. Researchers continue to study this phenomenon in search of its cause.

A stone on the road?

Spatial anemia could originate from the bone marrow or spleen, Trudel told ARSTechnica. “It’s the hemolysis that causes the anemia, but it’s the next step that causes the hemolysis,” he said.

For the experts, there is a clear relationship between the intensity of the syndrome and the time the astronaut spends in space. That is why they continue to investigate its cause. The era of human space conquest has begun, and the Artemis I mission is concrete proof of this. We need to understand these stones to get them out of the way. The challenges for sending manned missions to inhabit the Moon and Mars are varied and far from trivial: it is still necessary to study the effects of radiation on the female body, find a mechanism that prevents or mitigates space anemia, and reduce isolation time of astronauts by developing thrusters that significantly shorten travel time.

Our crusade through the skies has just begun. What a wonderful time to be alive.