Btw, I found something else wrong with this nature article:
"Those who travel beyond Earth's protective magnetic field are bombarded by cosmic rays - energetic particles left over from the Big Bang. Rats exposed to a lab equivalent are less motivated and able to learn. As missions lengthen, astronauts may face similar problems."

The Big Bang as far as I know has nothing to do with cosmic rays, but rather cosmic rays have to do with things like catastrophe events such as stars exploding and "normal" emission of billion of billion of billions of a wide variety of stellar objects that make up our universe.

You're right. The editor is obviously confused with the cosmic microwave background which is NOT a health concern for astronauts.