They don't: They screw in a vacuum.
That's impossible, because they can't climb the ladder.
Relatively few
One. They hold it in place and wait for the world to revolve around them.
Twenty. 1 to drop it, 19 to go "Pick it up, pick it up, pick it up".
An Astronaut
Because he was spaced out.
Because he was scared of vacuums!
Nothing.