No, they don't. There is so many (beyond numbers) galaxies that it is impossible to know everything.
Sally is a smart space scientists you know !
Scientists don't know everything, nor do they claim to know everything.There's a lot of compelling evidence to suggest that the dinosaurs were killed of by a massive meteorite impact.
It helps scientists know how much of what is needed to make for example the fuel or how much of gases they need to give the astronauts oxygen.
Black holes
because they know it and they went into space
scientists use spacecraft without people to explore space because scientists need to know more about space and the solar system
They are smart and know everything
yes
If has been proven by many scientists.
because everything is consider chemicals
Everything that you can think of about space (that is factual) is what humans know about space. Humans are the only reason we know space contains planets, stars, and moons.
they know everything