NASA hopes to send humans to Mars by 2030 on a round-trip mission that could take up to three years -- far longer than any human has ever traveled in space. Such long-term spaceflights could adversely affect certain cells in the immune systems of astronauts, according to a new study led by University of Arizona researchers.
"What NASA and other space agencies are concerned about is whether or not the immune system is going to be compromised during very prolonged spaceflight missions," said Richard Simpson, senior author and associate professor of nutritional sciences at the UA. "What clinical risks are there to the astronauts during these missions when they're exposed to things like microgravity, radiation and isolation stress? Could it be catastrophic to the level that the astronaut wouldn't be able to complete the mission?"
Simpson and his team of researchers at the UA, the University of Houston, Louisiana State University and NASA-Johnson Space Center, studied the effects of spaceflights of six months or more on natural killer cells, or NK cells, a type of white blood cell that kills cancerous cells in the body and prevents old viruses from reactivating.
"Cancer is a big risk to astronauts during very prolonged spaceflight missions because of the exposure to radiation," Simpson said. "[NK-cells] are also very important to kill off virally infected cells. When you're in the space station, it's a very sterile environment -- you're not likely to pick up the flu or a rhinovirus or some community-type infection -- but the infections that are a problem are the viruses that are already in your body. These are mostly viruses that cause things like shingles, mononucleosis or cold sores; they stay in your body for the rest of your life, and they do reactivate when you're stressed."
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