1.} how do they know there is water on the moon ?
They know there is frozen water, better known as ice (liquid and gaseous water can't exist in the low gravity and non-existent atmosphere of the Moon), because of visual observations from space but ice wasn't confirmed until the Clementine Program which had a satellite orbit the moon and take detailed pictures of it which confirmed the presence of ice.

2.} who invented NASA?
NASA was formed from several divisions of the government in 1958, partly in response to the development of the Soviet space program. Late in 1957, the Soviets launched Sputnik, the first human object to leave the atmosphere of Earth. NASA wasn't invented by any one person but was created to make a space program that was competitive with the Soviets. Eisenhower was president at this time and was actively involved in seeing that the United States' space and rocket programs were successful. Check out the history section of the NASA website (http://www.nasa.gov) for more information.

3.} why do they call it the moon?
I was unable to find any references to check this but I think the word moon comes from the Greek word for the moon which is Luna (pronounced loona). Over the last 2,000 or 3,000 years, this word has changed with the development of languages (in the 16th century in Britain, Moon was spelled Moone) to the word Moon as we know it today. Other related languages say it differently (luna in spanish, lune in french, lua in portuguese) but you can see how they are related to the original Luna. I'm really not sure how the "l" got changed to an "m" in english but I think it has the same root.

4.} what year did the Astronaute go to the moon and what are their names?
The first astronauts arrived on the moon on July 16, 1969 on the Apollo 11 mission. The first man to step on the moon was Neil Armstrong who was with Edwin "Buzz" Aldrin in the lunar lander. Also part of that mission was Michael Collins who stayed in the command module that orbited the moon.

Just recently, scientists have used radar to detect water on the moon.The radar bounces off of the moon, and it reflects differently when water is present, so they were able to determine that there actually is water on the moon. Actually the moon is very cold, so the water is stored as ice.

NASA was founded on October 1, 1958. NASA stands for the National Aeronautics and Space Administration. This organization was created to replace the National Advisory Committee on Aeronautics. There were a lot of people involved in creating NASA, so it is hard to single out a single person, especially since it was an expanded version of an existing organization. Here's a question for you to research. What event led to the creation of NASA? Hint: It happened on October 4, 1957.

The word moon means "a fairly large object orbiting around a planet." Another word which means the same thing as "moon" is "satellite." We use the word "moon" to describe satellites of other planets. We say: Europa is one of Jupiter's moons. Since Earth only has one moon, I guess that people just started calling it "the moon." Later, when people discovered moons around other planets, they started calling them moons" as well, and also gave them other names.

The first astronauts to walk on the moon were Neil Armstrong and Edwin "Buzz" Aldrin on July 20, 1969. There have been a number of others to walk on the moon and you can find their names and dates in an almanac or encyclopedia. For some space history you can look on the web at:
http://www.foxnews.com/scitech/features/sputnik/index.sml