Astronaut Karen Nyberg of NASA uses a fundoscope. Photo: NASA

Humanity is planning its forays out to reach Mars over the next few decades. Such trips would have to traverse an average 140 million miles of vacuum, and take about three years, roundtrip. But the health effects of space are only becoming better understood now.

Cancer risks could be seriously increased by the exposure to radiation out in the void, according to a new study published in the journal Leukemia.

Wake Forest Baptist Medical Center researchers found a double-whammy effect: the radiation not only caused mutations in key cells, but also weakened immune response – meaning the body would not be able to rid itself of the malignant cells. 

“Our results are troubling because they show radiation exposure could potentially increase the risk of leukemia in two ways,” said Christopher Porada, associate professor of regenerative medicine, and the senior Wake Forest researcher.

The human hematopoietic stem cells (HSCs) from healthy people of astronaut age were exposed to solar energetic particles and galactic cosmic ray radiation. The HSCs were placed in both in vitro and in vivo (mouse) models. The experiments were conducted at the NASA Space Radiation Laboratory at Brookhaven National Laboratory.

The cells and mice were then shipped to Wake Forest for assessing the damage done.

The HSCs are a small minority of bone marrow cells (less than 0.1 percent), but they are a vital link in making cells crucial to fighting infections and transporting oxygen, the Wake Forest team explains.

The radiation essentially shut them down, reducing their ability to produce blood cells by as much as 80 percent.

The mice developed what the scientists believe to be T-cell acute lymphoblastic leukemia, they report.

“We found that genetic damage to HSCs directly led to leukemia,” Porada said. “Secondly, radiation also altered the ability of HSCs to generate T and B cells, types of white blood cells involved in fighting foreign ‘invaders’ like infections or tumor cells. This may reduce the ability of the astronaut’s immune system to eliminate malignant cells that arise as a result of radiation-induced mutations.”

“Appropriate physical and biomedical countermeasures” need to be developed prior to traveling major space distances, they conclude.

The work was part of the NASA’s Human Research Program to catalogue the effects of space on humans, who have not evolved to deal with space conditions like weightlessness. Previous research has shown that certain effects on the neurological system may even cause “space madness” if the conditions last long enough.