
Space Radiation Doesn't Seem to Be Causing Astronauts to Die from Cancer, Study Finds
That may be true for the short missions astronauts have gone on so far. But Mars will be a different story.
Inside your body there’s a bustling highway with your beating heart at the center. Learn all about your body’s 60,000 miles of microscopic blood vessels, 5 to 6 quarts of blood, and the sundry passengers (lymph, blood cells, nutrients and more) that ride it every day.
Related Topics: Respiratory System, Immune System, Lymphatic System, Nervous System