"Study hard, stay in school and dream big." That is what astronaut Charles Walker told students at Mayflower Mill Elementary School. Walker is in Indiana to participate in the Purdue University astronaut reunion.

Students from kindergarten through fifth grade filled the gymnasium to hear about Walker's adventures. He told the students he flew with NASAS's astronauts onboard three Space Shuttle flights in the 1980s. As an industrial payload specialist, his work included zero-gravity purification of biomedical proteins and cells. 

Walker told the students to think of Earth as their spaceship and they should consider their family, school, community and others as crew members. "We need to work together as a team," says Walker. 

After his presentation, Walker fielded several questions ranging from life in space to travel to other planets. Walker described zero gravity as "freedom." He also said it was like being a superhero being able to fly from one part of the ship to the other. He told the students that it is possible that astronauts will travel to Mars in the next 10 to 20 years.