NASA was created in response to the Space Race in 1958. NASA's most memorable achievement was landing on the moon in 1969. John F. Kennedy said in 1961 to land on the moon by the end of the decade. The funding for NASA between the years 1961 and 69 was $219 billion, adjusted for inflation. From 2000-08, the funding was $144 billion.
NASA effects our everyday lives. Satellites have become a major part of society with the rise of smartphones. If there were no satellites, there were be no phones, gps, weather forecasts, and more.
NASA employs over 18,000 people.
Many of the cons about funding NASA are what-ifs. What if a new microorganism came to earth from a landing shuttle? What if the shuttle explodes? The astronauts know they are taking a risk. Of the 833 crew members that partook in 135 missions, 14 died. That's less than 2%. If a new microorganism exists in space and not on Earth, there's probably a reason for that. Most likely, that organism can't live with the conditions on Earth.
Another main argument against NASA is spending money in other areas that need the money. The US government spent $645.7 billion in 2012 on military alone. That's more than the next 15 countries combined and more than double of the rest of the world. Of those next 15 top spenders, 14 are allies with the US, meaning they will most likely never go to war with us. Talk about unneeded spending.