Astronauts fly the craft and participate in experiments. They provide what is commonly called "human intelligence" regarding the outcome of these experiments.
Because astronauts used them to observed objects in the sky.
The answer is an umbilical cord. It keeps astronauts from floating out into the universe.
All the astronauts used by N.A.s.A have walked on the surface of the earth.
it is used to take astronauts and cargo into space
space shuttle
lunar rover
Oxygen (O2).
Practice and lots of trips.
atrophy
doctors
A cosmonaut would come from Russia. The term "cosmonaut" is used specifically for Russian astronauts, while "astronaut" is used for astronauts from other countries.
There have been around 350 male astronauts who have been to space. The number can vary depending on the selection criteria used.