Some useful facts about the manned space program:
In terms of cost spent versus value returned to the public, NASA is the most efficient government agency. The technology developed for the manned space program has led to advanced health-care devices (such as CAT scanners, or Doppler ultrasound stethoscopes), which have saved many lives. The drive to miniaturize electronic components for the space program has given way to the computer revolution, and the technology that has come from the manned space program has helped the United States become the world leader in high technology. And yet the total yearly budget for NASA works out to be only pennies per citizen per day--less than what is spent on alcohol and cigarettes.
It is impossible to survive with only an unmanned space program. There are only a limited number of "orbits"--places where satellites may be placed about the earth. Any more weather satellites--working or not--and the congestion will cause collisions that may destroy our ability to forecast the hurricane and flash flood warnings that save countless lives each year. So, with only a limited number of orbits, we must have some method of retrieving and repairing worn out satellites--we cannot simply launch more as we need them. And unmanned robots are too clumsy to execute the complex maneuvers which the space shuttle had to perform to fix a satellite in space.