NASA is especially concerned with how a lack of gravity and increased space radiation could hurt explorers on the way to the moon or Mars. On Earth, we are protected from most forms of radiation due to the atmosphere; in space, explorers in low-Earth orbit still get a little less radiation than in deep space due to Earth’s magnetic field, which deflects some radiation from space. But on the way to Mars, that’s not the case.
Norsk said that doctors still don’t understand how radiation can affect astronaut bone and muscle. It’s hard to simulate deep-space radiation on Earth, and we only sent a handful of astronauts to the moon back in the 1960s and 1970s.
5. Space attacks our immune system
One of the things that hurts astronauts in space is the loss of a regular “day” in space. The sun rises and sets 16 times in 24 hours aboard the ISS, because astronauts hurtle around the Earth once every 90 minutes. While crews do as much as possible to keep their bodies to a schedule – like eating at regular times and having firm sleep periods – it’s pretty difficult to fool the brain when light and dark keeps changing outside the window.
Right now, doctors are trying to better firm up the circadian cycle by improving sleep for astronauts, which means reducing noise, making their schedules less stressful in the evening so that they can wind down, and taking other measures.
“In-flight sleep is important,” says NASA immunologist Brian Crucian. “It can affect the immune system.”
The doctors also look closely at studies of crews working in isolated, confined environments such as Antarctica to get more ideas about how to improve human immune systems in space. Doctors have been looking at circadian disruptions for years using the saliva of crews that are staying over winter. In more recent years, as technology improved, they’ve been having the crews analyze their samples on site to deliver the science more quickly.
Doctors are still characterizing exactly how circadian problems affect Antarctic explorers, but the hope is in future years they’ll be able to implement countermeasures to help both the crews on Earth and the crews in space.