NASA has let Axiom Space make four visits to the International Space Station and a fifth next year, but on Thursday the agency announced a new private company would be allowed a mission as well.

NASA astronaut Jessica Meir will spend about eight months in orbit aboard the International Space Station studying how microgravity affects the human body.

If humankind is to explore deep space, one small passenger should not be left behind: microbes. In fact, it would be impossible to leave them behind, since they live on and in our bodies, surfaces and food.